merge(third_party/git): Merge squashed git subtree at v2.23.0 r/373

Merge commit '1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5' as 'third_party/git'

1 files changed, 2543 insertions, 0 deletions

diff --git a/third_party/git/compat/mingw.c b/third_party/git/compat/mingw.c
new file mode 100644
index 000000000000..738f0a826a51
--- /dev/null
+++ b/third_party/git/compat/mingw.c
@@ -0,0 +1,2543 @@
+#include "../git-compat-util.h"
+#include "win32.h"
+#include <conio.h>
+#include <wchar.h>
+#include "../strbuf.h"
+#include "../run-command.h"
+#include "../cache.h"
+#include "win32/lazyload.h"
+#include "../config.h"
+#include "dir.h"
+
+#define HCAST(type, handle) ((type)(intptr_t)handle)
+
+static const int delay[] = { 0, 1, 10, 20, 40 };
+
+int err_win_to_posix(DWORD winerr)
+{
+	int error = ENOSYS;
+	switch(winerr) {
+	case ERROR_ACCESS_DENIED: error = EACCES; break;
+	case ERROR_ACCOUNT_DISABLED: error = EACCES; break;
+	case ERROR_ACCOUNT_RESTRICTION: error = EACCES; break;
+	case ERROR_ALREADY_ASSIGNED: error = EBUSY; break;
+	case ERROR_ALREADY_EXISTS: error = EEXIST; break;
+	case ERROR_ARITHMETIC_OVERFLOW: error = ERANGE; break;
+	case ERROR_BAD_COMMAND: error = EIO; break;
+	case ERROR_BAD_DEVICE: error = ENODEV; break;
+	case ERROR_BAD_DRIVER_LEVEL: error = ENXIO; break;
+	case ERROR_BAD_EXE_FORMAT: error = ENOEXEC; break;
+	case ERROR_BAD_FORMAT: error = ENOEXEC; break;
+	case ERROR_BAD_LENGTH: error = EINVAL; break;
+	case ERROR_BAD_PATHNAME: error = ENOENT; break;
+	case ERROR_BAD_PIPE: error = EPIPE; break;
+	case ERROR_BAD_UNIT: error = ENODEV; break;
+	case ERROR_BAD_USERNAME: error = EINVAL; break;
+	case ERROR_BROKEN_PIPE: error = EPIPE; break;
+	case ERROR_BUFFER_OVERFLOW: error = ENAMETOOLONG; break;
+	case ERROR_BUSY: error = EBUSY; break;
+	case ERROR_BUSY_DRIVE: error = EBUSY; break;
+	case ERROR_CALL_NOT_IMPLEMENTED: error = ENOSYS; break;
+	case ERROR_CANNOT_MAKE: error = EACCES; break;
+	case ERROR_CANTOPEN: error = EIO; break;
+	case ERROR_CANTREAD: error = EIO; break;
+	case ERROR_CANTWRITE: error = EIO; break;
+	case ERROR_CRC: error = EIO; break;
+	case ERROR_CURRENT_DIRECTORY: error = EACCES; break;
+	case ERROR_DEVICE_IN_USE: error = EBUSY; break;
+	case ERROR_DEV_NOT_EXIST: error = ENODEV; break;
+	case ERROR_DIRECTORY: error = EINVAL; break;
+	case ERROR_DIR_NOT_EMPTY: error = ENOTEMPTY; break;
+	case ERROR_DISK_CHANGE: error = EIO; break;
+	case ERROR_DISK_FULL: error = ENOSPC; break;
+	case ERROR_DRIVE_LOCKED: error = EBUSY; break;
+	case ERROR_ENVVAR_NOT_FOUND: error = EINVAL; break;
+	case ERROR_EXE_MARKED_INVALID: error = ENOEXEC; break;
+	case ERROR_FILENAME_EXCED_RANGE: error = ENAMETOOLONG; break;
+	case ERROR_FILE_EXISTS: error = EEXIST; break;
+	case ERROR_FILE_INVALID: error = ENODEV; break;
+	case ERROR_FILE_NOT_FOUND: error = ENOENT; break;
+	case ERROR_GEN_FAILURE: error = EIO; break;
+	case ERROR_HANDLE_DISK_FULL: error = ENOSPC; break;
+	case ERROR_INSUFFICIENT_BUFFER: error = ENOMEM; break;
+	case ERROR_INVALID_ACCESS: error = EACCES; break;
+	case ERROR_INVALID_ADDRESS: error = EFAULT; break;
+	case ERROR_INVALID_BLOCK: error = EFAULT; break;
+	case ERROR_INVALID_DATA: error = EINVAL; break;
+	case ERROR_INVALID_DRIVE: error = ENODEV; break;
+	case ERROR_INVALID_EXE_SIGNATURE: error = ENOEXEC; break;
+	case ERROR_INVALID_FLAGS: error = EINVAL; break;
+	case ERROR_INVALID_FUNCTION: error = ENOSYS; break;
+	case ERROR_INVALID_HANDLE: error = EBADF; break;
+	case ERROR_INVALID_LOGON_HOURS: error = EACCES; break;
+	case ERROR_INVALID_NAME: error = EINVAL; break;
+	case ERROR_INVALID_OWNER: error = EINVAL; break;
+	case ERROR_INVALID_PARAMETER: error = EINVAL; break;
+	case ERROR_INVALID_PASSWORD: error = EPERM; break;
+	case ERROR_INVALID_PRIMARY_GROUP: error = EINVAL; break;
+	case ERROR_INVALID_SIGNAL_NUMBER: error = EINVAL; break;
+	case ERROR_INVALID_TARGET_HANDLE: error = EIO; break;
+	case ERROR_INVALID_WORKSTATION: error = EACCES; break;
+	case ERROR_IO_DEVICE: error = EIO; break;
+	case ERROR_IO_INCOMPLETE: error = EINTR; break;
+	case ERROR_LOCKED: error = EBUSY; break;
+	case ERROR_LOCK_VIOLATION: error = EACCES; break;
+	case ERROR_LOGON_FAILURE: error = EACCES; break;
+	case ERROR_MAPPED_ALIGNMENT: error = EINVAL; break;
+	case ERROR_META_EXPANSION_TOO_LONG: error = E2BIG; break;
+	case ERROR_MORE_DATA: error = EPIPE; break;
+	case ERROR_NEGATIVE_SEEK: error = ESPIPE; break;
+	case ERROR_NOACCESS: error = EFAULT; break;
+	case ERROR_NONE_MAPPED: error = EINVAL; break;
+	case ERROR_NOT_ENOUGH_MEMORY: error = ENOMEM; break;
+	case ERROR_NOT_READY: error = EAGAIN; break;
+	case ERROR_NOT_SAME_DEVICE: error = EXDEV; break;
+	case ERROR_NO_DATA: error = EPIPE; break;
+	case ERROR_NO_MORE_SEARCH_HANDLES: error = EIO; break;
+	case ERROR_NO_PROC_SLOTS: error = EAGAIN; break;
+	case ERROR_NO_SUCH_PRIVILEGE: error = EACCES; break;
+	case ERROR_OPEN_FAILED: error = EIO; break;
+	case ERROR_OPEN_FILES: error = EBUSY; break;
+	case ERROR_OPERATION_ABORTED: error = EINTR; break;
+	case ERROR_OUTOFMEMORY: error = ENOMEM; break;
+	case ERROR_PASSWORD_EXPIRED: error = EACCES; break;
+	case ERROR_PATH_BUSY: error = EBUSY; break;
+	case ERROR_PATH_NOT_FOUND: error = ENOENT; break;
+	case ERROR_PIPE_BUSY: error = EBUSY; break;
+	case ERROR_PIPE_CONNECTED: error = EPIPE; break;
+	case ERROR_PIPE_LISTENING: error = EPIPE; break;
+	case ERROR_PIPE_NOT_CONNECTED: error = EPIPE; break;
+	case ERROR_PRIVILEGE_NOT_HELD: error = EACCES; break;
+	case ERROR_READ_FAULT: error = EIO; break;
+	case ERROR_SEEK: error = EIO; break;
+	case ERROR_SEEK_ON_DEVICE: error = ESPIPE; break;
+	case ERROR_SHARING_BUFFER_EXCEEDED: error = ENFILE; break;
+	case ERROR_SHARING_VIOLATION: error = EACCES; break;
+	case ERROR_STACK_OVERFLOW: error = ENOMEM; break;
+	case ERROR_SWAPERROR: error = ENOENT; break;
+	case ERROR_TOO_MANY_MODULES: error = EMFILE; break;
+	case ERROR_TOO_MANY_OPEN_FILES: error = EMFILE; break;
+	case ERROR_UNRECOGNIZED_MEDIA: error = ENXIO; break;
+	case ERROR_UNRECOGNIZED_VOLUME: error = ENODEV; break;
+	case ERROR_WAIT_NO_CHILDREN: error = ECHILD; break;
+	case ERROR_WRITE_FAULT: error = EIO; break;
+	case ERROR_WRITE_PROTECT: error = EROFS; break;
+	}
+	return error;
+}
+
+static inline int is_file_in_use_error(DWORD errcode)
+{
+	switch (errcode) {
+	case ERROR_SHARING_VIOLATION:
+	case ERROR_ACCESS_DENIED:
+		return 1;
+	}
+
+	return 0;
+}
+
+static int read_yes_no_answer(void)
+{
+	char answer[1024];
+
+	if (fgets(answer, sizeof(answer), stdin)) {
+		size_t answer_len = strlen(answer);
+		int got_full_line = 0, c;
+
+		/* remove the newline */
+		if (answer_len >= 2 && answer[answer_len-2] == '\r') {
+			answer[answer_len-2] = '\0';
+			got_full_line = 1;
+		} else if (answer_len >= 1 && answer[answer_len-1] == '\n') {
+			answer[answer_len-1] = '\0';
+			got_full_line = 1;
+		}
+		/* flush the buffer in case we did not get the full line */
+		if (!got_full_line)
+			while ((c = getchar()) != EOF && c != '\n')
+				;
+	} else
+		/* we could not read, return the
+		 * default answer which is no */
+		return 0;
+
+	if (tolower(answer[0]) == 'y' && !answer[1])
+		return 1;
+	if (!strncasecmp(answer, "yes", sizeof(answer)))
+		return 1;
+	if (tolower(answer[0]) == 'n' && !answer[1])
+		return 0;
+	if (!strncasecmp(answer, "no", sizeof(answer)))
+		return 0;
+
+	/* did not find an answer we understand */
+	return -1;
+}
+
+static int ask_yes_no_if_possible(const char *format, ...)
+{
+	char question[4096];
+	const char *retry_hook[] = { NULL, NULL, NULL };
+	va_list args;
+
+	va_start(args, format);
+	vsnprintf(question, sizeof(question), format, args);
+	va_end(args);
+
+	if ((retry_hook[0] = mingw_getenv("GIT_ASK_YESNO"))) {
+		retry_hook[1] = question;
+		return !run_command_v_opt(retry_hook, 0);
+	}
+
+	if (!isatty(_fileno(stdin)) || !isatty(_fileno(stderr)))
+		return 0;
+
+	while (1) {
+		int answer;
+		fprintf(stderr, "%s (y/n) ", question);
+
+		if ((answer = read_yes_no_answer()) >= 0)
+			return answer;
+
+		fprintf(stderr, "Sorry, I did not understand your answer. "
+				"Please type 'y' or 'n'\n");
+	}
+}
+
+/* Windows only */
+enum hide_dotfiles_type {
+	HIDE_DOTFILES_FALSE = 0,
+	HIDE_DOTFILES_TRUE,
+	HIDE_DOTFILES_DOTGITONLY
+};
+
+static enum hide_dotfiles_type hide_dotfiles = HIDE_DOTFILES_DOTGITONLY;
+static char *unset_environment_variables;
+
+int mingw_core_config(const char *var, const char *value, void *cb)
+{
+	if (!strcmp(var, "core.hidedotfiles")) {
+		if (value && !strcasecmp(value, "dotgitonly"))
+			hide_dotfiles = HIDE_DOTFILES_DOTGITONLY;
+		else
+			hide_dotfiles = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (!strcmp(var, "core.unsetenvvars")) {
+		free(unset_environment_variables);
+		unset_environment_variables = xstrdup(value);
+		return 0;
+	}
+
+	return 0;
+}
+
+/* Normalizes NT paths as returned by some low-level APIs. */
+static wchar_t *normalize_ntpath(wchar_t *wbuf)
+{
+	int i;
+	/* fix absolute path prefixes */
+	if (wbuf[0] == '\\') {
+		/* strip NT namespace prefixes */
+		if (!wcsncmp(wbuf, L"\\??\\", 4) ||
+		    !wcsncmp(wbuf, L"\\\\?\\", 4))
+			wbuf += 4;
+		else if (!wcsnicmp(wbuf, L"\\DosDevices\\", 12))
+			wbuf += 12;
+		/* replace remaining '...UNC\' with '\\' */
+		if (!wcsnicmp(wbuf, L"UNC\\", 4)) {
+			wbuf += 2;
+			*wbuf = '\\';
+		}
+	}
+	/* convert backslashes to slashes */
+	for (i = 0; wbuf[i]; i++)
+		if (wbuf[i] == '\\')
+			wbuf[i] = '/';
+	return wbuf;
+}
+
+int mingw_unlink(const char *pathname)
+{
+	int ret, tries = 0;
+	wchar_t wpathname[MAX_PATH];
+	if (xutftowcs_path(wpathname, pathname) < 0)
+		return -1;
+
+	/* read-only files cannot be removed */
+	_wchmod(wpathname, 0666);
+	while ((ret = _wunlink(wpathname)) == -1 && tries < ARRAY_SIZE(delay)) {
+		if (!is_file_in_use_error(GetLastError()))
+			break;
+		/*
+		 * We assume that some other process had the source or
+		 * destination file open at the wrong moment and retry.
+		 * In order to give the other process a higher chance to
+		 * complete its operation, we give up our time slice now.
+		 * If we have to retry again, we do sleep a bit.
+		 */
+		Sleep(delay[tries]);
+		tries++;
+	}
+	while (ret == -1 && is_file_in_use_error(GetLastError()) &&
+	       ask_yes_no_if_possible("Unlink of file '%s' failed. "
+			"Should I try again?", pathname))
+	       ret = _wunlink(wpathname);
+	return ret;
+}
+
+static int is_dir_empty(const wchar_t *wpath)
+{
+	WIN32_FIND_DATAW findbuf;
+	HANDLE handle;
+	wchar_t wbuf[MAX_PATH + 2];
+	wcscpy(wbuf, wpath);
+	wcscat(wbuf, L"\\*");
+	handle = FindFirstFileW(wbuf, &findbuf);
+	if (handle == INVALID_HANDLE_VALUE)
+		return GetLastError() == ERROR_NO_MORE_FILES;
+
+	while (!wcscmp(findbuf.cFileName, L".") ||
+			!wcscmp(findbuf.cFileName, L".."))
+		if (!FindNextFileW(handle, &findbuf)) {
+			DWORD err = GetLastError();
+			FindClose(handle);
+			return err == ERROR_NO_MORE_FILES;
+		}
+	FindClose(handle);
+	return 0;
+}
+
+int mingw_rmdir(const char *pathname)
+{
+	int ret, tries = 0;
+	wchar_t wpathname[MAX_PATH];
+	if (xutftowcs_path(wpathname, pathname) < 0)
+		return -1;
+
+	while ((ret = _wrmdir(wpathname)) == -1 && tries < ARRAY_SIZE(delay)) {
+		if (!is_file_in_use_error(GetLastError()))
+			errno = err_win_to_posix(GetLastError());
+		if (errno != EACCES)
+			break;
+		if (!is_dir_empty(wpathname)) {
+			errno = ENOTEMPTY;
+			break;
+		}
+		/*
+		 * We assume that some other process had the source or
+		 * destination file open at the wrong moment and retry.
+		 * In order to give the other process a higher chance to
+		 * complete its operation, we give up our time slice now.
+		 * If we have to retry again, we do sleep a bit.
+		 */
+		Sleep(delay[tries]);
+		tries++;
+	}
+	while (ret == -1 && errno == EACCES && is_file_in_use_error(GetLastError()) &&
+	       ask_yes_no_if_possible("Deletion of directory '%s' failed. "
+			"Should I try again?", pathname))
+	       ret = _wrmdir(wpathname);
+	return ret;
+}
+
+static inline int needs_hiding(const char *path)
+{
+	const char *basename;
+
+	if (hide_dotfiles == HIDE_DOTFILES_FALSE)
+		return 0;
+
+	/* We cannot use basename(), as it would remove trailing slashes */
+	win32_skip_dos_drive_prefix((char **)&path);
+	if (!*path)
+		return 0;
+
+	for (basename = path; *path; path++)
+		if (is_dir_sep(*path)) {
+			do {
+				path++;
+			} while (is_dir_sep(*path));
+			/* ignore trailing slashes */
+			if (*path)
+				basename = path;
+		}
+
+	if (hide_dotfiles == HIDE_DOTFILES_TRUE)
+		return *basename == '.';
+
+	assert(hide_dotfiles == HIDE_DOTFILES_DOTGITONLY);
+	return !strncasecmp(".git", basename, 4) &&
+		(!basename[4] || is_dir_sep(basename[4]));
+}
+
+static int set_hidden_flag(const wchar_t *path, int set)
+{
+	DWORD original = GetFileAttributesW(path), modified;
+	if (set)
+		modified = original | FILE_ATTRIBUTE_HIDDEN;
+	else
+		modified = original & ~FILE_ATTRIBUTE_HIDDEN;
+	if (original == modified || SetFileAttributesW(path, modified))
+		return 0;
+	errno = err_win_to_posix(GetLastError());
+	return -1;
+}
+
+int mingw_mkdir(const char *path, int mode)
+{
+	int ret;
+	wchar_t wpath[MAX_PATH];
+	if (xutftowcs_path(wpath, path) < 0)
+		return -1;
+	ret = _wmkdir(wpath);
+	if (!ret && needs_hiding(path))
+		return set_hidden_flag(wpath, 1);
+	return ret;
+}
+
+/*
+ * Calling CreateFile() using FILE_APPEND_DATA and without FILE_WRITE_DATA
+ * is documented in [1] as opening a writable file handle in append mode.
+ * (It is believed that) this is atomic since it is maintained by the
+ * kernel unlike the O_APPEND flag which is racily maintained by the CRT.
+ *
+ * [1] https://docs.microsoft.com/en-us/windows/desktop/fileio/file-access-rights-constants
+ *
+ * This trick does not appear to work for named pipes.  Instead it creates
+ * a named pipe client handle that cannot be written to.  Callers should
+ * just use the regular _wopen() for them.  (And since client handle gets
+ * bound to a unique server handle, it isn't really an issue.)
+ */
+static int mingw_open_append(wchar_t const *wfilename, int oflags, ...)
+{
+	HANDLE handle;
+	int fd;
+	DWORD create = (oflags & O_CREAT) ? OPEN_ALWAYS : OPEN_EXISTING;
+
+	/* only these flags are supported */
+	if ((oflags & ~O_CREAT) != (O_WRONLY | O_APPEND))
+		return errno = ENOSYS, -1;
+
+	/*
+	 * FILE_SHARE_WRITE is required to permit child processes
+	 * to append to the file.
+	 */
+	handle = CreateFileW(wfilename, FILE_APPEND_DATA,
+			FILE_SHARE_WRITE | FILE_SHARE_READ,
+			NULL, create, FILE_ATTRIBUTE_NORMAL, NULL);
+	if (handle == INVALID_HANDLE_VALUE)
+		return errno = err_win_to_posix(GetLastError()), -1;
+
+	/*
+	 * No O_APPEND here, because the CRT uses it only to reset the
+	 * file pointer to EOF before each write(); but that is not
+	 * necessary (and may lead to races) for a file created with
+	 * FILE_APPEND_DATA.
+	 */
+	fd = _open_osfhandle((intptr_t)handle, O_BINARY);
+	if (fd < 0)
+		CloseHandle(handle);
+	return fd;
+}
+
+/*
+ * Does the pathname map to the local named pipe filesystem?
+ * That is, does it have a "//./pipe/" prefix?
+ */
+static int is_local_named_pipe_path(const char *filename)
+{
+	return (is_dir_sep(filename[0]) &&
+		is_dir_sep(filename[1]) &&
+		filename[2] == '.'  &&
+		is_dir_sep(filename[3]) &&
+		!strncasecmp(filename+4, "pipe", 4) &&
+		is_dir_sep(filename[8]) &&
+		filename[9]);
+}
+
+int mingw_open (const char *filename, int oflags, ...)
+{
+	typedef int (*open_fn_t)(wchar_t const *wfilename, int oflags, ...);
+	va_list args;
+	unsigned mode;
+	int fd;
+	wchar_t wfilename[MAX_PATH];
+	open_fn_t open_fn;
+
+	va_start(args, oflags);
+	mode = va_arg(args, int);
+	va_end(args);
+
+	if (filename && !strcmp(filename, "/dev/null"))
+		filename = "nul";
+
+	if ((oflags & O_APPEND) && !is_local_named_pipe_path(filename))
+		open_fn = mingw_open_append;
+	else
+		open_fn = _wopen;
+
+	if (xutftowcs_path(wfilename, filename) < 0)
+		return -1;
+	fd = open_fn(wfilename, oflags, mode);
+
+	if (fd < 0 && (oflags & O_ACCMODE) != O_RDONLY && errno == EACCES) {
+		DWORD attrs = GetFileAttributesW(wfilename);
+		if (attrs != INVALID_FILE_ATTRIBUTES && (attrs & FILE_ATTRIBUTE_DIRECTORY))
+			errno = EISDIR;
+	}
+	if ((oflags & O_CREAT) && needs_hiding(filename)) {
+		/*
+		 * Internally, _wopen() uses the CreateFile() API which errors
+		 * out with an ERROR_ACCESS_DENIED if CREATE_ALWAYS was
+		 * specified and an already existing file's attributes do not
+		 * match *exactly*. As there is no mode or flag we can set that
+		 * would correspond to FILE_ATTRIBUTE_HIDDEN, let's just try
+		 * again *without* the O_CREAT flag (that corresponds to the
+		 * CREATE_ALWAYS flag of CreateFile()).
+		 */
+		if (fd < 0 && errno == EACCES)
+			fd = open_fn(wfilename, oflags & ~O_CREAT, mode);
+		if (fd >= 0 && set_hidden_flag(wfilename, 1))
+			warning("could not mark '%s' as hidden.", filename);
+	}
+	return fd;
+}
+
+static BOOL WINAPI ctrl_ignore(DWORD type)
+{
+	return TRUE;
+}
+
+#undef fgetc
+int mingw_fgetc(FILE *stream)
+{
+	int ch;
+	if (!isatty(_fileno(stream)))
+		return fgetc(stream);
+
+	SetConsoleCtrlHandler(ctrl_ignore, TRUE);
+	while (1) {
+		ch = fgetc(stream);
+		if (ch != EOF || GetLastError() != ERROR_OPERATION_ABORTED)
+			break;
+
+		/* Ctrl+C was pressed, simulate SIGINT and retry */
+		mingw_raise(SIGINT);
+	}
+	SetConsoleCtrlHandler(ctrl_ignore, FALSE);
+	return ch;
+}
+
+#undef fopen
+FILE *mingw_fopen (const char *filename, const char *otype)
+{
+	int hide = needs_hiding(filename);
+	FILE *file;
+	wchar_t wfilename[MAX_PATH], wotype[4];
+	if (filename && !strcmp(filename, "/dev/null"))
+		filename = "nul";
+	if (xutftowcs_path(wfilename, filename) < 0 ||
+		xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0)
+		return NULL;
+	if (hide && !access(filename, F_OK) && set_hidden_flag(wfilename, 0)) {
+		error("could not unhide %s", filename);
+		return NULL;
+	}
+	file = _wfopen(wfilename, wotype);
+	if (!file && GetLastError() == ERROR_INVALID_NAME)
+		errno = ENOENT;
+	if (file && hide && set_hidden_flag(wfilename, 1))
+		warning("could not mark '%s' as hidden.", filename);
+	return file;
+}
+
+FILE *mingw_freopen (const char *filename, const char *otype, FILE *stream)
+{
+	int hide = needs_hiding(filename);
+	FILE *file;
+	wchar_t wfilename[MAX_PATH], wotype[4];
+	if (filename && !strcmp(filename, "/dev/null"))
+		filename = "nul";
+	if (xutftowcs_path(wfilename, filename) < 0 ||
+		xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0)
+		return NULL;
+	if (hide && !access(filename, F_OK) && set_hidden_flag(wfilename, 0)) {
+		error("could not unhide %s", filename);
+		return NULL;
+	}
+	file = _wfreopen(wfilename, wotype, stream);
+	if (file && hide && set_hidden_flag(wfilename, 1))
+		warning("could not mark '%s' as hidden.", filename);
+	return file;
+}
+
+#undef fflush
+int mingw_fflush(FILE *stream)
+{
+	int ret = fflush(stream);
+
+	/*
+	 * write() is used behind the scenes of stdio output functions.
+	 * Since git code does not check for errors after each stdio write
+	 * operation, it can happen that write() is called by a later
+	 * stdio function even if an earlier write() call failed. In the
+	 * case of a pipe whose readable end was closed, only the first
+	 * call to write() reports EPIPE on Windows. Subsequent write()
+	 * calls report EINVAL. It is impossible to notice whether this
+	 * fflush invocation triggered such a case, therefore, we have to
+	 * catch all EINVAL errors whole-sale.
+	 */
+	if (ret && errno == EINVAL)
+		errno = EPIPE;
+
+	return ret;
+}
+
+#undef write
+ssize_t mingw_write(int fd, const void *buf, size_t len)
+{
+	ssize_t result = write(fd, buf, len);
+
+	if (result < 0 && errno == EINVAL && buf) {
+		/* check if fd is a pipe */
+		HANDLE h = (HANDLE) _get_osfhandle(fd);
+		if (GetFileType(h) == FILE_TYPE_PIPE)
+			errno = EPIPE;
+		else
+			errno = EINVAL;
+	}
+
+	return result;
+}
+
+int mingw_access(const char *filename, int mode)
+{
+	wchar_t wfilename[MAX_PATH];
+	if (xutftowcs_path(wfilename, filename) < 0)
+		return -1;
+	/* X_OK is not supported by the MSVCRT version */
+	return _waccess(wfilename, mode & ~X_OK);
+}
+
+int mingw_chdir(const char *dirname)
+{
+	wchar_t wdirname[MAX_PATH];
+	if (xutftowcs_path(wdirname, dirname) < 0)
+		return -1;
+	return _wchdir(wdirname);
+}
+
+int mingw_chmod(const char *filename, int mode)
+{
+	wchar_t wfilename[MAX_PATH];
+	if (xutftowcs_path(wfilename, filename) < 0)
+		return -1;
+	return _wchmod(wfilename, mode);
+}
+
+/*
+ * The unit of FILETIME is 100-nanoseconds since January 1, 1601, UTC.
+ * Returns the 100-nanoseconds ("hekto nanoseconds") since the epoch.
+ */
+static inline long long filetime_to_hnsec(const FILETIME *ft)
+{
+	long long winTime = ((long long)ft->dwHighDateTime << 32) + ft->dwLowDateTime;
+	/* Windows to Unix Epoch conversion */
+	return winTime - 116444736000000000LL;
+}
+
+static inline void filetime_to_timespec(const FILETIME *ft, struct timespec *ts)
+{
+	long long hnsec = filetime_to_hnsec(ft);
+	ts->tv_sec = (time_t)(hnsec / 10000000);
+	ts->tv_nsec = (hnsec % 10000000) * 100;
+}
+
+/**
+ * Verifies that safe_create_leading_directories() would succeed.
+ */
+static int has_valid_directory_prefix(wchar_t *wfilename)
+{
+	int n = wcslen(wfilename);
+
+	while (n > 0) {
+		wchar_t c = wfilename[--n];
+		DWORD attributes;
+
+		if (!is_dir_sep(c))
+			continue;
+
+		wfilename[n] = L'\0';
+		attributes = GetFileAttributesW(wfilename);
+		wfilename[n] = c;
+		if (attributes == FILE_ATTRIBUTE_DIRECTORY ||
+				attributes == FILE_ATTRIBUTE_DEVICE)
+			return 1;
+		if (attributes == INVALID_FILE_ATTRIBUTES)
+			switch (GetLastError()) {
+			case ERROR_PATH_NOT_FOUND:
+				continue;
+			case ERROR_FILE_NOT_FOUND:
+				/* This implies parent directory exists. */
+				return 1;
+			}
+		return 0;
+	}
+	return 1;
+}
+
+/* We keep the do_lstat code in a separate function to avoid recursion.
+ * When a path ends with a slash, the stat will fail with ENOENT. In
+ * this case, we strip the trailing slashes and stat again.
+ *
+ * If follow is true then act like stat() and report on the link
+ * target. Otherwise report on the link itself.
+ */
+static int do_lstat(int follow, const char *file_name, struct stat *buf)
+{
+	WIN32_FILE_ATTRIBUTE_DATA fdata;
+	wchar_t wfilename[MAX_PATH];
+	if (xutftowcs_path(wfilename, file_name) < 0)
+		return -1;
+
+	if (GetFileAttributesExW(wfilename, GetFileExInfoStandard, &fdata)) {
+		buf->st_ino = 0;
+		buf->st_gid = 0;
+		buf->st_uid = 0;
+		buf->st_nlink = 1;
+		buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes);
+		buf->st_size = fdata.nFileSizeLow |
+			(((off_t)fdata.nFileSizeHigh)<<32);
+		buf->st_dev = buf->st_rdev = 0; /* not used by Git */
+		filetime_to_timespec(&(fdata.ftLastAccessTime), &(buf->st_atim));
+		filetime_to_timespec(&(fdata.ftLastWriteTime), &(buf->st_mtim));
+		filetime_to_timespec(&(fdata.ftCreationTime), &(buf->st_ctim));
+		if (fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
+			WIN32_FIND_DATAW findbuf;
+			HANDLE handle = FindFirstFileW(wfilename, &findbuf);
+			if (handle != INVALID_HANDLE_VALUE) {
+				if ((findbuf.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) &&
+						(findbuf.dwReserved0 == IO_REPARSE_TAG_SYMLINK)) {
+					if (follow) {
+						char buffer[MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
+						buf->st_size = readlink(file_name, buffer, MAXIMUM_REPARSE_DATA_BUFFER_SIZE);
+					} else {
+						buf->st_mode = S_IFLNK;
+					}
+					buf->st_mode |= S_IREAD;
+					if (!(findbuf.dwFileAttributes & FILE_ATTRIBUTE_READONLY))
+						buf->st_mode |= S_IWRITE;
+				}
+				FindClose(handle);
+			}
+		}
+		return 0;
+	}
+	switch (GetLastError()) {
+	case ERROR_ACCESS_DENIED:
+	case ERROR_SHARING_VIOLATION:
+	case ERROR_LOCK_VIOLATION:
+	case ERROR_SHARING_BUFFER_EXCEEDED:
+		errno = EACCES;
+		break;
+	case ERROR_BUFFER_OVERFLOW:
+		errno = ENAMETOOLONG;
+		break;
+	case ERROR_NOT_ENOUGH_MEMORY:
+		errno = ENOMEM;
+		break;
+	case ERROR_PATH_NOT_FOUND:
+		if (!has_valid_directory_prefix(wfilename)) {
+			errno = ENOTDIR;
+			break;
+		}
+		/* fallthru */
+	default:
+		errno = ENOENT;
+		break;
+	}
+	return -1;
+}
+
+/* We provide our own lstat/fstat functions, since the provided
+ * lstat/fstat functions are so slow. These stat functions are
+ * tailored for Git's usage (read: fast), and are not meant to be
+ * complete. Note that Git stat()s are redirected to mingw_lstat()
+ * too, since Windows doesn't really handle symlinks that well.
+ */
+static int do_stat_internal(int follow, const char *file_name, struct stat *buf)
+{
+	int namelen;
+	char alt_name[PATH_MAX];
+
+	if (!do_lstat(follow, file_name, buf))
+		return 0;
+
+	/* if file_name ended in a '/', Windows returned ENOENT;
+	 * try again without trailing slashes
+	 */
+	if (errno != ENOENT)
+		return -1;
+
+	namelen = strlen(file_name);
+	if (namelen && file_name[namelen-1] != '/')
+		return -1;
+	while (namelen && file_name[namelen-1] == '/')
+		--namelen;
+	if (!namelen || namelen >= PATH_MAX)
+		return -1;
+
+	memcpy(alt_name, file_name, namelen);
+	alt_name[namelen] = 0;
+	return do_lstat(follow, alt_name, buf);
+}
+
+static int get_file_info_by_handle(HANDLE hnd, struct stat *buf)
+{
+	BY_HANDLE_FILE_INFORMATION fdata;
+
+	if (!GetFileInformationByHandle(hnd, &fdata)) {
+		errno = err_win_to_posix(GetLastError());
+		return -1;
+	}
+
+	buf->st_ino = 0;
+	buf->st_gid = 0;
+	buf->st_uid = 0;
+	buf->st_nlink = 1;
+	buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes);
+	buf->st_size = fdata.nFileSizeLow |
+		(((off_t)fdata.nFileSizeHigh)<<32);
+	buf->st_dev = buf->st_rdev = 0; /* not used by Git */
+	filetime_to_timespec(&(fdata.ftLastAccessTime), &(buf->st_atim));
+	filetime_to_timespec(&(fdata.ftLastWriteTime), &(buf->st_mtim));
+	filetime_to_timespec(&(fdata.ftCreationTime), &(buf->st_ctim));
+	return 0;
+}
+
+int mingw_lstat(const char *file_name, struct stat *buf)
+{
+	return do_stat_internal(0, file_name, buf);
+}
+int mingw_stat(const char *file_name, struct stat *buf)
+{
+	return do_stat_internal(1, file_name, buf);
+}
+
+int mingw_fstat(int fd, struct stat *buf)
+{
+	HANDLE fh = (HANDLE)_get_osfhandle(fd);
+	DWORD avail, type = GetFileType(fh) & ~FILE_TYPE_REMOTE;
+
+	switch (type) {
+	case FILE_TYPE_DISK:
+		return get_file_info_by_handle(fh, buf);
+
+	case FILE_TYPE_CHAR:
+	case FILE_TYPE_PIPE:
+		/* initialize stat fields */
+		memset(buf, 0, sizeof(*buf));
+		buf->st_nlink = 1;
+
+		if (type == FILE_TYPE_CHAR) {
+			buf->st_mode = _S_IFCHR;
+		} else {
+			buf->st_mode = _S_IFIFO;
+			if (PeekNamedPipe(fh, NULL, 0, NULL, &avail, NULL))
+				buf->st_size = avail;
+		}
+		return 0;
+
+	default:
+		errno = EBADF;
+		return -1;
+	}
+}
+
+static inline void time_t_to_filetime(time_t t, FILETIME *ft)
+{
+	long long winTime = t * 10000000LL + 116444736000000000LL;
+	ft->dwLowDateTime = winTime;
+	ft->dwHighDateTime = winTime >> 32;
+}
+
+int mingw_utime (const char *file_name, const struct utimbuf *times)
+{
+	FILETIME mft, aft;
+	int fh, rc;
+	DWORD attrs;
+	wchar_t wfilename[MAX_PATH];
+	if (xutftowcs_path(wfilename, file_name) < 0)
+		return -1;
+
+	/* must have write permission */
+	attrs = GetFileAttributesW(wfilename);
+	if (attrs != INVALID_FILE_ATTRIBUTES &&
+	    (attrs & FILE_ATTRIBUTE_READONLY)) {
+		/* ignore errors here; open() will report them */
+		SetFileAttributesW(wfilename, attrs & ~FILE_ATTRIBUTE_READONLY);
+	}
+
+	if ((fh = _wopen(wfilename, O_RDWR | O_BINARY)) < 0) {
+		rc = -1;
+		goto revert_attrs;
+	}
+
+	if (times) {
+		time_t_to_filetime(times->modtime, &mft);
+		time_t_to_filetime(times->actime, &aft);
+	} else {
+		GetSystemTimeAsFileTime(&mft);
+		aft = mft;
+	}
+	if (!SetFileTime((HANDLE)_get_osfhandle(fh), NULL, &aft, &mft)) {
+		errno = EINVAL;
+		rc = -1;
+	} else
+		rc = 0;
+	close(fh);
+
+revert_attrs:
+	if (attrs != INVALID_FILE_ATTRIBUTES &&
+	    (attrs & FILE_ATTRIBUTE_READONLY)) {
+		/* ignore errors again */
+		SetFileAttributesW(wfilename, attrs);
+	}
+	return rc;
+}
+
+#undef strftime
+size_t mingw_strftime(char *s, size_t max,
+		      const char *format, const struct tm *tm)
+{
+	size_t ret = strftime(s, max, format, tm);
+
+	if (!ret && errno == EINVAL)
+		die("invalid strftime format: '%s'", format);
+	return ret;
+}
+
+unsigned int sleep (unsigned int seconds)
+{
+	Sleep(seconds*1000);
+	return 0;
+}
+
+char *mingw_mktemp(char *template)
+{
+	wchar_t wtemplate[MAX_PATH];
+	if (xutftowcs_path(wtemplate, template) < 0)
+		return NULL;
+	if (!_wmktemp(wtemplate))
+		return NULL;
+	if (xwcstoutf(template, wtemplate, strlen(template) + 1) < 0)
+		return NULL;
+	return template;
+}
+
+int mkstemp(char *template)
+{
+	char *filename = mktemp(template);
+	if (filename == NULL)
+		return -1;
+	return open(filename, O_RDWR | O_CREAT, 0600);
+}
+
+int gettimeofday(struct timeval *tv, void *tz)
+{
+	FILETIME ft;
+	long long hnsec;
+
+	GetSystemTimeAsFileTime(&ft);
+	hnsec = filetime_to_hnsec(&ft);
+	tv->tv_sec = hnsec / 10000000;
+	tv->tv_usec = (hnsec % 10000000) / 10;
+	return 0;
+}
+
+int pipe(int filedes[2])
+{
+	HANDLE h[2];
+
+	/* this creates non-inheritable handles */
+	if (!CreatePipe(&h[0], &h[1], NULL, 8192)) {
+		errno = err_win_to_posix(GetLastError());
+		return -1;
+	}
+	filedes[0] = _open_osfhandle(HCAST(int, h[0]), O_NOINHERIT);
+	if (filedes[0] < 0) {
+		CloseHandle(h[0]);
+		CloseHandle(h[1]);
+		return -1;
+	}
+	filedes[1] = _open_osfhandle(HCAST(int, h[1]), O_NOINHERIT);
+	if (filedes[1] < 0) {
+		close(filedes[0]);
+		CloseHandle(h[1]);
+		return -1;
+	}
+	return 0;
+}
+
+struct tm *gmtime_r(const time_t *timep, struct tm *result)
+{
+	/* gmtime() in MSVCRT.DLL is thread-safe, but not reentrant */
+	memcpy(result, gmtime(timep), sizeof(struct tm));
+	return result;
+}
+
+struct tm *localtime_r(const time_t *timep, struct tm *result)
+{
+	/* localtime() in MSVCRT.DLL is thread-safe, but not reentrant */
+	memcpy(result, localtime(timep), sizeof(struct tm));
+	return result;
+}
+
+char *mingw_getcwd(char *pointer, int len)
+{
+	wchar_t cwd[MAX_PATH], wpointer[MAX_PATH];
+	DWORD ret = GetCurrentDirectoryW(ARRAY_SIZE(cwd), cwd);
+
+	if (!ret || ret >= ARRAY_SIZE(cwd)) {
+		errno = ret ? ENAMETOOLONG : err_win_to_posix(GetLastError());
+		return NULL;
+	}
+	ret = GetLongPathNameW(cwd, wpointer, ARRAY_SIZE(wpointer));
+	if (!ret && GetLastError() == ERROR_ACCESS_DENIED) {
+		HANDLE hnd = CreateFileW(cwd, 0,
+			FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL,
+			OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
+		if (hnd == INVALID_HANDLE_VALUE)
+			return NULL;
+		ret = GetFinalPathNameByHandleW(hnd, wpointer, ARRAY_SIZE(wpointer), 0);
+		CloseHandle(hnd);
+		if (!ret || ret >= ARRAY_SIZE(wpointer))
+			return NULL;
+		if (xwcstoutf(pointer, normalize_ntpath(wpointer), len) < 0)
+			return NULL;
+		return pointer;
+	}
+	if (!ret || ret >= ARRAY_SIZE(wpointer))
+		return NULL;
+	if (xwcstoutf(pointer, wpointer, len) < 0)
+		return NULL;
+	convert_slashes(pointer);
+	return pointer;
+}
+
+/*
+ * See "Parsing C++ Command-Line Arguments" at Microsoft's Docs:
+ * https://docs.microsoft.com/en-us/cpp/cpp/parsing-cpp-command-line-arguments
+ */
+static const char *quote_arg_msvc(const char *arg)
+{
+	/* count chars to quote */
+	int len = 0, n = 0;
+	int force_quotes = 0;
+	char *q, *d;
+	const char *p = arg;
+	if (!*p) force_quotes = 1;
+	while (*p) {
+		if (isspace(*p) || *p == '*' || *p == '?' || *p == '{' || *p == '\'')
+			force_quotes = 1;
+		else if (*p == '"')
+			n++;
+		else if (*p == '\\') {
+			int count = 0;
+			while (*p == '\\') {
+				count++;
+				p++;
+				len++;
+			}
+			if (*p == '"')
+				n += count*2 + 1;
+			continue;
+		}
+		len++;
+		p++;
+	}
+	if (!force_quotes && n == 0)
+		return arg;
+
+	/* insert \ where necessary */
+	d = q = xmalloc(st_add3(len, n, 3));
+	*d++ = '"';
+	while (*arg) {
+		if (*arg == '"')
+			*d++ = '\\';
+		else if (*arg == '\\') {
+			int count = 0;
+			while (*arg == '\\') {
+				count++;
+				*d++ = *arg++;
+			}
+			if (*arg == '"') {
+				while (count-- > 0)
+					*d++ = '\\';
+				*d++ = '\\';
+			}
+		}
+		*d++ = *arg++;
+	}
+	*d++ = '"';
+	*d++ = 0;
+	return q;
+}
+
+#include "quote.h"
+
+static const char *quote_arg_msys2(const char *arg)
+{
+	struct strbuf buf = STRBUF_INIT;
+	const char *p2 = arg, *p;
+
+	for (p = arg; *p; p++) {
+		int ws = isspace(*p);
+		if (!ws && *p != '\\' && *p != '"' && *p != '{')
+			continue;
+		if (!buf.len)
+			strbuf_addch(&buf, '"');
+		if (p != p2)
+			strbuf_add(&buf, p2, p - p2);
+		if (!ws && *p != '{')
+			strbuf_addch(&buf, '\\');
+		p2 = p;
+	}
+
+	if (p == arg)
+		strbuf_addch(&buf, '"');
+	else if (!buf.len)
+		return arg;
+	else
+		strbuf_add(&buf, p2, p - p2),
+
+	strbuf_addch(&buf, '"');
+	return strbuf_detach(&buf, 0);
+}
+
+static const char *parse_interpreter(const char *cmd)
+{
+	static char buf[100];
+	char *p, *opt;
+	int n, fd;
+
+	/* don't even try a .exe */
+	n = strlen(cmd);
+	if (n >= 4 && !strcasecmp(cmd+n-4, ".exe"))
+		return NULL;
+
+	fd = open(cmd, O_RDONLY);
+	if (fd < 0)
+		return NULL;
+	n = read(fd, buf, sizeof(buf)-1);
+	close(fd);
+	if (n < 4)	/* at least '#!/x' and not error */
+		return NULL;
+
+	if (buf[0] != '#' || buf[1] != '!')
+		return NULL;
+	buf[n] = '\0';
+	p = buf + strcspn(buf, "\r\n");
+	if (!*p)
+		return NULL;
+
+	*p = '\0';
+	if (!(p = strrchr(buf+2, '/')) && !(p = strrchr(buf+2, '\\')))
+		return NULL;
+	/* strip options */
+	if ((opt = strchr(p+1, ' ')))
+		*opt = '\0';
+	return p+1;
+}
+
+/*
+ * exe_only means that we only want to detect .exe files, but not scripts
+ * (which do not have an extension)
+ */
+static char *lookup_prog(const char *dir, int dirlen, const char *cmd,
+			 int isexe, int exe_only)
+{
+	char path[MAX_PATH];
+	snprintf(path, sizeof(path), "%.*s\\%s.exe", dirlen, dir, cmd);
+
+	if (!isexe && access(path, F_OK) == 0)
+		return xstrdup(path);
+	path[strlen(path)-4] = '\0';
+	if ((!exe_only || isexe) && access(path, F_OK) == 0)
+		if (!(GetFileAttributes(path) & FILE_ATTRIBUTE_DIRECTORY))
+			return xstrdup(path);
+	return NULL;
+}
+
+/*
+ * Determines the absolute path of cmd using the split path in path.
+ * If cmd contains a slash or backslash, no lookup is performed.
+ */
+static char *path_lookup(const char *cmd, int exe_only)
+{
+	const char *path;
+	char *prog = NULL;
+	int len = strlen(cmd);
+	int isexe = len >= 4 && !strcasecmp(cmd+len-4, ".exe");
+
+	if (strchr(cmd, '/') || strchr(cmd, '\\'))
+		return xstrdup(cmd);
+
+	path = mingw_getenv("PATH");
+	if (!path)
+		return NULL;
+
+	while (!prog) {
+		const char *sep = strchrnul(path, ';');
+		int dirlen = sep - path;
+		if (dirlen)
+			prog = lookup_prog(path, dirlen, cmd, isexe, exe_only);
+		if (!*sep)
+			break;
+		path = sep + 1;
+	}
+
+	return prog;
+}
+
+static const wchar_t *wcschrnul(const wchar_t *s, wchar_t c)
+{
+	while (*s && *s != c)
+		s++;
+	return s;
+}
+
+/* Compare only keys */
+static int wenvcmp(const void *a, const void *b)
+{
+	wchar_t *p = *(wchar_t **)a, *q = *(wchar_t **)b;
+	size_t p_len, q_len;
+
+	/* Find the keys */
+	p_len = wcschrnul(p, L'=') - p;
+	q_len = wcschrnul(q, L'=') - q;
+
+	/* If the length differs, include the shorter key's NUL */
+	if (p_len < q_len)
+		p_len++;
+	else if (p_len > q_len)
+		p_len = q_len + 1;
+
+	return _wcsnicmp(p, q, p_len);
+}
+
+/* We need a stable sort to convert the environment between UTF-16 <-> UTF-8 */
+#ifndef INTERNAL_QSORT
+#include "qsort.c"
+#endif
+
+/*
+ * Build an environment block combining the inherited environment
+ * merged with the given list of settings.
+ *
+ * Values of the form "KEY=VALUE" in deltaenv override inherited values.
+ * Values of the form "KEY" in deltaenv delete inherited values.
+ *
+ * Multiple entries in deltaenv for the same key are explicitly allowed.
+ *
+ * We return a contiguous block of UNICODE strings with a final trailing
+ * zero word.
+ */
+static wchar_t *make_environment_block(char **deltaenv)
+{
+	wchar_t *wenv = GetEnvironmentStringsW(), *wdeltaenv, *result, *p;
+	size_t wlen, s, delta_size, size;
+
+	wchar_t **array = NULL;
+	size_t alloc = 0, nr = 0, i;
+
+	size = 1; /* for extra NUL at the end */
+
+	/* If there is no deltaenv to apply, simply return a copy. */
+	if (!deltaenv || !*deltaenv) {
+		for (p = wenv; p && *p; ) {
+			size_t s = wcslen(p) + 1;
+			size += s;
+			p += s;
+		}
+
+		ALLOC_ARRAY(result, size);
+		memcpy(result, wenv, size * sizeof(*wenv));
+		FreeEnvironmentStringsW(wenv);
+		return result;
+	}
+
+	/*
+	 * If there is a deltaenv, let's accumulate all keys into `array`,
+	 * sort them using the stable git_qsort() and then copy, skipping
+	 * duplicate keys
+	 */
+	for (p = wenv; p && *p; ) {
+		ALLOC_GROW(array, nr + 1, alloc);
+		s = wcslen(p) + 1;
+		array[nr++] = p;
+		p += s;
+		size += s;
+	}
+
+	/* (over-)assess size needed for wchar version of deltaenv */
+	for (delta_size = 0, i = 0; deltaenv[i]; i++)
+		delta_size += strlen(deltaenv[i]) * 2 + 1;
+	ALLOC_ARRAY(wdeltaenv, delta_size);
+
+	/* convert the deltaenv, appending to array */
+	for (i = 0, p = wdeltaenv; deltaenv[i]; i++) {
+		ALLOC_GROW(array, nr + 1, alloc);
+		wlen = xutftowcs(p, deltaenv[i], wdeltaenv + delta_size - p);
+		array[nr++] = p;
+		p += wlen + 1;
+	}
+
+	git_qsort(array, nr, sizeof(*array), wenvcmp);
+	ALLOC_ARRAY(result, size + delta_size);
+
+	for (p = result, i = 0; i < nr; i++) {
+		/* Skip any duplicate keys; last one wins */
+		while (i + 1 < nr && !wenvcmp(array + i, array + i + 1))
+		       i++;
+
+		/* Skip "to delete" entry */
+		if (!wcschr(array[i], L'='))
+			continue;
+
+		size = wcslen(array[i]) + 1;
+		memcpy(p, array[i], size * sizeof(*p));
+		p += size;
+	}
+	*p = L'\0';
+
+	free(array);
+	free(wdeltaenv);
+	FreeEnvironmentStringsW(wenv);
+	return result;
+}
+
+static void do_unset_environment_variables(void)
+{
+	static int done;
+	char *p = unset_environment_variables;
+
+	if (done || !p)
+		return;
+	done = 1;
+
+	for (;;) {
+		char *comma = strchr(p, ',');
+
+		if (comma)
+			*comma = '\0';
+		unsetenv(p);
+		if (!comma)
+			break;
+		p = comma + 1;
+	}
+}
+
+struct pinfo_t {
+	struct pinfo_t *next;
+	pid_t pid;
+	HANDLE proc;
+};
+static struct pinfo_t *pinfo = NULL;
+CRITICAL_SECTION pinfo_cs;
+
+/* Used to match and chomp off path components */
+static inline int match_last_path_component(const char *path, size_t *len,
+					    const char *component)
+{
+	size_t component_len = strlen(component);
+	if (*len < component_len + 1 ||
+	    !is_dir_sep(path[*len - component_len - 1]) ||
+	    fspathncmp(path + *len - component_len, component, component_len))
+		return 0;
+	*len -= component_len + 1;
+	/* chomp off repeated dir separators */
+	while (*len > 0 && is_dir_sep(path[*len - 1]))
+		(*len)--;
+	return 1;
+}
+
+static int is_msys2_sh(const char *cmd)
+{
+	if (cmd && !strcmp(cmd, "sh")) {
+		static int ret = -1;
+		char *p;
+
+		if (ret >= 0)
+			return ret;
+
+		p = path_lookup(cmd, 0);
+		if (!p)
+			ret = 0;
+		else {
+			size_t len = strlen(p);
+
+			ret = match_last_path_component(p, &len, "sh.exe") &&
+				match_last_path_component(p, &len, "bin") &&
+				match_last_path_component(p, &len, "usr");
+			free(p);
+		}
+		return ret;
+	}
+	return 0;
+}
+
+static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaenv,
+			      const char *dir,
+			      int prepend_cmd, int fhin, int fhout, int fherr)
+{
+	STARTUPINFOW si;
+	PROCESS_INFORMATION pi;
+	struct strbuf args;
+	wchar_t wcmd[MAX_PATH], wdir[MAX_PATH], *wargs, *wenvblk = NULL;
+	unsigned flags = CREATE_UNICODE_ENVIRONMENT;
+	BOOL ret;
+	HANDLE cons;
+	const char *(*quote_arg)(const char *arg) =
+		is_msys2_sh(*argv) ? quote_arg_msys2 : quote_arg_msvc;
+
+	do_unset_environment_variables();
+
+	/* Determine whether or not we are associated to a console */
+	cons = CreateFileW(L"CONOUT$", GENERIC_WRITE,
+			FILE_SHARE_WRITE, NULL, OPEN_EXISTING,
+			FILE_ATTRIBUTE_NORMAL, NULL);
+	if (cons == INVALID_HANDLE_VALUE) {
+		/* There is no console associated with this process.
+		 * Since the child is a console process, Windows
+		 * would normally create a console window. But
+		 * since we'll be redirecting std streams, we do
+		 * not need the console.
+		 * It is necessary to use DETACHED_PROCESS
+		 * instead of CREATE_NO_WINDOW to make ssh
+		 * recognize that it has no console.
+		 */
+		flags |= DETACHED_PROCESS;
+	} else {
+		/* There is already a console. If we specified
+		 * DETACHED_PROCESS here, too, Windows would
+		 * disassociate the child from the console.
+		 * The same is true for CREATE_NO_WINDOW.
+		 * Go figure!
+		 */
+		CloseHandle(cons);
+	}
+	memset(&si, 0, sizeof(si));
+	si.cb = sizeof(si);
+	si.dwFlags = STARTF_USESTDHANDLES;
+	si.hStdInput = winansi_get_osfhandle(fhin);
+	si.hStdOutput = winansi_get_osfhandle(fhout);
+	si.hStdError = winansi_get_osfhandle(fherr);
+
+	if (*argv && !strcmp(cmd, *argv))
+		wcmd[0] = L'\0';
+	else if (xutftowcs_path(wcmd, cmd) < 0)
+		return -1;
+	if (dir && xutftowcs_path(wdir, dir) < 0)
+		return -1;
+
+	/* concatenate argv, quoting args as we go */
+	strbuf_init(&args, 0);
+	if (prepend_cmd) {
+		char *quoted = (char *)quote_arg(cmd);
+		strbuf_addstr(&args, quoted);
+		if (quoted != cmd)
+			free(quoted);
+	}
+	for (; *argv; argv++) {
+		char *quoted = (char *)quote_arg(*argv);
+		if (*args.buf)
+			strbuf_addch(&args, ' ');
+		strbuf_addstr(&args, quoted);
+		if (quoted != *argv)
+			free(quoted);
+	}
+
+	ALLOC_ARRAY(wargs, st_add(st_mult(2, args.len), 1));
+	xutftowcs(wargs, args.buf, 2 * args.len + 1);
+	strbuf_release(&args);
+
+	wenvblk = make_environment_block(deltaenv);
+
+	memset(&pi, 0, sizeof(pi));
+	ret = CreateProcessW(*wcmd ? wcmd : NULL, wargs, NULL, NULL, TRUE,
+		flags, wenvblk, dir ? wdir : NULL, &si, &pi);
+
+	free(wenvblk);
+	free(wargs);
+
+	if (!ret) {
+		errno = ENOENT;
+		return -1;
+	}
+	CloseHandle(pi.hThread);
+
+	/*
+	 * The process ID is the human-readable identifier of the process
+	 * that we want to present in log and error messages. The handle
+	 * is not useful for this purpose. But we cannot close it, either,
+	 * because it is not possible to turn a process ID into a process
+	 * handle after the process terminated.
+	 * Keep the handle in a list for waitpid.
+	 */
+	EnterCriticalSection(&pinfo_cs);
+	{
+		struct pinfo_t *info = xmalloc(sizeof(struct pinfo_t));
+		info->pid = pi.dwProcessId;
+		info->proc = pi.hProcess;
+		info->next = pinfo;
+		pinfo = info;
+	}
+	LeaveCriticalSection(&pinfo_cs);
+
+	return (pid_t)pi.dwProcessId;
+}
+
+static pid_t mingw_spawnv(const char *cmd, const char **argv, int prepend_cmd)
+{
+	return mingw_spawnve_fd(cmd, argv, NULL, NULL, prepend_cmd, 0, 1, 2);
+}
+
+pid_t mingw_spawnvpe(const char *cmd, const char **argv, char **deltaenv,
+		     const char *dir,
+		     int fhin, int fhout, int fherr)
+{
+	pid_t pid;
+	char *prog = path_lookup(cmd, 0);
+
+	if (!prog) {
+		errno = ENOENT;
+		pid = -1;
+	}
+	else {
+		const char *interpr = parse_interpreter(prog);
+
+		if (interpr) {
+			const char *argv0 = argv[0];
+			char *iprog = path_lookup(interpr, 1);
+			argv[0] = prog;
+			if (!iprog) {
+				errno = ENOENT;
+				pid = -1;
+			}
+			else {
+				pid = mingw_spawnve_fd(iprog, argv, deltaenv, dir, 1,
+						       fhin, fhout, fherr);
+				free(iprog);
+			}
+			argv[0] = argv0;
+		}
+		else
+			pid = mingw_spawnve_fd(prog, argv, deltaenv, dir, 0,
+					       fhin, fhout, fherr);
+		free(prog);
+	}
+	return pid;
+}
+
+static int try_shell_exec(const char *cmd, char *const *argv)
+{
+	const char *interpr = parse_interpreter(cmd);
+	char *prog;
+	int pid = 0;
+
+	if (!interpr)
+		return 0;
+	prog = path_lookup(interpr, 1);
+	if (prog) {
+		int exec_id;
+		int argc = 0;
+#ifndef _MSC_VER
+		const
+#endif
+		char **argv2;
+		while (argv[argc]) argc++;
+		ALLOC_ARRAY(argv2, argc + 1);
+		argv2[0] = (char *)cmd;	/* full path to the script file */
+		memcpy(&argv2[1], &argv[1], sizeof(*argv) * argc);
+		exec_id = trace2_exec(prog, argv2);
+		pid = mingw_spawnv(prog, argv2, 1);
+		if (pid >= 0) {
+			int status;
+			if (waitpid(pid, &status, 0) < 0)
+				status = 255;
+			trace2_exec_result(exec_id, status);
+			exit(status);
+		}
+		trace2_exec_result(exec_id, -1);
+		pid = 1;	/* indicate that we tried but failed */
+		free(prog);
+		free(argv2);
+	}
+	return pid;
+}
+
+int mingw_execv(const char *cmd, char *const *argv)
+{
+	/* check if git_command is a shell script */
+	if (!try_shell_exec(cmd, argv)) {
+		int pid, status;
+		int exec_id;
+
+		exec_id = trace2_exec(cmd, (const char **)argv);
+		pid = mingw_spawnv(cmd, (const char **)argv, 0);
+		if (pid < 0) {
+			trace2_exec_result(exec_id, -1);
+			return -1;
+		}
+		if (waitpid(pid, &status, 0) < 0)
+			status = 255;
+		trace2_exec_result(exec_id, status);
+		exit(status);
+	}
+	return -1;
+}
+
+int mingw_execvp(const char *cmd, char *const *argv)
+{
+	char *prog = path_lookup(cmd, 0);
+
+	if (prog) {
+		mingw_execv(prog, argv);
+		free(prog);
+	} else
+		errno = ENOENT;
+
+	return -1;
+}
+
+int mingw_kill(pid_t pid, int sig)
+{
+	if (pid > 0 && sig == SIGTERM) {
+		HANDLE h = OpenProcess(PROCESS_TERMINATE, FALSE, pid);
+
+		if (TerminateProcess(h, -1)) {
+			CloseHandle(h);
+			return 0;
+		}
+
+		errno = err_win_to_posix(GetLastError());
+		CloseHandle(h);
+		return -1;
+	} else if (pid > 0 && sig == 0) {
+		HANDLE h = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pid);
+		if (h) {
+			CloseHandle(h);
+			return 0;
+		}
+	}
+
+	errno = EINVAL;
+	return -1;
+}
+
+/*
+ * UTF-8 versions of getenv(), putenv() and unsetenv().
+ * Internally, they use the CRT's stock UNICODE routines
+ * to avoid data loss.
+ */
+char *mingw_getenv(const char *name)
+{
+#define GETENV_MAX_RETAIN 64
+	static char *values[GETENV_MAX_RETAIN];
+	static int value_counter;
+	int len_key, len_value;
+	wchar_t *w_key;
+	char *value;
+	wchar_t w_value[32768];
+
+	if (!name || !*name)
+		return NULL;
+
+	len_key = strlen(name) + 1;
+	/* We cannot use xcalloc() here because that uses getenv() itself */
+	w_key = calloc(len_key, sizeof(wchar_t));
+	if (!w_key)
+		die("Out of memory, (tried to allocate %u wchar_t's)", len_key);
+	xutftowcs(w_key, name, len_key);
+	len_value = GetEnvironmentVariableW(w_key, w_value, ARRAY_SIZE(w_value));
+	if (!len_value && GetLastError() == ERROR_ENVVAR_NOT_FOUND) {
+		free(w_key);
+		return NULL;
+	}
+	free(w_key);
+
+	len_value = len_value * 3 + 1;
+	/* We cannot use xcalloc() here because that uses getenv() itself */
+	value = calloc(len_value, sizeof(char));
+	if (!value)
+		die("Out of memory, (tried to allocate %u bytes)", len_value);
+	xwcstoutf(value, w_value, len_value);
+
+	/*
+	 * We return `value` which is an allocated value and the caller is NOT
+	 * expecting to have to free it, so we keep a round-robin array,
+	 * invalidating the buffer after GETENV_MAX_RETAIN getenv() calls.
+	 */
+	free(values[value_counter]);
+	values[value_counter++] = value;
+	if (value_counter >= ARRAY_SIZE(values))
+		value_counter = 0;
+
+	return value;
+}
+
+int mingw_putenv(const char *namevalue)
+{
+	int size;
+	wchar_t *wide, *equal;
+	BOOL result;
+
+	if (!namevalue || !*namevalue)
+		return 0;
+
+	size = strlen(namevalue) * 2 + 1;
+	wide = calloc(size, sizeof(wchar_t));
+	if (!wide)
+		die("Out of memory, (tried to allocate %u wchar_t's)", size);
+	xutftowcs(wide, namevalue, size);
+	equal = wcschr(wide, L'=');
+	if (!equal)
+		result = SetEnvironmentVariableW(wide, NULL);
+	else {
+		*equal = L'\0';
+		result = SetEnvironmentVariableW(wide, equal + 1);
+	}
+	free(wide);
+
+	if (!result)
+		errno = err_win_to_posix(GetLastError());
+
+	return result ? 0 : -1;
+}
+
+static void ensure_socket_initialization(void)
+{
+	WSADATA wsa;
+	static int initialized = 0;
+
+	if (initialized)
+		return;
+
+	if (WSAStartup(MAKEWORD(2,2), &wsa))
+		die("unable to initialize winsock subsystem, error %d",
+			WSAGetLastError());
+
+	atexit((void(*)(void)) WSACleanup);
+	initialized = 1;
+}
+
+#undef gethostname
+int mingw_gethostname(char *name, int namelen)
+{
+    ensure_socket_initialization();
+    return gethostname(name, namelen);
+}
+
+#undef gethostbyname
+struct hostent *mingw_gethostbyname(const char *host)
+{
+	ensure_socket_initialization();
+	return gethostbyname(host);
+}
+
+#undef getaddrinfo
+int mingw_getaddrinfo(const char *node, const char *service,
+		      const struct addrinfo *hints, struct addrinfo **res)
+{
+	ensure_socket_initialization();
+	return getaddrinfo(node, service, hints, res);
+}
+
+int mingw_socket(int domain, int type, int protocol)
+{
+	int sockfd;
+	SOCKET s;
+
+	ensure_socket_initialization();
+	s = WSASocket(domain, type, protocol, NULL, 0, 0);
+	if (s == INVALID_SOCKET) {
+		/*
+		 * WSAGetLastError() values are regular BSD error codes
+		 * biased by WSABASEERR.
+		 * However, strerror() does not know about networking
+		 * specific errors, which are values beginning at 38 or so.
+		 * Therefore, we choose to leave the biased error code
+		 * in errno so that _if_ someone looks up the code somewhere,
+		 * then it is at least the number that are usually listed.
+		 */
+		errno = WSAGetLastError();
+		return -1;
+	}
+	/* convert into a file descriptor */
+	if ((sockfd = _open_osfhandle(s, O_RDWR|O_BINARY)) < 0) {
+		closesocket(s);
+		return error("unable to make a socket file descriptor: %s",
+			strerror(errno));
+	}
+	return sockfd;
+}
+
+#undef connect
+int mingw_connect(int sockfd, struct sockaddr *sa, size_t sz)
+{
+	SOCKET s = (SOCKET)_get_osfhandle(sockfd);
+	return connect(s, sa, sz);
+}
+
+#undef bind
+int mingw_bind(int sockfd, struct sockaddr *sa, size_t sz)
+{
+	SOCKET s = (SOCKET)_get_osfhandle(sockfd);
+	return bind(s, sa, sz);
+}
+
+#undef setsockopt
+int mingw_setsockopt(int sockfd, int lvl, int optname, void *optval, int optlen)
+{
+	SOCKET s = (SOCKET)_get_osfhandle(sockfd);
+	return setsockopt(s, lvl, optname, (const char*)optval, optlen);
+}
+
+#undef shutdown
+int mingw_shutdown(int sockfd, int how)
+{
+	SOCKET s = (SOCKET)_get_osfhandle(sockfd);
+	return shutdown(s, how);
+}
+
+#undef listen
+int mingw_listen(int sockfd, int backlog)
+{
+	SOCKET s = (SOCKET)_get_osfhandle(sockfd);
+	return listen(s, backlog);
+}
+
+#undef accept
+int mingw_accept(int sockfd1, struct sockaddr *sa, socklen_t *sz)
+{
+	int sockfd2;
+
+	SOCKET s1 = (SOCKET)_get_osfhandle(sockfd1);
+	SOCKET s2 = accept(s1, sa, sz);
+
+	/* convert into a file descriptor */
+	if ((sockfd2 = _open_osfhandle(s2, O_RDWR|O_BINARY)) < 0) {
+		int err = errno;
+		closesocket(s2);
+		return error("unable to make a socket file descriptor: %s",
+			strerror(err));
+	}
+	return sockfd2;
+}
+
+#undef rename
+int mingw_rename(const char *pold, const char *pnew)
+{
+	DWORD attrs, gle;
+	int tries = 0;
+	wchar_t wpold[MAX_PATH], wpnew[MAX_PATH];
+	if (xutftowcs_path(wpold, pold) < 0 || xutftowcs_path(wpnew, pnew) < 0)
+		return -1;
+
+	/*
+	 * Try native rename() first to get errno right.
+	 * It is based on MoveFile(), which cannot overwrite existing files.
+	 */
+	if (!_wrename(wpold, wpnew))
+		return 0;
+	if (errno != EEXIST)
+		return -1;
+repeat:
+	if (MoveFileExW(wpold, wpnew, MOVEFILE_REPLACE_EXISTING))
+		return 0;
+	/* TODO: translate more errors */
+	gle = GetLastError();
+	if (gle == ERROR_ACCESS_DENIED &&
+	    (attrs = GetFileAttributesW(wpnew)) != INVALID_FILE_ATTRIBUTES) {
+		if (attrs & FILE_ATTRIBUTE_DIRECTORY) {
+			DWORD attrsold = GetFileAttributesW(wpold);
+			if (attrsold == INVALID_FILE_ATTRIBUTES ||
+			    !(attrsold & FILE_ATTRIBUTE_DIRECTORY))
+				errno = EISDIR;
+			else if (!_wrmdir(wpnew))
+				goto repeat;
+			return -1;
+		}
+		if ((attrs & FILE_ATTRIBUTE_READONLY) &&
+		    SetFileAttributesW(wpnew, attrs & ~FILE_ATTRIBUTE_READONLY)) {
+			if (MoveFileExW(wpold, wpnew, MOVEFILE_REPLACE_EXISTING))
+				return 0;
+			gle = GetLastError();
+			/* revert file attributes on failure */
+			SetFileAttributesW(wpnew, attrs);
+		}
+	}
+	if (tries < ARRAY_SIZE(delay) && gle == ERROR_ACCESS_DENIED) {
+		/*
+		 * We assume that some other process had the source or
+		 * destination file open at the wrong moment and retry.
+		 * In order to give the other process a higher chance to
+		 * complete its operation, we give up our time slice now.
+		 * If we have to retry again, we do sleep a bit.
+		 */
+		Sleep(delay[tries]);
+		tries++;
+		goto repeat;
+	}
+	if (gle == ERROR_ACCESS_DENIED &&
+	       ask_yes_no_if_possible("Rename from '%s' to '%s' failed. "
+		       "Should I try again?", pold, pnew))
+		goto repeat;
+
+	errno = EACCES;
+	return -1;
+}
+
+/*
+ * Note that this doesn't return the actual pagesize, but
+ * the allocation granularity. If future Windows specific git code
+ * needs the real getpagesize function, we need to find another solution.
+ */
+int mingw_getpagesize(void)
+{
+	SYSTEM_INFO si;
+	GetSystemInfo(&si);
+	return si.dwAllocationGranularity;
+}
+
+/* See https://msdn.microsoft.com/en-us/library/windows/desktop/ms724435.aspx */
+enum EXTENDED_NAME_FORMAT {
+	NameDisplay = 3,
+	NameUserPrincipal = 8
+};
+
+static char *get_extended_user_info(enum EXTENDED_NAME_FORMAT type)
+{
+	DECLARE_PROC_ADDR(secur32.dll, BOOL, GetUserNameExW,
+		enum EXTENDED_NAME_FORMAT, LPCWSTR, PULONG);
+	static wchar_t wbuffer[1024];
+	DWORD len;
+
+	if (!INIT_PROC_ADDR(GetUserNameExW))
+		return NULL;
+
+	len = ARRAY_SIZE(wbuffer);
+	if (GetUserNameExW(type, wbuffer, &len)) {
+		char *converted = xmalloc((len *= 3));
+		if (xwcstoutf(converted, wbuffer, len) >= 0)
+			return converted;
+		free(converted);
+	}
+
+	return NULL;
+}
+
+char *mingw_query_user_email(void)
+{
+	return get_extended_user_info(NameUserPrincipal);
+}
+
+struct passwd *getpwuid(int uid)
+{
+	static unsigned initialized;
+	static char user_name[100];
+	static struct passwd *p;
+	wchar_t buf[100];
+	DWORD len;
+
+	if (initialized)
+		return p;
+
+	len = ARRAY_SIZE(buf);
+	if (!GetUserNameW(buf, &len)) {
+		initialized = 1;
+		return NULL;
+	}
+
+	if (xwcstoutf(user_name, buf, sizeof(user_name)) < 0) {
+		initialized = 1;
+		return NULL;
+	}
+
+	p = xmalloc(sizeof(*p));
+	p->pw_name = user_name;
+	p->pw_gecos = get_extended_user_info(NameDisplay);
+	if (!p->pw_gecos)
+		p->pw_gecos = "unknown";
+	p->pw_dir = NULL;
+
+	initialized = 1;
+	return p;
+}
+
+static HANDLE timer_event;
+static HANDLE timer_thread;
+static int timer_interval;
+static int one_shot;
+static sig_handler_t timer_fn = SIG_DFL, sigint_fn = SIG_DFL;
+
+/* The timer works like this:
+ * The thread, ticktack(), is a trivial routine that most of the time
+ * only waits to receive the signal to terminate. The main thread tells
+ * the thread to terminate by setting the timer_event to the signalled
+ * state.
+ * But ticktack() interrupts the wait state after the timer's interval
+ * length to call the signal handler.
+ */
+
+static unsigned __stdcall ticktack(void *dummy)
+{
+	while (WaitForSingleObject(timer_event, timer_interval) == WAIT_TIMEOUT) {
+		mingw_raise(SIGALRM);
+		if (one_shot)
+			break;
+	}
+	return 0;
+}
+
+static int start_timer_thread(void)
+{
+	timer_event = CreateEvent(NULL, FALSE, FALSE, NULL);
+	if (timer_event) {
+		timer_thread = (HANDLE) _beginthreadex(NULL, 0, ticktack, NULL, 0, NULL);
+		if (!timer_thread )
+			return errno = ENOMEM,
+				error("cannot start timer thread");
+	} else
+		return errno = ENOMEM,
+			error("cannot allocate resources for timer");
+	return 0;
+}
+
+static void stop_timer_thread(void)
+{
+	if (timer_event)
+		SetEvent(timer_event);	/* tell thread to terminate */
+	if (timer_thread) {
+		int rc = WaitForSingleObject(timer_thread, 10000);
+		if (rc == WAIT_TIMEOUT)
+			error("timer thread did not terminate timely");
+		else if (rc != WAIT_OBJECT_0)
+			error("waiting for timer thread failed: %lu",
+			      GetLastError());
+		CloseHandle(timer_thread);
+	}
+	if (timer_event)
+		CloseHandle(timer_event);
+	timer_event = NULL;
+	timer_thread = NULL;
+}
+
+static inline int is_timeval_eq(const struct timeval *i1, const struct timeval *i2)
+{
+	return i1->tv_sec == i2->tv_sec && i1->tv_usec == i2->tv_usec;
+}
+
+int setitimer(int type, struct itimerval *in, struct itimerval *out)
+{
+	static const struct timeval zero;
+	static int atexit_done;
+
+	if (out != NULL)
+		return errno = EINVAL,
+			error("setitimer param 3 != NULL not implemented");
+	if (!is_timeval_eq(&in->it_interval, &zero) &&
+	    !is_timeval_eq(&in->it_interval, &in->it_value))
+		return errno = EINVAL,
+			error("setitimer: it_interval must be zero or eq it_value");
+
+	if (timer_thread)
+		stop_timer_thread();
+
+	if (is_timeval_eq(&in->it_value, &zero) &&
+	    is_timeval_eq(&in->it_interval, &zero))
+		return 0;
+
+	timer_interval = in->it_value.tv_sec * 1000 + in->it_value.tv_usec / 1000;
+	one_shot = is_timeval_eq(&in->it_interval, &zero);
+	if (!atexit_done) {
+		atexit(stop_timer_thread);
+		atexit_done = 1;
+	}
+	return start_timer_thread();
+}
+
+int sigaction(int sig, struct sigaction *in, struct sigaction *out)
+{
+	if (sig != SIGALRM)
+		return errno = EINVAL,
+			error("sigaction only implemented for SIGALRM");
+	if (out != NULL)
+		return errno = EINVAL,
+			error("sigaction: param 3 != NULL not implemented");
+
+	timer_fn = in->sa_handler;
+	return 0;
+}
+
+#undef signal
+sig_handler_t mingw_signal(int sig, sig_handler_t handler)
+{
+	sig_handler_t old;
+
+	switch (sig) {
+	case SIGALRM:
+		old = timer_fn;
+		timer_fn = handler;
+		break;
+
+	case SIGINT:
+		old = sigint_fn;
+		sigint_fn = handler;
+		break;
+
+	default:
+		return signal(sig, handler);
+	}
+
+	return old;
+}
+
+#undef raise
+int mingw_raise(int sig)
+{
+	switch (sig) {
+	case SIGALRM:
+		if (timer_fn == SIG_DFL) {
+			if (isatty(STDERR_FILENO))
+				fputs("Alarm clock\n", stderr);
+			exit(128 + SIGALRM);
+		} else if (timer_fn != SIG_IGN)
+			timer_fn(SIGALRM);
+		return 0;
+
+	case SIGINT:
+		if (sigint_fn == SIG_DFL)
+			exit(128 + SIGINT);
+		else if (sigint_fn != SIG_IGN)
+			sigint_fn(SIGINT);
+		return 0;
+
+#if defined(_MSC_VER)
+	case SIGILL:
+	case SIGFPE:
+	case SIGSEGV:
+	case SIGTERM:
+	case SIGBREAK:
+	case SIGABRT:
+	case SIGABRT_COMPAT:
+		/*
+		 * The <signal.h> header in the MS C Runtime defines 8 signals
+		 * as being supported on the platform. Anything else causes an
+		 * "Invalid signal or error" (which in DEBUG builds causes the
+		 * Abort/Retry/Ignore dialog). We by-pass the CRT for things we
+		 * already know will fail.
+		 */
+		return raise(sig);
+	default:
+		errno = EINVAL;
+		return -1;
+
+#else
+
+	default:
+		return raise(sig);
+
+#endif
+
+	}
+}
+
+int link(const char *oldpath, const char *newpath)
+{
+	wchar_t woldpath[MAX_PATH], wnewpath[MAX_PATH];
+	if (xutftowcs_path(woldpath, oldpath) < 0 ||
+		xutftowcs_path(wnewpath, newpath) < 0)
+		return -1;
+
+	if (!CreateHardLinkW(wnewpath, woldpath, NULL)) {
+		errno = err_win_to_posix(GetLastError());
+		return -1;
+	}
+	return 0;
+}
+
+pid_t waitpid(pid_t pid, int *status, int options)
+{
+	HANDLE h = OpenProcess(SYNCHRONIZE | PROCESS_QUERY_INFORMATION,
+	    FALSE, pid);
+	if (!h) {
+		errno = ECHILD;
+		return -1;
+	}
+
+	if (pid > 0 && options & WNOHANG) {
+		if (WAIT_OBJECT_0 != WaitForSingleObject(h, 0)) {
+			CloseHandle(h);
+			return 0;
+		}
+		options &= ~WNOHANG;
+	}
+
+	if (options == 0) {
+		struct pinfo_t **ppinfo;
+		if (WaitForSingleObject(h, INFINITE) != WAIT_OBJECT_0) {
+			CloseHandle(h);
+			return 0;
+		}
+
+		if (status)
+			GetExitCodeProcess(h, (LPDWORD)status);
+
+		EnterCriticalSection(&pinfo_cs);
+
+		ppinfo = &pinfo;
+		while (*ppinfo) {
+			struct pinfo_t *info = *ppinfo;
+			if (info->pid == pid) {
+				CloseHandle(info->proc);
+				*ppinfo = info->next;
+				free(info);
+				break;
+			}
+			ppinfo = &info->next;
+		}
+
+		LeaveCriticalSection(&pinfo_cs);
+
+		CloseHandle(h);
+		return pid;
+	}
+	CloseHandle(h);
+
+	errno = EINVAL;
+	return -1;
+}
+
+int xutftowcsn(wchar_t *wcs, const char *utfs, size_t wcslen, int utflen)
+{
+	int upos = 0, wpos = 0;
+	const unsigned char *utf = (const unsigned char*) utfs;
+	if (!utf || !wcs || wcslen < 1) {
+		errno = EINVAL;
+		return -1;
+	}
+	/* reserve space for \0 */
+	wcslen--;
+	if (utflen < 0)
+		utflen = INT_MAX;
+
+	while (upos < utflen) {
+		int c = utf[upos++] & 0xff;
+		if (utflen == INT_MAX && c == 0)
+			break;
+
+		if (wpos >= wcslen) {
+			wcs[wpos] = 0;
+			errno = ERANGE;
+			return -1;
+		}
+
+		if (c < 0x80) {
+			/* ASCII */
+			wcs[wpos++] = c;
+		} else if (c >= 0xc2 && c < 0xe0 && upos < utflen &&
+				(utf[upos] & 0xc0) == 0x80) {
+			/* 2-byte utf-8 */
+			c = ((c & 0x1f) << 6);
+			c |= (utf[upos++] & 0x3f);
+			wcs[wpos++] = c;
+		} else if (c >= 0xe0 && c < 0xf0 && upos + 1 < utflen &&
+				!(c == 0xe0 && utf[upos] < 0xa0) && /* over-long encoding */
+				(utf[upos] & 0xc0) == 0x80 &&
+				(utf[upos + 1] & 0xc0) == 0x80) {
+			/* 3-byte utf-8 */
+			c = ((c & 0x0f) << 12);
+			c |= ((utf[upos++] & 0x3f) << 6);
+			c |= (utf[upos++] & 0x3f);
+			wcs[wpos++] = c;
+		} else if (c >= 0xf0 && c < 0xf5 && upos + 2 < utflen &&
+				wpos + 1 < wcslen &&
+				!(c == 0xf0 && utf[upos] < 0x90) && /* over-long encoding */
+				!(c == 0xf4 && utf[upos] >= 0x90) && /* > \u10ffff */
+				(utf[upos] & 0xc0) == 0x80 &&
+				(utf[upos + 1] & 0xc0) == 0x80 &&
+				(utf[upos + 2] & 0xc0) == 0x80) {
+			/* 4-byte utf-8: convert to \ud8xx \udcxx surrogate pair */
+			c = ((c & 0x07) << 18);
+			c |= ((utf[upos++] & 0x3f) << 12);
+			c |= ((utf[upos++] & 0x3f) << 6);
+			c |= (utf[upos++] & 0x3f);
+			c -= 0x10000;
+			wcs[wpos++] = 0xd800 | (c >> 10);
+			wcs[wpos++] = 0xdc00 | (c & 0x3ff);
+		} else if (c >= 0xa0) {
+			/* invalid utf-8 byte, printable unicode char: convert 1:1 */
+			wcs[wpos++] = c;
+		} else {
+			/* invalid utf-8 byte, non-printable unicode: convert to hex */
+			static const char *hex = "0123456789abcdef";
+			wcs[wpos++] = hex[c >> 4];
+			if (wpos < wcslen)
+				wcs[wpos++] = hex[c & 0x0f];
+		}
+	}
+	wcs[wpos] = 0;
+	return wpos;
+}
+
+int xwcstoutf(char *utf, const wchar_t *wcs, size_t utflen)
+{
+	if (!wcs || !utf || utflen < 1) {
+		errno = EINVAL;
+		return -1;
+	}
+	utflen = WideCharToMultiByte(CP_UTF8, 0, wcs, -1, utf, utflen, NULL, NULL);
+	if (utflen)
+		return utflen - 1;
+	errno = ERANGE;
+	return -1;
+}
+
+static void setup_windows_environment(void)
+{
+	char *tmp = getenv("TMPDIR");
+
+	/* on Windows it is TMP and TEMP */
+	if (!tmp) {
+		if (!(tmp = getenv("TMP")))
+			tmp = getenv("TEMP");
+		if (tmp) {
+			setenv("TMPDIR", tmp, 1);
+			tmp = getenv("TMPDIR");
+		}
+	}
+
+	if (tmp) {
+		/*
+		 * Convert all dir separators to forward slashes,
+		 * to help shell commands called from the Git
+		 * executable (by not mistaking the dir separators
+		 * for escape characters).
+		 */
+		convert_slashes(tmp);
+	}
+
+	/* simulate TERM to enable auto-color (see color.c) */
+	if (!getenv("TERM"))
+		setenv("TERM", "cygwin", 1);
+
+	/* calculate HOME if not set */
+	if (!getenv("HOME")) {
+		/*
+		 * try $HOMEDRIVE$HOMEPATH - the home share may be a network
+		 * location, thus also check if the path exists (i.e. is not
+		 * disconnected)
+		 */
+		if ((tmp = getenv("HOMEDRIVE"))) {
+			struct strbuf buf = STRBUF_INIT;
+			strbuf_addstr(&buf, tmp);
+			if ((tmp = getenv("HOMEPATH"))) {
+				strbuf_addstr(&buf, tmp);
+				if (is_directory(buf.buf))
+					setenv("HOME", buf.buf, 1);
+				else
+					tmp = NULL; /* use $USERPROFILE */
+			}
+			strbuf_release(&buf);
+		}
+		/* use $USERPROFILE if the home share is not available */
+		if (!tmp && (tmp = getenv("USERPROFILE")))
+			setenv("HOME", tmp, 1);
+	}
+}
+
+#if !defined(_MSC_VER)
+/*
+ * Disable MSVCRT command line wildcard expansion (__getmainargs called from
+ * mingw startup code, see init.c in mingw runtime).
+ */
+int _CRT_glob = 0;
+#endif
+
+static NORETURN void die_startup(void)
+{
+	fputs("fatal: not enough memory for initialization", stderr);
+	exit(128);
+}
+
+static void *malloc_startup(size_t size)
+{
+	void *result = malloc(size);
+	if (!result)
+		die_startup();
+	return result;
+}
+
+static char *wcstoutfdup_startup(char *buffer, const wchar_t *wcs, size_t len)
+{
+	len = xwcstoutf(buffer, wcs, len) + 1;
+	return memcpy(malloc_startup(len), buffer, len);
+}
+
+static void maybe_redirect_std_handle(const wchar_t *key, DWORD std_id, int fd,
+				      DWORD desired_access, DWORD flags)
+{
+	DWORD create_flag = fd ? OPEN_ALWAYS : OPEN_EXISTING;
+	wchar_t buf[MAX_PATH];
+	DWORD max = ARRAY_SIZE(buf);
+	HANDLE handle;
+	DWORD ret = GetEnvironmentVariableW(key, buf, max);
+
+	if (!ret || ret >= max)
+		return;
+
+	/* make sure this does not leak into child processes */
+	SetEnvironmentVariableW(key, NULL);
+	if (!wcscmp(buf, L"off")) {
+		close(fd);
+		handle = GetStdHandle(std_id);
+		if (handle != INVALID_HANDLE_VALUE)
+			CloseHandle(handle);
+		return;
+	}
+	if (std_id == STD_ERROR_HANDLE && !wcscmp(buf, L"2>&1")) {
+		handle = GetStdHandle(STD_OUTPUT_HANDLE);
+		if (handle == INVALID_HANDLE_VALUE) {
+			close(fd);
+			handle = GetStdHandle(std_id);
+			if (handle != INVALID_HANDLE_VALUE)
+				CloseHandle(handle);
+		} else {
+			int new_fd = _open_osfhandle((intptr_t)handle, O_BINARY);
+			SetStdHandle(std_id, handle);
+			dup2(new_fd, fd);
+			/* do *not* close the new_fd: that would close stdout */
+		}
+		return;
+	}
+	handle = CreateFileW(buf, desired_access, 0, NULL, create_flag,
+			     flags, NULL);
+	if (handle != INVALID_HANDLE_VALUE) {
+		int new_fd = _open_osfhandle((intptr_t)handle, O_BINARY);
+		SetStdHandle(std_id, handle);
+		dup2(new_fd, fd);
+		close(new_fd);
+	}
+}
+
+static void maybe_redirect_std_handles(void)
+{
+	maybe_redirect_std_handle(L"GIT_REDIRECT_STDIN", STD_INPUT_HANDLE, 0,
+				  GENERIC_READ, FILE_ATTRIBUTE_NORMAL);
+	maybe_redirect_std_handle(L"GIT_REDIRECT_STDOUT", STD_OUTPUT_HANDLE, 1,
+				  GENERIC_WRITE, FILE_ATTRIBUTE_NORMAL);
+	maybe_redirect_std_handle(L"GIT_REDIRECT_STDERR", STD_ERROR_HANDLE, 2,
+				  GENERIC_WRITE, FILE_FLAG_NO_BUFFERING);
+}
+
+#ifdef _MSC_VER
+#ifdef _DEBUG
+#include <crtdbg.h>
+#endif
+#endif
+
+/*
+ * We implement wmain() and compile with -municode, which would
+ * normally ignore main(), but we call the latter from the former
+ * so that we can handle non-ASCII command-line parameters
+ * appropriately.
+ *
+ * To be more compatible with the core git code, we convert
+ * argv into UTF8 and pass them directly to main().
+ */
+int wmain(int argc, const wchar_t **wargv)
+{
+	int i, maxlen, exit_status;
+	char *buffer, **save;
+	const char **argv;
+
+	trace2_initialize_clock();
+
+#ifdef _MSC_VER
+#ifdef _DEBUG
+	_CrtSetReportMode(_CRT_ASSERT, _CRTDBG_MODE_DEBUG);
+#endif
+
+#ifdef USE_MSVC_CRTDBG
+	_CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF);
+#endif
+#endif
+
+	maybe_redirect_std_handles();
+
+	/* determine size of argv and environ conversion buffer */
+	maxlen = wcslen(wargv[0]);
+	for (i = 1; i < argc; i++)
+		maxlen = max(maxlen, wcslen(wargv[i]));
+
+	/* allocate buffer (wchar_t encodes to max 3 UTF-8 bytes) */
+	maxlen = 3 * maxlen + 1;
+	buffer = malloc_startup(maxlen);
+
+	/*
+	 * Create a UTF-8 version of w_argv. Also create a "save" copy
+	 * to remember all the string pointers because parse_options()
+	 * will remove claimed items from the argv that we pass down.
+	 */
+	ALLOC_ARRAY(argv, argc + 1);
+	ALLOC_ARRAY(save, argc + 1);
+	for (i = 0; i < argc; i++)
+		argv[i] = save[i] = wcstoutfdup_startup(buffer, wargv[i], maxlen);
+	argv[i] = save[i] = NULL;
+	free(buffer);
+
+	/* fix Windows specific environment settings */
+	setup_windows_environment();
+
+	unset_environment_variables = xstrdup("PERL5LIB");
+
+	/* initialize critical section for waitpid pinfo_t list */
+	InitializeCriticalSection(&pinfo_cs);
+
+	/* set up default file mode and file modes for stdin/out/err */
+	_fmode = _O_BINARY;
+	_setmode(_fileno(stdin), _O_BINARY);
+	_setmode(_fileno(stdout), _O_BINARY);
+	_setmode(_fileno(stderr), _O_BINARY);
+
+	/* initialize Unicode console */
+	winansi_init();
+
+	/* invoke the real main() using our utf8 version of argv. */
+	exit_status = main(argc, argv);
+
+	for (i = 0; i < argc; i++)
+		free(save[i]);
+	free(save);
+	free(argv);
+
+	return exit_status;
+}
+
+int uname(struct utsname *buf)
+{
+	unsigned v = (unsigned)GetVersion();
+	memset(buf, 0, sizeof(*buf));
+	xsnprintf(buf->sysname, sizeof(buf->sysname), "Windows");
+	xsnprintf(buf->release, sizeof(buf->release),
+		 "%u.%u", v & 0xff, (v >> 8) & 0xff);
+	/* assuming NT variants only.. */
+	xsnprintf(buf->version, sizeof(buf->version),
+		  "%u", (v >> 16) & 0x7fff);
+	return 0;
+}