[PATCH] Added hook in git-receive-pack

Just before updating a ref,

    $GIT_DIR/hooks/update refname old-sha1 new-sha1

is called if executable.  The hook can decline the ref to be
updated by exiting with a non-zero status, or allow it to be
updated by exiting with a zero status.  The mechanism also
allows e.g sending of a mail with pushed commits on the remote
repository.

Documentation update with an example hook is included.

jc: The credits of the basic idea and initial implementation go
to Josef, but I ended up rewriting major parts of his patch, so
bugs are all mine.  Also I changed the semantics for the hook
from his original version (which were post-update hook) so that
the hook can optionally decline to update the ref, and also can
be used to implement the overall cleanups.  The latter was
primarily to implement a suggestion from Linus that calling
update-server-info should be made optional.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/Documentation/git-receive-pack.txt b/Documentation/git-receive-pack.txt
index d3a835d4ba575c2173e6c6c7165968979a9cba9e..7f95e44046ce2a28053bdddaec8d730257c873a0 100644 (file)
--- a/Documentation/git-receive-pack.txt
+++ b/Documentation/git-receive-pack.txt
@@ -22,6 +22,55 @@ program pair is meant to be used to push updates to remote
 repository.  For pull operations, see 'git-fetch-pack' and
 'git-clone-pack'.
 
+The command allows for creation and fast forwarding of sha1 refs
+(heads/tags) on the remote end (strictly speaking, it is the
+local end receive-pack runs, but to the user who is sitting at
+the send-pack end, it is updating the remote.  Confused?)
+
+Before each ref is updated, if $GIT_DIR/hooks/update file exists
+and executable, it is called with three parameters:
+
+       $GIT_DIR/hooks/update refname sha1-old sha1-new
+
+The refname parameter is relative to $GIT_DIR; e.g. for the
+master head this is "refs/heads/master".  Two sha1 are the
+object names for the refname before and after the update.  Note
+that the hook is called before the refname is updated, so either
+sha1-old is 0{40} (meaning there is no such ref yet), or it
+should match what is recorded in refname.
+
+The hook should exit with non-zero status if it wants to
+disallow updating the named ref.  Otherwise it should exit with
+zero.
+
+The same hook is also called with an empty string as refname and
+no other arguments just before git-receive-pack exits.  This can
+be used to implement repository wide cleanup task if needed.
+The exit code from this hook invocation is ignored; the only
+thing left for git-receive-pack to do at that point is to exit
+itself anyway.
+
+Using this hook, it is easy to generate mails on updates to
+the local repository. This example script sends a mail with
+the commits pushed to the repository:
+
+       #!/bin/sh
+       case "$#,$1" in
+       1,) # help packed repository pulled via dumb protocol.
+           git-update-server-info
+           ;;
+       *)  # mail out commit update information.
+           if expr "$2" : '0*$' >/dev/null
+           then
+               echo "Created now ref."
+               git-rev-list --pretty "$2"
+           else
+               echo "New commits"
+               git-rev-list --pretty "$3" "^$2"
+           fi |
+           mail -s "Changes to ref $1" commit-list@mydomain
+        esac
+       exit 0
 
 OPTIONS
 -------

diff --git a/Makefile b/Makefile
index 1b0ebb4ce8abce524fe7272b4419c731c126daa3..b4aa706c773e56a944062577ea3e8dbf9370bb90 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -98,6 +98,9 @@ LIB_OBJS=read-cache.o sha1_file.o usage.o object.o commit.o tree.o blob.o \
 LIB_H += rev-cache.h
 LIB_OBJS += rev-cache.o
 
+LIB_H += run-command.h
+LIB_OBJS += run-command.o
+
 LIB_H += strbuf.h
 LIB_OBJS += strbuf.o
 

diff --git a/receive-pack.c b/receive-pack.c
index d4e82bf99397d2e719e8bbe1e0e72142d04fb4cb..85bf8569f8d2b9f5756e8bc5829688ea6bc2420b 100644 (file)
--- a/receive-pack.c
+++ b/receive-pack.c
@@ -1,11 +1,12 @@
 #include "cache.h"
 #include "refs.h"
 #include "pkt-line.h"
+#include "run-command.h"
 #include <sys/wait.h>
 
 static const char receive_pack_usage[] = "git-receive-pack <git-dir>";
 
-static const char *unpacker = "git-unpack-objects";
+static const char unpacker[] = "git-unpack-objects";
 
 static int show_ref(const char *path, const unsigned char *sha1)
 {
@@ -55,6 +56,38 @@ static int verify_old_ref(const char *name, char *hex_contents)
        return 0;
 }
 
+static char update_hook[] = "hooks/update";
+
+static int run_update_hook(const char *refname,
+                          char *old_hex, char *new_hex)
+{
+       int code;
+
+       if (access(update_hook, X_OK) < 0)
+               return 0;
+       code = run_command(update_hook, refname, old_hex, new_hex, NULL);
+       switch (code) {
+       case 0:
+               return 0;
+       case -ERR_RUN_COMMAND_FORK:
+               die("hook fork failed");
+       case -ERR_RUN_COMMAND_EXEC:
+               die("hook execute failed");
+       case -ERR_RUN_COMMAND_WAITPID:
+               die("waitpid failed");
+       case -ERR_RUN_COMMAND_WAITPID_WRONG_PID:
+               die("waitpid is confused");
+       case -ERR_RUN_COMMAND_WAITPID_SIGNAL:
+               fprintf(stderr, "%s died of signal", update_hook);
+               return -1;
+       case -ERR_RUN_COMMAND_WAITPID_NOEXIT:
+               die("%s died strangely", update_hook);
+       default:
+               error("%s exited with error code %d", update_hook, -code);
+               return -code;
+       }
+}
+
 static void update(const char *name, unsigned char *old_sha1, unsigned char *new_sha1)
 {
        char new_hex[60], *old_hex, *lock_name;
@@ -90,11 +123,16 @@ static void update(const char *name, unsigned char *old_sha1, unsigned char *new
                unlink(lock_name);
                die("%s changed during push", name);
        }
-       if (rename(lock_name, name) < 0) {
+       if (run_update_hook(name, old_hex, new_hex)) {
+               unlink(lock_name);
+               fprintf(stderr, "hook declined to update %s\n", name);
+       }
+       else if (rename(lock_name, name) < 0) {
                unlink(lock_name);
                die("unable to replace %s", name);
        }
-       fprintf(stderr, "%s: %s -> %s\n", name, old_hex, new_hex);
+       else
+               fprintf(stderr, "%s: %s -> %s\n", name, old_hex, new_hex);
 }
 
 
@@ -110,7 +148,7 @@ static void execute_commands(void)
                update(cmd->ref_name, cmd->old_sha1, cmd->new_sha1);
                cmd = cmd->next;
        }
-       update_server_info(0);
+       run_update_hook("", NULL, NULL);
 }
 
 static void read_head_info(void)
@@ -145,34 +183,24 @@ static void read_head_info(void)
 
 static void unpack(void)
 {
-       pid_t pid = fork();
-
-       if (pid < 0)
+       int code = run_command(unpacker, NULL);
+       switch (code) {
+       case 0:
+               return 0;
+       case -ERR_RUN_COMMAND_FORK:
                die("unpack fork failed");
-       if (!pid) {
-               execlp(unpacker, unpacker, NULL);
+       case -ERR_RUN_COMMAND_EXEC:
                die("unpack execute failed");
-       }
-
-       for (;;) {
-               int status, code;
-               int retval = waitpid(pid, &status, 0);
-
-               if (retval < 0) {
-                       if (errno == EINTR)
-                               continue;
-                       die("waitpid failed (%s)", strerror(retval));
-               }
-               if (retval != pid)
-                       die("waitpid is confused");
-               if (WIFSIGNALED(status))
-                       die("%s died of signal %d", unpacker, WTERMSIG(status));
-               if (!WIFEXITED(status))
-                       die("%s died out of really strange complications", unpacker);
-               code = WEXITSTATUS(status);
-               if (code)
-                       die("%s exited with error code %d", unpacker, code);
-               return;
+       case -ERR_RUN_COMMAND_WAITPID:
+               die("waitpid failed");
+       case -ERR_RUN_COMMAND_WAITPID_WRONG_PID:
+               die("waitpid is confused");
+       case -ERR_RUN_COMMAND_WAITPID_SIGNAL:
+               die("%s died of signal", unpacker);
+       case -ERR_RUN_COMMAND_WAITPID_NOEXIT:
+               die("%s died strangely", unpacker);
+       default:
+               die("%s exited with error code %d", unpacker, -code);
        }
 }
 

diff --git a/run-command.c b/run-command.c
new file mode 100644 (file)
index 0000000..5117f62
--- /dev/null
+++ b/run-command.c
@@ -0,0 +1,60 @@
+#include "cache.h"
+#include "run-command.h"
+#include <sys/wait.h>
+
+static int run_external_command(int argc, const char **argv)
+{
+       pid_t pid = fork();
+
+       if (pid < 0)
+               return -ERR_RUN_COMMAND_FORK;
+       if (!pid) {
+               execvp(argv[0], (char *const*) argv);
+               return -ERR_RUN_COMMAND_EXEC;
+       }
+       for (;;) {
+               int status, code;
+               int retval = waitpid(pid, &status, 0);
+
+               if (retval < 0) {
+                       if (errno == EINTR)
+                               continue;
+                       error("waitpid failed (%s)", strerror(retval));
+                       return -ERR_RUN_COMMAND_WAITPID;
+               }
+               if (retval != pid)
+                       return -ERR_RUN_COMMAND_WAITPID_WRONG_PID;
+               if (WIFSIGNALED(status))
+                       return -ERR_RUN_COMMAND_WAITPID_SIGNAL;
+
+               if (!WIFEXITED(status))
+                       return -ERR_RUN_COMMAND_WAITPID_NOEXIT;
+               code = WEXITSTATUS(status);
+               if (code)
+                       return -code;
+               return 0;
+       }
+}
+
+int run_command(const char *cmd, ...)
+{
+       int argc;
+       const char *argv[MAX_RUN_COMMAND_ARGS];
+       const char *arg;
+       va_list param;
+
+       fprintf(stderr, "run-command %s (%d)\n", cmd, ERR_RUN_COMMAND_EXEC);
+
+       va_start(param, cmd);
+       argv[0] = cmd;
+       argc = 1;
+       while (argc < MAX_RUN_COMMAND_ARGS) {
+               arg = argv[argc++] = va_arg(param, char *);
+               if (!arg)
+                       break;
+       }
+       va_end(param);
+       if (MAX_RUN_COMMAND_ARGS <= argc)
+               return error("too many args to run %s", cmd);
+       return run_external_command(argc, argv);
+}

diff --git a/run-command.h b/run-command.h
new file mode 100644 (file)
index 0000000..4f64613
--- /dev/null
+++ b/run-command.h
@@ -0,0 +1,16 @@
+#ifndef RUN_COMMAND_H
+#define RUN_COMMAND_H
+
+#define MAX_RUN_COMMAND_ARGS 256
+enum {
+       ERR_RUN_COMMAND_FORK = 10000,
+       ERR_RUN_COMMAND_EXEC,
+       ERR_RUN_COMMAND_WAITPID,
+       ERR_RUN_COMMAND_WAITPID_WRONG_PID,
+       ERR_RUN_COMMAND_WAITPID_SIGNAL,
+       ERR_RUN_COMMAND_WAITPID_NOEXIT,
+};
+
+int run_command(const char *cmd, ...);
+
+#endif