diff options
Diffstat (limited to 'sub-process.c')
| -rw-r--r-- | sub-process.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/sub-process.c b/sub-process.c new file mode 100644 index 0000000..1b1af9d --- /dev/null +++ b/sub-process.c @@ -0,0 +1,216 @@ +/* + * Generic implementation of background process infrastructure. + */ +#include "sub-process.h" +#include "sigchain.h" +#include "pkt-line.h" + +int cmd2process_cmp(const void *unused_cmp_data, + const struct hashmap_entry *eptr, + const struct hashmap_entry *entry_or_key, + const void *unused_keydata) +{ + const struct subprocess_entry *e1, *e2; + + e1 = container_of(eptr, const struct subprocess_entry, ent); + e2 = container_of(entry_or_key, const struct subprocess_entry, ent); + + return strcmp(e1->cmd, e2->cmd); +} + +struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd) +{ + struct subprocess_entry key; + + hashmap_entry_init(&key.ent, strhash(cmd)); + key.cmd = cmd; + return hashmap_get_entry(hashmap, &key, ent, NULL); +} + +int subprocess_read_status(int fd, struct strbuf *status) +{ + struct strbuf **pair; + char *line; + int len; + + for (;;) { + len = packet_read_line_gently(fd, NULL, &line); + if ((len < 0) || !line) + break; + pair = strbuf_split_str(line, '=', 2); + if (pair[0] && pair[0]->len && pair[1]) { + /* the last "status=<foo>" line wins */ + if (!strcmp(pair[0]->buf, "status=")) { + strbuf_reset(status); + strbuf_addbuf(status, pair[1]); + } + } + strbuf_list_free(pair); + } + + return (len < 0) ? len : 0; +} + +void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry) +{ + if (!entry) + return; + + entry->process.clean_on_exit = 0; + kill(entry->process.pid, SIGTERM); + finish_command(&entry->process); + + hashmap_remove(hashmap, &entry->ent, NULL); +} + +static void subprocess_exit_handler(struct child_process *process) +{ + sigchain_push(SIGPIPE, SIG_IGN); + /* Closing the pipe signals the subprocess to initiate a shutdown. */ + close(process->in); + close(process->out); + sigchain_pop(SIGPIPE); + /* Finish command will wait until the shutdown is complete. */ + finish_command(process); +} + +int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd, + subprocess_start_fn startfn) +{ + int err; + struct child_process *process; + + entry->cmd = cmd; + process = &entry->process; + + child_process_init(process); + argv_array_push(&process->args, cmd); + process->use_shell = 1; + process->in = -1; + process->out = -1; + process->clean_on_exit = 1; + process->clean_on_exit_handler = subprocess_exit_handler; + process->trace2_child_class = "subprocess"; + + err = start_command(process); + if (err) { + error("cannot fork to run subprocess '%s'", cmd); + return err; + } + + hashmap_entry_init(&entry->ent, strhash(cmd)); + + err = startfn(entry); + if (err) { + error("initialization for subprocess '%s' failed", cmd); + subprocess_stop(hashmap, entry); + return err; + } + + hashmap_add(hashmap, &entry->ent); + return 0; +} + +static int handshake_version(struct child_process *process, + const char *welcome_prefix, int *versions, + int *chosen_version) +{ + int version_scratch; + int i; + char *line; + const char *p; + + if (!chosen_version) + chosen_version = &version_scratch; + + if (packet_write_fmt_gently(process->in, "%s-client\n", + welcome_prefix)) + return error("Could not write client identification"); + for (i = 0; versions[i]; i++) { + if (packet_write_fmt_gently(process->in, "version=%d\n", + versions[i])) + return error("Could not write requested version"); + } + if (packet_flush_gently(process->in)) + return error("Could not write flush packet"); + + if (!(line = packet_read_line(process->out, NULL)) || + !skip_prefix(line, welcome_prefix, &p) || + strcmp(p, "-server")) + return error("Unexpected line '%s', expected %s-server", + line ? line : "<flush packet>", welcome_prefix); + if (!(line = packet_read_line(process->out, NULL)) || + !skip_prefix(line, "version=", &p) || + strtol_i(p, 10, chosen_version)) + return error("Unexpected line '%s', expected version", + line ? line : "<flush packet>"); + if ((line = packet_read_line(process->out, NULL))) + return error("Unexpected line '%s', expected flush", line); + + /* Check to make sure that the version received is supported */ + for (i = 0; versions[i]; i++) { + if (versions[i] == *chosen_version) + break; + } + if (!versions[i]) + return error("Version %d not supported", *chosen_version); + + return 0; +} + +static int handshake_capabilities(struct child_process *process, + struct subprocess_capability *capabilities, + unsigned int *supported_capabilities) +{ + int i; + char *line; + + for (i = 0; capabilities[i].name; i++) { + if (packet_write_fmt_gently(process->in, "capability=%s\n", + capabilities[i].name)) + return error("Could not write requested capability"); + } + if (packet_flush_gently(process->in)) + return error("Could not write flush packet"); + + while ((line = packet_read_line(process->out, NULL))) { + const char *p; + if (!skip_prefix(line, "capability=", &p)) + continue; + + for (i = 0; + capabilities[i].name && strcmp(p, capabilities[i].name); + i++) + ; + if (capabilities[i].name) { + if (supported_capabilities) + *supported_capabilities |= capabilities[i].flag; + } else { + die("subprocess '%s' requested unsupported capability '%s'", + process->argv[0], p); + } + } + + 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 retval; + struct child_process *process = &entry->process; + + sigchain_push(SIGPIPE, SIG_IGN); + + retval = handshake_version(process, welcome_prefix, versions, + chosen_version) || + handshake_capabilities(process, capabilities, + supported_capabilities); + + sigchain_pop(SIGPIPE); + return retval; +} |