From ca8db1424d1808a1f78bc9905efd267f7c154d8e Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 25 Sep 2005 09:59:37 -0700 Subject: [PATCH] [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 Signed-off-by: Junio C Hamano --- cache.h | 1 + refs.c | 73 +++++++++++++++++++++++++++++------------------------ sha1_name.c | 17 +------------ 3 files changed, 42 insertions(+), 49 deletions(-) diff --git a/cache.h b/cache.h index b8e3d9bfa..958c96e14 100644 --- a/cache.h +++ b/cache.h @@ -229,6 +229,7 @@ extern int has_pack_index(const unsigned char *sha1); extern int get_sha1(const char *str, unsigned char *sha1); extern int get_sha1_hex(const char *hex, unsigned char *sha1); extern char *sha1_to_hex(const unsigned char *sha1); /* static buffer result! */ +extern int read_ref(const char *filename, unsigned char *sha1); /* General helper functions */ extern void usage(const char *err) NORETURN; diff --git a/refs.c b/refs.c index 161018097..d4f361248 100644 --- a/refs.c +++ b/refs.c @@ -2,17 +2,43 @@ #include "cache.h" #include +#include -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; + + while ((fd = open(filename, O_RDONLY)) >= 0) { + char buffer[256]; + int len = read(fd, buffer, sizeof(buffer)-1); - if (fd >= 0) { - char buffer[60]; - if (read(fd, buffer, sizeof(buffer)) >= 40) - ret = get_sha1_hex(buffer, sha1); 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 @@ static int do_for_each_ref(const char *base, int (*fn)(const char *path, const u 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 @@ static int do_for_each_ref(const char *base, int (*fn)(const char *path, const u 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 @@ static char *ref_lock_file_name(const char *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; + 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 @@ static int lock_ref_file(const char *filename, const char *lock_filename, 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); diff --git a/sha1_name.c b/sha1_name.c index b4fed924f..57e6cd3bd 100644 --- a/sha1_name.c +++ b/sha1_name.c @@ -119,21 +119,6 @@ static int get_short_sha1(const char *name, int len, unsigned char *sha1) return -1; } -static int get_sha1_file(const char *path, unsigned char *result) -{ - char buffer[60]; - int fd = open(path, O_RDONLY); - int len; - - if (fd < 0) - return -1; - len = read(fd, buffer, sizeof(buffer)); - close(fd); - if (len < 40) - return -1; - return get_sha1_hex(buffer, result); -} - static int get_sha1_basic(const char *str, int len, unsigned char *sha1) { static const char *prefix[] = { @@ -150,7 +135,7 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1) for (p = prefix; *p; p++) { char *pathname = git_path("%s/%.*s", *p, len, str); - if (!get_sha1_file(pathname, sha1)) + if (!read_ref(pathname, sha1)) return 0; } -- 2.30.2