From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukas Fleischer Subject: [PATCH v2] Refactor recv_sideband() Date: Tue, 14 Jun 2016 23:00:38 +0200 Message-ID: <20160614210038.31465-1-lfleischer@lfos.de> References: <20160613195224.13398-1-lfleischer@lfos.de> Cc: Nicolas Pitre , Johannes Sixt To: git@vger.kernel.org X-From: git-owner@vger.kernel.org Tue Jun 14 23:00:52 2016 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bCvS7-0007FL-9B for gcvg-git-2@plane.gmane.org; Tue, 14 Jun 2016 23:00:51 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932322AbcFNVAr (ORCPT ); Tue, 14 Jun 2016 17:00:47 -0400 Received: from elnino.cryptocrack.de ([46.165.227.75]:48619 "EHLO elnino.cryptocrack.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932123AbcFNVAq (ORCPT ); Tue, 14 Jun 2016 17:00:46 -0400 Received: by elnino.cryptocrack.de (OpenSMTPD) with ESMTPSA id eeea5499 TLS version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO; Tue, 14 Jun 2016 23:00:43 +0200 (CEST) X-Mailer: git-send-email 2.8.3 In-Reply-To: <20160613195224.13398-1-lfleischer@lfos.de> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Improve the readability of recv_sideband() significantly by replacing fragile buffer manipulations with string buffers and more sophisticated format strings. Note that each line is printed using a single write() syscall to avoid garbled output when multiple processes write to stderr in parallel, see 9ac13ec (atomic write for sideband remote messages, 2006-10-11) for details. 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 --- Now uses a single write() invocation per line. Thanks to Nicolas and Junio for bringing 9ac13ec to my attention. sideband.c | 97 +++++++++++++++++++++----------------------------------------- 1 file changed, 33 insertions(+), 64 deletions(-) diff --git a/sideband.c b/sideband.c index fde8adc..8340a1b 100644 --- a/sideband.c +++ b/sideband.c @@ -13,103 +13,72 @@ * 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; + const char *b, *brk; - memcpy(buf, PREFIX, pf); + strbuf_addf(&outbuf, "%s", PREFIX); 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) { + strbuf_addf(&outbuf, "%.*s%s%c", + linelen, b, suffix, *brk); } else { - int l = brk ? brk : len; - fprintf(stderr, "%.*s", l, b); - len -= l; + strbuf_addf(&outbuf, "%c", *brk); } + xwrite(STDERR_FILENO, outbuf.buf, outbuf.len); + strbuf_reset(&outbuf); + strbuf_addf(&outbuf, "%s", PREFIX); + + b = brk + 1; + } - skip_pf = !brk; - memmove(buf + pf+1, b + brk, len); - } while (len); + if (*b) { + xwrite(STDERR_FILENO, outbuf.buf, outbuf.len); + /* Incomplete line, skip the next prefix. */ + strbuf_reset(&outbuf); + } 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