Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 214 insertions, 0 deletions

diff --git a/sub-process.c b/sub-process.c
new file mode 100644
index 000000000000..3f4af935557c
--- /dev/null
+++ b/sub-process.c
@@ -0,0 +1,214 @@
+/*
+ * 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;
+	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, 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;
+}