From 8e9faf27c11d515b2eef526f2a15c1c2a4ac8d4e Mon Sep 17 00:00:00 2001 From: Jeff King Date: Wed, 10 Dec 2014 04:47:02 -0500 Subject: pkt-line: allow writing of LARGE_PACKET_MAX buffers When we send out pkt-lines with refnames, we use a static 1000-byte buffer. This means that the maximum size of a ref over the git protocol is around 950 bytes (the exact size depends on the protocol line being written, but figure on a sha1 plus some boilerplate). This is enough for any sane workflow, but occasionally odd things happen (e.g., a bug may create a ref "foo/foo/foo/..." accidentally). With the current code, you cannot even use "push" to delete such a ref from a remote. Let's switch to using a strbuf, with a hard-limit of LARGE_PACKET_MAX (which is specified by the protocol). This matches the size of the readers, as of 74543a0 (pkt-line: provide a LARGE_PACKET_MAX static buffer, 2013-02-20). Versions of git older than that will complain about our large packets, but it's really no worse than the current behavior. Right now the sender barfs with "impossibly long line" trying to send the packet, and afterwards the reader will barf with "protocol error: bad line length %d", which is arguably better anyway. Note that we're not really _solving_ the problem here, but just bumping the limits. In theory, the length of a ref is unbounded, and pkt-line can only represent sizes up to 65531 bytes. So we are just bumping the limit, not removing it. But hopefully 64K should be enough for anyone. As a bonus, by using a strbuf for the formatting we can eliminate an unnecessary copy in format_buf_write. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano diff --git a/pkt-line.c b/pkt-line.c index 8bc89b1..187a229 100644 --- a/pkt-line.c +++ b/pkt-line.c @@ -64,44 +64,45 @@ void packet_buf_flush(struct strbuf *buf) } #define hex(a) (hexchar[(a) & 15]) -static char buffer[1000]; -static unsigned format_packet(const char *fmt, va_list args) +static void format_packet(struct strbuf *out, const char *fmt, va_list args) { static char hexchar[] = "0123456789abcdef"; - unsigned n; + size_t orig_len, n; - n = vsnprintf(buffer + 4, sizeof(buffer) - 4, fmt, args); - if (n >= sizeof(buffer)-4) + orig_len = out->len; + strbuf_addstr(out, "0000"); + strbuf_vaddf(out, fmt, args); + n = out->len - orig_len; + + if (n > LARGE_PACKET_MAX) die("protocol error: impossibly long line"); - n += 4; - buffer[0] = hex(n >> 12); - buffer[1] = hex(n >> 8); - buffer[2] = hex(n >> 4); - buffer[3] = hex(n); - packet_trace(buffer+4, n-4, 1); - return n; + + out->buf[orig_len + 0] = hex(n >> 12); + out->buf[orig_len + 1] = hex(n >> 8); + out->buf[orig_len + 2] = hex(n >> 4); + out->buf[orig_len + 3] = hex(n); + packet_trace(out->buf + orig_len + 4, n - 4, 1); } void packet_write(int fd, const char *fmt, ...) { + static struct strbuf buf = STRBUF_INIT; va_list args; - unsigned n; + strbuf_reset(&buf); va_start(args, fmt); - n = format_packet(fmt, args); + format_packet(&buf, fmt, args); va_end(args); - write_or_die(fd, buffer, n); + write_or_die(fd, buf.buf, buf.len); } void packet_buf_write(struct strbuf *buf, const char *fmt, ...) { va_list args; - unsigned n; va_start(args, fmt); - n = format_packet(fmt, args); + format_packet(buf, fmt, args); va_end(args); - strbuf_add(buf, buffer, n); } static int get_packet_data(int fd, char **src_buf, size_t *src_size, diff --git a/t/t5527-fetch-odd-refs.sh b/t/t5527-fetch-odd-refs.sh index edea9f9..207899a 100755 --- a/t/t5527-fetch-odd-refs.sh +++ b/t/t5527-fetch-odd-refs.sh @@ -26,4 +26,37 @@ test_expect_success 'suffix ref is ignored during fetch' ' test_cmp expect actual ' +test_expect_success 'try to create repo with absurdly long refname' ' + ref240=$_z40/$_z40/$_z40/$_z40/$_z40/$_z40 && + ref1440=$ref240/$ref240/$ref240/$ref240/$ref240/$ref240 && + git init long && + ( + cd long && + test_commit long && + test_commit master + ) && + if git -C long update-ref refs/heads/$ref1440 long; then + test_set_prereq LONG_REF + else + echo >&2 "long refs not supported" + fi +' + +test_expect_success LONG_REF 'fetch handles extremely long refname' ' + git fetch long refs/heads/*:refs/remotes/long/* && + cat >expect <<-\EOF && + long + master + EOF + git for-each-ref --format="%(subject)" refs/remotes/long >actual && + test_cmp expect actual +' + +test_expect_success LONG_REF 'push handles extremely long refname' ' + git push long :refs/heads/$ref1440 && + git -C long for-each-ref --format="%(subject)" refs/heads >actual && + echo master >expect && + test_cmp expect actual +' + test_done -- cgit v0.10.2-6-g49f6