1 files changed, 251 insertions, 0 deletions
diff --git a/refs.c b/refs.c
new file mode 100644
index 0000000000..161018097d
--- /dev/null
+++ b/refs.c
@@ -0,0 +1,251 @@
+#include "refs.h"
+#include "cache.h"
+
+#include <errno.h>
+
+static int read_ref(const char *refname, unsigned char *sha1)
+{
+	int ret = -1;
+	int fd = open(git_path("%s", refname), O_RDONLY);
+
+	if (fd >= 0) {
+		char buffer[60];
+		if (read(fd, buffer, sizeof(buffer)) >= 40)
+			ret = get_sha1_hex(buffer, sha1);
+		close(fd);
+	}
+	return ret;
+}
+
+static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1))
+{
+	int retval = 0;
+	DIR *dir = opendir(git_path("%s", base));
+
+	if (dir) {
+		struct dirent *de;
+		int baselen = strlen(base);
+		char *path = xmalloc(baselen + 257);
+
+		if (!strncmp(base, "./", 2)) {
+			base += 2;
+			baselen -= 2;
+		}
+		memcpy(path, base, baselen);
+		if (baselen && base[baselen-1] != '/')
+			path[baselen++] = '/';
+
+		while ((de = readdir(dir)) != NULL) {
+			unsigned char sha1[20];
+			struct stat st;
+			int namelen;
+
+			if (de->d_name[0] == '.')
+				continue;
+			namelen = strlen(de->d_name);
+			if (namelen > 255)
+				continue;
+			memcpy(path + baselen, de->d_name, namelen+1);
+			if (stat(git_path("%s", path), &st) < 0)
+				continue;
+			if (S_ISDIR(st.st_mode)) {
+				retval = do_for_each_ref(path, fn);
+				if (retval)
+					break;
+				continue;
+			}
+			if (read_ref(path, sha1) < 0)
+				continue;
+			if (!has_sha1_file(sha1))
+				continue;
+			retval = fn(path, sha1);
+			if (retval)
+				break;
+		}
+		free(path);
+		closedir(dir);
+	}
+	return retval;
+}
+
+int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
+{
+	unsigned char sha1[20];
+	if (!read_ref("HEAD", sha1))
+		return fn("HEAD", sha1);
+	return 0;
+}
+
+int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
+{
+	return do_for_each_ref("refs", fn);
+}
+
+static char *ref_file_name(const char *ref)
+{
+	char *base = get_refs_directory();
+	int baselen = strlen(base);
+	int reflen = strlen(ref);
+	char *ret = xmalloc(baselen + 2 + reflen);
+	sprintf(ret, "%s/%s", base, ref);
+	return ret;
+}
+
+static char *ref_lock_file_name(const char *ref)
+{
+	char *base = get_refs_directory();
+	int baselen = strlen(base);
+	int reflen = strlen(ref);
+	char *ret = xmalloc(baselen + 7 + reflen);
+	sprintf(ret, "%s/%s.lock", base, ref);
+	return ret;
+}
+
+static int read_ref_file(const char *filename, unsigned char *sha1) {
+	int fd = open(filename, O_RDONLY);
+	char hex[41];
+	if (fd < 0) {
+		return error("Couldn't open %s\n", filename);
+	}
+	if ((read(fd, hex, 41) < 41) ||
+	    (hex[40] != '\n') ||
+	    get_sha1_hex(hex, sha1)) {
+		error("Couldn't read a hash from %s\n", filename);
+		close(fd);
+		return -1;
+	}
+	close(fd);
+	return 0;
+}
+
+int get_ref_sha1(const char *ref, unsigned char *sha1)
+{
+	char *filename;
+	int retval;
+	if (check_ref_format(ref))
+		return -1;
+	filename = ref_file_name(ref);
+	retval = read_ref_file(filename, sha1);
+	free(filename);
+	return retval;
+}
+
+static int lock_ref_file(const char *filename, const char *lock_filename,
+			 const unsigned char *old_sha1)
+{
+	int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
+	unsigned char current_sha1[20];
+	int retval;
+	if (fd < 0) {
+		return error("Couldn't open lock file for %s: %s",
+			     filename, strerror(errno));
+	}
+	retval = read_ref_file(filename, current_sha1);
+	if (old_sha1) {
+		if (retval) {
+			close(fd);
+			unlink(lock_filename);
+			return error("Could not read the current value of %s",
+				     filename);
+		}
+		if (memcmp(current_sha1, old_sha1, 20)) {
+			close(fd);
+			unlink(lock_filename);
+			error("The current value of %s is %s",
+			      filename, sha1_to_hex(current_sha1));
+			return error("Expected %s",
+				     sha1_to_hex(old_sha1));
+		}
+	} else {
+		if (!retval) {
+			close(fd);
+			unlink(lock_filename);
+			return error("Unexpectedly found a value of %s for %s",
+				     sha1_to_hex(current_sha1), filename);
+		}
+	}
+	return fd;
+}
+
+int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
+{
+	char *filename;
+	char *lock_filename;
+	int retval;
+	if (check_ref_format(ref))
+		return -1;
+	filename = ref_file_name(ref);
+	lock_filename = ref_lock_file_name(ref);
+	retval = lock_ref_file(filename, lock_filename, old_sha1);
+	free(filename);
+	free(lock_filename);
+	return retval;
+}
+
+static int write_ref_file(const char *filename,
+			  const char *lock_filename, int fd,
+			  const unsigned char *sha1)
+{
+	char *hex = sha1_to_hex(sha1);
+	char term = '\n';
+	if (write(fd, hex, 40) < 40 ||
+	    write(fd, &term, 1) < 1) {
+		error("Couldn't write %s\n", filename);
+		close(fd);
+		return -1;
+	}
+	close(fd);
+	rename(lock_filename, filename);
+	return 0;
+}
+
+int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
+{
+	char *filename;
+	char *lock_filename;
+	int retval;
+	if (fd < 0)
+		return -1;
+	if (check_ref_format(ref))
+		return -1;
+	filename = ref_file_name(ref);
+	lock_filename = ref_lock_file_name(ref);
+	retval = write_ref_file(filename, lock_filename, fd, sha1);
+	free(filename);
+	free(lock_filename);
+	return retval;
+}
+
+int check_ref_format(const char *ref)
+{
+	char *middle;
+	if (ref[0] == '.' || ref[0] == '/')
+		return -1;
+	middle = strchr(ref, '/');
+	if (!middle || !middle[1])
+		return -1;
+	if (strchr(middle + 1, '/'))
+		return -1;
+	return 0;
+}
+
+int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
+{
+	char *filename;
+	char *lock_filename;
+	int fd;
+	int retval;
+	if (check_ref_format(ref))
+		return -1;
+	filename = ref_file_name(ref);
+	lock_filename = ref_lock_file_name(ref);
+	fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
+	if (fd < 0) {
+		error("Writing %s", lock_filename);
+		perror("Open");
+	}
+	retval = write_ref_file(filename, lock_filename, fd, sha1);
+	free(filename);
+	free(lock_filename);
+	return retval;
+}