sideband.c: refactor recv_sideband()

We used character buffer manipulations to split messages from the
sideband at line breaks and insert "remote: " at the beginning of
each line, using the packet size to determine the end of a message.

However, since it is safe to assume that diagnostic messages from
the sideband never contain NUL characters, we can also NUL-terminate
the buffer, use strpbrk() for splitting lines and use format strings
to insert the prefix, to make the code easier to read and maintain.

A strbuf is used for accumulating the output which is then printed
using a single write(2) call to ensure the atomicity of the output.
See 9ac13ec (atomic write for sideband remote messages, 2006-10-11)
for details.

Helped-by: Jeff King <peff@peff.net>
Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Lukas Fleischer <lfleischer@lfos.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/sideband.c b/sideband.c
index 7f9dc229fbc82d005b5c2b417c2af2fc9f6b497a..2782df800382eb00ab7d50f1371d71bb2849d0ba 100644 (file)
--- a/sideband.c
+++ b/sideband.c
@@ -13,111 +13,95 @@
  * the remote died unexpectedly.  A flush() concludes the stream.
  */
 
  * the remote died unexpectedly.  A flush() concludes the stream.
  */
 

-#define PREFIX "remote:"
+#define PREFIX "remote: "

 
 #define ANSI_SUFFIX "\033[K"
 #define DUMB_SUFFIX "        "
 
 
 #define ANSI_SUFFIX "\033[K"
 #define DUMB_SUFFIX "        "
 

-#define FIX_SIZE 10  /* large enough for any of the above */
-

 int recv_sideband(const char *me, int in_stream, int out)
 {
 int recv_sideband(const char *me, int in_stream, int out)
 {

-       unsigned pf = strlen(PREFIX);
-       unsigned sf;
-       char buf[LARGE_PACKET_MAX + 2*FIX_SIZE];
-       char *suffix, *term;
-       int skip_pf = 0;
+       const char *term, *suffix;
+       char buf[LARGE_PACKET_MAX + 1];
+       struct strbuf outbuf = STRBUF_INIT;
+       int retval = 0;

 
 

-       memcpy(buf, PREFIX, pf);

        term = getenv("TERM");
        if (isatty(2) && term && strcmp(term, "dumb"))
                suffix = ANSI_SUFFIX;
        else
                suffix = DUMB_SUFFIX;
        term = getenv("TERM");
        if (isatty(2) && term && strcmp(term, "dumb"))
                suffix = ANSI_SUFFIX;
        else
                suffix = DUMB_SUFFIX;

-       sf = strlen(suffix);

 
 

-       while (1) {
+       while (!retval) {
+               const char *b, *brk;

                int band, len;
                int band, len;

-               len = packet_read(in_stream, NULL, NULL, buf + pf, LARGE_PACKET_MAX, 0);
+               len = packet_read(in_stream, NULL, NULL, buf, LARGE_PACKET_MAX, 0);

                if (len == 0)
                        break;
                if (len < 1) {
                if (len == 0)
                        break;
                if (len < 1) {

-                       fprintf(stderr, "%s: protocol error: no band designator\n", me);
-                       return SIDEBAND_PROTOCOL_ERROR;
+                       strbuf_addf(&outbuf,
+                                   "%s%s: protocol error: no band designator",
+                                   outbuf.len ? "\n" : "", me);
+                       retval = SIDEBAND_PROTOCOL_ERROR;
+                       break;

                }
                }

-               band = buf[pf] & 0xff;
+               band = buf[0] & 0xff;
+               buf[len] = '\0';

                len--;
                switch (band) {
                case 3:
                len--;
                switch (band) {
                case 3:

-                       buf[pf] = ' ';
-                       buf[pf+1+len] = '\0';
-                       fprintf(stderr, "%s\n", buf);
-                       return SIDEBAND_REMOTE_ERROR;
+                       strbuf_addf(&outbuf, "%s%s%s", outbuf.len ? "\n" : "",
+                                   PREFIX, buf + 1);
+                       retval = SIDEBAND_REMOTE_ERROR;
+                       break;

                case 2:
                case 2:

-                       buf[pf] = ' ';
-                       do {
-                               char *b = buf;
-                               int brk = 0;
+                       b = buf + 1;

 
 

-                               /*
-                                * If the last buffer didn't end with a line
-                                * break then we should not print a prefix
-                                * this time around.
-                                */
-                               if (skip_pf) {
-                                       b += pf+1;
-                               } else {
-                                       len += pf+1;
-                                       brk += pf+1;
-                               }
-
-                               /* Look for a line break. */
-                               for (;;) {
-                                       brk++;
-                                       if (brk > len) {
-                                               brk = 0;
-                                               break;
-                                       }
-                                       if (b[brk-1] == '\n' ||
-                                           b[brk-1] == '\r')
-                                               break;
-                               }
+                       /*
+                        * Append a suffix to each nonempty line to clear the
+                        * end of the screen line.
+                        *
+                        * The output is accumulated in a buffer and
+                        * each line is printed to stderr using
+                        * write(2) to ensure inter-process atomicity.
+                        */
+                       while ((brk = strpbrk(b, "\n\r"))) {
+                               int linelen = brk - b;

 
 

-                               /*
-                                * Let's insert a suffix to clear the end
-                                * of the screen line if a line break was
-                                * found.  Also, if we don't skip the
-                                * prefix, then a non-empty string must be
-                                * present too.
-                                */
-                               if (brk > (skip_pf ? 0 : (pf+1 + 1))) {
-                                       char save[FIX_SIZE];
-                                       memcpy(save, b + brk, sf);
-                                       b[brk + sf - 1] = b[brk - 1];
-                                       memcpy(b + brk - 1, suffix, sf);
-                                       fprintf(stderr, "%.*s", brk + sf, b);
-                                       memcpy(b + brk, save, sf);
-                                       len -= brk;
+                               if (!outbuf.len)
+                                       strbuf_addf(&outbuf, "%s", PREFIX);
+                               if (linelen > 0) {
+                                       strbuf_addf(&outbuf, "%.*s%s%c",
+                                                   linelen, b, suffix, *brk);

                                } else {
                                } else {

-                                       int l = brk ? brk : len;
-                                       fprintf(stderr, "%.*s", l, b);
-                                       len -= l;
+                                       strbuf_addf(&outbuf, "%c", *brk);

                                }
                                }

+                               xwrite(2, outbuf.buf, outbuf.len);
+                               strbuf_reset(&outbuf);

 
 

-                               skip_pf = !brk;
-                               memmove(buf + pf+1, b + brk, len);
-                       } while (len);
-                       continue;
+                               b = brk + 1;
+                       }
+
+                       if (*b)
+                               strbuf_addf(&outbuf, "%s%s",
+                                           outbuf.len ? "" : PREFIX, b);
+                       break;

                case 1:
                case 1:

-                       write_or_die(out, buf + pf+1, len);
-                       continue;
+                       write_or_die(out, buf + 1, len);
+                       break;

                default:
                default:

-                       fprintf(stderr, "%s: protocol error: bad band #%d\n",
-                               me, band);
-                       return SIDEBAND_PROTOCOL_ERROR;
+                       strbuf_addf(&outbuf, "%s%s: protocol error: bad band #%d",
+                                   outbuf.len ? "\n" : "", me, band);
+                       retval = SIDEBAND_PROTOCOL_ERROR;
+                       break;

                }
        }
                }
        }

-       return 0;
+
+       if (outbuf.len) {
+               strbuf_addf(&outbuf, "\n");
+               xwrite(2, outbuf.buf, outbuf.len);
+       }
+       strbuf_release(&outbuf);
+       return retval;

 }
 
 /*
 }
 
 /*