Refactor, into a common function, the version and capability negotiation done when invoking a long-running process as a clean or smudge filter. This will be useful for other Git code that needs to interact similarly with a long-running process.
Signed-off-by: Jonathan Tan <jonathanta...@google.com> --- This will be useful for anyone implementing functionality like that in [1]. It is unfortunate that the code grew larger because it had to be more generic, but I think this is better than having (in the future) 2 or more separate handshake functions. I also don't think that the protocol should be permissive - I think things would be simpler if all protocol errors were fatal errors. As it is, most parts are permissive, but packet_read_line() already dies anyway upon a malformed packet, so it may not be too drastic a change to change this. For reference, the original protocol comes from [2]. [1] https://public-inbox.org/git/20170714132651.170708-2-benpe...@microsoft.com/ [2] edcc858 ("convert: add filter.<driver>.process option", 2016-10-17) --- convert.c | 61 ++++----------------------------- pkt-line.c | 19 ----------- pkt-line.h | 2 -- sub-process.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++ sub-process.h | 18 ++++++++++ t/t0021-conversion.sh | 2 +- 6 files changed, 120 insertions(+), 76 deletions(-) diff --git a/convert.c b/convert.c index deaf0ba7b..ec8ecc2ea 100644 --- a/convert.c +++ b/convert.c @@ -512,62 +512,15 @@ static struct hashmap subprocess_map; static int start_multi_file_filter_fn(struct subprocess_entry *subprocess) { - int err; + static int versions[] = {2, 0}; + static struct subprocess_capability capabilities[] = { + {"clean", CAP_CLEAN}, {"smudge", CAP_SMUDGE}, {NULL, 0} + }; struct cmd2process *entry = (struct cmd2process *)subprocess; - struct string_list cap_list = STRING_LIST_INIT_NODUP; - char *cap_buf; - const char *cap_name; - struct child_process *process = &subprocess->process; - const char *cmd = subprocess->cmd; - - sigchain_push(SIGPIPE, SIG_IGN); - - err = packet_writel(process->in, "git-filter-client", "version=2", NULL); - if (err) - goto done; - - err = strcmp(packet_read_line(process->out, NULL), "git-filter-server"); - if (err) { - error("external filter '%s' does not support filter protocol version 2", cmd); - goto done; - } - err = strcmp(packet_read_line(process->out, NULL), "version=2"); - if (err) - goto done; - err = packet_read_line(process->out, NULL) != NULL; - if (err) - goto done; - - err = packet_writel(process->in, "capability=clean", "capability=smudge", NULL); - - for (;;) { - cap_buf = packet_read_line(process->out, NULL); - if (!cap_buf) - break; - string_list_split_in_place(&cap_list, cap_buf, '=', 1); - - if (cap_list.nr != 2 || strcmp(cap_list.items[0].string, "capability")) - continue; - - cap_name = cap_list.items[1].string; - if (!strcmp(cap_name, "clean")) { - entry->supported_capabilities |= CAP_CLEAN; - } else if (!strcmp(cap_name, "smudge")) { - entry->supported_capabilities |= CAP_SMUDGE; - } else { - warning( - "external filter '%s' requested unsupported filter capability '%s'", - cmd, cap_name - ); - } - - string_list_clear(&cap_list, 0); - } - -done: - sigchain_pop(SIGPIPE); - return err; + return subprocess_handshake(subprocess, "git-filter-", versions, NULL, + capabilities, + &entry->supported_capabilities); } static int apply_multi_file_filter(const char *path, const char *src, size_t len, diff --git a/pkt-line.c b/pkt-line.c index 9d845ecc3..7db911957 100644 --- a/pkt-line.c +++ b/pkt-line.c @@ -171,25 +171,6 @@ int packet_write_fmt_gently(int fd, const char *fmt, ...) return status; } -int packet_writel(int fd, const char *line, ...) -{ - va_list args; - int err; - va_start(args, line); - for (;;) { - if (!line) - break; - if (strlen(line) > LARGE_PACKET_DATA_MAX) - return -1; - err = packet_write_fmt_gently(fd, "%s\n", line); - if (err) - return err; - line = va_arg(args, const char*); - } - va_end(args); - return packet_flush_gently(fd); -} - static int packet_write_gently(const int fd_out, const char *buf, size_t size) { static char packet_write_buffer[LARGE_PACKET_MAX]; diff --git a/pkt-line.h b/pkt-line.h index 450183b64..66ef610fc 100644 --- a/pkt-line.h +++ b/pkt-line.h @@ -25,8 +25,6 @@ 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_gently(int fd); int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3))); -LAST_ARG_MUST_BE_NULL -int packet_writel(int fd, const char *line, ...); int write_packetized_from_fd(int fd_in, int fd_out); int write_packetized_from_buf(const char *src_in, size_t len, int fd_out); diff --git a/sub-process.c b/sub-process.c index a3cfab1a9..1a3f39bdf 100644 --- a/sub-process.c +++ b/sub-process.c @@ -105,3 +105,97 @@ int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, co hashmap_add(hashmap, entry); return 0; } + +int subprocess_handshake(struct subprocess_entry *entry, + const char *welcome_prefix, + int *versions, + int *chosen_version, + struct subprocess_capability *capabilities, + unsigned int *supported_capabilities) { + int version_scratch; + unsigned int capabilities_scratch; + struct child_process *process = &entry->process; + int i; + char *line; + const char *p; + + if (!chosen_version) + chosen_version = &version_scratch; + if (!supported_capabilities) + supported_capabilities = &capabilities_scratch; + + sigchain_push(SIGPIPE, SIG_IGN); + + if (packet_write_fmt_gently(process->in, "%sclient\n", + welcome_prefix)) { + error("Could not write client identification"); + goto error; + } + for (i = 0; versions[i]; i++) { + if (packet_write_fmt_gently(process->in, "version=%d\n", + versions[i])) { + error("Could not write requested version"); + goto error; + } + } + if (packet_flush_gently(process->in)) + goto error; + + if (!(line = packet_read_line(process->out, NULL)) || + !skip_prefix(line, welcome_prefix, &p) || + strcmp(p, "server")) { + error("Unexpected line '%s', expected %sserver", + line ? line : "<flush packet>", welcome_prefix); + goto error; + } + if (!(line = packet_read_line(process->out, NULL)) || + !skip_prefix(line, "version=", &p) || + strtol_i(p, 10, chosen_version)) { + error("Unexpected line '%s', expected version", + line ? line : "<flush packet>"); + goto error; + } + for (i = 0; versions[i]; i++) { + if (versions[i] == *chosen_version) + goto version_found; + } + error("Version %d not supported", *chosen_version); + goto error; +version_found: + if ((line = packet_read_line(process->out, NULL))) { + error("Unexpected line '%s', expected flush", line); + goto error; + } + + for (i = 0; capabilities[i].name; i++) { + if (packet_write_fmt_gently(process->in, "capability=%s\n", + capabilities[i].name)) { + error("Could not write requested capability"); + goto error; + } + } + if (packet_flush_gently(process->in)) + goto error; + + while ((line = packet_read_line(process->out, NULL))) { + if (!skip_prefix(line, "capability=", &p)) + continue; + + for (i = 0; capabilities[i].name; i++) { + if (!strcmp(p, capabilities[i].name)) { + *supported_capabilities |= capabilities[i].flag; + goto capability_found; + } + } + warning("external filter requested unsupported filter capability '%s'", + p); +capability_found: + ; + } + + sigchain_pop(SIGPIPE); + return 0; +error: + sigchain_pop(SIGPIPE); + return 1; +} diff --git a/sub-process.h b/sub-process.h index 96a2cca36..a72e7f7cf 100644 --- a/sub-process.h +++ b/sub-process.h @@ -18,6 +18,11 @@ struct subprocess_entry { struct child_process process; }; +struct subprocess_capability { + const char *name; + unsigned int flag; +}; + /* subprocess functions */ extern int cmd2process_cmp(const void *unused_cmp_data, @@ -41,6 +46,19 @@ static inline struct child_process *subprocess_get_child_process( return &entry->process; } +/* + * Perform the handshake to a long-running process as described in the + * gitattributes documentation using the given requested versions and + * capabilities. The "versions" and "capabilities" parameters are arrays + * terminated by a 0 or blank struct. + */ +int subprocess_handshake(struct subprocess_entry *entry, + const char *welcome_prefix, + int *versions, + int *chosen_version, + struct subprocess_capability *capabilities, + unsigned int *supported_capabilities); + /* * Helper function that will read packets looking for "status=<foo>" * key/value pairs and return the value from the last "status" packet diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh index 161f56044..d191a7228 100755 --- a/t/t0021-conversion.sh +++ b/t/t0021-conversion.sh @@ -697,7 +697,7 @@ test_expect_success PERL 'invalid process filter must fail (and not hang!)' ' cp "$TEST_ROOT/test.o" test.r && test_must_fail git add . 2>git-stderr.log && - grep "does not support filter protocol version" git-stderr.log + grep "expected git-filter-server" git-stderr.log ) ' -- 2.14.0.rc0.400.g1c36432dff-goog
