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
  15 #define PREFIX "remote:"
  16 #define SUFFIX "\033[K"  /* change to "        " if ANSI sequences don't work */
  17
  18 int recv_sideband(const char *me, int in_stream, int out, int err)
  19 {
  20         unsigned pf = strlen(PREFIX);
  21         unsigned sf = strlen(SUFFIX);
  22         char buf[pf + LARGE_PACKET_MAX + sf + 1];
  23         memcpy(buf, PREFIX, pf);
  24         while (1) {
  25                 int band, len;
  26                 len = packet_read_line(in_stream, buf + pf, LARGE_PACKET_MAX);
  27                 if (len == 0)
  28                         break;
  29                 if (len < 1) {
  30                         len = sprintf(buf, "%s: protocol error: no band designator\n", me);
  31                         safe_write(err, buf, len);
  32                         return SIDEBAND_PROTOCOL_ERROR;
  33                 }
  34                 band = buf[pf] & 0xff;
  35                 len--;
  36                 switch (band) {
  37                 case 3:
  38                         buf[pf] = ' ';
  39                         buf[pf+1+len] = '\n';
  40                         safe_write(err, buf, pf+1+len+1);
  41                         return SIDEBAND_REMOTE_ERROR;
  42                 case 2:
  43                         buf[pf] = ' ';
  44                         len += pf+1;
  45                         while (1) {
  46                                 int brk = pf+1;
  47
  48                                 /* Break the buffer into separate lines. */
  49                                 while (brk < len) {
  50                                         brk++;
  51                                         if (buf[brk-1] == '\n' ||
  52                                             buf[brk-1] == '\r')
  53                                                 break;
  54                                 }
  55
  56                                 /*
  57                                  * Let's insert a suffix to clear the end
  58                                  * of the screen line, but only if current
  59                                  * line data actually contains something.
  60                                  */
  61                                 if (brk > pf+1 + 1) {
  62                                         char save[sf];
  63                                         memcpy(save, buf + brk, sf);
  64                                         buf[brk + sf - 1] = buf[brk - 1];
  65                                         memcpy(buf + brk - 1, SUFFIX, sf);
  66                                         safe_write(err, buf, brk + sf);
  67                                         memcpy(buf + brk, save, sf);
  68                                 } else
  69                                         safe_write(err, buf, brk);
  70
  71                                 if (brk < len) {
  72                                         memmove(buf + pf+1, buf + brk, len - brk);
  73                                         len = len - brk + pf+1;
  74                                 } else
  75                                         break;
  76                         }
  77                         continue;
  78                 case 1:
  79                         safe_write(out, buf + pf+1, len);
  80                         continue;
  81                 default:
  82                         len = sprintf(buf,
  83                                       "%s: protocol error: bad band #%d\n",
  84                                       me, band);
  85                         safe_write(err, buf, len);
  86                         return SIDEBAND_PROTOCOL_ERROR;
  87                 }
  88         }
  89         return 0;
  90 }
  91
  92 /*
  93  * fd is connected to the remote side; send the sideband data
  94  * over multiplexed packet stream.
  95  */
  96 ssize_t send_sideband(int fd, int band, const char *data, ssize_t sz, int packet_max)
  97 {
  98         ssize_t ssz = sz;
  99         const char *p = data;
 100
 101         while (sz) {
 102                 unsigned n;
 103                 char hdr[5];
 104
 105                 n = sz;
 106                 if (packet_max - 5 < n)
 107                         n = packet_max - 5;
 108                 sprintf(hdr, "%04x", n + 5);
 109                 hdr[4] = band;
 110                 safe_write(fd, hdr, 5);
 111                 safe_write(fd, p, n);
 112                 p += n;
 113                 sz -= n;
 114         }
 115         return ssz;
 116 }