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
  17 #define ANSI_SUFFIX "\033[K"
  18 #define DUMB_SUFFIX "        "
  19
  20 #define FIX_SIZE 10  /* large enough for any of the above */
  21
  22 int recv_sideband(const char *me, int in_stream, int out, int err)
  23 {
  24         unsigned pf = strlen(PREFIX);
  25         unsigned sf;
  26         char buf[LARGE_PACKET_MAX + 2*FIX_SIZE];
  27         char *suffix, *term;
  28         int skip_pf = 0;
  29
  30         memcpy(buf, PREFIX, pf);
  31         term = getenv("TERM");
  32         if (term && strcmp(term, "dumb"))
  33                 suffix = ANSI_SUFFIX;
  34         else
  35                 suffix = DUMB_SUFFIX;
  36         sf = strlen(suffix);
  37
  38         while (1) {
  39                 int band, len;
  40                 len = packet_read_line(in_stream, buf + pf, LARGE_PACKET_MAX);
  41                 if (len == 0)
  42                         break;
  43                 if (len < 1) {
  44                         len = sprintf(buf, "%s: protocol error: no band designator\n", me);
  45                         safe_write(err, buf, len);
  46                         return SIDEBAND_PROTOCOL_ERROR;
  47                 }
  48                 band = buf[pf] & 0xff;
  49                 len--;
  50                 switch (band) {
  51                 case 3:
  52                         buf[pf] = ' ';
  53                         buf[pf+1+len] = '\n';
  54                         safe_write(err, buf, pf+1+len+1);
  55                         return SIDEBAND_REMOTE_ERROR;
  56                 case 2:
  57                         buf[pf] = ' ';
  58                         do {
  59                                 char *b = buf;
  60                                 int brk = 0;
  61
  62                                 /*
  63                                  * If the last buffer didn't end with a line
  64                                  * break then we should not print a prefix
  65                                  * this time around.
  66                                  */
  67                                 if (skip_pf) {
  68                                         b += pf+1;
  69                                 } else {
  70                                         len += pf+1;
  71                                         brk += pf+1;
  72                                 }
  73
  74                                 /* Look for a line break. */
  75                                 for (;;) {
  76                                         brk++;
  77                                         if (brk > len) {
  78                                                 brk = 0;
  79                                                 break;
  80                                         }
  81                                         if (b[brk-1] == '\n' ||
  82                                             b[brk-1] == '\r')
  83                                                 break;
  84                                 }
  85
  86                                 /*
  87                                  * Let's insert a suffix to clear the end
  88                                  * of the screen line if a line break was
  89                                  * found.  Also, if we don't skip the
  90                                  * prefix, then a non-empty string must be
  91                                  * present too.
  92                                  */
  93                                 if (brk > (skip_pf ? 0 : (pf+1 + 1))) {
  94                                         char save[FIX_SIZE];
  95                                         memcpy(save, b + brk, sf);
  96                                         b[brk + sf - 1] = b[brk - 1];
  97                                         memcpy(b + brk - 1, suffix, sf);
  98                                         safe_write(err, b, brk + sf);
  99                                         memcpy(b + brk, save, sf);
 100                                         len -= brk;
 101                                 } else {
 102                                         int l = brk ? brk : len;
 103                                         safe_write(err, b, l);
 104                                         len -= l;
 105                                 }
 106
 107                                 skip_pf = !brk;
 108                                 memmove(buf + pf+1, b + brk, len);
 109                         } while (len);
 110                         continue;
 111                 case 1:
 112                         safe_write(out, buf + pf+1, len);
 113                         continue;
 114                 default:
 115                         len = sprintf(buf,
 116                                       "%s: protocol error: bad band #%d\n",
 117                                       me, band);
 118                         safe_write(err, buf, len);
 119                         return SIDEBAND_PROTOCOL_ERROR;
 120                 }
 121         }
 122         return 0;
 123 }
 124
 125 /*
 126  * fd is connected to the remote side; send the sideband data
 127  * over multiplexed packet stream.
 128  */
 129 ssize_t send_sideband(int fd, int band, const char *data, ssize_t sz, int packet_max)
 130 {
 131         ssize_t ssz = sz;
 132         const char *p = data;
 133
 134         while (sz) {
 135                 unsigned n;
 136                 char hdr[5];
 137
 138                 n = sz;
 139                 if (packet_max - 5 < n)
 140                         n = packet_max - 5;
 141                 sprintf(hdr, "%04x", n + 5);
 142                 hdr[4] = band;
 143                 safe_write(fd, hdr, 5);
 144                 safe_write(fd, p, n);
 145                 p += n;
 146                 sz -= n;
 147         }
 148         return ssz;
 149 }