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git/upload-pack.c
Johannes Sixt 4c324c0050 upload-pack: Use finish_{command,async}() instead of waitpid(). 
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@telecom.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-11-05 22:47:28 -08:00

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#include "cache.h"
#include "refs.h"
#include "pkt-line.h"
#include "sideband.h"
#include "tag.h"
#include "object.h"
#include "commit.h"
#include "exec_cmd.h"
#include "diff.h"
#include "revision.h"
#include "list-objects.h"
#include "run-command.h"
static const char upload_pack_usage[] = "git-upload-pack [--strict] [--timeout=nn] <dir>";
/* bits #0..7 in revision.h, #8..10 in commit.c */
#define THEY_HAVE (1u << 11)
#define OUR_REF (1u << 12)
#define WANTED (1u << 13)
#define COMMON_KNOWN (1u << 14)
#define REACHABLE (1u << 15)
#define SHALLOW (1u << 16)
#define NOT_SHALLOW (1u << 17)
#define CLIENT_SHALLOW (1u << 18)
static unsigned long oldest_have;
static int multi_ack, nr_our_refs;
static int use_thin_pack, use_ofs_delta, no_progress;
static struct object_array have_obj;
static struct object_array want_obj;
static unsigned int timeout;
/* 0 for no sideband,
* otherwise maximum packet size (up to 65520 bytes).
*/
static int use_sideband;
static void reset_timeout(void)
{
alarm(timeout);
}
static int strip(char *line, int len)
{
if (len && line[len-1] == '\n')
line[--len] = 0;
return len;
}
static ssize_t send_client_data(int fd, const char *data, ssize_t sz)
{
if (use_sideband)
return send_sideband(1, fd, data, sz, use_sideband);
if (fd == 3)
/* emergency quit */
fd = 2;
if (fd == 2) {
/* XXX: are we happy to lose stuff here? */
xwrite(fd, data, sz);
return sz;
}
return safe_write(fd, data, sz);
}
static FILE *pack_pipe = NULL;
static void show_commit(struct commit *commit)
{
if (commit->object.flags & BOUNDARY)
fputc('-', pack_pipe);
if (fputs(sha1_to_hex(commit->object.sha1), pack_pipe) < 0)
die("broken output pipe");
fputc('\n', pack_pipe);
fflush(pack_pipe);
free(commit->buffer);
commit->buffer = NULL;
}
static void show_object(struct object_array_entry *p)
{
/* An object with name "foo\n0000000..." can be used to
* confuse downstream git-pack-objects very badly.
*/
const char *ep = strchr(p->name, '\n');
if (ep) {
fprintf(pack_pipe, "%s %.*s\n", sha1_to_hex(p->item->sha1),
(int) (ep - p->name),
p->name);
}
else
fprintf(pack_pipe, "%s %s\n",
sha1_to_hex(p->item->sha1), p->name);
}
static void show_edge(struct commit *commit)
{
fprintf(pack_pipe, "-%s\n", sha1_to_hex(commit->object.sha1));
}
static int do_rev_list(int fd, void *create_full_pack)
{
int i;
struct rev_info revs;
pack_pipe = fdopen(fd, "w");
if (create_full_pack)
use_thin_pack = 0; /* no point doing it */
init_revisions(&revs, NULL);
revs.tag_objects = 1;
revs.tree_objects = 1;
revs.blob_objects = 1;
if (use_thin_pack)
revs.edge_hint = 1;
if (create_full_pack) {
const char *args[] = {"rev-list", "--all", NULL};
setup_revisions(2, args, &revs, NULL);
} else {
for (i = 0; i < want_obj.nr; i++) {
struct object *o = want_obj.objects[i].item;
/* why??? */
o->flags &= ~UNINTERESTING;
add_pending_object(&revs, o, NULL);
}
for (i = 0; i < have_obj.nr; i++) {
struct object *o = have_obj.objects[i].item;
o->flags |= UNINTERESTING;
add_pending_object(&revs, o, NULL);
}
setup_revisions(0, NULL, &revs, NULL);
}
prepare_revision_walk(&revs);
mark_edges_uninteresting(revs.commits, &revs, show_edge);
traverse_commit_list(&revs, show_commit, show_object);
return 0;
}
static void create_pack_file(void)
{
struct async rev_list;
struct child_process pack_objects;
int create_full_pack = (nr_our_refs == want_obj.nr && !have_obj.nr);
char data[8193], progress[128];
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;
rev_list.proc = do_rev_list;
/* .data is just a boolean: any non-NULL value will do */
rev_list.data = create_full_pack ? &rev_list : NULL;
if (start_async(&rev_list))
die("git-upload-pack: unable to fork git-rev-list");
argv[arg++] = "pack-objects";
argv[arg++] = "--stdout";
if (!no_progress)
argv[arg++] = "--progress";
if (use_ofs_delta)
argv[arg++] = "--delta-base-offset";
argv[arg++] = NULL;
memset(&pack_objects, 0, sizeof(pack_objects));
pack_objects.in = rev_list.out; /* start_command closes it */
pack_objects.out = -1;
pack_objects.err = -1;
pack_objects.git_cmd = 1;
pack_objects.argv = argv;
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) {
struct pollfd pfd[2];
int pe, pu, pollsize;
reset_timeout();
pollsize = 0;
pe = pu = -1;
if (0 <= pack_objects.out) {
pfd[pollsize].fd = pack_objects.out;
pfd[pollsize].events = POLLIN;
pu = pollsize;
pollsize++;
}
if (0 <= pack_objects.err) {
pfd[pollsize].fd = pack_objects.err;
pfd[pollsize].events = POLLIN;
pe = pollsize;
pollsize++;
}
if (!pollsize)
break;
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 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;
}
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 (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:
send_client_data(3, abort_msg, sizeof(abort_msg));
die("git-upload-pack: %s", abort_msg);
}
static int got_sha1(char *hex, unsigned char *sha1)
{
struct object *o;
int we_knew_they_have = 0;
if (get_sha1_hex(hex, sha1))
die("git-upload-pack: expected SHA1 object, got '%s'", hex);
if (!has_sha1_file(sha1))
return -1;
o = lookup_object(sha1);
if (!(o && o->parsed))
o = parse_object(sha1);
if (!o)
die("oops (%s)", sha1_to_hex(sha1));
if (o->type == OBJ_COMMIT) {
struct commit_list *parents;
struct commit *commit = (struct commit *)o;
if (o->flags & THEY_HAVE)
we_knew_they_have = 1;
else
o->flags |= THEY_HAVE;
if (!oldest_have || (commit->date < oldest_have))
oldest_have = commit->date;
for (parents = commit->parents;
parents;
parents = parents->next)
parents->item->object.flags |= THEY_HAVE;
}
if (!we_knew_they_have) {
add_object_array(o, NULL, &have_obj);
return 1;
}
return 0;
}
static int reachable(struct commit *want)
{
struct commit_list *work = NULL;
insert_by_date(want, &work);
while (work) {
struct commit_list *list = work->next;
struct commit *commit = work->item;
free(work);
work = list;
if (commit->object.flags & THEY_HAVE) {
want->object.flags |= COMMON_KNOWN;
break;
}
if (!commit->object.parsed)
parse_object(commit->object.sha1);
if (commit->object.flags & REACHABLE)
continue;
commit->object.flags |= REACHABLE;
if (commit->date < oldest_have)
continue;
for (list = commit->parents; list; list = list->next) {
struct commit *parent = list->item;
if (!(parent->object.flags & REACHABLE))
insert_by_date(parent, &work);
}
}
want->object.flags |= REACHABLE;
clear_commit_marks(want, REACHABLE);
free_commit_list(work);
return (want->object.flags & COMMON_KNOWN);
}
static int ok_to_give_up(void)
{
int i;
if (!have_obj.nr)
return 0;
for (i = 0; i < want_obj.nr; i++) {
struct object *want = want_obj.objects[i].item;
if (want->flags & COMMON_KNOWN)
continue;
want = deref_tag(want, "a want line", 0);
if (!want || want->type != OBJ_COMMIT) {
/* no way to tell if this is reachable by
* looking at the ancestry chain alone, so
* leave a note to ourselves not to worry about
* this object anymore.
*/
want_obj.objects[i].item->flags |= COMMON_KNOWN;
continue;
}
if (!reachable((struct commit *)want))
return 0;
}
return 1;
}
static int get_common_commits(void)
{
static char line[1000];
unsigned char sha1[20];
char hex[41], last_hex[41];
int len;
track_object_refs = 0;
save_commit_buffer = 0;
for(;;) {
len = packet_read_line(0, line, sizeof(line));
reset_timeout();
if (!len) {
if (have_obj.nr == 0 || multi_ack)
packet_write(1, "NAK\n");
continue;
}
len = strip(line, len);
if (!prefixcmp(line, "have ")) {
switch (got_sha1(line+5, sha1)) {
case -1: /* they have what we do not */
if (multi_ack && ok_to_give_up())
packet_write(1, "ACK %s continue\n",
sha1_to_hex(sha1));
break;
default:
memcpy(hex, sha1_to_hex(sha1), 41);
if (multi_ack) {
const char *msg = "ACK %s continue\n";
packet_write(1, msg, hex);
memcpy(last_hex, hex, 41);
}
else if (have_obj.nr == 1)
packet_write(1, "ACK %s\n", hex);
break;
}
continue;
}
if (!strcmp(line, "done")) {
if (have_obj.nr > 0) {
if (multi_ack)
packet_write(1, "ACK %s\n", last_hex);
return 0;
}
packet_write(1, "NAK\n");
return -1;
}
die("git-upload-pack: expected SHA1 list, got '%s'", line);
}
}
static void receive_needs(void)
{
struct object_array shallows = {0, 0, NULL};
static char line[1000];
int len, depth = 0;
for (;;) {
struct object *o;
unsigned char sha1_buf[20];
len = packet_read_line(0, line, sizeof(line));
reset_timeout();
if (!len)
break;
if (!prefixcmp(line, "shallow ")) {
unsigned char sha1[20];
struct object *object;
use_thin_pack = 0;
if (get_sha1(line + 8, sha1))
die("invalid shallow line: %s", line);
object = parse_object(sha1);
if (!object)
die("did not find object for %s", line);
object->flags |= CLIENT_SHALLOW;
add_object_array(object, NULL, &shallows);
continue;
}
if (!prefixcmp(line, "deepen ")) {
char *end;
use_thin_pack = 0;
depth = strtol(line + 7, &end, 0);
if (end == line + 7 || depth <= 0)
die("Invalid deepen: %s", line);
continue;
}
if (prefixcmp(line, "want ") ||
get_sha1_hex(line+5, sha1_buf))
die("git-upload-pack: protocol error, "
"expected to get sha, not '%s'", line);
if (strstr(line+45, "multi_ack"))
multi_ack = 1;
if (strstr(line+45, "thin-pack"))
use_thin_pack = 1;
if (strstr(line+45, "ofs-delta"))
use_ofs_delta = 1;
if (strstr(line+45, "side-band-64k"))
use_sideband = LARGE_PACKET_MAX;
else if (strstr(line+45, "side-band"))
use_sideband = DEFAULT_PACKET_MAX;
if (strstr(line+45, "no-progress"))
no_progress = 1;
/* We have sent all our refs already, and the other end
* should have chosen out of them; otherwise they are
* asking for nonsense.
*
* Hmph. We may later want to allow "want" line that
* asks for something like "master~10" (symbolic)...
* would it make sense? I don't know.
*/
o = lookup_object(sha1_buf);
if (!o || !(o->flags & OUR_REF))
die("git-upload-pack: not our ref %s", line+5);
if (!(o->flags & WANTED)) {
o->flags |= WANTED;
add_object_array(o, NULL, &want_obj);
}
}
if (depth == 0 && shallows.nr == 0)
return;
if (depth > 0) {
struct commit_list *result, *backup;
int i;
backup = result = get_shallow_commits(&want_obj, depth,
SHALLOW, NOT_SHALLOW);
while (result) {
struct object *object = &result->item->object;
if (!(object->flags & (CLIENT_SHALLOW|NOT_SHALLOW))) {
packet_write(1, "shallow %s",
sha1_to_hex(object->sha1));
register_shallow(object->sha1);
}
result = result->next;
}
free_commit_list(backup);
for (i = 0; i < shallows.nr; i++) {
struct object *object = shallows.objects[i].item;
if (object->flags & NOT_SHALLOW) {
struct commit_list *parents;
packet_write(1, "unshallow %s",
sha1_to_hex(object->sha1));
object->flags &= ~CLIENT_SHALLOW;
/* make sure the real parents are parsed */
unregister_shallow(object->sha1);
object->parsed = 0;
parse_commit((struct commit *)object);
parents = ((struct commit *)object)->parents;
while (parents) {
add_object_array(&parents->item->object,
NULL, &want_obj);
parents = parents->next;
}
}
/* make sure commit traversal conforms to client */
register_shallow(object->sha1);
}
packet_flush(1);
} else
if (shallows.nr > 0) {
int i;
for (i = 0; i < shallows.nr; i++)
register_shallow(shallows.objects[i].item->sha1);
}
free(shallows.objects);
}
static int send_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
{
static const char *capabilities = "multi_ack thin-pack side-band"
" side-band-64k ofs-delta shallow no-progress";
struct object *o = parse_object(sha1);
if (!o)
die("git-upload-pack: cannot find object %s:", sha1_to_hex(sha1));
if (capabilities)
packet_write(1, "%s %s%c%s\n", sha1_to_hex(sha1), refname,
0, capabilities);
else
packet_write(1, "%s %s\n", sha1_to_hex(sha1), refname);
capabilities = NULL;
if (!(o->flags & OUR_REF)) {
o->flags |= OUR_REF;
nr_our_refs++;
}
if (o->type == OBJ_TAG) {
o = deref_tag(o, refname, 0);
packet_write(1, "%s %s^{}\n", sha1_to_hex(o->sha1), refname);
}
return 0;
}
static void upload_pack(void)
{
reset_timeout();
head_ref(send_ref, NULL);
for_each_ref(send_ref, NULL);
packet_flush(1);
receive_needs();
if (want_obj.nr) {
get_common_commits();
create_pack_file();
}
}
int main(int argc, char **argv)
{
char *dir;
int i;
int strict = 0;
for (i = 1; i < argc; i++) {
char *arg = argv[i];
if (arg[0] != '-')
break;
if (!strcmp(arg, "--strict")) {
strict = 1;
continue;
}
if (!prefixcmp(arg, "--timeout=")) {
timeout = atoi(arg+10);
continue;
}
if (!strcmp(arg, "--")) {
i++;
break;
}
}
if (i != argc-1)
usage(upload_pack_usage);
dir = argv[i];
if (!enter_repo(dir, strict))
die("'%s': unable to chdir or not a git archive", dir);
if (is_repository_shallow())
die("attempt to fetch/clone from a shallow repository");
upload_pack();
return 0;
}
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