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-rw-r--r--sub-process.c213
1 files changed, 213 insertions, 0 deletions
diff --git a/sub-process.c b/sub-process.c
new file mode 100644
index 0000000000..8d2a1707cf
--- /dev/null
+++ b/sub-process.c
@@ -0,0 +1,213 @@
+/*
+ * 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 void *entry,
+ const void *entry_or_key,
+ const void *unused_keydata)
+{
+ const struct subprocess_entry *e1 = entry;
+ const struct subprocess_entry *e2 = entry_or_key;
+
+ 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, strhash(cmd));
+ key.cmd = cmd;
+ return hashmap_get(hashmap, &key, 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, 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;
+
+ err = start_command(process);
+ if (err) {
+ error("cannot fork to run subprocess '%s'", cmd);
+ return err;
+ }
+
+ hashmap_entry_init(entry, strhash(cmd));
+
+ err = startfn(entry);
+ if (err) {
+ error("initialization for subprocess '%s' failed", cmd);
+ subprocess_stop(hashmap, entry);
+ return err;
+ }
+
+ hashmap_add(hashmap, entry);
+ 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;
+}