From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-9.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 5D9C31FE4E for ; Tue, 28 Jun 2016 04:35:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752322AbcF1Efv (ORCPT ); Tue, 28 Jun 2016 00:35:51 -0400 Received: from elnino.cryptocrack.de ([46.165.227.75]:36772 "EHLO elnino.cryptocrack.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752039AbcF1Efv (ORCPT ); Tue, 28 Jun 2016 00:35:51 -0400 Received: by elnino.cryptocrack.de (OpenSMTPD) with ESMTPSA id 89e0359f TLS version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO; Tue, 28 Jun 2016 06:35:41 +0200 (CEST) From: Lukas Fleischer To: git@vger.kernel.org Cc: Nicolas Pitre , Johannes Schindelin , Junio C Hamano , Jeff King Subject: [PATCH v4] Refactor recv_sideband() Date: Tue, 28 Jun 2016 06:35:26 +0200 Message-Id: <20160628043526.19403-1-lfleischer@lfos.de> X-Mailer: git-send-email 2.9.0 In-Reply-To: <20160613195224.13398-1-lfleischer@lfos.de> References: <20160613195224.13398-1-lfleischer@lfos.de> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Before this patch, 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. A strbuf is used for accumulating the output which is then printed using a single fprintf() call with a single conversion specifier per line, such that the atomicity of the output is preserved. See 9ac13ec (atomic write for sideband remote messages, 2006-10-11) for details. Helped-by: Jeff King Helped-by: Junio C Hamano Helped-by: Nicolas Pitre Signed-off-by: Lukas Fleischer --- Changes since v3: * The new code always frees the strbuf used for the output. * Switched back to fprintf() to support ANSI codes under Windows. * Added a comment on the tradeoff between atomicity and Windows support. sideband.c | 125 ++++++++++++++++++++++++++----------------------------------- 1 file changed, 54 insertions(+), 71 deletions(-) diff --git a/sideband.c b/sideband.c index fde8adc..835d77d 100644 --- a/sideband.c +++ b/sideband.c @@ -13,111 +13,94 @@ * 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; + int retval = 0; - 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) { + while (retval == 0) { 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; + 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; + fprintf(stderr, "%s%s\n", PREFIX, buf + 1); + retval = SIDEBAND_REMOTE_ERROR; + break; 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. + * + * The output is accumulated in a buffer and each line + * is printed to stderr using fprintf() with a single + * conversion specifier. This is a "best effort" + * approach to supporting both inter-process atomicity + * (single conversion specifiers are likely to end up + * in single atomic write() system calls) and the ANSI + * control code emulation under Windows. + */ + 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); } + fprintf(stderr, "%.*s", (int)outbuf.len, + outbuf.buf); + strbuf_reset(&outbuf); + strbuf_addf(&outbuf, "%s", PREFIX); + + b = brk + 1; + } - skip_pf = !brk; - memmove(buf + pf+1, b + brk, len); - } while (len); - continue; + if (*b) + strbuf_addf(&outbuf, "%s", 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; + retval = SIDEBAND_PROTOCOL_ERROR; + break; } } - return 0; + + if (outbuf.len > 0) + fprintf(stderr, "%.*s", (int)outbuf.len, outbuf.buf); + strbuf_release(&outbuf); + return retval; } /* -- 2.9.0