/*

 * 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;

}