1
0
Fork 0
mirror of https://github.com/git/git.git synced 2024-10-30 13:57:54 +01:00
git/pkt-line.c
Jeff King 323598387d pkt-line: support tracing verbatim pack contents
When debugging the pack protocol, it is sometimes useful to
store the verbatim pack that we sent or received on the
wire. Looking at the on-disk result is often not helpful for
a few reasons:

  1. If the operation is a clone, we destroy the repo on
     failure, leaving nothing on disk.

  2. If the pack is small, we unpack it immediately, and the
     full pack never hits the disk.

  3. If we feed the pack to "index-pack --fix-thin", the
     resulting pack has the extra delta bases added to it.

We already have a GIT_TRACE_PACKET mechanism for tracing
packets. Let's extend it with GIT_TRACE_PACKFILE to dump the
verbatim packfile.

There are a few other positive fallouts that come from
rearranging this code:

 - We currently disable the packet trace after seeing the
   PACK header, even though we may get human-readable lines
   on other sidebands; now we include them in the trace.

 - We currently try to print "PACK ..." in the trace to
   indicate that the packfile has started. But because we
   disable packet tracing, we never printed this line. We
   will now do so.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-06-16 13:24:22 -07:00

244 lines
5.3 KiB
C

#include "cache.h"
#include "pkt-line.h"
char packet_buffer[LARGE_PACKET_MAX];
static const char *packet_trace_prefix = "git";
static struct trace_key trace_packet = TRACE_KEY_INIT(PACKET);
static struct trace_key trace_pack = TRACE_KEY_INIT(PACKFILE);
void packet_trace_identity(const char *prog)
{
packet_trace_prefix = xstrdup(prog);
}
static int packet_trace_pack(const char *buf, unsigned int len, int sideband)
{
if (!sideband) {
trace_verbatim(&trace_pack, buf, len);
return 1;
} else if (len && *buf == '\1') {
trace_verbatim(&trace_pack, buf + 1, len - 1);
return 1;
} else {
/* it's another non-pack sideband */
return 0;
}
}
static void packet_trace(const char *buf, unsigned int len, int write)
{
int i;
struct strbuf out;
static int in_pack, sideband;
if (!trace_want(&trace_packet) && !trace_want(&trace_pack))
return;
if (in_pack) {
if (packet_trace_pack(buf, len, sideband))
return;
} else if (starts_with(buf, "PACK") || starts_with(buf, "\1PACK")) {
in_pack = 1;
sideband = *buf == '\1';
packet_trace_pack(buf, len, sideband);
/*
* Make a note in the human-readable trace that the pack data
* started.
*/
buf = "PACK ...";
len = strlen(buf);
}
if (!trace_want(&trace_packet))
return;
/* +32 is just a guess for header + quoting */
strbuf_init(&out, len+32);
strbuf_addf(&out, "packet: %12s%c ",
packet_trace_prefix, write ? '>' : '<');
/* XXX we should really handle printable utf8 */
for (i = 0; i < len; i++) {
/* suppress newlines */
if (buf[i] == '\n')
continue;
if (buf[i] >= 0x20 && buf[i] <= 0x7e)
strbuf_addch(&out, buf[i]);
else
strbuf_addf(&out, "\\%o", buf[i]);
}
strbuf_addch(&out, '\n');
trace_strbuf(&trace_packet, &out);
strbuf_release(&out);
}
/*
* If we buffered things up above (we don't, but we should),
* we'd flush it here
*/
void packet_flush(int fd)
{
packet_trace("0000", 4, 1);
write_or_die(fd, "0000", 4);
}
void packet_buf_flush(struct strbuf *buf)
{
packet_trace("0000", 4, 1);
strbuf_add(buf, "0000", 4);
}
#define hex(a) (hexchar[(a) & 15])
static void format_packet(struct strbuf *out, const char *fmt, va_list args)
{
static char hexchar[] = "0123456789abcdef";
size_t orig_len, n;
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");
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;
strbuf_reset(&buf);
va_start(args, fmt);
format_packet(&buf, fmt, args);
va_end(args);
write_or_die(fd, buf.buf, buf.len);
}
void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
format_packet(buf, fmt, args);
va_end(args);
}
static int get_packet_data(int fd, char **src_buf, size_t *src_size,
void *dst, unsigned size, int options)
{
ssize_t ret;
if (fd >= 0 && src_buf && *src_buf)
die("BUG: multiple sources given to packet_read");
/* Read up to "size" bytes from our source, whatever it is. */
if (src_buf && *src_buf) {
ret = size < *src_size ? size : *src_size;
memcpy(dst, *src_buf, ret);
*src_buf += ret;
*src_size -= ret;
} else {
ret = read_in_full(fd, dst, size);
if (ret < 0)
die_errno("read error");
}
/* And complain if we didn't get enough bytes to satisfy the read. */
if (ret < size) {
if (options & PACKET_READ_GENTLE_ON_EOF)
return -1;
die("The remote end hung up unexpectedly");
}
return ret;
}
static int packet_length(const char *linelen)
{
int n;
int len = 0;
for (n = 0; n < 4; n++) {
unsigned char c = linelen[n];
len <<= 4;
if (c >= '0' && c <= '9') {
len += c - '0';
continue;
}
if (c >= 'a' && c <= 'f') {
len += c - 'a' + 10;
continue;
}
if (c >= 'A' && c <= 'F') {
len += c - 'A' + 10;
continue;
}
return -1;
}
return len;
}
int packet_read(int fd, char **src_buf, size_t *src_len,
char *buffer, unsigned size, int options)
{
int len, ret;
char linelen[4];
ret = get_packet_data(fd, src_buf, src_len, linelen, 4, options);
if (ret < 0)
return ret;
len = packet_length(linelen);
if (len < 0)
die("protocol error: bad line length character: %.4s", linelen);
if (!len) {
packet_trace("0000", 4, 0);
return 0;
}
len -= 4;
if (len >= size)
die("protocol error: bad line length %d", len);
ret = get_packet_data(fd, src_buf, src_len, buffer, len, options);
if (ret < 0)
return ret;
if ((options & PACKET_READ_CHOMP_NEWLINE) &&
len && buffer[len-1] == '\n')
len--;
buffer[len] = 0;
packet_trace(buffer, len, 0);
return len;
}
static char *packet_read_line_generic(int fd,
char **src, size_t *src_len,
int *dst_len)
{
int len = packet_read(fd, src, src_len,
packet_buffer, sizeof(packet_buffer),
PACKET_READ_CHOMP_NEWLINE);
if (dst_len)
*dst_len = len;
return len ? packet_buffer : NULL;
}
char *packet_read_line(int fd, int *len_p)
{
return packet_read_line_generic(fd, NULL, NULL, len_p);
}
char *packet_read_line_buf(char **src, size_t *src_len, int *dst_len)
{
return packet_read_line_generic(-1, src, src_len, dst_len);
}