merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

24 files changed, 880 insertions, 238 deletions

diff --git a/third_party/git/compat/bswap.h b/third_party/git/compat/bswap.h
index e4e25735ce..c0bb744adc 100644
--- a/third_party/git/compat/bswap.h
+++ b/third_party/git/compat/bswap.h
@@ -145,28 +145,6 @@ static inline uint64_t git_bswap64(uint64_t x)
 
 #endif
 
-/*
- * Performance might be improved if the CPU architecture is OK with
- * unaligned 32-bit loads and a fast ntohl() is available.
- * Otherwise fall back to byte loads and shifts which is portable,
- * and is faster on architectures with memory alignment issues.
- */
-
-#if !defined(NO_UNALIGNED_LOADS) && ( \
-    defined(__i386__) || defined(__x86_64__) || \
-    defined(_M_IX86) || defined(_M_X64) || \
-    defined(__ppc__) || defined(__ppc64__) || \
-    defined(__powerpc__) || defined(__powerpc64__) || \
-    defined(__s390__) || defined(__s390x__))
-
-#define get_be16(p)	ntohs(*(unsigned short *)(p))
-#define get_be32(p)	ntohl(*(unsigned int *)(p))
-#define get_be64(p)	ntohll(*(uint64_t *)(p))
-#define put_be32(p, v)	do { *(unsigned int *)(p) = htonl(v); } while (0)
-#define put_be64(p, v)	do { *(uint64_t *)(p) = htonll(v); } while (0)
-
-#else
-
 static inline uint16_t get_be16(const void *ptr)
 {
 	const unsigned char *p = ptr;
@@ -212,6 +190,4 @@ static inline void put_be64(void *ptr, uint64_t value)
 	p[7] = value >>  0;
 }
 
-#endif
-
 #endif /* COMPAT_BSWAP_H */
diff --git a/third_party/git/compat/compiler.h b/third_party/git/compat/compiler.h
new file mode 100644
index 0000000000..10dbb65937
--- /dev/null
+++ b/third_party/git/compat/compiler.h
@@ -0,0 +1,41 @@
+#ifndef COMPILER_H
+#define COMPILER_H
+
+#include "git-compat-util.h"
+#include "strbuf.h"
+
+#ifdef __GLIBC__
+#include <gnu/libc-version.h>
+#endif
+
+static inline void get_compiler_info(struct strbuf *info)
+{
+	int len = info->len;
+#ifdef __clang__
+	strbuf_addf(info, "clang: %s\n", __clang_version__);
+#elif defined(__GNUC__)
+	strbuf_addf(info, "gnuc: %d.%d\n", __GNUC__, __GNUC_MINOR__);
+#endif
+
+#ifdef _MSC_VER
+	strbuf_addf(info, "MSVC version: %02d.%02d.%05d\n",
+		    _MSC_VER / 100, _MSC_VER % 100, _MSC_FULL_VER % 100000);
+#endif
+
+	if (len == info->len)
+		strbuf_addstr(info, _("no compiler information available\n"));
+}
+
+static inline void get_libc_info(struct strbuf *info)
+{
+	int len = info->len;
+
+#ifdef __GLIBC__
+	strbuf_addf(info, "glibc: %s\n", gnu_get_libc_version());
+#endif
+
+	if (len == info->len)
+		strbuf_addstr(info, _("no libc information available\n"));
+}
+
+#endif /* COMPILER_H */
diff --git a/third_party/git/compat/gmtime.c b/third_party/git/compat/gmtime.c
deleted file mode 100644
index e8362dd2b9..0000000000
--- a/third_party/git/compat/gmtime.c
+++ /dev/null
@@ -1,29 +0,0 @@
-#include "../git-compat-util.h"
-#undef gmtime
-#undef gmtime_r
-
-struct tm *git_gmtime(const time_t *timep)
-{
-	static struct tm result;
-	return git_gmtime_r(timep, &result);
-}
-
-struct tm *git_gmtime_r(const time_t *timep, struct tm *result)
-{
-	struct tm *ret;
-
-	memset(result, 0, sizeof(*result));
-	ret = gmtime_r(timep, result);
-
-	/*
-	 * Rather than NULL, FreeBSD gmtime simply leaves the "struct tm"
-	 * untouched when it encounters overflow. Since "mday" cannot otherwise
-	 * be zero, we can test this very quickly.
-	 */
-	if (ret && !ret->tm_mday) {
-		ret = NULL;
-		errno = EOVERFLOW;
-	}
-
-	return ret;
-}
diff --git a/third_party/git/compat/mingw.c b/third_party/git/compat/mingw.c
index 738f0a826a..a00f331230 100644
--- a/third_party/git/compat/mingw.c
+++ b/third_party/git/compat/mingw.c
@@ -13,6 +13,19 @@
 
 static const int delay[] = { 0, 1, 10, 20, 40 };
 
+void open_in_gdb(void)
+{
+	static struct child_process cp = CHILD_PROCESS_INIT;
+	extern char *_pgmptr;
+
+	strvec_pushl(&cp.args, "mintty", "gdb", NULL);
+	strvec_pushf(&cp.args, "--pid=%d", getpid());
+	cp.clean_on_exit = 1;
+	if (start_command(&cp) < 0)
+		die_errno("Could not start gdb");
+	sleep(1);
+}
+
 int err_win_to_posix(DWORD winerr)
 {
 	int error = ENOSYS;
@@ -114,6 +127,7 @@ int err_win_to_posix(DWORD winerr)
 	case ERROR_SHARING_BUFFER_EXCEEDED: error = ENFILE; break;
 	case ERROR_SHARING_VIOLATION: error = EACCES; break;
 	case ERROR_STACK_OVERFLOW: error = ENOMEM; break;
+	case ERROR_SUCCESS: BUG("err_win_to_posix() called without an error!");
 	case ERROR_SWAPERROR: error = ENOENT; break;
 	case ERROR_TOO_MANY_MODULES: error = EMFILE; break;
 	case ERROR_TOO_MANY_OPEN_FILES: error = EMFILE; break;
@@ -212,6 +226,7 @@ enum hide_dotfiles_type {
 	HIDE_DOTFILES_DOTGITONLY
 };
 
+static int core_restrict_inherited_handles = -1;
 static enum hide_dotfiles_type hide_dotfiles = HIDE_DOTFILES_DOTGITONLY;
 static char *unset_environment_variables;
 
@@ -231,6 +246,15 @@ int mingw_core_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
+	if (!strcmp(var, "core.restrictinheritedhandles")) {
+		if (value && !strcasecmp(value, "auto"))
+			core_restrict_inherited_handles = -1;
+		else
+			core_restrict_inherited_handles =
+				git_config_bool(var, value);
+		return 0;
+	}
+
 	return 0;
 }
 
@@ -266,6 +290,9 @@ int mingw_unlink(const char *pathname)
 	if (xutftowcs_path(wpathname, pathname) < 0)
 		return -1;
 
+	if (DeleteFileW(wpathname))
+		return 0;
+
 	/* read-only files cannot be removed */
 	_wchmod(wpathname, 0666);
 	while ((ret = _wunlink(wpathname)) == -1 && tries < ARRAY_SIZE(delay)) {
@@ -363,6 +390,8 @@ static inline int needs_hiding(const char *path)
 			/* ignore trailing slashes */
 			if (*path)
 				basename = path;
+			else
+				break;
 		}
 
 	if (hide_dotfiles == HIDE_DOTFILES_TRUE)
@@ -390,6 +419,12 @@ int mingw_mkdir(const char *path, int mode)
 {
 	int ret;
 	wchar_t wpath[MAX_PATH];
+
+	if (!is_valid_win32_path(path, 0)) {
+		errno = EINVAL;
+		return -1;
+	}
+
 	if (xutftowcs_path(wpath, path) < 0)
 		return -1;
 	ret = _wmkdir(wpath);
@@ -428,8 +463,21 @@ static int mingw_open_append(wchar_t const *wfilename, int oflags, ...)
 	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;
+	if (handle == INVALID_HANDLE_VALUE) {
+		DWORD err = GetLastError();
+
+		/*
+		 * Some network storage solutions (e.g. Isilon) might return
+		 * ERROR_INVALID_PARAMETER instead of expected error
+		 * ERROR_PATH_NOT_FOUND, which results in an unknown error. If
+		 * so, let's turn the error to ERROR_PATH_NOT_FOUND instead.
+		 */
+		if (err == ERROR_INVALID_PARAMETER)
+			err = ERROR_PATH_NOT_FOUND;
+
+		errno = err_win_to_posix(err);
+		return -1;
+	}
 
 	/*
 	 * No O_APPEND here, because the CRT uses it only to reset the
@@ -463,7 +511,7 @@ 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;
+	int fd, create = (oflags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL);
 	wchar_t wfilename[MAX_PATH];
 	open_fn_t open_fn;
 
@@ -471,16 +519,21 @@ int mingw_open (const char *filename, int oflags, ...)
 	mode = va_arg(args, int);
 	va_end(args);
 
-	if (filename && !strcmp(filename, "/dev/null"))
-		filename = "nul";
+	if (!is_valid_win32_path(filename, !create)) {
+		errno = create ? EINVAL : ENOENT;
+		return -1;
+	}
 
 	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)
+	if (filename && !strcmp(filename, "/dev/null"))
+		wcscpy(wfilename, L"nul");
+	else if (xutftowcs_path(wfilename, filename) < 0)
 		return -1;
+
 	fd = open_fn(wfilename, oflags, mode);
 
 	if (fd < 0 && (oflags & O_ACCMODE) != O_RDONLY && errno == EACCES) {
@@ -538,10 +591,17 @@ FILE *mingw_fopen (const char *filename, const char *otype)
 	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)
+		wcscpy(wfilename, L"nul");
+	else if (!is_valid_win32_path(filename, 1)) {
+		int create = otype && strchr(otype, 'w');
+		errno = create ? EINVAL : ENOENT;
 		return NULL;
+	} else if (xutftowcs_path(wfilename, filename) < 0)
+		return NULL;
+
+	if (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;
@@ -560,10 +620,17 @@ FILE *mingw_freopen (const char *filename, const char *otype, FILE *stream)
 	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)
+		wcscpy(wfilename, L"nul");
+	else if (!is_valid_win32_path(filename, 1)) {
+		int create = otype && strchr(otype, 'w');
+		errno = create ? EINVAL : ENOENT;
 		return NULL;
+	} else if (xutftowcs_path(wfilename, filename) < 0)
+		return NULL;
+
+	if (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;
@@ -913,7 +980,16 @@ revert_attrs:
 size_t mingw_strftime(char *s, size_t max,
 		      const char *format, const struct tm *tm)
 {
-	size_t ret = strftime(s, max, format, tm);
+	/* a pointer to the original strftime in case we can't find the UCRT version */
+	static size_t (*fallback)(char *, size_t, const char *, const struct tm *) = strftime;
+	size_t ret;
+	DECLARE_PROC_ADDR(ucrtbase.dll, size_t, strftime, char *, size_t,
+		const char *, const struct tm *);
+
+	if (INIT_PROC_ADDR(strftime))
+		ret = strftime(s, max, format, tm);
+	else
+		ret = fallback(s, max, format, tm);
 
 	if (!ret && errno == EINVAL)
 		die("invalid strftime format: '%s'", format);
@@ -984,16 +1060,16 @@ int pipe(int filedes[2])
 
 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;
+	if (gmtime_s(result, timep) == 0)
+		return result;
+	return NULL;
 }
 
 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;
+	if (localtime_s(result, timep) == 0)
+		return result;
+	return NULL;
 }
 
 char *mingw_getcwd(char *pointer, int len)
@@ -1052,7 +1128,7 @@ static const char *quote_arg_msvc(const char *arg)
 				p++;
 				len++;
 			}
-			if (*p == '"')
+			if (*p == '"' || !*p)
 				n += count*2 + 1;
 			continue;
 		}
@@ -1074,16 +1150,19 @@ static const char *quote_arg_msvc(const char *arg)
 				count++;
 				*d++ = *arg++;
 			}
-			if (*arg == '"') {
+			if (*arg == '"' || !*arg) {
 				while (count-- > 0)
 					*d++ = '\\';
+				/* don't escape the surrounding end quote */
+				if (!*arg)
+					break;
 				*d++ = '\\';
 			}
 		}
 		*d++ = *arg++;
 	}
 	*d++ = '"';
-	*d++ = 0;
+	*d++ = '\0';
 	return q;
 }
 
@@ -1096,13 +1175,14 @@ static const char *quote_arg_msys2(const char *arg)
 
 	for (p = arg; *p; p++) {
 		int ws = isspace(*p);
-		if (!ws && *p != '\\' && *p != '"' && *p != '{')
+		if (!ws && *p != '\\' && *p != '"' && *p != '{' && *p != '\'' &&
+		    *p != '?' && *p != '*' && *p != '~')
 			continue;
 		if (!buf.len)
 			strbuf_addch(&buf, '"');
 		if (p != p2)
 			strbuf_add(&buf, p2, p - p2);
-		if (!ws && *p != '{')
+		if (*p == '\\' || *p == '"')
 			strbuf_addch(&buf, '\\');
 		p2 = p;
 	}
@@ -1112,7 +1192,7 @@ static const char *quote_arg_msys2(const char *arg)
 	else if (!buf.len)
 		return arg;
 	else
-		strbuf_add(&buf, p2, p - p2),
+		strbuf_add(&buf, p2, p - p2);
 
 	strbuf_addch(&buf, '"');
 	return strbuf_detach(&buf, 0);
@@ -1161,14 +1241,21 @@ static char *lookup_prog(const char *dir, int dirlen, const char *cmd,
 			 int isexe, int exe_only)
 {
 	char path[MAX_PATH];
+	wchar_t wpath[MAX_PATH];
 	snprintf(path, sizeof(path), "%.*s\\%s.exe", dirlen, dir, cmd);
 
-	if (!isexe && access(path, F_OK) == 0)
+	if (xutftowcs_path(wpath, path) < 0)
+		return NULL;
+
+	if (!isexe && _waccess(wpath, 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))
+	wpath[wcslen(wpath)-4] = '\0';
+	if ((!exe_only || isexe) && _waccess(wpath, F_OK) == 0) {
+		if (!(GetFileAttributesW(wpath) & FILE_ATTRIBUTE_DIRECTORY)) {
+			path[strlen(path)-4] = '\0';
 			return xstrdup(path);
+		}
+	}
 	return NULL;
 }
 
@@ -1183,7 +1270,7 @@ static char *path_lookup(const char *cmd, int exe_only)
 	int len = strlen(cmd);
 	int isexe = len >= 4 && !strcasecmp(cmd+len-4, ".exe");
 
-	if (strchr(cmd, '/') || strchr(cmd, '\\'))
+	if (strpbrk(cmd, "/\\"))
 		return xstrdup(cmd);
 
 	path = mingw_getenv("PATH");
@@ -1229,11 +1316,6 @@ static int wenvcmp(const void *a, const void *b)
 	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.
@@ -1265,15 +1347,15 @@ static wchar_t *make_environment_block(char **deltaenv)
 		}
 
 		ALLOC_ARRAY(result, size);
-		memcpy(result, wenv, size * sizeof(*wenv));
+		COPY_ARRAY(result, wenv, size);
 		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
+	 * sort them using the stable git_stable_qsort() and then copy,
+	 * skipping duplicate keys
 	 */
 	for (p = wenv; p && *p; ) {
 		ALLOC_GROW(array, nr + 1, alloc);
@@ -1296,7 +1378,7 @@ static wchar_t *make_environment_block(char **deltaenv)
 		p += wlen + 1;
 	}
 
-	git_qsort(array, nr, sizeof(*array), wenvcmp);
+	git_stable_qsort(array, nr, sizeof(*array), wenvcmp);
 	ALLOC_ARRAY(result, size + delta_size);
 
 	for (p = result, i = 0; i < nr; i++) {
@@ -1309,7 +1391,7 @@ static wchar_t *make_environment_block(char **deltaenv)
 			continue;
 
 		size = wcslen(array[i]) + 1;
-		memcpy(p, array[i], size * sizeof(*p));
+		COPY_ARRAY(p, array[i], size);
 		p += size;
 	}
 	*p = L'\0';
@@ -1367,7 +1449,10 @@ static inline int match_last_path_component(const char *path, size_t *len,
 
 static int is_msys2_sh(const char *cmd)
 {
-	if (cmd && !strcmp(cmd, "sh")) {
+	if (!cmd)
+		return 0;
+
+	if (!strcmp(cmd, "sh")) {
 		static int ret = -1;
 		char *p;
 
@@ -1387,6 +1472,16 @@ static int is_msys2_sh(const char *cmd)
 		}
 		return ret;
 	}
+
+	if (ends_with(cmd, "\\sh.exe")) {
+		static char *sh;
+
+		if (!sh)
+			sh = path_lookup("sh", 0);
+
+		return !fspathcmp(cmd, sh);
+	}
+
 	return 0;
 }
 
@@ -1394,15 +1489,35 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 			      const char *dir,
 			      int prepend_cmd, int fhin, int fhout, int fherr)
 {
-	STARTUPINFOW si;
+	static int restrict_handle_inheritance = -1;
+	STARTUPINFOEXW si;
 	PROCESS_INFORMATION pi;
+	LPPROC_THREAD_ATTRIBUTE_LIST attr_list = NULL;
+	HANDLE stdhandles[3];
+	DWORD stdhandles_count = 0;
+	SIZE_T size;
 	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;
+		is_msys2_sh(cmd ? cmd : *argv) ?
+		quote_arg_msys2 : quote_arg_msvc;
+	const char *strace_env;
+
+	/* Make sure to override previous errors, if any */
+	errno = 0;
+
+	if (restrict_handle_inheritance < 0)
+		restrict_handle_inheritance = core_restrict_inherited_handles;
+	/*
+	 * The following code to restrict which handles are inherited seems
+	 * to work properly only on Windows 7 and later, so let's disable it
+	 * on Windows Vista and 2008.
+	 */
+	if (restrict_handle_inheritance < 0)
+		restrict_handle_inheritance = GetVersion() >> 16 >= 7601;
 
 	do_unset_environment_variables();
 
@@ -1431,11 +1546,23 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 		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);
+	si.StartupInfo.cb = sizeof(si);
+	si.StartupInfo.hStdInput = winansi_get_osfhandle(fhin);
+	si.StartupInfo.hStdOutput = winansi_get_osfhandle(fhout);
+	si.StartupInfo.hStdError = winansi_get_osfhandle(fherr);
+
+	/* The list of handles cannot contain duplicates */
+	if (si.StartupInfo.hStdInput != INVALID_HANDLE_VALUE)
+		stdhandles[stdhandles_count++] = si.StartupInfo.hStdInput;
+	if (si.StartupInfo.hStdOutput != INVALID_HANDLE_VALUE &&
+	    si.StartupInfo.hStdOutput != si.StartupInfo.hStdInput)
+		stdhandles[stdhandles_count++] = si.StartupInfo.hStdOutput;
+	if (si.StartupInfo.hStdError != INVALID_HANDLE_VALUE &&
+	    si.StartupInfo.hStdError != si.StartupInfo.hStdInput &&
+	    si.StartupInfo.hStdError != si.StartupInfo.hStdOutput)
+		stdhandles[stdhandles_count++] = si.StartupInfo.hStdError;
+	if (stdhandles_count)
+		si.StartupInfo.dwFlags |= STARTF_USESTDHANDLES;
 
 	if (*argv && !strcmp(cmd, *argv))
 		wcmd[0] = L'\0';
@@ -1461,6 +1588,31 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 			free(quoted);
 	}
 
+	strace_env = getenv("GIT_STRACE_COMMANDS");
+	if (strace_env) {
+		char *p = path_lookup("strace.exe", 1);
+		if (!p)
+			return error("strace not found!");
+		if (xutftowcs_path(wcmd, p) < 0) {
+			free(p);
+			return -1;
+		}
+		free(p);
+		if (!strcmp("1", strace_env) ||
+		    !strcasecmp("yes", strace_env) ||
+		    !strcasecmp("true", strace_env))
+			strbuf_insert(&args, 0, "strace ", 7);
+		else {
+			const char *quoted = quote_arg(strace_env);
+			struct strbuf buf = STRBUF_INIT;
+			strbuf_addf(&buf, "strace -o %s ", quoted);
+			if (quoted != strace_env)
+				free((char *)quoted);
+			strbuf_insert(&args, 0, buf.buf, buf.len);
+			strbuf_release(&buf);
+		}
+	}
+
 	ALLOC_ARRAY(wargs, st_add(st_mult(2, args.len), 1));
 	xutftowcs(wargs, args.buf, 2 * args.len + 1);
 	strbuf_release(&args);
@@ -1468,16 +1620,98 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 	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);
+	if (restrict_handle_inheritance && stdhandles_count &&
+	    (InitializeProcThreadAttributeList(NULL, 1, 0, &size) ||
+	     GetLastError() == ERROR_INSUFFICIENT_BUFFER) &&
+	    (attr_list = (LPPROC_THREAD_ATTRIBUTE_LIST)
+			(HeapAlloc(GetProcessHeap(), 0, size))) &&
+	    InitializeProcThreadAttributeList(attr_list, 1, 0, &size) &&
+	    UpdateProcThreadAttribute(attr_list, 0,
+				      PROC_THREAD_ATTRIBUTE_HANDLE_LIST,
+				      stdhandles,
+				      stdhandles_count * sizeof(HANDLE),
+				      NULL, NULL)) {
+		si.lpAttributeList = attr_list;
+		flags |= EXTENDED_STARTUPINFO_PRESENT;
+	}
+
+	ret = CreateProcessW(*wcmd ? wcmd : NULL, wargs, NULL, NULL,
+			     stdhandles_count ? TRUE : FALSE,
+			     flags, wenvblk, dir ? wdir : NULL,
+			     &si.StartupInfo, &pi);
+
+	/*
+	 * On Windows 2008 R2, it seems that specifying certain types of handles
+	 * (such as FILE_TYPE_CHAR or FILE_TYPE_PIPE) will always produce an
+	 * error. Rather than playing finicky and fragile games, let's just try
+	 * to detect this situation and simply try again without restricting any
+	 * handle inheritance. This is still better than failing to create
+	 * processes.
+	 */
+	if (!ret && restrict_handle_inheritance && stdhandles_count) {
+		DWORD err = GetLastError();
+		struct strbuf buf = STRBUF_INIT;
+
+		if (err != ERROR_NO_SYSTEM_RESOURCES &&
+		    /*
+		     * On Windows 7 and earlier, handles on pipes and character
+		     * devices are inherited automatically, and cannot be
+		     * specified in the thread handle list. Rather than trying
+		     * to catch each and every corner case (and running the
+		     * chance of *still* forgetting a few), let's just fall
+		     * back to creating the process without trying to limit the
+		     * handle inheritance.
+		     */
+		    !(err == ERROR_INVALID_PARAMETER &&
+		      GetVersion() >> 16 < 9200) &&
+		    !getenv("SUPPRESS_HANDLE_INHERITANCE_WARNING")) {
+			DWORD fl = 0;
+			int i;
+
+			setenv("SUPPRESS_HANDLE_INHERITANCE_WARNING", "1", 1);
+
+			for (i = 0; i < stdhandles_count; i++) {
+				HANDLE h = stdhandles[i];
+				strbuf_addf(&buf, "handle #%d: %p (type %lx, "
+					    "handle info (%d) %lx\n", i, h,
+					    GetFileType(h),
+					    GetHandleInformation(h, &fl),
+					    fl);
+			}
+			strbuf_addstr(&buf, "\nThis is a bug; please report it "
+				      "at\nhttps://github.com/git-for-windows/"
+				      "git/issues/new\n\n"
+				      "To suppress this warning, please set "
+				      "the environment variable\n\n"
+				      "\tSUPPRESS_HANDLE_INHERITANCE_WARNING=1"
+				      "\n");
+		}
+		restrict_handle_inheritance = 0;
+		flags &= ~EXTENDED_STARTUPINFO_PRESENT;
+		ret = CreateProcessW(*wcmd ? wcmd : NULL, wargs, NULL, NULL,
+				     TRUE, flags, wenvblk, dir ? wdir : NULL,
+				     &si.StartupInfo, &pi);
+		if (!ret)
+			errno = err_win_to_posix(GetLastError());
+		if (ret && buf.len) {
+			warning("failed to restrict file handles (%ld)\n\n%s",
+				err, buf.buf);
+		}
+		strbuf_release(&buf);
+	} else if (!ret)
+		errno = err_win_to_posix(GetLastError());
+
+	if (si.lpAttributeList)
+		DeleteProcThreadAttributeList(si.lpAttributeList);
+	if (attr_list)
+		HeapFree(GetProcessHeap(), 0, attr_list);
 
 	free(wenvblk);
 	free(wargs);
 
-	if (!ret) {
-		errno = ENOENT;
+	if (!ret)
 		return -1;
-	}
+
 	CloseHandle(pi.hThread);
 
 	/*
@@ -1562,7 +1796,7 @@ static int try_shell_exec(const char *cmd, char *const *argv)
 		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);
+		COPY_ARRAY(&argv2[1], &argv[1], argc);
 		exec_id = trace2_exec(prog, argv2);
 		pid = mingw_spawnv(prog, argv2, 1);
 		if (pid >= 0) {
@@ -1663,6 +1897,8 @@ char *mingw_getenv(const char *name)
 	if (!w_key)
 		die("Out of memory, (tried to allocate %u wchar_t's)", len_key);
 	xutftowcs(w_key, name, len_key);
+	/* GetEnvironmentVariableW() only sets the last error upon failure */
+	SetLastError(ERROR_SUCCESS);
 	len_value = GetEnvironmentVariableW(w_key, w_value, ARRAY_SIZE(w_value));
 	if (!len_value && GetLastError() == ERROR_ENVVAR_NOT_FOUND) {
 		free(w_key);
@@ -2361,6 +2597,130 @@ static void setup_windows_environment(void)
 	}
 }
 
+int is_valid_win32_path(const char *path, int allow_literal_nul)
+{
+	const char *p = path;
+	int preceding_space_or_period = 0, i = 0, periods = 0;
+
+	if (!protect_ntfs)
+		return 1;
+
+	skip_dos_drive_prefix((char **)&path);
+	goto segment_start;
+
+	for (;;) {
+		char c = *(path++);
+		switch (c) {
+		case '\0':
+		case '/': case '\\':
+			/* cannot end in ` ` or `.`, except for `.` and `..` */
+			if (preceding_space_or_period &&
+			    (i != periods || periods > 2))
+				return 0;
+			if (!c)
+				return 1;
+
+			i = periods = preceding_space_or_period = 0;
+
+segment_start:
+			switch (*path) {
+			case 'a': case 'A': /* AUX */
+				if (((c = path[++i]) != 'u' && c != 'U') ||
+				    ((c = path[++i]) != 'x' && c != 'X')) {
+not_a_reserved_name:
+					path += i;
+					continue;
+				}
+				break;
+			case 'c': case 'C':
+				/* COM1 ... COM9, CON, CONIN$, CONOUT$ */
+				if ((c = path[++i]) != 'o' && c != 'O')
+					goto not_a_reserved_name;
+				c = path[++i];
+				if (c == 'm' || c == 'M') { /* COM1 ... COM9 */
+					c = path[++i];
+					if (c < '1' || c > '9')
+						goto not_a_reserved_name;
+				} else if (c == 'n' || c == 'N') { /* CON */
+					c = path[i + 1];
+					if ((c == 'i' || c == 'I') &&
+					    ((c = path[i + 2]) == 'n' ||
+					     c == 'N') &&
+					    path[i + 3] == '$')
+						i += 3; /* CONIN$ */
+					else if ((c == 'o' || c == 'O') &&
+						 ((c = path[i + 2]) == 'u' ||
+						  c == 'U') &&
+						 ((c = path[i + 3]) == 't' ||
+						  c == 'T') &&
+						 path[i + 4] == '$')
+						i += 4; /* CONOUT$ */
+				} else
+					goto not_a_reserved_name;
+				break;
+			case 'l': case 'L': /* LPT<N> */
+				if (((c = path[++i]) != 'p' && c != 'P') ||
+				    ((c = path[++i]) != 't' && c != 'T') ||
+				    !isdigit(path[++i]))
+					goto not_a_reserved_name;
+				break;
+			case 'n': case 'N': /* NUL */
+				if (((c = path[++i]) != 'u' && c != 'U') ||
+				    ((c = path[++i]) != 'l' && c != 'L') ||
+				    (allow_literal_nul &&
+				     !path[i + 1] && p == path))
+					goto not_a_reserved_name;
+				break;
+			case 'p': case 'P': /* PRN */
+				if (((c = path[++i]) != 'r' && c != 'R') ||
+				    ((c = path[++i]) != 'n' && c != 'N'))
+					goto not_a_reserved_name;
+				break;
+			default:
+				continue;
+			}
+
+			/*
+			 * So far, this looks like a reserved name. Let's see
+			 * whether it actually is one: trailing spaces, a file
+			 * extension, or an NTFS Alternate Data Stream do not
+			 * matter, the name is still reserved if any of those
+			 * follow immediately after the actual name.
+			 */
+			i++;
+			if (path[i] == ' ') {
+				preceding_space_or_period = 1;
+				while (path[++i] == ' ')
+					; /* skip all spaces */
+			}
+
+			c = path[i];
+			if (c && c != '.' && c != ':' && c != '/' && c != '\\')
+				goto not_a_reserved_name;
+
+			/* contains reserved name */
+			return 0;
+		case '.':
+			periods++;
+			/* fallthru */
+		case ' ':
+			preceding_space_or_period = 1;
+			i++;
+			continue;
+		case ':': /* DOS drive prefix was already skipped */
+		case '<': case '>': case '"': case '|': case '?': case '*':
+			/* illegal character */
+			return 0;
+		default:
+			if (c > '\0' && c < '\x20')
+				/* illegal character */
+				return 0;
+		}
+		preceding_space_or_period = 0;
+		i++;
+	}
+}
+
 #if !defined(_MSC_VER)
 /*
  * Disable MSVCRT command line wildcard expansion (__getmainargs called from
diff --git a/third_party/git/compat/mingw.h b/third_party/git/compat/mingw.h
index a03e40e6e2..af8eddd73e 100644
--- a/third_party/git/compat/mingw.h
+++ b/third_party/git/compat/mingw.h
@@ -11,7 +11,7 @@ typedef _sigset_t sigset_t;
 #undef _POSIX_THREAD_SAFE_FUNCTIONS
 #endif
 
-extern int mingw_core_config(const char *var, const char *value, void *cb);
+int mingw_core_config(const char *var, const char *value, void *cb);
 #define platform_core_config mingw_core_config
 
 /*
@@ -443,7 +443,7 @@ static inline void convert_slashes(char *path)
 			*path = '/';
 }
 #define PATH_SEP ';'
-extern char *mingw_query_user_email(void);
+char *mingw_query_user_email(void);
 #define query_user_email mingw_query_user_email
 #if !defined(__MINGW64_VERSION_MAJOR) && (!defined(_MSC_VER) || _MSC_VER < 1800)
 #define PRIuMAX "I64u"
@@ -453,6 +453,27 @@ extern char *mingw_query_user_email(void);
 #endif
 
 /**
+ * Verifies that the given path is a valid one on Windows.
+ *
+ * In particular, path segments are disallowed which
+ *
+ * - end in a period or a space (except the special directories `.` and `..`).
+ *
+ * - contain any of the reserved characters, e.g. `:`, `;`, `*`, etc
+ *
+ * - correspond to reserved names (such as `AUX`, `PRN`, etc)
+ *
+ * The `allow_literal_nul` parameter controls whether the path `NUL` should
+ * be considered valid (this makes sense e.g. before opening files, as it is
+ * perfectly legitimate to open `NUL` on Windows, just as it is to open
+ * `/dev/null` on Unix/Linux).
+ *
+ * Returns 1 upon success, otherwise 0.
+ */
+int is_valid_win32_path(const char *path, int allow_literal_nul);
+#define is_valid_path(path) is_valid_win32_path(path, 0)
+
+/**
  * Converts UTF-8 encoded string to UTF-16LE.
  *
  * To support repositories with legacy-encoded file names, invalid UTF-8 bytes
@@ -558,7 +579,7 @@ int xwcstoutf(char *utf, const wchar_t *wcs, size_t utflen);
 
 /*
  * A critical section used in the implementation of the spawn
- * functions (mingw_spawnv[p]e()) and waitpid(). Intialised in
+ * functions (mingw_spawnv[p]e()) and waitpid(). Initialised in
  * the replacement main() macro below.
  */
 extern CRITICAL_SECTION pinfo_cs;
@@ -578,6 +599,16 @@ int wmain(int argc, const wchar_t **w_argv);
 int main(int argc, const char **argv);
 
 /*
+ * For debugging: if a problem occurs, say, in a Git process that is spawned
+ * from another Git process which in turn is spawned from yet another Git
+ * process, it can be quite daunting to figure out what is going on.
+ *
+ * Call this function to open a new MinTTY (this assumes you are in Git for
+ * Windows' SDK) with a GDB that attaches to the current process right away.
+ */
+void open_in_gdb(void);
+
+/*
  * Used by Pthread API implementation for Windows
  */
-extern int err_win_to_posix(DWORD winerr);
+int err_win_to_posix(DWORD winerr);
diff --git a/third_party/git/compat/nedmalloc/malloc.c.h b/third_party/git/compat/nedmalloc/malloc.c.h
index b833ff9225..814845d4b3 100644
--- a/third_party/git/compat/nedmalloc/malloc.c.h
+++ b/third_party/git/compat/nedmalloc/malloc.c.h
@@ -1564,7 +1564,7 @@ static FORCEINLINE void* win32direct_mmap(size_t size) {
   return (ptr != 0)? ptr: MFAIL;
 }
 
-/* This function supports releasing coalesed segments */
+/* This function supports releasing coalesced segments */
 static FORCEINLINE int win32munmap(void* ptr, size_t size) {
   MEMORY_BASIC_INFORMATION minfo;
   char* cptr = (char*)ptr;
@@ -1655,7 +1655,7 @@ static FORCEINLINE int win32munmap(void* ptr, size_t size) {
     #define CALL_MREMAP(addr, osz, nsz, mv)     MFAIL
 #endif /* HAVE_MMAP && HAVE_MREMAP */
 
-/* mstate bit set if continguous morecore disabled or failed */
+/* mstate bit set if contiguous morecore disabled or failed */
 #define USE_NONCONTIGUOUS_BIT (4U)
 
 /* segment bit set in create_mspace_with_base */
@@ -1755,10 +1755,10 @@ static FORCEINLINE void pthread_release_lock (MLOCK_T *sl) {
   assert(sl->l != 0);
   assert(sl->threadid == CURRENT_THREAD);
   if (--sl->c == 0) {
-    sl->threadid = 0;
     volatile unsigned int* lp = &sl->l;
     int prev = 0;
     int ret;
+    sl->threadid = 0;
     __asm__ __volatile__ ("lock; xchgl %0, %1"
 			  : "=r" (ret)
 			  : "m" (*(lp)), "0"(prev)
@@ -2485,7 +2485,7 @@ typedef struct malloc_segment* msegmentptr;
 
   Trim support
     Fields holding the amount of unused topmost memory that should trigger
-    timming, and a counter to force periodic scanning to release unused
+    timing, and a counter to force periodic scanning to release unused
     non-topmost segments.
 
   Locking
@@ -3066,7 +3066,7 @@ static int init_mparams(void) {
 #if !ONLY_MSPACES
     /* Set up lock for main malloc area */
     gm->mflags = mparams.default_mflags;
-    INITIAL_LOCK(&gm->mutex);
+    (void)INITIAL_LOCK(&gm->mutex);
 #endif
 
 #if (FOOTERS && !INSECURE)
@@ -5017,7 +5017,7 @@ static mstate init_user_mstate(char* tbase, size_t tsize) {
   mchunkptr msp = align_as_chunk(tbase);
   mstate m = (mstate)(chunk2mem(msp));
   memset(m, 0, msize);
-  INITIAL_LOCK(&m->mutex);
+  (void)INITIAL_LOCK(&m->mutex);
   msp->head = (msize|PINUSE_BIT|CINUSE_BIT);
   m->seg.base = m->least_addr = tbase;
   m->seg.size = m->footprint = m->max_footprint = tsize;
diff --git a/third_party/git/compat/obstack.h b/third_party/git/compat/obstack.h
index ae36ed6a66..f90a46d9b9 100644
--- a/third_party/git/compat/obstack.h
+++ b/third_party/git/compat/obstack.h
@@ -79,7 +79,7 @@ change its address during its lifetime.
 When the chars burst over a chunk boundary, we allocate a larger
 chunk, and then copy the partly formed object from the end of the old
 chunk to the beginning of the new larger chunk.  We then carry on
-accreting characters to the end of the object as we normally would.
+accrediting characters to the end of the object as we normally would.
 
 A special macro is provided to add a single char at a time to a
 growing object.  This allows the use of register variables, which
@@ -135,8 +135,10 @@ extern "C" {
    alignment relative to 0.  */
 
 #define __PTR_ALIGN(B, P, A)						    \
-  __BPTR_ALIGN (sizeof (PTR_INT_TYPE) < sizeof (void *) ? (B) : (char *) 0, \
-		P, A)
+  (sizeof (PTR_INT_TYPE) < sizeof(void *) ?                                 \
+   __BPTR_ALIGN((B), (P), (A)) :                                            \
+   (void *)__BPTR_ALIGN((PTR_INT_TYPE)(void *)0, (PTR_INT_TYPE)(P), (A))            \
+  )
 
 #include <string.h>
 
diff --git a/third_party/git/compat/poll/poll.c b/third_party/git/compat/poll/poll.c
index 0e95dd493c..afa6d24584 100644
--- a/third_party/git/compat/poll/poll.c
+++ b/third_party/git/compat/poll/poll.c
@@ -139,22 +139,10 @@ win32_compute_revents (HANDLE h, int *p_sought)
   INPUT_RECORD *irbuffer;
   DWORD avail, nbuffer;
   BOOL bRet;
-  IO_STATUS_BLOCK iosb;
-  FILE_PIPE_LOCAL_INFORMATION fpli;
-  static PNtQueryInformationFile NtQueryInformationFile;
-  static BOOL once_only;
 
   switch (GetFileType (h))
     {
     case FILE_TYPE_PIPE:
-      if (!once_only)
-	{
-	  NtQueryInformationFile = (PNtQueryInformationFile)(void (*)(void))
-	    GetProcAddress (GetModuleHandleW (L"ntdll.dll"),
-			    "NtQueryInformationFile");
-	  once_only = TRUE;
-	}
-
       happened = 0;
       if (PeekNamedPipe (h, NULL, 0, NULL, &avail, NULL) != 0)
 	{
@@ -166,22 +154,9 @@ win32_compute_revents (HANDLE h, int *p_sought)
 
       else
 	{
-	  /* It was the write-end of the pipe.  Check if it is writable.
-	     If NtQueryInformationFile fails, optimistically assume the pipe is
-	     writable.  This could happen on Win9x, where NtQueryInformationFile
-	     is not available, or if we inherit a pipe that doesn't permit
-	     FILE_READ_ATTRIBUTES access on the write end (I think this should
-	     not happen since WinXP SP2; WINE seems fine too).  Otherwise,
-	     ensure that enough space is available for atomic writes.  */
-	  memset (&iosb, 0, sizeof (iosb));
-	  memset (&fpli, 0, sizeof (fpli));
-
-	  if (!NtQueryInformationFile
-	      || NtQueryInformationFile (h, &iosb, &fpli, sizeof (fpli),
-					 FilePipeLocalInformation)
-	      || fpli.WriteQuotaAvailable >= PIPE_BUF
-	      || (fpli.OutboundQuota < PIPE_BUF &&
-		  fpli.WriteQuotaAvailable == fpli.OutboundQuota))
+	  /* It was the write-end of the pipe. Unfortunately there is no
+	     reliable way of knowing if it can be written without blocking.
+	     Just say that it's all good. */
 	    happened |= *p_sought & (POLLOUT | POLLWRNORM | POLLWRBAND);
 	}
       return happened;
diff --git a/third_party/git/compat/qsort.c b/third_party/git/compat/qsort.c
deleted file mode 100644
index 7d071afb70..0000000000
--- a/third_party/git/compat/qsort.c
+++ /dev/null
@@ -1,62 +0,0 @@
-#include "../git-compat-util.h"
-
-/*
- * A merge sort implementation, simplified from the qsort implementation
- * by Mike Haertel, which is a part of the GNU C Library.
- */
-
-static void msort_with_tmp(void *b, size_t n, size_t s,
-			   int (*cmp)(const void *, const void *),
-			   char *t)
-{
-	char *tmp;
-	char *b1, *b2;
-	size_t n1, n2;
-
-	if (n <= 1)
-		return;
-
-	n1 = n / 2;
-	n2 = n - n1;
-	b1 = b;
-	b2 = (char *)b + (n1 * s);
-
-	msort_with_tmp(b1, n1, s, cmp, t);
-	msort_with_tmp(b2, n2, s, cmp, t);
-
-	tmp = t;
-
-	while (n1 > 0 && n2 > 0) {
-		if (cmp(b1, b2) <= 0) {
-			memcpy(tmp, b1, s);
-			tmp += s;
-			b1 += s;
-			--n1;
-		} else {
-			memcpy(tmp, b2, s);
-			tmp += s;
-			b2 += s;
-			--n2;
-		}
-	}
-	if (n1 > 0)
-		memcpy(tmp, b1, n1 * s);
-	memcpy(b, t, (n - n2) * s);
-}
-
-void git_qsort(void *b, size_t n, size_t s,
-	       int (*cmp)(const void *, const void *))
-{
-	const size_t size = st_mult(n, s);
-	char buf[1024];
-
-	if (size < sizeof(buf)) {
-		/* The temporary array fits on the small on-stack buffer. */
-		msort_with_tmp(b, n, s, cmp, buf);
-	} else {
-		/* It's somewhat large, so malloc it.  */
-		char *tmp = xmalloc(size);
-		msort_with_tmp(b, n, s, cmp, tmp);
-		free(tmp);
-	}
-}
diff --git a/third_party/git/compat/regex/regcomp.c b/third_party/git/compat/regex/regcomp.c
index c0d838834a..d1bc09e49b 100644
--- a/third_party/git/compat/regex/regcomp.c
+++ b/third_party/git/compat/regex/regcomp.c
@@ -3462,7 +3462,7 @@ build_equiv_class (bitset_t sbcset, const unsigned char *name)
 	/* This isn't a valid character.  */
 	return REG_ECOLLATE;
 
-      /* Build single byte matcing table for this equivalence class.  */
+      /* Build single byte matching table for this equivalence class.  */
       char_buf[1] = (unsigned char) '\0';
       len = weights[idx1 & 0xffffff];
       for (ch = 0; ch < SBC_MAX; ++ch)
diff --git a/third_party/git/compat/regex/regex.c b/third_party/git/compat/regex/regex.c
index f3e03a9eab..e6f4a5d177 100644
--- a/third_party/git/compat/regex/regex.c
+++ b/third_party/git/compat/regex/regex.c
@@ -60,6 +60,7 @@
    #undefs RE_DUP_MAX and sets it to the right value.  */
 #include <limits.h>
 #include <stdint.h>
+#include <stdlib.h>
 
 #ifdef GAWK
 #undef alloca
diff --git a/third_party/git/compat/regex/regex.h b/third_party/git/compat/regex/regex.h
index 4d81358a83..2d3412860d 100644
--- a/third_party/git/compat/regex/regex.h
+++ b/third_party/git/compat/regex/regex.h
@@ -41,6 +41,11 @@
 extern "C" {
 #endif
 
+#define regcomp git_regcomp
+#define regexec git_regexec
+#define regerror git_regerror
+#define regfree git_regfree
+
 /* The following two types have to be signed and unsigned integer type
    wide enough to hold a value of a pointer.  For most ANSI compilers
    ptrdiff_t and size_t should be likely OK.  Still size of these two
@@ -322,7 +327,7 @@ typedef enum
   /* POSIX regcomp return error codes.  (In the order listed in the
      standard.)  */
   REG_BADPAT,		/* Invalid pattern.  */
-  REG_ECOLLATE,		/* Inalid collating element.  */
+  REG_ECOLLATE,		/* Invalid collating element.  */
   REG_ECTYPE,		/* Invalid character class name.  */
   REG_EESCAPE,		/* Trailing backslash.  */
   REG_ESUBREG,		/* Invalid back reference.  */
diff --git a/third_party/git/compat/regex/regex_internal.c b/third_party/git/compat/regex/regex_internal.c
index 59bf151336..ec51cf3446 100644
--- a/third_party/git/compat/regex/regex_internal.c
+++ b/third_party/git/compat/regex/regex_internal.c
@@ -1616,7 +1616,7 @@ free_state (re_dfastate_t *state)
   re_free (state);
 }
 
-/* Create the new state which is independ of contexts.
+/* Create the new state which is independent of contexts.
    Return the new state if succeeded, otherwise return NULL.  */
 
 static re_dfastate_t *
diff --git a/third_party/git/compat/regex/regex_internal.h b/third_party/git/compat/regex/regex_internal.h
index 3ee8aae59d..0bad8b841e 100644
--- a/third_party/git/compat/regex/regex_internal.h
+++ b/third_party/git/compat/regex/regex_internal.h
@@ -23,7 +23,6 @@
 #include <assert.h>
 #include <ctype.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 
 #if defined HAVE_LANGINFO_H || defined HAVE_LANGINFO_CODESET || defined _LIBC
diff --git a/third_party/git/compat/regex/regexec.c b/third_party/git/compat/regex/regexec.c
index 1b5d89fd5e..49358ae475 100644
--- a/third_party/git/compat/regex/regexec.c
+++ b/third_party/git/compat/regex/regexec.c
@@ -2420,7 +2420,7 @@ find_recover_state (reg_errcode_t *err, re_match_context_t *mctx)
 /* From the node set CUR_NODES, pick up the nodes whose types are
    OP_OPEN_SUBEXP and which have corresponding back references in the regular
    expression. And register them to use them later for evaluating the
-   correspoding back references.  */
+   corresponding back references.  */
 
 static reg_errcode_t
 internal_function
@@ -3347,7 +3347,7 @@ build_trtable (const re_dfa_t *dfa, re_dfastate_t *state)
   dests_node = dests_alloc->dests_node;
   dests_ch = dests_alloc->dests_ch;
 
-  /* Initialize transiton table.  */
+  /* Initialize transition table.  */
   state->word_trtable = state->trtable = NULL;
 
   /* At first, group all nodes belonging to `state' into several
diff --git a/third_party/git/compat/terminal.c b/third_party/git/compat/terminal.c
index fa13ee672d..43b73ddc75 100644
--- a/third_party/git/compat/terminal.c
+++ b/third_party/git/compat/terminal.c
@@ -2,6 +2,9 @@
 #include "compat/terminal.h"
 #include "sigchain.h"
 #include "strbuf.h"
+#include "run-command.h"
+#include "string-list.h"
+#include "hashmap.h"
 
 #if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE)
 
@@ -32,7 +35,7 @@ static void restore_term(void)
 	term_fd = -1;
 }
 
-static int disable_echo(void)
+static int disable_bits(tcflag_t bits)
 {
 	struct termios t;
 
@@ -43,7 +46,7 @@ static int disable_echo(void)
 	old_term = t;
 	sigchain_push_common(restore_term_on_signal);
 
-	t.c_lflag &= ~ECHO;
+	t.c_lflag &= ~bits;
 	if (!tcsetattr(term_fd, TCSAFLUSH, &t))
 		return 0;
 
@@ -53,17 +56,44 @@ error:
 	return -1;
 }
 
+static int disable_echo(void)
+{
+	return disable_bits(ECHO);
+}
+
+static int enable_non_canonical(void)
+{
+	return disable_bits(ICANON | ECHO);
+}
+
 #elif defined(GIT_WINDOWS_NATIVE)
 
 #define INPUT_PATH "CONIN$"
 #define OUTPUT_PATH "CONOUT$"
 #define FORCE_TEXT "t"
 
+static int use_stty = 1;
+static struct string_list stty_restore = STRING_LIST_INIT_DUP;
 static HANDLE hconin = INVALID_HANDLE_VALUE;
 static DWORD cmode;
 
 static void restore_term(void)
 {
+	if (use_stty) {
+		int i;
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		if (stty_restore.nr == 0)
+			return;
+
+		strvec_push(&cp.args, "stty");
+		for (i = 0; i < stty_restore.nr; i++)
+			strvec_push(&cp.args, stty_restore.items[i].string);
+		run_command(&cp);
+		string_list_clear(&stty_restore, 0);
+		return;
+	}
+
 	if (hconin == INVALID_HANDLE_VALUE)
 		return;
 
@@ -72,8 +102,39 @@ static void restore_term(void)
 	hconin = INVALID_HANDLE_VALUE;
 }
 
-static int disable_echo(void)
+static int disable_bits(DWORD bits)
 {
+	if (use_stty) {
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		strvec_push(&cp.args, "stty");
+
+		if (bits & ENABLE_LINE_INPUT) {
+			string_list_append(&stty_restore, "icanon");
+			strvec_push(&cp.args, "-icanon");
+		}
+
+		if (bits & ENABLE_ECHO_INPUT) {
+			string_list_append(&stty_restore, "echo");
+			strvec_push(&cp.args, "-echo");
+		}
+
+		if (bits & ENABLE_PROCESSED_INPUT) {
+			string_list_append(&stty_restore, "-ignbrk");
+			string_list_append(&stty_restore, "intr");
+			string_list_append(&stty_restore, "^c");
+			strvec_push(&cp.args, "ignbrk");
+			strvec_push(&cp.args, "intr");
+			strvec_push(&cp.args, "");
+		}
+
+		if (run_command(&cp) == 0)
+			return 0;
+
+		/* `stty` could not be executed; access the Console directly */
+		use_stty = 0;
+	}
+
 	hconin = CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE,
 	    FILE_SHARE_READ, NULL, OPEN_EXISTING,
 	    FILE_ATTRIBUTE_NORMAL, NULL);
@@ -82,7 +143,7 @@ static int disable_echo(void)
 
 	GetConsoleMode(hconin, &cmode);
 	sigchain_push_common(restore_term_on_signal);
-	if (!SetConsoleMode(hconin, cmode & (~ENABLE_ECHO_INPUT))) {
+	if (!SetConsoleMode(hconin, cmode & ~bits)) {
 		CloseHandle(hconin);
 		hconin = INVALID_HANDLE_VALUE;
 		return -1;
@@ -91,6 +152,47 @@ static int disable_echo(void)
 	return 0;
 }
 
+static int disable_echo(void)
+{
+	return disable_bits(ENABLE_ECHO_INPUT);
+}
+
+static int enable_non_canonical(void)
+{
+	return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
+}
+
+/*
+ * Override `getchar()`, as the default implementation does not use
+ * `ReadFile()`.
+ *
+ * This poses a problem when we want to see whether the standard
+ * input has more characters, as the default of Git for Windows is to start the
+ * Bash in a MinTTY, which uses a named pipe to emulate a pty, in which case
+ * our `poll()` emulation calls `PeekNamedPipe()`, which seems to require
+ * `ReadFile()` to be called first to work properly (it only reports 0
+ * available bytes, otherwise).
+ *
+ * So let's just override `getchar()` with a version backed by `ReadFile()` and
+ * go our merry ways from here.
+ */
+static int mingw_getchar(void)
+{
+	DWORD read = 0;
+	unsigned char ch;
+
+	if (!ReadFile(GetStdHandle(STD_INPUT_HANDLE), &ch, 1, &read, NULL))
+		return EOF;
+
+	if (!read) {
+		error("Unexpected 0 read");
+		return EOF;
+	}
+
+	return ch;
+}
+#define getchar mingw_getchar
+
 #endif
 
 #ifndef FORCE_TEXT
@@ -137,6 +239,126 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return buf.buf;
 }
 
+/*
+ * The `is_known_escape_sequence()` function returns 1 if the passed string
+ * corresponds to an Escape sequence that the terminal capabilities contains.
+ *
+ * To avoid depending on ncurses or other platform-specific libraries, we rely
+ * on the presence of the `infocmp` executable to do the job for us (failing
+ * silently if the program is not available or refused to run).
+ */
+struct escape_sequence_entry {
+	struct hashmap_entry entry;
+	char sequence[FLEX_ARRAY];
+};
+
+static int sequence_entry_cmp(const void *hashmap_cmp_fn_data,
+			      const struct escape_sequence_entry *e1,
+			      const struct escape_sequence_entry *e2,
+			      const void *keydata)
+{
+	return strcmp(e1->sequence, keydata ? keydata : e2->sequence);
+}
+
+static int is_known_escape_sequence(const char *sequence)
+{
+	static struct hashmap sequences;
+	static int initialized;
+
+	if (!initialized) {
+		struct child_process cp = CHILD_PROCESS_INIT;
+		struct strbuf buf = STRBUF_INIT;
+		char *p, *eol;
+
+		hashmap_init(&sequences, (hashmap_cmp_fn)sequence_entry_cmp,
+			     NULL, 0);
+
+		strvec_pushl(&cp.args, "infocmp", "-L", "-1", NULL);
+		if (pipe_command(&cp, NULL, 0, &buf, 0, NULL, 0))
+			strbuf_setlen(&buf, 0);
+
+		for (eol = p = buf.buf; *p; p = eol + 1) {
+			p = strchr(p, '=');
+			if (!p)
+				break;
+			p++;
+			eol = strchrnul(p, '\n');
+
+			if (starts_with(p, "\\E")) {
+				char *comma = memchr(p, ',', eol - p);
+				struct escape_sequence_entry *e;
+
+				p[0] = '^';
+				p[1] = '[';
+				FLEX_ALLOC_MEM(e, sequence, p, comma - p);
+				hashmap_entry_init(&e->entry,
+						   strhash(e->sequence));
+				hashmap_add(&sequences, &e->entry);
+			}
+			if (!*eol)
+				break;
+		}
+		initialized = 1;
+	}
+
+	return !!hashmap_get_from_hash(&sequences, strhash(sequence), sequence);
+}
+
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	int ch;
+
+	if (warning_displayed || enable_non_canonical() < 0) {
+		if (!warning_displayed) {
+			warning("reading single keystrokes not supported on "
+				"this platform; reading line instead");
+			warning_displayed = 1;
+		}
+
+		return strbuf_getline(buf, stdin);
+	}
+
+	strbuf_reset(buf);
+	ch = getchar();
+	if (ch == EOF) {
+		restore_term();
+		return EOF;
+	}
+	strbuf_addch(buf, ch);
+
+	if (ch == '\033' /* ESC */) {
+		/*
+		 * We are most likely looking at an Escape sequence. Let's try
+		 * to read more bytes, waiting at most half a second, assuming
+		 * that the sequence is complete if we did not receive any byte
+		 * within that time.
+		 *
+		 * Start by replacing the Escape byte with ^[ */
+		strbuf_splice(buf, buf->len - 1, 1, "^[", 2);
+
+		/*
+		 * Query the terminal capabilities once about all the Escape
+		 * sequences it knows about, so that we can avoid waiting for
+		 * half a second when we know that the sequence is complete.
+		 */
+		while (!is_known_escape_sequence(buf->buf)) {
+			struct pollfd pfd = { .fd = 0, .events = POLLIN };
+
+			if (poll(&pfd, 1, 500) < 1)
+				break;
+
+			ch = getchar();
+			if (ch == EOF)
+				return 0;
+			strbuf_addch(buf, ch);
+		}
+	}
+
+	restore_term();
+	return 0;
+}
+
 #else
 
 char *git_terminal_prompt(const char *prompt, int echo)
@@ -144,4 +366,23 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return getpass(prompt);
 }
 
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	const char *res;
+
+	if (!warning_displayed) {
+		warning("reading single keystrokes not supported on this "
+			"platform; reading line instead");
+		warning_displayed = 1;
+	}
+
+	res = getpass("");
+	strbuf_reset(buf);
+	if (!res)
+		return EOF;
+	strbuf_addstr(buf, res);
+	return 0;
+}
+
 #endif
diff --git a/third_party/git/compat/terminal.h b/third_party/git/compat/terminal.h
index 97db7cd69d..a9d52b8464 100644
--- a/third_party/git/compat/terminal.h
+++ b/third_party/git/compat/terminal.h
@@ -3,4 +3,7 @@
 
 char *git_terminal_prompt(const char *prompt, int echo);
 
+/* Read a single keystroke, without echoing it to the terminal */
+int read_key_without_echo(struct strbuf *buf);
+
 #endif /* COMPAT_TERMINAL_H */
diff --git a/third_party/git/compat/vcbuild/README b/third_party/git/compat/vcbuild/README
index 1b6dabf5a2..51fb083dbb 100644
--- a/third_party/git/compat/vcbuild/README
+++ b/third_party/git/compat/vcbuild/README
@@ -26,8 +26,8 @@ The Steps to Build Git with VS2015 or VS2017 from the command line.
    Use ONE of the following forms which should match how you want to
    compile git.exe.
 
-   $ ./compat/vcbuild/vcpkg_copy_packages.bat debug
-   $ ./compat/vcbuild/vcpkg_copy_packages.bat release
+   $ ./compat/vcbuild/vcpkg_copy_dlls.bat debug
+   $ ./compat/vcbuild/vcpkg_copy_dlls.bat release
 
 3. Build git using MSVC from an SDK bash window using one of the
    following commands:
@@ -92,8 +92,8 @@ The Steps of Build Git with VS2008
    the git operations.
 
 3. Inside Git's directory run the command:
-       make command-list.h
-   to generate the command-list.h file needed to compile git.
+       make command-list.h config-list.h
+   to generate the header file needed to compile git.
 
 4. Then either build Git with the GNU Make Makefile in the Git projects
    root
diff --git a/third_party/git/compat/vcbuild/find_vs_env.bat b/third_party/git/compat/vcbuild/find_vs_env.bat
index 40194dd230..b35d264c0e 100644
--- a/third_party/git/compat/vcbuild/find_vs_env.bat
+++ b/third_party/git/compat/vcbuild/find_vs_env.bat
@@ -18,7 +18,7 @@ REM and MAKE, we must blend these two different worlds.  This script
 REM attempts to do that.
 REM ================================================================
 REM This BAT file starts in a plain (non-developer) command prompt,
-REM searches for the "best" commmand prompt setup script, installs
+REM searches for the "best" command prompt setup script, installs
 REM it into the current CMD process, and exports the various MSVC
 REM environment variables for use by MAKE.
 REM
diff --git a/third_party/git/compat/vcbuild/scripts/clink.pl b/third_party/git/compat/vcbuild/scripts/clink.pl
index c7b021bfac..df167d1e1a 100755
--- a/third_party/git/compat/vcbuild/scripts/clink.pl
+++ b/third_party/git/compat/vcbuild/scripts/clink.pl
@@ -23,7 +23,9 @@ while (@ARGV) {
 	    # before any "-l*" flags.
 	    $is_debug = 1;
 	}
-	if ("$arg" =~ /^-[DIMGOZ]/) {
+	if ("$arg" =~ /^-I\/mingw(32|64)/) {
+		# eat
+	} elsif ("$arg" =~ /^-[DIMGOZ]/) {
 		push(@cflags, $arg);
 	} elsif ("$arg" eq "-o") {
 		my $file_out = shift @ARGV;
@@ -45,9 +47,9 @@ while (@ARGV) {
 	} elsif ("$arg" eq "-liconv") {
 		push(@args, "libiconv.lib");
 	} elsif ("$arg" eq "-lcrypto") {
-		push(@args, "libeay32.lib");
+		push(@args, "libcrypto.lib");
 	} elsif ("$arg" eq "-lssl") {
-		push(@args, "ssleay32.lib");
+		push(@args, "libssl.lib");
 	} elsif ("$arg" eq "-lcurl") {
 		my $lib = "";
 		# Newer vcpkg definitions call this libcurl_imp.lib; Do we
@@ -64,12 +66,58 @@ while (@ARGV) {
 		}
 		push(@args, $lib);
 	} elsif ("$arg" eq "-lexpat") {
-		push(@args, "expat.lib");
+		push(@args, "libexpat.lib");
 	} elsif ("$arg" =~ /^-L/ && "$arg" ne "-LTCG") {
 		$arg =~ s/^-L/-LIBPATH:/;
 		push(@lflags, $arg);
-	} elsif ("$arg" =~ /^-R/) {
+	} elsif ("$arg" =~ /^-[Rl]/) {
 		# eat
+	} elsif ("$arg" eq "-Werror") {
+		push(@cflags, "-WX");
+	} elsif ("$arg" eq "-Wall") {
+		# cl.exe understands -Wall, but it is really overzealous
+		push(@cflags, "-W4");
+		# disable the "signed/unsigned mismatch" warnings; our source code violates that
+		push(@cflags, "-wd4018");
+		push(@cflags, "-wd4245");
+		push(@cflags, "-wd4389");
+		# disable the "unreferenced formal parameter" warning; our source code violates that
+		push(@cflags, "-wd4100");
+		# disable the "conditional expression is constant" warning; our source code violates that
+		push(@cflags, "-wd4127");
+		# disable the "const object should be initialized" warning; these warnings affect only objects that are `static`
+		push(@cflags, "-wd4132");
+		# disable the "function/data pointer conversion in expression" warning; our source code violates that
+		push(@cflags, "-wd4152");
+		# disable the "non-constant aggregate initializer" warning; our source code violates that
+		push(@cflags, "-wd4204");
+		# disable the "cannot be initialized using address of automatic variable" warning; our source code violates that
+		push(@cflags, "-wd4221");
+		# disable the "possible loss of data" warnings; our source code violates that
+		push(@cflags, "-wd4244");
+		push(@cflags, "-wd4267");
+		# disable the "array is too small to include a terminating null character" warning; we ab-use strings to initialize OIDs
+		push(@cflags, "-wd4295");
+		# disable the "'<<': result of 32-bit shift implicitly converted to 64 bits" warning; our source code violates that
+		push(@cflags, "-wd4334");
+		# disable the "declaration hides previous local declaration" warning; our source code violates that
+		push(@cflags, "-wd4456");
+		# disable the "declaration hides function parameter" warning; our source code violates that
+		push(@cflags, "-wd4457");
+		# disable the "declaration hides global declaration" warning; our source code violates that
+		push(@cflags, "-wd4459");
+		# disable the "potentially uninitialized local variable '<name>' used" warning; our source code violates that
+		push(@cflags, "-wd4701");
+		# disable the "unreachable code" warning; our source code violates that
+		push(@cflags, "-wd4702");
+		# disable the "potentially uninitialized local pointer variable used" warning; our source code violates that
+		push(@cflags, "-wd4703");
+		# disable the "assignment within conditional expression" warning; our source code violates that
+		push(@cflags, "-wd4706");
+		# disable the "'inet_ntoa': Use inet_ntop() or InetNtop() instead" warning; our source code violates that
+		push(@cflags, "-wd4996");
+	} elsif ("$arg" =~ /^-W[a-z]/) {
+		# let's ignore those
 	} else {
 		push(@args, $arg);
 	}
diff --git a/third_party/git/compat/win32/path-utils.c b/third_party/git/compat/win32/path-utils.c
index d9d3641de8..ebf2f12eb6 100644
--- a/third_party/git/compat/win32/path-utils.c
+++ b/third_party/git/compat/win32/path-utils.c
@@ -1,5 +1,29 @@
 #include "../../git-compat-util.h"
 
+int win32_has_dos_drive_prefix(const char *path)
+{
+	int i;
+
+	/*
+	 * Does it start with an ASCII letter (i.e. highest bit not set),
+	 * followed by a colon?
+	 */
+	if (!(0x80 & (unsigned char)*path))
+		return *path && path[1] == ':' ? 2 : 0;
+
+	/*
+	 * While drive letters must be letters of the English alphabet, it is
+	 * possible to assign virtually _any_ Unicode character via `subst` as
+	 * a drive letter to "virtual drives". Even `1`, or `ä`. Or fun stuff
+	 * like this:
+	 *
+	 *      subst ֍: %USERPROFILE%\Desktop
+	 */
+	for (i = 1; i < 4 && (0x80 & (unsigned char)path[i]); i++)
+		; /* skip first UTF-8 character */
+	return path[i] == ':' ? i + 1 : 0;
+}
+
 int win32_skip_dos_drive_prefix(char **path)
 {
 	int ret = has_dos_drive_prefix(*path);
diff --git a/third_party/git/compat/win32/path-utils.h b/third_party/git/compat/win32/path-utils.h
index 0f70d43920..bba2b64408 100644
--- a/third_party/git/compat/win32/path-utils.h
+++ b/third_party/git/compat/win32/path-utils.h
@@ -1,5 +1,9 @@
-#define has_dos_drive_prefix(path) \
-	(isalpha(*(path)) && (path)[1] == ':' ? 2 : 0)
+#ifndef WIN32_PATH_UTILS_H
+#define WIN32_PATH_UTILS_H
+
+int win32_has_dos_drive_prefix(const char *path);
+#define has_dos_drive_prefix win32_has_dos_drive_prefix
+
 int win32_skip_dos_drive_prefix(char **path);
 #define skip_dos_drive_prefix win32_skip_dos_drive_prefix
 static inline int win32_is_dir_sep(int c)
@@ -16,5 +20,18 @@ static inline char *win32_find_last_dir_sep(const char *path)
 	return ret;
 }
 #define find_last_dir_sep win32_find_last_dir_sep
+static inline int win32_has_dir_sep(const char *path)
+{
+	/*
+	 * See how long the non-separator part of the given path is, and
+	 * if and only if it covers the whole path (i.e. path[len] is NUL),
+	 * there is no separator in the path---otherwise there is a separator.
+	 */
+	size_t len = strcspn(path, "/\\");
+	return !!path[len];
+}
+#define has_dir_sep(path) win32_has_dir_sep(path)
 int win32_offset_1st_component(const char *path);
 #define offset_1st_component win32_offset_1st_component
+
+#endif
diff --git a/third_party/git/compat/win32/pthread.h b/third_party/git/compat/win32/pthread.h
index c6cb8dd219..737983d00b 100644
--- a/third_party/git/compat/win32/pthread.h
+++ b/third_party/git/compat/win32/pthread.h
@@ -50,8 +50,8 @@ typedef struct {
 	DWORD tid;
 } pthread_t;
 
-extern int pthread_create(pthread_t *thread, const void *unused,
-			  void *(*start_routine)(void*), void *arg);
+int pthread_create(pthread_t *thread, const void *unused,
+		   void *(*start_routine)(void*), void *arg);
 
 /*
  * To avoid the need of copying a struct, we use small macro wrapper to pass
@@ -59,10 +59,10 @@ extern int pthread_create(pthread_t *thread, const void *unused,
  */
 #define pthread_join(a, b) win32_pthread_join(&(a), (b))
 
-extern int win32_pthread_join(pthread_t *thread, void **value_ptr);
+int win32_pthread_join(pthread_t *thread, void **value_ptr);
 
 #define pthread_equal(t1, t2) ((t1).tid == (t2).tid)
-extern pthread_t pthread_self(void);
+pthread_t pthread_self(void);
 
 static inline void NORETURN pthread_exit(void *ret)
 {
diff --git a/third_party/git/compat/winansi.c b/third_party/git/compat/winansi.c
index cacd82c833..c27b20a79d 100644
--- a/third_party/git/compat/winansi.c
+++ b/third_party/git/compat/winansi.c
@@ -546,7 +546,7 @@ static HANDLE swap_osfhnd(int fd, HANDLE new_handle)
 typedef struct _OBJECT_NAME_INFORMATION
 {
 	UNICODE_STRING Name;
-	WCHAR NameBuffer[0];
+	WCHAR NameBuffer[FLEX_ARRAY];
 } OBJECT_NAME_INFORMATION, *POBJECT_NAME_INFORMATION;
 
 #define ObjectNameInformation 1
@@ -662,10 +662,20 @@ void winansi_init(void)
  */
 HANDLE winansi_get_osfhandle(int fd)
 {
+	HANDLE ret;
+
 	if (fd == 1 && (fd_is_interactive[1] & FD_SWAPPED))
 		return hconsole1;
 	if (fd == 2 && (fd_is_interactive[2] & FD_SWAPPED))
 		return hconsole2;
 
-	return (HANDLE)_get_osfhandle(fd);
+	ret = (HANDLE)_get_osfhandle(fd);
+
+	/*
+	 * There are obviously circumstances under which _get_osfhandle()
+	 * returns (HANDLE)-2. This is not documented anywhere, but that is so
+	 * clearly an invalid handle value that we can just work around this
+	 * and return the correct value for invalid handles.
+	 */
+	return ret == (HANDLE)-2 ? INVALID_HANDLE_VALUE : ret;
 }