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[93.219.77.85]) by smtp.gmail.com with ESMTPSA id x6sm27330673wjk.26.2016.07.31.14.45.08 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sun, 31 Jul 2016 14:45:09 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: [PATCH v3 03/10] pkt-line: add packet_flush_gentle() From: Lars Schneider In-Reply-To: <63231F5B-959F-4A9D-89B9-E4A42AF34AB1@web.de> Date: Sun, 31 Jul 2016 23:45:08 +0200 Cc: "git@vger.kernel.org" , "gitster@pobox.com" , "jnareb@gmail.com" , "mlbright@gmail.com" , "e@80x24.org" , "peff@peff.net" Content-Transfer-Encoding: 8BIT Message-Id: <8FC2D283-AF8D-4643-834E-3D1927C558C0@gmail.com> References: <20160727000605.49982-1-larsxschneider%40gmail.com/> <20160729233801.82844-1-larsxschneider@gmail.com> <20160729233801.82844-4-larsxschneider@gmail.com> <63231F5B-959F-4A9D-89B9-E4A42AF34AB1@web.de> To: =?utf-8?Q?Torstem_B=C3=B6gershausen?= X-Mailer: Apple Mail (2.3124) Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org > On 31 Jul 2016, at 22:36, Torstem Bögershausen wrote: > > > >> Am 29.07.2016 um 20:37 schrieb larsxschneider@gmail.com: >> >> From: Lars Schneider >> >> packet_flush() would die in case of a write error even though for some callers >> an error would be acceptable. > What happens if there is a write error ? > Basically the protocol is out of synch. > Lenght information is mixed up with payload, or the other way > around. > It may be, that the consequences of a write error are acceptable, > because a filter is allowed to fail. > What is not acceptable is a "broken" protocol. > The consequence schould be to close the fd and tear down all > resources. connected to it. > In our case to terminate the external filter daemon in some way, > and to never use this instance again. Correct! That is exactly what is happening in kill_protocol2_filter() here: +static int apply_protocol2_filter(const char *path, const char *src, size_t len, + int fd, struct strbuf *dst, const char *cmd, + const int wanted_capability) +{ ... + if (ret) { + strbuf_swap(dst, &nbuf); + } else { + if (!filter_result || strcmp(filter_result, "reject")) { + // Something went wrong with the protocol filter. Force shutdown! + error("external filter '%s' failed", cmd); + kill_protocol2_filter(&cmd_process_map, entry); + } + } + strbuf_release(&nbuf); + return ret; +} More context: https://github.com/larsxschneider/git/blob/e128326070847ac596e8bb21adebc8abab2003fc/convert.c#L821 - Lars > > >> Add packet_flush_gentle() which writes a pkt-line >> flush packet and returns `0` for success and `1` for failure. >> >> Signed-off-by: Lars Schneider >> --- >> pkt-line.c | 6 ++++++ >> pkt-line.h | 1 + >> 2 files changed, 7 insertions(+) >> >> diff --git a/pkt-line.c b/pkt-line.c >> index 6fae508..1728690 100644 >> --- a/pkt-line.c >> +++ b/pkt-line.c >> @@ -91,6 +91,12 @@ void packet_flush(int fd) >> write_or_die(fd, "0000", 4); >> } >> >> +int packet_flush_gentle(int fd) >> +{ >> + packet_trace("0000", 4, 1); >> + return !write_or_whine_pipe(fd, "0000", 4, "flush packet"); >> +} >> + >> void packet_buf_flush(struct strbuf *buf) >> { >> packet_trace("0000", 4, 1); >> diff --git a/pkt-line.h b/pkt-line.h >> index 02dcced..3953c98 100644 >> --- a/pkt-line.h >> +++ b/pkt-line.h >> @@ -23,6 +23,7 @@ void packet_flush(int fd); >> void packet_write(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3))); >> void packet_buf_flush(struct strbuf *buf); >> void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3))); >> +int packet_flush_gentle(int fd); >> int direct_packet_write(int fd, char *buf, size_t size, int gentle); >> int direct_packet_write_data(int fd, const char *buf, size_t size, int gentle); >> >> -- >> 2.9.0 >>