upload-pack spawns two processes, rev-list and pack-objects, and carefully
monitors their status so that it can report failure to the remote end.
This change removes the complicated procedures on the grounds of the
following observations:
- If everything is OK, rev-list closes its output pipe end, upon which
pack-objects (which reads from the pipe) sees EOF and terminates itself,
closing its output (and error) pipes. upload-pack reads from both until
it sees EOF in both. It collects the exit codes of the child processes
(which indicate success) and terminates successfully.
- If rev-list sees an error, it closes its output and terminates with
failure. pack-objects sees EOF in its input and terminates successfully.
Again upload-pack reads its inputs until EOF. When it now collects
the exit codes of its child processes, it notices the failure of rev-list
and signals failure to the remote end.
- If pack-objects sees an error, it terminates with failure. Since this
breaks the pipe to rev-list, rev-list is killed with SIGPIPE.
upload-pack reads its input until EOF, then collects the exit codes of
the child processes, notices their failures, and signals failure to the
remote end.
- If upload-pack itself dies unexpectedly, pack-objects is killed with
SIGPIPE, and subsequently also rev-list.
The upshot of this is that precise monitoring of child processes is not
required because both terminate if either one of them dies unexpectedly.
This allows us to use finish_command() and finish_async() instead of
an explicit waitpid(2) call.
The change is smaller than it looks because most of it only reduces the
indentation of a large part of the inner loop.
Signed-off-by: Johannes Sixt <johannes.sixt@xxxxxxxxxx>
---
This patch allows us to reduce the differences to the
MinGW port even further. It goes on top of js/forkexec
(which meanwhile is in master).
The test case checks for failures in rev-list (a missing
object). Any hints how to trigger a failure in pack-objects
that does not also trigger in rev-list would be welcome.
BTW, I don't know what it means to process zombies if the
parent does not waitpid(), but just terminates. Does this
work as expected, ie. no zombies are left behind?
-- Hannes
t/t5530-upload-pack-error.sh | 49 +++++++++++
upload-pack.c | 192 +++++++++++++++++-------------------------
2 files changed, 126 insertions(+), 115 deletions(-)
create mode 100755 t/t5530-upload-pack-error.sh
diff --git a/t/t5530-upload-pack-error.sh b/t/t5530-upload-pack-error.sh
new file mode 100755
index 0000000..9923ba0
--- /dev/null
+++ b/t/t5530-upload-pack-error.sh
@@ -0,0 +1,49 @@
+#!/bin/sh
+
+test_description='errors in upload-pack'
+
+. ./test-lib.sh
+
+D=`pwd`
+
+test_expect_success 'setup and corrupt repository' '
+
+ echo file >file &&
+ git add file &&
+ git rev-parse :file &&
+ git commit -a -m original &&
+ test_tick &&
+ echo changed >file &&
+ git commit -a -m changed &&
+ rm -f .git/objects/f7/3f3093ff865c514c6c51f867e35f693487d0d3
+
+'
+
+test_expect_failure 'fsck fails' '
+
+ git fsck
+'
+
+test_expect_failure 'upload pack fails due to error in rev-list' '
+
+ echo "0032want $(git rev-parse HEAD)
+00000009done
+0000" | git-upload-pack . > /dev/null
+
+'
+
+test_expect_success 'create empty repository' '
+
+ mkdir foo &&
+ cd foo &&
+ git init
+
+'
+
+test_expect_failure 'fetch fails' '
+
+ git fetch .. master
+
+'
+
+test_done
diff --git a/upload-pack.c b/upload-pack.c
index 6799468..7e04311 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -144,6 +144,7 @@ static void create_pack_file(void)
char abort_msg[] = "aborting due to possible repository "
"corruption on the remote side.";
int buffered = -1;
+ ssize_t sz;
const char *argv[10];
int arg = 0;
@@ -168,22 +169,15 @@ static void create_pack_file(void)
pack_objects.git_cmd = 1;
pack_objects.argv = argv;
- if (start_command(&pack_objects)) {
- /* daemon sets things up to ignore TERM */
- kill(rev_list.pid, SIGKILL);
+ if (start_command(&pack_objects))
die("git-upload-pack: unable to fork git-pack-objects");
- }
/* We read from pack_objects.err to capture stderr output for
* progress bar, and pack_objects.out to capture the pack data.
*/
while (1) {
- const char *who;
struct pollfd pfd[2];
- pid_t pid;
- int status;
- ssize_t sz;
int pe, pu, pollsize;
reset_timeout();
@@ -204,123 +198,91 @@ static void create_pack_file(void)
pollsize++;
}
- if (pollsize) {
- if (poll(pfd, pollsize, -1) < 0) {
- if (errno != EINTR) {
- error("poll failed, resuming: %s",
- strerror(errno));
- sleep(1);
- }
- continue;
- }
- if (0 <= pu && (pfd[pu].revents & (POLLIN|POLLHUP))) {
- /* Data ready; we keep the last byte
- * to ourselves in case we detect
- * broken rev-list, so that we can
- * leave the stream corrupted. This
- * is unfortunate -- unpack-objects
- * would happily accept a valid pack
- * data with trailing garbage, so
- * appending garbage after we pass all
- * the pack data is not good enough to
- * signal breakage to downstream.
- */
- char *cp = data;
- ssize_t outsz = 0;
- if (0 <= buffered) {
- *cp++ = buffered;
- outsz++;
- }
- sz = xread(pack_objects.out, cp,
- sizeof(data) - outsz);
- if (0 < sz)
- ;
- else if (sz == 0) {
- close(pack_objects.out);
- pack_objects.out = -1;
- }
- else
- goto fail;
- sz += outsz;
- if (1 < sz) {
- buffered = data[sz-1] & 0xFF;
- sz--;
- }
- else
- buffered = -1;
- sz = send_client_data(1, data, sz);
- if (sz < 0)
- goto fail;
- }
- if (0 <= pe && (pfd[pe].revents & (POLLIN|POLLHUP))) {
- /* Status ready; we ship that in the side-band
- * or dump to the standard error.
- */
- sz = xread(pack_objects.err, progress,
- sizeof(progress));
- if (0 < sz)
- send_client_data(2, progress, sz);
- else if (sz == 0) {
- close(pack_objects.err);
- pack_objects.err = -1;
- }
- else
- goto fail;
+ if (!pollsize)
+ break;
+
+ if (poll(pfd, pollsize, -1) < 0) {
+ if (errno != EINTR) {
+ error("poll failed, resuming: %s",
+ strerror(errno));
+ sleep(1);
}
+ continue;
}
-
- /* See if the children are still there */
- if (rev_list.pid || pack_objects.pid) {
- pid = waitpid(-1, &status, WNOHANG);
- if (!pid)
- continue;
- who = ((pid == rev_list.pid) ? "git-rev-list" :
- (pid == pack_objects.pid) ? "git-pack-objects" :
- NULL);
- if (!who) {
- if (pid < 0) {
- error("git-upload-pack: %s",
- strerror(errno));
- goto fail;
- }
- error("git-upload-pack: we weren't "
- "waiting for %d", pid);
- continue;
+ if (0 <= pu && (pfd[pu].revents & (POLLIN|POLLHUP))) {
+ /* Data ready; we keep the last byte to ourselves
+ * in case we detect broken rev-list, so that we
+ * can leave the stream corrupted. This is
+ * unfortunate -- unpack-objects would happily
+ * accept a valid packdata with trailing garbage,
+ * so appending garbage after we pass all the
+ * pack data is not good enough to signal
+ * breakage to downstream.
+ */
+ char *cp = data;
+ ssize_t outsz = 0;
+ if (0 <= buffered) {
+ *cp++ = buffered;
+ outsz++;
+ }
+ sz = xread(pack_objects.out, cp,
+ sizeof(data) - outsz);
+ if (0 < sz)
+ ;
+ else if (sz == 0) {
+ close(pack_objects.out);
+ pack_objects.out = -1;
}
- if (!WIFEXITED(status) || WEXITSTATUS(status) > 0) {
- error("git-upload-pack: %s died with error.",
- who);
+ else
goto fail;
+ sz += outsz;
+ if (1 < sz) {
+ buffered = data[sz-1] & 0xFF;
+ sz--;
}
- if (pid == rev_list.pid)
- rev_list.pid = 0;
- if (pid == pack_objects.pid)
- pack_objects.pid = 0;
- if (rev_list.pid || pack_objects.pid)
- continue;
- }
-
- /* both died happily */
- if (pollsize)
- continue;
-
- /* flush the data */
- if (0 <= buffered) {
- data[0] = buffered;
- sz = send_client_data(1, data, 1);
+ else
+ buffered = -1;
+ sz = send_client_data(1, data, sz);
if (sz < 0)
goto fail;
- fprintf(stderr, "flushed.\n");
}
- if (use_sideband)
- packet_flush(1);
- return;
+ if (0 <= pe && (pfd[pe].revents & (POLLIN|POLLHUP))) {
+ /* Status ready; we ship that in the side-band
+ * or dump to the standard error.
+ */
+ sz = xread(pack_objects.err, progress,
+ sizeof(progress));
+ if (0 < sz)
+ send_client_data(2, progress, sz);
+ else if (sz == 0) {
+ close(pack_objects.err);
+ pack_objects.err = -1;
+ }
+ else
+ goto fail;
+ }
+ }
+
+ if (finish_command(&pack_objects)) {
+ error("git-upload-pack: git-pack-objects died with error.");
+ goto fail;
+ }
+ if (finish_async(&rev_list))
+ goto fail; /* error was already reported */
+
+ /* flush the data */
+ if (0 <= buffered) {
+ data[0] = buffered;
+ sz = send_client_data(1, data, 1);
+ if (sz < 0)
+ goto fail;
+ fprintf(stderr, "flushed.\n");
}
+ if (use_sideband)
+ packet_flush(1);
+ return;
+
fail:
- if (pack_objects.pid)
- kill(pack_objects.pid, SIGKILL);
- if (rev_list.pid)
- kill(rev_list.pid, SIGKILL);
send_client_data(3, abort_msg, sizeof(abort_msg));
die("git-upload-pack: %s", abort_msg);
}
--
1.5.3.4.315.g2ce38
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