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git/builtin/upload-archive.c
Jeff King 74543a0423 pkt-line: provide a LARGE_PACKET_MAX static buffer
Most of the callers of packet_read_line just read into a
static 1000-byte buffer (callers which handle arbitrary
binary data already use LARGE_PACKET_MAX). This works fine
in practice, because:

  1. The only variable-sized data in these lines is a ref
     name, and refs tend to be a lot shorter than 1000
     characters.

  2. When sending ref lines, git-core always limits itself
     to 1000 byte packets.

However, the only limit given in the protocol specification
in Documentation/technical/protocol-common.txt is
LARGE_PACKET_MAX; the 1000 byte limit is mentioned only in
pack-protocol.txt, and then only describing what we write,
not as a specific limit for readers.

This patch lets us bump the 1000-byte limit to
LARGE_PACKET_MAX. Even though git-core will never write a
packet where this makes a difference, there are two good
reasons to do this:

  1. Other git implementations may have followed
     protocol-common.txt and used a larger maximum size. We
     don't bump into it in practice because it would involve
     very long ref names.

  2. We may want to increase the 1000-byte limit one day.
     Since packets are transferred before any capabilities,
     it's difficult to do this in a backwards-compatible
     way. But if we bump the size of buffer the readers can
     handle, eventually older versions of git will be
     obsolete enough that we can justify bumping the
     writers, as well. We don't have plans to do this
     anytime soon, but there is no reason not to start the
     clock ticking now.

Just bumping all of the reading bufs to LARGE_PACKET_MAX
would waste memory. Instead, since most readers just read
into a temporary buffer anyway, let's provide a single
static buffer that all callers can use. We can further wrap
this detail away by having the packet_read_line wrapper just
use the buffer transparently and return a pointer to the
static storage.  That covers most of the cases, and the
remaining ones already read into their own LARGE_PACKET_MAX
buffers.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-02-20 13:42:22 -08:00

129 lines
3 KiB
C

/*
* Copyright (c) 2006 Franck Bui-Huu
*/
#include "cache.h"
#include "builtin.h"
#include "archive.h"
#include "pkt-line.h"
#include "sideband.h"
#include "run-command.h"
#include "argv-array.h"
static const char upload_archive_usage[] =
"git upload-archive <repo>";
static const char deadchild[] =
"git upload-archive: archiver died with error";
#define MAX_ARGS (64)
int cmd_upload_archive_writer(int argc, const char **argv, const char *prefix)
{
struct argv_array sent_argv = ARGV_ARRAY_INIT;
const char *arg_cmd = "argument ";
if (argc != 2)
usage(upload_archive_usage);
if (!enter_repo(argv[1], 0))
die("'%s' does not appear to be a git repository", argv[1]);
/* put received options in sent_argv[] */
argv_array_push(&sent_argv, "git-upload-archive");
for (;;) {
char *buf = packet_read_line(0, NULL);
if (!buf)
break; /* got a flush */
if (sent_argv.argc > MAX_ARGS)
die("Too many options (>%d)", MAX_ARGS - 1);
if (prefixcmp(buf, arg_cmd))
die("'argument' token or flush expected");
argv_array_push(&sent_argv, buf + strlen(arg_cmd));
}
/* parse all options sent by the client */
return write_archive(sent_argv.argc, sent_argv.argv, prefix, 0, NULL, 1);
}
__attribute__((format (printf, 1, 2)))
static void error_clnt(const char *fmt, ...)
{
char buf[1024];
va_list params;
int len;
va_start(params, fmt);
len = vsprintf(buf, fmt, params);
va_end(params);
send_sideband(1, 3, buf, len, LARGE_PACKET_MAX);
die("sent error to the client: %s", buf);
}
static ssize_t process_input(int child_fd, int band)
{
char buf[16384];
ssize_t sz = read(child_fd, buf, sizeof(buf));
if (sz < 0) {
if (errno != EAGAIN && errno != EINTR)
error_clnt("read error: %s\n", strerror(errno));
return sz;
}
send_sideband(1, band, buf, sz, LARGE_PACKET_MAX);
return sz;
}
int cmd_upload_archive(int argc, const char **argv, const char *prefix)
{
struct child_process writer = { argv };
/*
* Set up sideband subprocess.
*
* We (parent) monitor and read from child, sending its fd#1 and fd#2
* multiplexed out to our fd#1. If the child dies, we tell the other
* end over channel #3.
*/
argv[0] = "upload-archive--writer";
writer.out = writer.err = -1;
writer.git_cmd = 1;
if (start_command(&writer)) {
int err = errno;
packet_write(1, "NACK unable to spawn subprocess\n");
die("upload-archive: %s", strerror(err));
}
packet_write(1, "ACK\n");
packet_flush(1);
while (1) {
struct pollfd pfd[2];
pfd[0].fd = writer.out;
pfd[0].events = POLLIN;
pfd[1].fd = writer.err;
pfd[1].events = POLLIN;
if (poll(pfd, 2, -1) < 0) {
if (errno != EINTR) {
error("poll failed resuming: %s",
strerror(errno));
sleep(1);
}
continue;
}
if (pfd[1].revents & POLLIN)
/* Status stream ready */
if (process_input(pfd[1].fd, 2))
continue;
if (pfd[0].revents & POLLIN)
/* Data stream ready */
if (process_input(pfd[0].fd, 1))
continue;
if (finish_command(&writer))
error_clnt("%s", deadchild);
packet_flush(1);
break;
}
return 0;
}