sideband.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "sideband.h"
   4
   5 /*
   6  * Receive multiplexed output stream over git native protocol.
   7  * in_stream is the input stream from the remote, which carries data
   8  * in pkt_line format with band designator.  Demultiplex it into out
   9  * and err and return error appropriately.  Band #1 carries the
  10  * primary payload.  Things coming over band #2 is not necessarily
  11  * error; they are usually informative message on the standard error
  12  * stream, aka "verbose").  A message over band #3 is a signal that
  13  * the remote died unexpectedly.  A flush() concludes the stream.
  14  */
  15
  16 #define PREFIX "remote: "
  17
  18 #define ANSI_SUFFIX "\033[K"
  19 #define DUMB_SUFFIX "        "
  20
  21 int recv_sideband(const char *me, int in_stream, int out)
  22 {
  23         const char *suffix;
  24         char buf[LARGE_PACKET_MAX + 1];
  25         struct strbuf outbuf = STRBUF_INIT;
  26         int retval = 0;
  27
  28         if (isatty(2) && !is_terminal_dumb())
  29                 suffix = ANSI_SUFFIX;
  30         else
  31                 suffix = DUMB_SUFFIX;
  32
  33         while (!retval) {
  34                 const char *b, *brk;
  35                 int band, len;
  36                 len = packet_read(in_stream, NULL, NULL, buf, LARGE_PACKET_MAX, 0);
  37                 if (len == 0)
  38                         break;
  39                 if (len < 1) {
  40                         strbuf_addf(&outbuf,
  41                                     "%s%s: protocol error: no band designator",
  42                                     outbuf.len ? "\n" : "", me);
  43                         retval = SIDEBAND_PROTOCOL_ERROR;
  44                         break;
  45                 }
  46                 band = buf[0] & 0xff;
  47                 buf[len] = '\0';
  48                 len--;
  49                 switch (band) {
  50                 case 3:
  51                         strbuf_addf(&outbuf, "%s%s%s", outbuf.len ? "\n" : "",
  52                                     PREFIX, buf + 1);
  53                         retval = SIDEBAND_REMOTE_ERROR;
  54                         break;
  55                 case 2:
  56                         b = buf + 1;
  57
  58                         /*
  59                          * Append a suffix to each nonempty line to clear the
  60                          * end of the screen line.
  61                          *
  62                          * The output is accumulated in a buffer and
  63                          * each line is printed to stderr using
  64                          * write(2) to ensure inter-process atomicity.
  65                          */
  66                         while ((brk = strpbrk(b, "\n\r"))) {
  67                                 int linelen = brk - b;
  68
  69                                 if (!outbuf.len)
  70                                         strbuf_addstr(&outbuf, PREFIX);
  71                                 if (linelen > 0) {
  72                                         strbuf_addf(&outbuf, "%.*s%s%c",
  73                                                     linelen, b, suffix, *brk);
  74                                 } else {
  75                                         strbuf_addch(&outbuf, *brk);
  76                                 }
  77                                 xwrite(2, outbuf.buf, outbuf.len);
  78                                 strbuf_reset(&outbuf);
  79
  80                                 b = brk + 1;
  81                         }
  82
  83                         if (*b)
  84                                 strbuf_addf(&outbuf, "%s%s",
  85                                             outbuf.len ? "" : PREFIX, b);
  86                         break;
  87                 case 1:
  88                         write_or_die(out, buf + 1, len);
  89                         break;
  90                 default:
  91                         strbuf_addf(&outbuf, "%s%s: protocol error: bad band #%d",
  92                                     outbuf.len ? "\n" : "", me, band);
  93                         retval = SIDEBAND_PROTOCOL_ERROR;
  94                         break;
  95                 }
  96         }
  97
  98         if (outbuf.len) {
  99                 strbuf_addch(&outbuf, '\n');
 100                 xwrite(2, outbuf.buf, outbuf.len);
 101         }
 102         strbuf_release(&outbuf);
 103         return retval;
 104 }
 105
 106 /*
 107  * fd is connected to the remote side; send the sideband data
 108  * over multiplexed packet stream.
 109  */
 110 void send_sideband(int fd, int band, const char *data, ssize_t sz, int packet_max)
 111 {
 112         const char *p = data;
 113
 114         while (sz) {
 115                 unsigned n;
 116                 char hdr[5];
 117
 118                 n = sz;
 119                 if (packet_max - 5 < n)
 120                         n = packet_max - 5;
 121                 if (0 <= band) {
 122                         xsnprintf(hdr, sizeof(hdr), "%04x", n + 5);
 123                         hdr[4] = band;
 124                         write_or_die(fd, hdr, 5);
 125                 } else {
 126                         xsnprintf(hdr, sizeof(hdr), "%04x", n + 4);
 127                         write_or_die(fd, hdr, 4);
 128                 }
 129                 write_or_die(fd, p, n);
 130                 p += n;
 131                 sz -= n;
 132         }
 133 }