git/sideband.c

   1 #include "pkt-line.h"
   2 #include "sideband.h"
   3
   4 /*
   5  * Receive multiplexed output stream over git native protocol.
   6  * in_stream is the input stream from the remote, which carries data
   7  * in pkt_line format with band designator.  Demultiplex it into out
   8  * and err and return error appropriately.  Band #1 carries the
   9  * primary payload.  Things coming over band #2 is not necessarily
  10  * error; they are usually informative message on the standard error
  11  * stream, aka "verbose").  A message over band #3 is a signal that
  12  * the remote died unexpectedly.  A flush() concludes the stream.
  13  */
  14 int recv_sideband(const char *me, int in_stream, int out, int err)
  15 {
  16         char buf[7 + LARGE_PACKET_MAX + 1];
  17         strcpy(buf, "remote:");
  18         while (1) {
  19                 int band, len;
  20                 len     = packet_read_line(in_stream, buf+7, LARGE_PACKET_MAX);
  21                 if (len == 0)
  22                         break;
  23                 if (len < 1) {
  24                         len = sprintf(buf, "%s: protocol error: no band designator\n", me);
  25                         safe_write(err, buf, len);
  26                         return SIDEBAND_PROTOCOL_ERROR;
  27                 }
  28                 band = buf[7] & 0xff;
  29                 len--;
  30                 switch (band) {
  31                 case 3:
  32                         buf[7] = ' ';
  33                         buf[8+len] = '\n';
  34                         safe_write(err, buf, 8+len+1);
  35                         return SIDEBAND_REMOTE_ERROR;
  36                 case 2:
  37                         buf[7] = ' ';
  38                         safe_write(err, buf, 8+len);
  39                         continue;
  40                 case 1:
  41                         safe_write(out, buf+8, len);
  42                         continue;
  43                 default:
  44                         len = sprintf(buf,
  45                                       "%s: protocol error: bad band #%d\n",
  46                                       me, band);
  47                         safe_write(err, buf, len);
  48                         return SIDEBAND_PROTOCOL_ERROR;
  49                 }
  50         }
  51         return 0;
  52 }
  53
  54 /*
  55  * fd is connected to the remote side; send the sideband data
  56  * over multiplexed packet stream.
  57  */
  58 ssize_t send_sideband(int fd, int band, const char *data, ssize_t sz, int packet_max)
  59 {
  60         ssize_t ssz = sz;
  61         const char *p = data;
  62
  63         while (sz) {
  64                 unsigned n;
  65                 char hdr[5];
  66
  67                 n = sz;
  68                 if (packet_max - 5 < n)
  69                         n = packet_max - 5;
  70                 sprintf(hdr, "%04x", n + 5);
  71                 hdr[4] = band;
  72                 safe_write(fd, hdr, 5);
  73                 safe_write(fd, p, n);
  74                 p += n;
  75                 sz -= n;
  76         }
  77         return ssz;
  78 }