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sideband.c: refactor recv_sideband()

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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>
This commit is contained in:
Lukas Fleischer 2016-06-28 06:35:26 +02:00 committed by Junio C Hamano
parent 765428699a
commit 5e5be9e257
1 changed files with 58 additions and 74 deletions
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132
sideband.c
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@ -13,111 +13,95 @@
* the remote died unexpectedly. A flush() concludes the stream.
*/
#define PREFIX "remote:"
#define PREFIX "remote: "
#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)
{
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;
sf = strlen(suffix);
while (1) {
while (!retval) {
const char *b, *brk;
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) {
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:
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:
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;
/*
* 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;
if (!outbuf.len)
strbuf_addf(&outbuf, "%s", PREFIX);
if (linelen > 0) {
strbuf_addf(&outbuf, "%.*s%s%c",
linelen, b, suffix, *brk);
} else {
len += pf+1;
brk += pf+1;
strbuf_addf(&outbuf, "%c", *brk);
}
xwrite(2, outbuf.buf, outbuf.len);
strbuf_reset(&outbuf);
/* Look for a line break. */
for (;;) {
brk++;
if (brk > len) {
brk = 0;
break;
}
if (b[brk-1] == '\n' ||
b[brk-1] == '\r')
break;
}
b = brk + 1;
}
/*
* 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;
} else {
int l = brk ? brk : len;
fprintf(stderr, "%.*s", l, b);
len -= l;
}
skip_pf = !brk;
memmove(buf + pf+1, b + brk, len);
} while (len);
continue;
if (*b)
strbuf_addf(&outbuf, "%s%s",
outbuf.len ? "" : PREFIX, b);
break;
case 1:
write_or_die(out, buf + pf+1, len);
continue;
write_or_die(out, buf + 1, len);
break;
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;
}
/*