Merging upstream version 1.29.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 377 insertions, 0 deletions

diff --git a/spawn/spawn_server.c b/spawn/spawn_server.c
new file mode 100644
index 00000000..f84fab1c
--- /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);
+}