[PATCH] Allow reading "symbolic refs" that point to other refs
This extends the ref reading to understand a "symbolic ref": a ref file
that starts with "ref: " and points to another ref file, and thus
introduces the notion of ref aliases.
This is in preparation of allowing HEAD to eventually not be a symlink,
but one of these symbolic refs instead.
[jc: Linus originally required the prefix to be "ref: " five bytes
and nothing else, but I changed it to allow and strip any number of
leading whitespaces to match what update-ref.c does.]
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/refs.c b/refs.c
index 1610180..d4f3612 100644
--- a/refs.c
+++ b/refs.c
@@ -2,17 +2,43 @@
#include "cache.h"
#include <errno.h>
+#include <ctype.h>
-static int read_ref(const char *refname, unsigned char *sha1)
+/* We allow "recursive" symbolic refs. Only within reason, though */
+#define MAXDEPTH 5
+
+int read_ref(const char *filename, unsigned char *sha1)
{
- int ret = -1;
- int fd = open(git_path("%s", refname), O_RDONLY);
+ int depth = 0;
+ int ret = -1, fd;
- if (fd >= 0) {
- char buffer[60];
- if (read(fd, buffer, sizeof(buffer)) >= 40)
- ret = get_sha1_hex(buffer, sha1);
+ while ((fd = open(filename, O_RDONLY)) >= 0) {
+ char buffer[256];
+ int len = read(fd, buffer, sizeof(buffer)-1);
+
close(fd);
+ if (len < 0)
+ break;
+
+ buffer[len] = 0;
+ while (len && isspace(buffer[len-1]))
+ buffer[--len] = 0;
+
+ if (!strncmp(buffer, "ref:", 4)) {
+ char *buf;
+ if (depth > MAXDEPTH)
+ break;
+ depth++;
+ buf = buffer + 4;
+ len -= 4;
+ while (len && isspace(*buf))
+ buf++, len--;
+ filename = git_path("%.*s", len, buf);
+ continue;
+ }
+ if (len >= 40)
+ ret = get_sha1_hex(buffer, sha1);
+ break;
}
return ret;
}
@@ -54,7 +80,7 @@
break;
continue;
}
- if (read_ref(path, sha1) < 0)
+ if (read_ref(git_path("%s", path), sha1) < 0)
continue;
if (!has_sha1_file(sha1))
continue;
@@ -71,7 +97,7 @@
int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
{
unsigned char sha1[20];
- if (!read_ref("HEAD", sha1))
+ if (!read_ref(git_path("HEAD"), sha1))
return fn("HEAD", sha1);
return 0;
}
@@ -101,33 +127,14 @@
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;
+ const char *filename;
+
if (check_ref_format(ref))
return -1;
- filename = ref_file_name(ref);
- retval = read_ref_file(filename, sha1);
- free(filename);
- return retval;
+ filename = git_path("refs/%s", ref);
+ return read_ref(filename, sha1);
}
static int lock_ref_file(const char *filename, const char *lock_filename,
@@ -140,7 +147,7 @@
return error("Couldn't open lock file for %s: %s",
filename, strerror(errno));
}
- retval = read_ref_file(filename, current_sha1);
+ retval = read_ref(filename, current_sha1);
if (old_sha1) {
if (retval) {
close(fd);
