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authorDaniel Barkalow <barkalow@iabervon.org>2005-06-06 20:31:29 (GMT)
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-07 00:09:45 (GMT)
commit95fc75129acf14d980bdd56b9b2ee74190f81d91 (patch)
treed3a6988ffe8b9ae0b554ddb4485ffb0f1cac0dc7
parent451322512f2f72fe07461a8aeae0df4cfce7fda1 (diff)
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[PATCH] Operations on refs
This patch adds code to read a hash out of a specified file under {GIT_DIR}/refs/, and to write such files atomically and optionally with an compare and lock. Signed-off-by: Daniel Barkalow <barkalow@iabervon.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--Makefile3
-rw-r--r--cache.h1
-rw-r--r--refs.c173
-rw-r--r--refs.h21
-rw-r--r--sha1_file.c11
5 files changed, 207 insertions, 2 deletions
diff --git a/Makefile b/Makefile
index 5d5c856..50eb01c 100644
--- a/Makefile
+++ b/Makefile
@@ -40,7 +40,8 @@ install: $(PROG) $(SCRIPTS)
$(INSTALL) $(PROG) $(SCRIPTS) $(dest)$(bin)
LIB_OBJS=read-cache.o sha1_file.o usage.o object.o commit.o tree.o blob.o \
- tag.o delta.o date.o index.o diff-delta.o patch-delta.o entry.o epoch.o
+ tag.o delta.o date.o index.o diff-delta.o patch-delta.o entry.o \
+ epoch.o refs.o
LIB_FILE=libgit.a
LIB_H=cache.h object.h blob.h tree.h commit.h tag.h delta.h epoch.h
diff --git a/cache.h b/cache.h
index 95353a1..74307f1 100644
--- a/cache.h
+++ b/cache.h
@@ -117,6 +117,7 @@ extern unsigned int active_nr, active_alloc, active_cache_changed;
#define INDEX_ENVIRONMENT "GIT_INDEX_FILE"
extern char *get_object_directory(void);
+extern char *get_refs_directory(void);
extern char *get_index_file(void);
#define ALTERNATE_DB_ENVIRONMENT "GIT_ALTERNATE_OBJECT_DIRECTORIES"
diff --git a/refs.c b/refs.c
new file mode 100644
index 0000000..9973d1f
--- /dev/null
+++ b/refs.c
@@ -0,0 +1,173 @@
+#include "refs.h"
+#include "cache.h"
+
+#include <errno.h>
+
+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;
+}
diff --git a/refs.h b/refs.h
new file mode 100644
index 0000000..60cf480
--- /dev/null
+++ b/refs.h
@@ -0,0 +1,21 @@
+#ifndef REFS_H
+#define REFS_H
+
+/** Reads the refs file specified into sha1 **/
+extern int get_ref_sha1(const char *ref, unsigned char *sha1);
+
+/** Locks ref and returns the fd to give to write_ref_sha1() if the ref
+ * has the given value currently; otherwise, returns -1.
+ **/
+extern int lock_ref_sha1(const char *ref, const unsigned char *old_sha1);
+
+/** Writes sha1 into the refs file specified, locked with the given fd. **/
+extern int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1);
+
+/** Writes sha1 into the refs file specified. **/
+extern int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1);
+
+/** Returns 0 if target has the right format for a ref. **/
+extern int check_ref_format(const char *target);
+
+#endif /* REFS_H */
diff --git a/sha1_file.c b/sha1_file.c
index a2ba4c8..7cfd43c 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -58,7 +58,7 @@ static int get_sha1_file(const char *path, unsigned char *result)
return get_sha1_hex(buffer, result);
}
-static char *git_dir, *git_object_dir, *git_index_file;
+static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir;
static void setup_git_env(void)
{
git_dir = gitenv(GIT_DIR_ENVIRONMENT);
@@ -69,6 +69,8 @@ static void setup_git_env(void)
git_object_dir = xmalloc(strlen(git_dir) + 9);
sprintf(git_object_dir, "%s/objects", git_dir);
}
+ git_refs_dir = xmalloc(strlen(git_dir) + 6);
+ sprintf(git_refs_dir, "%s/refs", git_dir);
git_index_file = gitenv(INDEX_ENVIRONMENT);
if (!git_index_file) {
git_index_file = xmalloc(strlen(git_dir) + 7);
@@ -83,6 +85,13 @@ char *get_object_directory(void)
return git_object_dir;
}
+char *get_refs_directory(void)
+{
+ if (!git_refs_dir)
+ setup_git_env();
+ return git_refs_dir;
+}
+
char *get_index_file(void)
{
if (!git_index_file)