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spawn.c
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spawn.c
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/* Copyright 2012-present Facebook, Inc.
* Licensed under the Apache License, Version 2.0 */
#include "watchman.h"
// Maps pid => root
static w_ht_t *running_kids = NULL;
static pthread_mutex_t spawn_lock = PTHREAD_MUTEX_INITIALIZER;
static void spawn_command(w_root_t *root,
struct watchman_trigger_command *cmd,
w_query_res *res,
struct w_clockspec *since_spec);
// Caller must hold spawn_lock
static w_root_t *lookup_running_pid(pid_t pid)
{
if (!running_kids) {
return NULL;
}
return w_ht_val_ptr(w_ht_get(running_kids, pid));
}
// Caller must hold spawn_lock
static void delete_running_pid(pid_t pid)
{
if (!running_kids) {
return;
}
w_ht_del(running_kids, pid);
}
// Caller must hold spawn_lock
static void insert_running_pid(pid_t pid, w_root_t *root)
{
if (!running_kids) {
running_kids = w_ht_new(2, NULL);
}
w_ht_set(running_kids, pid, w_ht_ptr_val(root));
}
void w_mark_dead(pid_t pid)
{
w_root_t *root = NULL;
w_ht_iter_t iter;
pthread_mutex_lock(&spawn_lock);
root = lookup_running_pid(pid);
if (!root) {
pthread_mutex_unlock(&spawn_lock);
return;
}
delete_running_pid(pid);
pthread_mutex_unlock(&spawn_lock);
w_log(W_LOG_DBG, "mark_dead: %.*s child pid %d\n",
root->root_path->len, root->root_path->buf, (int)pid);
/* now walk the cmds and try to find our match */
w_root_lock(root);
/* walk the list of triggers, and run their rules */
if (w_ht_first(root->commands, &iter)) do {
struct watchman_trigger_command *cmd;
cmd = w_ht_val_ptr(iter.value);
if (cmd->current_proc != pid) {
w_log(W_LOG_DBG, "mark_dead: is [%.*s] %d == %d\n",
cmd->triggername->len, cmd->triggername->buf,
(int)cmd->current_proc, (int)pid);
continue;
}
/* first mark the process as dead */
cmd->current_proc = 0;
if (root->cancelled) {
w_log(W_LOG_DBG, "mark_dead: root was cancelled\n");
break;
}
w_assess_trigger(root, cmd);
break;
} while (w_ht_next(root->commands, &iter));
w_root_unlock(root);
w_root_delref(root);
}
static w_stm_t prepare_stdin(
struct watchman_trigger_command *cmd,
w_query_res *res)
{
uint32_t n_files;
char stdin_file_name[WATCHMAN_NAME_MAX];
w_stm_t stdin_file = NULL;
if (cmd->stdin_style == input_dev_null) {
return w_stm_open("/dev/null", O_RDONLY|O_CLOEXEC);
}
n_files = res->num_results;
if (cmd->max_files_stdin > 0) {
n_files = MIN(cmd->max_files_stdin, n_files);
}
/* prepare the input stream for the child process */
snprintf(stdin_file_name, sizeof(stdin_file_name), "%s%cwmanXXXXXX",
watchman_tmp_dir, WATCHMAN_DIR_SEP);
stdin_file = w_mkstemp(stdin_file_name);
if (!stdin_file) {
w_log(W_LOG_ERR, "unable to create a temporary file: %s %s\n",
stdin_file_name, strerror(errno));
return NULL;
}
/* unlink the file, we don't need it in the filesystem;
* we'll pass the fd on to the child as stdin */
unlink(stdin_file_name); // FIXME: windows path translation
switch (cmd->stdin_style) {
case input_json:
{
w_jbuffer_t buffer;
json_t *file_list;
if (!w_json_buffer_init(&buffer)) {
w_log(W_LOG_ERR, "failed to init json buffer\n");
w_stm_close(stdin_file);
return NULL;
}
file_list = w_query_results_to_json(&cmd->field_list,
n_files, res->results);
w_log(W_LOG_ERR, "input_json: sending json object to stm\n");
if (!w_json_buffer_write(&buffer, stdin_file, file_list, 0)) {
w_log(W_LOG_ERR,
"input_json: failed to write json data to stream: %s\n",
strerror(errno));
w_stm_close(stdin_file);
return NULL;
}
w_json_buffer_free(&buffer);
json_decref(file_list);
break;
}
case input_name_list:
{
uint32_t i;
for (i = 0; i < n_files; i++) {
if (w_stm_write(stdin_file, res->results[i].relname->buf,
res->results[i].relname->len) != (int)res->results[i].relname->len
|| w_stm_write(stdin_file, "\n", 1) != 1) {
w_log(W_LOG_ERR,
"write failure while producing trigger stdin: %s\n",
strerror(errno));
w_stm_close(stdin_file);
return NULL;
}
}
break;
}
case input_dev_null:
// already handled above
break;
}
w_stm_rewind(stdin_file);
return stdin_file;
}
static void spawn_command(w_root_t *root,
struct watchman_trigger_command *cmd,
w_query_res *res,
struct w_clockspec *since_spec)
{
char **envp = NULL;
uint32_t i = 0;
int ret;
w_stm_t stdin_file = NULL;
json_t *args;
char **argv = NULL;
uint32_t env_size;
posix_spawn_file_actions_t actions;
posix_spawnattr_t attr;
#ifndef _WIN32
sigset_t mask;
#endif
long arg_max;
size_t argspace_remaining;
bool file_overflow = false;
int result_log_level;
char clockbuf[128];
w_string_t *working_dir = NULL;
#ifdef _WIN32
arg_max = 32*1024;
#else
arg_max = sysconf(_SC_ARG_MAX);
#endif
if (arg_max <= 0) {
argspace_remaining = UINT_MAX;
} else {
argspace_remaining = (uint32_t)arg_max;
}
// Allow some misc working overhead
argspace_remaining -= 32;
stdin_file = prepare_stdin(cmd, res);
if (!stdin_file) {
w_log(W_LOG_ERR, "trigger %.*s:%s %s\n",
(int)root->root_path->len,
root->root_path->buf,
cmd->triggername->buf, strerror(errno));
return;
}
// Assumption: that only one thread will be executing on a given
// cmd instance so that mutation of cmd->envht is safe.
// This is guaranteed in the current architecture.
if (cmd->max_files_stdin > 0 && res->num_results > cmd->max_files_stdin) {
file_overflow = true;
}
// It is way too much of a hassle to try to recreate the clock value if it's
// not a relative clock spec, and it's only going to happen on the first run
// anyway, so just skip doing that entirely.
if (since_spec && since_spec->tag == w_cs_clock &&
clock_id_string(since_spec->clock.root_number, since_spec->clock.ticks,
clockbuf, sizeof(clockbuf))) {
w_envp_set_cstring(cmd->envht, "WATCHMAN_SINCE", clockbuf);
} else {
w_envp_unset(cmd->envht, "WATCHMAN_SINCE");
}
if (clock_id_string(res->root_number, res->ticks,
clockbuf, sizeof(clockbuf))) {
w_envp_set_cstring(cmd->envht, "WATCHMAN_CLOCK", clockbuf);
} else {
w_envp_unset(cmd->envht, "WATCHMAN_CLOCK");
}
if (cmd->query->relative_root) {
w_envp_set(cmd->envht, "WATCHMAN_RELATIVE_ROOT", cmd->query->relative_root);
} else {
w_envp_unset(cmd->envht, "WATCHMAN_RELATIVE_ROOT");
}
// Compute args
args = json_deep_copy(cmd->command);
if (cmd->append_files) {
// Measure how much space the base args take up
for (i = 0; i < json_array_size(args); i++) {
const char *ele = json_string_value(json_array_get(args, i));
argspace_remaining -= strlen(ele) + 1 + sizeof(char*);
}
// Dry run with env to compute space
envp = w_envp_make_from_ht(cmd->envht, &env_size);
free(envp);
envp = NULL;
argspace_remaining -= env_size;
for (i = 0; i < res->num_results; i++) {
// also: NUL terminator and entry in argv
uint32_t size = res->results[i].relname->len + 1 + sizeof(char*);
if (argspace_remaining < size) {
file_overflow = true;
break;
}
argspace_remaining -= size;
json_array_append_new(
args,
json_string_nocheck(res->results[i].relname->buf)
);
}
}
argv = w_argv_copy_from_json(args, 0);
json_decref(args);
args = NULL;
w_envp_set_bool(cmd->envht, "WATCHMAN_FILES_OVERFLOW", file_overflow);
envp = w_envp_make_from_ht(cmd->envht, &env_size);
posix_spawnattr_init(&attr);
#ifndef _WIN32
sigemptyset(&mask);
posix_spawnattr_setsigmask(&attr, &mask);
#endif
posix_spawnattr_setflags(&attr,
POSIX_SPAWN_SETSIGMASK|
#ifdef POSIX_SPAWN_CLOEXEC_DEFAULT
// Darwin: close everything except what we put in file actions
POSIX_SPAWN_CLOEXEC_DEFAULT|
#endif
POSIX_SPAWN_SETPGROUP);
posix_spawn_file_actions_init(&actions);
#ifndef _WIN32
posix_spawn_file_actions_adddup2(&actions, w_stm_fileno(stdin_file),
STDIN_FILENO);
#else
posix_spawn_file_actions_adddup2_handle_np(&actions,
w_stm_handle(stdin_file), STDIN_FILENO);
#endif
if (cmd->stdout_name) {
posix_spawn_file_actions_addopen(&actions, STDOUT_FILENO,
cmd->stdout_name, cmd->stdout_flags, 0666);
} else {
posix_spawn_file_actions_adddup2(&actions, STDOUT_FILENO, STDOUT_FILENO);
}
if (cmd->stderr_name) {
posix_spawn_file_actions_addopen(&actions, STDERR_FILENO,
cmd->stderr_name, cmd->stderr_flags, 0666);
} else {
posix_spawn_file_actions_adddup2(&actions, STDERR_FILENO, STDERR_FILENO);
}
// Figure out the appropriate cwd
{
const char *cwd = NULL;
working_dir = NULL;
if (cmd->query->relative_root) {
working_dir = cmd->query->relative_root;
} else {
working_dir = root->root_path;
}
w_string_addref(working_dir);
json_unpack(cmd->definition, "{s:s}", "chdir", &cwd);
if (cwd) {
w_string_t *cwd_str = w_string_new(cwd);
if (w_is_path_absolute(cwd)) {
w_string_delref(working_dir);
working_dir = cwd_str;
} else {
w_string_t *joined;
joined = w_string_path_cat(working_dir, cwd_str);
w_string_delref(cwd_str);
w_string_delref(working_dir);
working_dir = joined;
}
}
w_log(W_LOG_DBG, "using %.*s for working dir\n", working_dir->len, working_dir->buf);
}
pthread_mutex_lock(&spawn_lock);
#ifndef _WIN32
ignore_result(chdir(working_dir->buf));
#else
posix_spawnattr_setcwd_np(&attr, working_dir->buf);
#endif
w_string_delref(working_dir);
working_dir = NULL;
ret = posix_spawnp(&cmd->current_proc, argv[0], &actions, &attr, argv, envp);
if (ret == 0) {
w_root_addref(root);
insert_running_pid(cmd->current_proc, root);
} else {
// On Darwin (at least), posix_spawn can fail but will still populate the
// pid. Since we use the pid to gate future spawns, we need to ensure
// that we clear out the pid on failure, otherwise the trigger would be
// effectively disabled for the rest of the watch lifetime
cmd->current_proc = 0;
}
#ifndef _WIN32
ignore_result(chdir("/"));
#endif
pthread_mutex_unlock(&spawn_lock);
// If failed, we want to make sure we log enough info to figure out why
result_log_level = res == 0 ? W_LOG_DBG : W_LOG_ERR;
w_log(result_log_level, "posix_spawnp:\n");
for (i = 0; argv[i]; i++) {
w_log(result_log_level, "argv[%d] %s\n", i, argv[i]);
}
for (i = 0; envp[i]; i++) {
w_log(result_log_level, "envp[%d] %s\n", i, envp[i]);
}
w_log(result_log_level, "trigger %.*s:%s pid=%d ret=%d %s\n",
(int)root->root_path->len,
root->root_path->buf,
cmd->triggername->buf, (int)cmd->current_proc, ret, strerror(ret));
free(argv);
free(envp);
posix_spawnattr_destroy(&attr);
posix_spawn_file_actions_destroy(&actions);
if (stdin_file) {
w_stm_close(stdin_file);
}
}
static bool trigger_generator(
w_query *query,
w_root_t *root,
struct w_query_ctx *ctx,
void *gendata)
{
struct watchman_file *f;
struct watchman_trigger_command *cmd = gendata;
w_log(W_LOG_DBG, "assessing trigger %s %p\n",
cmd->triggername->buf, cmd);
// Walk back in time until we hit the boundary
for (f = root->latest_file; f; f = f->next) {
if (ctx->since.is_timestamp &&
w_timeval_compare(f->otime.tv, ctx->since.timestamp) < 0) {
break;
}
if (!ctx->since.is_timestamp &&
f->otime.ticks <= ctx->since.clock.ticks) {
break;
}
if (!w_query_file_matches_relative_root(ctx, f)) {
continue;
}
if (!w_query_process_file(query, ctx, f)) {
return false;
}
}
return true;
}
void w_assess_trigger(w_root_t *root, struct watchman_trigger_command *cmd)
{
w_query_res res;
struct w_clockspec *since_spec = cmd->query->since_spec;
if (since_spec && since_spec->tag == w_cs_clock) {
w_log(W_LOG_DBG, "running trigger rules! since %" PRIu32 "\n",
since_spec->clock.ticks);
} else {
w_log(W_LOG_DBG, "running trigger rules!\n");
}
// Triggers never need to sync explicitly; we are only dispatched
// at settle points which are by definition sync'd to the present time
cmd->query->sync_timeout = 0;
if (!w_query_execute(cmd->query, root, &res, trigger_generator, cmd)) {
w_log(W_LOG_ERR, "error running trigger query: %s", res.errmsg);
w_query_result_free(&res);
return;
}
w_log(W_LOG_DBG, "trigger generated %" PRIu32 " results\n",
res.num_results);
// create a new spec that will be used the next time
cmd->query->since_spec = w_clockspec_new_clock(res.root_number, res.ticks);
if (res.num_results) {
spawn_command(root, cmd, &res, since_spec);
}
if (since_spec) {
w_clockspec_free(since_spec);
since_spec = NULL;
}
w_query_result_free(&res);
}
/* vim:ts=2:sw=2:et:
*/