On Mon, 13 Jun 2016, Lukas Fleischer wrote:
> Improve the readability of recv_sideband() significantly by replacing
> fragile buffer manipulations with more sophisticated format strings.
> Also, reorganize the overall control flow, remove some superfluous
> variables and replace a custom implementation of strpbrk() with a call
> to the standard C library function.
>
> Signed-off-by: Lukas Fleischer <lfleisc...@lfos.de>
The previous code was a total abomination, even if I happen to know who
wrote it.
Acked-by: Nicolas Pitre <n...@fluxnic.net>
> I had a really hard time reading and understanding this function when I
> came up with my last patch. What I ended up with is almost a complete
> rewrite of recv_sideband() and I find the end result to be much more
> readable than what we have now. Given that this is quite invasive, it
> would be good to have some more eyes and opinions...
>
> If you want me to split this patch into smaller changes, please let me
> know. However, finding a good way to split this into logical changes
> might not be easy given that the new code does not have much in common
> with what we had before.
Indeed. Anyway, numbers speak for themselves:
> 1 file changed, 30 insertions(+), 64 deletions(-)
>
> diff --git a/sideband.c b/sideband.c
> index fde8adc..0a078c3 100644
> --- a/sideband.c
> +++ b/sideband.c
> @@ -13,103 +13,69 @@
> * 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;
> + const char *prefix = PREFIX, *suffix;
> + char buf[LARGE_PACKET_MAX + 1];
> + const char *b, *brk;
>
> - 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) {
> 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;
> }
> - 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);
> + fprintf(stderr, "%s%s\n", PREFIX, buf + 1);
> return SIDEBAND_REMOTE_ERROR;
> case 2:
> - buf[pf] = ' ';
> - do {
> - char *b = buf;
> - int brk = 0;
> -
> - /*
> - * 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;
> - }
> + b = buf + 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.
> + */
> + 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 (linelen > 0) {
> + fprintf(stderr, "%s%.*s%s%c", prefix,
> + linelen, b, suffix, *brk);
> } else {
> - int l = brk ? brk : len;
> - fprintf(stderr, "%.*s", l, b);
> - len -= l;
> + fprintf(stderr, "%s%c", prefix, *brk);
> }
>
> - skip_pf = !brk;
> - memmove(buf + pf+1, b + brk, len);
> - } while (len);
> + b = brk + 1;
> + prefix = PREFIX;
> + }
> +
> + if (*b) {
> + fprintf(stderr, "%s%s", prefix, b);
> + /* Incomplete line, skip the next prefix. */
> + prefix = "";
> + }
> continue;
> case 1:
> - write_or_die(out, buf + pf+1, len);
> + write_or_die(out, buf + 1, len);
> continue;
> default:
> fprintf(stderr, "%s: protocol error: bad band #%d\n",
> --
> 2.8.3
>
> --
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