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-rw-r--r--spawn/spawn_server.c377
1 files changed, 377 insertions, 0 deletions
diff --git a/spawn/spawn_server.c b/spawn/spawn_server.c
new file mode 100644
index 000000000..f84fab1ca
--- /dev/null
+++ b/spawn/spawn_server.c
@@ -0,0 +1,377 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "spawn.h"
+
+static uv_loop_t *loop;
+static uv_pipe_t server_pipe;
+
+static int server_shutdown = 0;
+
+static uv_thread_t thread;
+
+/* spawn outstanding execution structure */
+static avl_tree_lock spawn_outstanding_exec_tree;
+
+static char prot_buffer[MAX_COMMAND_LENGTH];
+static unsigned prot_buffer_len = 0;
+
+struct spawn_execution_info {
+ avl avl;
+
+ void *handle;
+ int exit_status;
+ pid_t pid;
+ struct spawn_execution_info *next;
+};
+
+int spawn_exec_compare(void *a, void *b)
+{
+ struct spawn_execution_info *spwna = a, *spwnb = b;
+
+ if (spwna->pid < spwnb->pid) return -1;
+ if (spwna->pid > spwnb->pid) return 1;
+
+ return 0;
+}
+
+/* wake up waiter thread to reap the spawned processes */
+static uv_mutex_t wait_children_mutex;
+static uv_cond_t wait_children_cond;
+static uint8_t spawned_processes;
+static struct spawn_execution_info *child_waited_list;
+static uv_async_t child_waited_async;
+
+static inline struct spawn_execution_info *dequeue_child_waited_list(void)
+{
+ struct spawn_execution_info *exec_info;
+
+ uv_mutex_lock(&wait_children_mutex);
+ if (NULL == child_waited_list) {
+ exec_info = NULL;
+ } else {
+ exec_info = child_waited_list;
+ child_waited_list = exec_info->next;
+ }
+ uv_mutex_unlock(&wait_children_mutex);
+
+ return exec_info;
+}
+
+static inline void enqueue_child_waited_list(struct spawn_execution_info *exec_info)
+{
+ uv_mutex_lock(&wait_children_mutex);
+ exec_info->next = child_waited_list;
+ child_waited_list = exec_info;
+ uv_mutex_unlock(&wait_children_mutex);
+}
+
+static void after_pipe_write(uv_write_t *req, int status)
+{
+ (void)status;
+#ifdef SPAWN_DEBUG
+ fprintf(stderr, "SERVER %s called status=%d\n", __func__, status);
+#endif
+ freez(req->data);
+}
+
+static void child_waited_async_cb(uv_async_t *async_handle)
+{
+ uv_buf_t writebuf[2];
+ int ret;
+ struct spawn_execution_info *exec_info;
+ struct write_context *write_ctx;
+
+ (void)async_handle;
+ while (NULL != (exec_info = dequeue_child_waited_list())) {
+ write_ctx = mallocz(sizeof(*write_ctx));
+ write_ctx->write_req.data = write_ctx;
+
+
+ write_ctx->header.opcode = SPAWN_PROT_CMD_EXIT_STATUS;
+ write_ctx->header.handle = exec_info->handle;
+ write_ctx->exit_status.exec_exit_status = exec_info->exit_status;
+ writebuf[0] = uv_buf_init((char *) &write_ctx->header, sizeof(write_ctx->header));
+ writebuf[1] = uv_buf_init((char *) &write_ctx->exit_status, sizeof(write_ctx->exit_status));
+#ifdef SPAWN_DEBUG
+ fprintf(stderr, "SERVER %s SPAWN_PROT_CMD_EXIT_STATUS\n", __func__);
+#endif
+ ret = uv_write(&write_ctx->write_req, (uv_stream_t *) &server_pipe, writebuf, 2, after_pipe_write);
+ fatal_assert(ret == 0);
+
+ freez(exec_info);
+ }
+}
+
+static void wait_children(void *arg)
+{
+ siginfo_t i;
+ struct spawn_execution_info tmp, *exec_info;
+ avl *ret_avl;
+
+ (void)arg;
+ while (!server_shutdown) {
+ uv_mutex_lock(&wait_children_mutex);
+ while (!spawned_processes) {
+ uv_cond_wait(&wait_children_cond, &wait_children_mutex);
+ }
+ spawned_processes = 0;
+ uv_mutex_unlock(&wait_children_mutex);
+
+ while (!server_shutdown) {
+ i.si_pid = 0;
+ if (waitid(P_ALL, (id_t) 0, &i, WEXITED) == -1) {
+ if (errno != ECHILD)
+ fprintf(stderr, "SPAWN: Failed to wait: %s\n", strerror(errno));
+ break;
+ }
+ if (i.si_pid == 0) {
+ fprintf(stderr, "SPAWN: No child exited.\n");
+ break;
+ }
+#ifdef SPAWN_DEBUG
+ fprintf(stderr, "SPAWN: Successfully waited for pid:%d.\n", (int) i.si_pid);
+#endif
+ fatal_assert(CLD_EXITED == i.si_code);
+ tmp.pid = (pid_t)i.si_pid;
+ while (NULL == (ret_avl = avl_remove_lock(&spawn_outstanding_exec_tree, (avl *)&tmp))) {
+ fprintf(stderr,
+ "SPAWN: race condition detected, waiting for child process %d to be indexed.\n",
+ (int)tmp.pid);
+ (void)sleep_usec(10000); /* 10 msec */
+ }
+ exec_info = (struct spawn_execution_info *)ret_avl;
+ exec_info->exit_status = i.si_status;
+ enqueue_child_waited_list(exec_info);
+
+ /* wake up event loop */
+ fatal_assert(0 == uv_async_send(&child_waited_async));
+ }
+ }
+}
+
+void spawn_protocol_execute_command(void *handle, char *command_to_run, uint16_t command_length)
+{
+ uv_buf_t writebuf[2];
+ int ret;
+ avl *avl_ret;
+ struct spawn_execution_info *exec_info;
+ struct write_context *write_ctx;
+
+ write_ctx = mallocz(sizeof(*write_ctx));
+ write_ctx->write_req.data = write_ctx;
+
+ command_to_run[command_length] = '\0';
+#ifdef SPAWN_DEBUG
+ fprintf(stderr, "SPAWN: executing command '%s'\n", command_to_run);
+#endif
+ if (netdata_spawn(command_to_run, &write_ctx->spawn_result.exec_pid)) {
+ fprintf(stderr, "SPAWN: Cannot spawn(\"%s\", \"r\").\n", command_to_run);
+ write_ctx->spawn_result.exec_pid = 0;
+ } else { /* successfully spawned command */
+ write_ctx->spawn_result.exec_run_timestamp = now_realtime_sec();
+
+ /* record it for when the process finishes execution */
+ exec_info = mallocz(sizeof(*exec_info));
+ exec_info->handle = handle;
+ exec_info->pid = write_ctx->spawn_result.exec_pid;
+ avl_ret = avl_insert_lock(&spawn_outstanding_exec_tree, (avl *)exec_info);
+ fatal_assert(avl_ret == (avl *)exec_info);
+
+ /* wake up the thread that blocks waiting for processes to exit */
+ uv_mutex_lock(&wait_children_mutex);
+ spawned_processes = 1;
+ uv_cond_signal(&wait_children_cond);
+ uv_mutex_unlock(&wait_children_mutex);
+ }
+
+ write_ctx->header.opcode = SPAWN_PROT_SPAWN_RESULT;
+ write_ctx->header.handle = handle;
+ writebuf[0] = uv_buf_init((char *)&write_ctx->header, sizeof(write_ctx->header));
+ writebuf[1] = uv_buf_init((char *)&write_ctx->spawn_result, sizeof(write_ctx->spawn_result));
+#ifdef SPAWN_DEBUG
+ fprintf(stderr, "SERVER %s SPAWN_PROT_SPAWN_RESULT\n", __func__);
+#endif
+ ret = uv_write(&write_ctx->write_req, (uv_stream_t *)&server_pipe, writebuf, 2, after_pipe_write);
+ fatal_assert(ret == 0);
+}
+
+static void server_parse_spawn_protocol(unsigned source_len, char *source)
+{
+ unsigned required_len;
+ struct spawn_prot_header *header;
+ struct spawn_prot_exec_cmd *payload;
+ uint16_t command_length;
+
+ while (source_len) {
+ required_len = sizeof(*header);
+ if (prot_buffer_len < required_len)
+ copy_to_prot_buffer(prot_buffer, &prot_buffer_len, required_len - prot_buffer_len, &source, &source_len);
+ if (prot_buffer_len < required_len)
+ return; /* Source buffer ran out */
+
+ header = (struct spawn_prot_header *)prot_buffer;
+ fatal_assert(SPAWN_PROT_EXEC_CMD == header->opcode);
+ fatal_assert(NULL != header->handle);
+
+ required_len += sizeof(*payload);
+ if (prot_buffer_len < required_len)
+ copy_to_prot_buffer(prot_buffer, &prot_buffer_len, required_len - prot_buffer_len, &source, &source_len);
+ if (prot_buffer_len < required_len)
+ return; /* Source buffer ran out */
+
+ payload = (struct spawn_prot_exec_cmd *)(header + 1);
+ command_length = payload->command_length;
+
+ required_len += command_length;
+ if (unlikely(required_len > MAX_COMMAND_LENGTH - 1)) {
+ fprintf(stderr, "SPAWN: Ran out of protocol buffer space.\n");
+ command_length = (MAX_COMMAND_LENGTH - 1) - (sizeof(*header) + sizeof(*payload));
+ required_len = MAX_COMMAND_LENGTH - 1;
+ }
+ if (prot_buffer_len < required_len)
+ copy_to_prot_buffer(prot_buffer, &prot_buffer_len, required_len - prot_buffer_len, &source, &source_len);
+ if (prot_buffer_len < required_len)
+ return; /* Source buffer ran out */
+
+ spawn_protocol_execute_command(header->handle, payload->command_to_run, command_length);
+ prot_buffer_len = 0;
+ }
+}
+
+static void on_pipe_read(uv_stream_t *pipe, ssize_t nread, const uv_buf_t *buf)
+{
+ if (0 == nread) {
+ fprintf(stderr, "SERVER %s: Zero bytes read from spawn pipe.\n", __func__);
+ } else if (UV_EOF == nread) {
+ fprintf(stderr, "EOF found in spawn pipe.\n");
+ } else if (nread < 0) {
+ fprintf(stderr, "%s: %s\n", __func__, uv_strerror(nread));
+ }
+
+ if (nread < 0) { /* stop spawn server due to EOF or error */
+ int error;
+
+ uv_mutex_lock(&wait_children_mutex);
+ server_shutdown = 1;
+ spawned_processes = 1;
+ uv_cond_signal(&wait_children_cond);
+ uv_mutex_unlock(&wait_children_mutex);
+
+ fprintf(stderr, "Shutting down spawn server event loop.\n");
+ /* cleanup operations of the event loop */
+ (void)uv_read_stop((uv_stream_t *) pipe);
+ uv_close((uv_handle_t *)&server_pipe, NULL);
+
+ error = uv_thread_join(&thread);
+ if (error) {
+ fprintf(stderr, "uv_thread_create(): %s", uv_strerror(error));
+ }
+ /* After joining it is safe to destroy child_waited_async */
+ uv_close((uv_handle_t *)&child_waited_async, NULL);
+ } else if (nread) {
+#ifdef SPAWN_DEBUG
+ fprintf(stderr, "SERVER %s nread %u\n", __func__, (unsigned)nread);
+#endif
+ server_parse_spawn_protocol(nread, buf->base);
+ }
+ if (buf && buf->len) {
+ freez(buf->base);
+ }
+}
+
+static void on_read_alloc(uv_handle_t *handle,
+ size_t suggested_size,
+ uv_buf_t* buf)
+{
+ (void)handle;
+ buf->base = mallocz(suggested_size);
+ buf->len = suggested_size;
+}
+
+static void ignore_signal_handler(int signo) {
+ /*
+ * By having a signal handler we allow spawned processes to reset default signal dispositions. Setting SIG_IGN
+ * would be inherited by the spawned children which is not desirable.
+ */
+ (void)signo;
+}
+
+void spawn_server(void)
+{
+ int error;
+
+ test_clock_boottime();
+ test_clock_monotonic_coarse();
+
+ // close all open file descriptors, except the standard ones
+ // the caller may have left open files (lxc-attach has this issue)
+ int fd;
+ for(fd = (int)(sysconf(_SC_OPEN_MAX) - 1) ; fd > 2 ; --fd)
+ if(fd_is_valid(fd))
+ close(fd);
+
+ // Have the libuv IPC pipe be closed when forking child processes
+ (void) fcntl(0, F_SETFD, FD_CLOEXEC);
+ fprintf(stderr, "Spawn server is up.\n");
+
+ // Define signals we want to ignore
+ struct sigaction sa;
+ int signals_to_ignore[] = {SIGPIPE, SIGINT, SIGQUIT, SIGTERM, SIGHUP, SIGUSR1, SIGUSR2, SIGBUS, SIGCHLD};
+ unsigned ignore_length = sizeof(signals_to_ignore) / sizeof(signals_to_ignore[0]);
+
+ unsigned i;
+ for (i = 0; i < ignore_length ; ++i) {
+ sa.sa_flags = 0;
+ sigemptyset(&sa.sa_mask);
+ sa.sa_handler = ignore_signal_handler;
+ if(sigaction(signals_to_ignore[i], &sa, NULL) == -1)
+ fprintf(stderr, "SPAWN: Failed to change signal handler for signal: %d.\n", signals_to_ignore[i]);
+ }
+
+ signals_unblock();
+
+ loop = uv_default_loop();
+ loop->data = NULL;
+
+ error = uv_pipe_init(loop, &server_pipe, 1);
+ if (error) {
+ fprintf(stderr, "uv_pipe_init(): %s\n", uv_strerror(error));
+ exit(error);
+ }
+ fatal_assert(server_pipe.ipc);
+
+ error = uv_pipe_open(&server_pipe, 0 /* UV_STDIN_FD */);
+ if (error) {
+ fprintf(stderr, "uv_pipe_open(): %s\n", uv_strerror(error));
+ exit(error);
+ }
+ avl_init_lock(&spawn_outstanding_exec_tree, spawn_exec_compare);
+
+ spawned_processes = 0;
+ fatal_assert(0 == uv_cond_init(&wait_children_cond));
+ fatal_assert(0 == uv_mutex_init(&wait_children_mutex));
+ child_waited_list = NULL;
+ error = uv_async_init(loop, &child_waited_async, child_waited_async_cb);
+ if (error) {
+ fprintf(stderr, "uv_async_init(): %s\n", uv_strerror(error));
+ exit(error);
+ }
+
+ error = uv_thread_create(&thread, wait_children, NULL);
+ if (error) {
+ fprintf(stderr, "uv_thread_create(): %s\n", uv_strerror(error));
+ exit(error);
+ }
+
+ prot_buffer_len = 0;
+ error = uv_read_start((uv_stream_t *)&server_pipe, on_read_alloc, on_pipe_read);
+ fatal_assert(error == 0);
+
+ while (!server_shutdown) {
+ uv_run(loop, UV_RUN_DEFAULT);
+ }
+ fprintf(stderr, "Shutting down spawn server loop complete.\n");
+ fatal_assert(0 == uv_loop_close(loop));
+
+ exit(0);
+}