1 files changed, 270 insertions, 0 deletions
diff --git a/abspath.c b/abspath.c
new file mode 100644
index 000000000000..985798532994
--- /dev/null
+++ b/abspath.c
@@ -0,0 +1,270 @@
+#include "cache.h"
+
+/*
+ * Do not use this for inspecting *tracked* content.  When path is a
+ * symlink to a directory, we do not want to say it is a directory when
+ * dealing with tracked content in the working tree.
+ */
+int is_directory(const char *path)
+{
+	struct stat st;
+	return (!stat(path, &st) && S_ISDIR(st.st_mode));
+}
+
+/* removes the last path component from 'path' except if 'path' is root */
+static void strip_last_component(struct strbuf *path)
+{
+	size_t offset = offset_1st_component(path->buf);
+	size_t len = path->len;
+
+	/* Find start of the last component */
+	while (offset < len && !is_dir_sep(path->buf[len - 1]))
+		len--;
+	/* Skip sequences of multiple path-separators */
+	while (offset < len && is_dir_sep(path->buf[len - 1]))
+		len--;
+
+	strbuf_setlen(path, len);
+}
+
+/* get (and remove) the next component in 'remaining' and place it in 'next' */
+static void get_next_component(struct strbuf *next, struct strbuf *remaining)
+{
+	char *start = NULL;
+	char *end = NULL;
+
+	strbuf_reset(next);
+
+	/* look for the next component */
+	/* Skip sequences of multiple path-separators */
+	for (start = remaining->buf; is_dir_sep(*start); start++)
+		; /* nothing */
+	/* Find end of the path component */
+	for (end = start; *end && !is_dir_sep(*end); end++)
+		; /* nothing */
+
+	strbuf_add(next, start, end - start);
+	/* remove the component from 'remaining' */
+	strbuf_remove(remaining, 0, end - remaining->buf);
+}
+
+/* copies root part from remaining to resolved, canonicalizing it on the way */
+static void get_root_part(struct strbuf *resolved, struct strbuf *remaining)
+{
+	int offset = offset_1st_component(remaining->buf);
+
+	strbuf_reset(resolved);
+	strbuf_add(resolved, remaining->buf, offset);
+#ifdef GIT_WINDOWS_NATIVE
+	convert_slashes(resolved->buf);
+#endif
+	strbuf_remove(remaining, 0, offset);
+}
+
+/* We allow "recursive" symbolic links. Only within reason, though. */
+#ifndef MAXSYMLINKS
+#define MAXSYMLINKS 32
+#endif
+
+/*
+ * Return the real path (i.e., absolute path, with symlinks resolved
+ * and extra slashes removed) equivalent to the specified path.  (If
+ * you want an absolute path but don't mind links, use
+ * absolute_path().)  Places the resolved realpath in the provided strbuf.
+ *
+ * The directory part of path (i.e., everything up to the last
+ * dir_sep) must denote a valid, existing directory, but the last
+ * component need not exist.  If die_on_error is set, then die with an
+ * informative error message if there is a problem.  Otherwise, return
+ * NULL on errors (without generating any output).
+ */
+char *strbuf_realpath(struct strbuf *resolved, const char *path,
+		      int die_on_error)
+{
+	struct strbuf remaining = STRBUF_INIT;
+	struct strbuf next = STRBUF_INIT;
+	struct strbuf symlink = STRBUF_INIT;
+	char *retval = NULL;
+	int num_symlinks = 0;
+	struct stat st;
+
+	if (!*path) {
+		if (die_on_error)
+			die("The empty string is not a valid path");
+		else
+			goto error_out;
+	}
+
+	strbuf_addstr(&remaining, path);
+	get_root_part(resolved, &remaining);
+
+	if (!resolved->len) {
+		/* relative path; can use CWD as the initial resolved path */
+		if (strbuf_getcwd(resolved)) {
+			if (die_on_error)
+				die_errno("unable to get current working directory");
+			else
+				goto error_out;
+		}
+	}
+
+	/* Iterate over the remaining path components */
+	while (remaining.len > 0) {
+		get_next_component(&next, &remaining);
+
+		if (next.len == 0) {
+			continue; /* empty component */
+		} else if (next.len == 1 && !strcmp(next.buf, ".")) {
+			continue; /* '.' component */
+		} else if (next.len == 2 && !strcmp(next.buf, "..")) {
+			/* '..' component; strip the last path component */
+			strip_last_component(resolved);
+			continue;
+		}
+
+		/* append the next component and resolve resultant path */
+		if (!is_dir_sep(resolved->buf[resolved->len - 1]))
+			strbuf_addch(resolved, '/');
+		strbuf_addbuf(resolved, &next);
+
+		if (lstat(resolved->buf, &st)) {
+			/* error out unless this was the last component */
+			if (errno != ENOENT || remaining.len) {
+				if (die_on_error)
+					die_errno("Invalid path '%s'",
+						  resolved->buf);
+				else
+					goto error_out;
+			}
+		} else if (S_ISLNK(st.st_mode)) {
+			ssize_t len;
+			strbuf_reset(&symlink);
+
+			if (num_symlinks++ > MAXSYMLINKS) {
+				errno = ELOOP;
+
+				if (die_on_error)
+					die("More than %d nested symlinks "
+					    "on path '%s'", MAXSYMLINKS, path);
+				else
+					goto error_out;
+			}
+
+			len = strbuf_readlink(&symlink, resolved->buf,
+					      st.st_size);
+			if (len < 0) {
+				if (die_on_error)
+					die_errno("Invalid symlink '%s'",
+						  resolved->buf);
+				else
+					goto error_out;
+			}
+
+			if (is_absolute_path(symlink.buf)) {
+				/* absolute symlink; set resolved to root */
+				get_root_part(resolved, &symlink);
+			} else {
+				/*
+				 * relative symlink
+				 * strip off the last component since it will
+				 * be replaced with the contents of the symlink
+				 */
+				strip_last_component(resolved);
+			}
+
+			/*
+			 * if there are still remaining components to resolve
+			 * then append them to symlink
+			 */
+			if (remaining.len) {
+				strbuf_addch(&symlink, '/');
+				strbuf_addbuf(&symlink, &remaining);
+			}
+
+			/*
+			 * use the symlink as the remaining components that
+			 * need to be resolved
+			 */
+			strbuf_swap(&symlink, &remaining);
+		}
+	}
+
+	retval = resolved->buf;
+
+error_out:
+	strbuf_release(&remaining);
+	strbuf_release(&next);
+	strbuf_release(&symlink);
+
+	if (!retval)
+		strbuf_reset(resolved);
+
+	return retval;
+}
+
+/*
+ * Resolve `path` into an absolute, cleaned-up path. The return value
+ * comes from a shared buffer.
+ */
+const char *real_path(const char *path)
+{
+	static struct strbuf realpath = STRBUF_INIT;
+	return strbuf_realpath(&realpath, path, 1);
+}
+
+const char *real_path_if_valid(const char *path)
+{
+	static struct strbuf realpath = STRBUF_INIT;
+	return strbuf_realpath(&realpath, path, 0);
+}
+
+char *real_pathdup(const char *path, int die_on_error)
+{
+	struct strbuf realpath = STRBUF_INIT;
+	char *retval = NULL;
+
+	if (strbuf_realpath(&realpath, path, die_on_error))
+		retval = strbuf_detach(&realpath, NULL);
+
+	strbuf_release(&realpath);
+
+	return retval;
+}
+
+/*
+ * Use this to get an absolute path from a relative one. If you want
+ * to resolve links, you should use real_path.
+ */
+const char *absolute_path(const char *path)
+{
+	static struct strbuf sb = STRBUF_INIT;
+	strbuf_reset(&sb);
+	strbuf_add_absolute_path(&sb, path);
+	return sb.buf;
+}
+
+char *absolute_pathdup(const char *path)
+{
+	struct strbuf sb = STRBUF_INIT;
+	strbuf_add_absolute_path(&sb, path);
+	return strbuf_detach(&sb, NULL);
+}
+
+char *prefix_filename(const char *pfx, const char *arg)
+{
+	struct strbuf path = STRBUF_INIT;
+	size_t pfx_len = pfx ? strlen(pfx) : 0;
+
+	if (!pfx_len)
+		; /* nothing to prefix */
+	else if (is_absolute_path(arg))
+		pfx_len = 0;
+	else
+		strbuf_add(&path, pfx, pfx_len);
+
+	strbuf_addstr(&path, arg);
+#ifdef GIT_WINDOWS_NATIVE
+	convert_slashes(path.buf + pfx_len);
+#endif
+	return strbuf_detach(&path, NULL);
+}