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![Jeff King](/assets/img/avatar_default.png)
We sometimes sprintf into fixed-size buffers when we know that the buffer is large enough to fit the input (either because it's a constant, or because it's numeric input that is bounded in size). Likewise with strcpy of constant strings. However, these sites make it hard to audit sprintf and strcpy calls for buffer overflows, as a reader has to cross-reference the size of the array with the input. Let's use xsnprintf instead, which communicates to a reader that we don't expect this to overflow (and catches the mistake in case we do). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
153 lines
3.4 KiB
C
153 lines
3.4 KiB
C
#include "cache.h"
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#include "pkt-line.h"
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#include "sideband.h"
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/*
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* Receive multiplexed output stream over git native protocol.
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* in_stream is the input stream from the remote, which carries data
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* in pkt_line format with band designator. Demultiplex it into out
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* and err and return error appropriately. Band #1 carries the
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* primary payload. Things coming over band #2 is not necessarily
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* error; they are usually informative message on the standard error
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* stream, aka "verbose"). A message over band #3 is a signal that
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* the remote died unexpectedly. A flush() concludes the stream.
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*/
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#define PREFIX "remote:"
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#define ANSI_SUFFIX "\033[K"
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#define DUMB_SUFFIX " "
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#define FIX_SIZE 10 /* large enough for any of the above */
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int recv_sideband(const char *me, int in_stream, int out)
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{
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unsigned pf = strlen(PREFIX);
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unsigned sf;
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char buf[LARGE_PACKET_MAX + 2*FIX_SIZE];
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char *suffix, *term;
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int skip_pf = 0;
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memcpy(buf, PREFIX, pf);
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term = getenv("TERM");
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if (isatty(2) && term && strcmp(term, "dumb"))
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suffix = ANSI_SUFFIX;
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else
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suffix = DUMB_SUFFIX;
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sf = strlen(suffix);
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while (1) {
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int band, len;
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len = packet_read(in_stream, NULL, NULL, buf + pf, LARGE_PACKET_MAX, 0);
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if (len == 0)
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break;
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if (len < 1) {
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fprintf(stderr, "%s: protocol error: no band designator\n", me);
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return SIDEBAND_PROTOCOL_ERROR;
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}
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band = buf[pf] & 0xff;
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len--;
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switch (band) {
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case 3:
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buf[pf] = ' ';
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buf[pf+1+len] = '\0';
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fprintf(stderr, "%s\n", buf);
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return SIDEBAND_REMOTE_ERROR;
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case 2:
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buf[pf] = ' ';
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do {
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char *b = buf;
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int brk = 0;
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/*
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* If the last buffer didn't end with a line
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* break then we should not print a prefix
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* this time around.
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*/
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if (skip_pf) {
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b += pf+1;
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} else {
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len += pf+1;
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brk += pf+1;
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}
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/* Look for a line break. */
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for (;;) {
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brk++;
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if (brk > len) {
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brk = 0;
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break;
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}
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if (b[brk-1] == '\n' ||
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b[brk-1] == '\r')
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break;
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}
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/*
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* Let's insert a suffix to clear the end
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* of the screen line if a line break was
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* found. Also, if we don't skip the
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* prefix, then a non-empty string must be
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* present too.
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*/
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if (brk > (skip_pf ? 0 : (pf+1 + 1))) {
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char save[FIX_SIZE];
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memcpy(save, b + brk, sf);
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b[brk + sf - 1] = b[brk - 1];
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memcpy(b + brk - 1, suffix, sf);
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fprintf(stderr, "%.*s", brk + sf, b);
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memcpy(b + brk, save, sf);
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len -= brk;
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} else {
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int l = brk ? brk : len;
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fprintf(stderr, "%.*s", l, b);
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len -= l;
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}
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skip_pf = !brk;
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memmove(buf + pf+1, b + brk, len);
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} while (len);
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continue;
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case 1:
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write_or_die(out, buf + pf+1, len);
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continue;
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default:
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fprintf(stderr, "%s: protocol error: bad band #%d\n",
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me, band);
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return SIDEBAND_PROTOCOL_ERROR;
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}
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}
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return 0;
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}
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/*
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* fd is connected to the remote side; send the sideband data
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* over multiplexed packet stream.
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*/
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ssize_t send_sideband(int fd, int band, const char *data, ssize_t sz, int packet_max)
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{
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ssize_t ssz = sz;
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const char *p = data;
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while (sz) {
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unsigned n;
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char hdr[5];
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n = sz;
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if (packet_max - 5 < n)
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n = packet_max - 5;
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if (0 <= band) {
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xsnprintf(hdr, sizeof(hdr), "%04x", n + 5);
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hdr[4] = band;
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write_or_die(fd, hdr, 5);
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} else {
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xsnprintf(hdr, sizeof(hdr), "%04x", n + 4);
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write_or_die(fd, hdr, 4);
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}
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write_or_die(fd, p, n);
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p += n;
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sz -= n;
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}
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return ssz;
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}
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