1 files changed, 127 insertions, 0 deletions
diff --git a/setup.c b/setup.c
new file mode 100644
index 0000000000..9e20160d94
--- /dev/null
+++ b/setup.c
@@ -0,0 +1,127 @@
+#include "cache.h"
+
+const char *prefix_path(const char *prefix, int len, const char *path)
+{
+	const char *orig = path;
+	for (;;) {
+		char c;
+		if (*path != '.')
+			break;
+		c = path[1];
+		/* "." */
+		if (!c) {
+			path++;
+			break;
+		}
+		/* "./" */
+		if (c == '/') {
+			path += 2;
+			continue;
+		}
+		if (c != '.')
+			break;
+		c = path[2];
+		if (!c)
+			path += 2;
+		else if (c == '/')
+			path += 3;
+		else
+			break;
+		/* ".." and "../" */
+		/* Remove last component of the prefix */
+		do {
+			if (!len)
+				die("'%s' is outside repository", orig);
+			len--;
+		} while (len && prefix[len-1] != '/');
+		continue;
+	}
+	if (len) {
+		int speclen = strlen(path);
+		char *n = xmalloc(speclen + len + 1);
+	
+		memcpy(n, prefix, len);
+		memcpy(n + len, path, speclen+1);
+		path = n;
+	}
+	return path;
+}
+
+const char **get_pathspec(const char *prefix, const char **pathspec)
+{
+	const char *entry = *pathspec;
+	const char **p;
+	int prefixlen;
+
+	if (!prefix && !entry)
+		return NULL;
+
+	if (!entry) {
+		static const char *spec[2];
+		spec[0] = prefix;
+		spec[1] = NULL;
+		return spec;
+	}
+
+	/* Otherwise we have to re-write the entries.. */
+	p = pathspec;
+	prefixlen = prefix ? strlen(prefix) : 0;
+	do {
+		*p = prefix_path(prefix, prefixlen, entry);
+	} while ((entry = *++p) != NULL);
+	return (const char **) pathspec;
+}
+
+/*
+ * Test it it looks like we're at the top
+ * level git directory. We want to see a
+ *
+ *  - a HEAD symlink and a refs/ directory under ".git"
+ *  - either a .git/objects/ directory _or_ the proper
+ *    GIT_OBJECT_DIRECTORY environment variable
+ */
+static int is_toplevel_directory(void)
+{
+	struct stat st;
+
+	return	!lstat(".git/HEAD", &st) &&
+		S_ISLNK(st.st_mode) &&
+		!access(".git/refs/", X_OK) &&
+		(getenv(DB_ENVIRONMENT) || !access(".git/objects/", X_OK));
+}
+
+const char *setup_git_directory(void)
+{
+	static char cwd[PATH_MAX+1];
+	int len, offset;
+
+	/*
+	 * If GIT_DIR is set explicitly, we're not going
+	 * to do any discovery
+	 */
+	if (getenv(GIT_DIR_ENVIRONMENT))
+		return NULL;
+
+	if (!getcwd(cwd, sizeof(cwd)) || cwd[0] != '/')
+		die("Unable to read current working directory");
+
+	offset = len = strlen(cwd);
+	for (;;) {
+		if (is_toplevel_directory())
+			break;
+		chdir("..");
+		do {
+			if (!offset)
+				die("Not a git repository");
+		} while (cwd[--offset] != '/');
+	}
+
+	if (offset == len)
+		return NULL;
+
+	/* Make "offset" point to past the '/', and add a '/' at the end */
+	offset++;
+	cwd[len++] = '/';
+	cwd[len] = 0;
+	return cwd + offset;
+}