logwrap: convert to C++, rename function logwrap_fork_execvp().
Call the function now logwrap_fork_execvp() and fix const correctness
issues, so no longer do callers need to const_cast<> their args.
Test: logwrapper still works
Change-Id: Iea34f5cae90a06a37d395bf9a91e01fb38c35fa6
diff --git a/logwrapper/logwrap.cpp b/logwrapper/logwrap.cpp
new file mode 100644
index 0000000..5337801
--- /dev/null
+++ b/logwrapper/logwrap.cpp
@@ -0,0 +1,615 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <libgen.h>
+#include <poll.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include <algorithm>
+
+#include <android-base/macros.h>
+#include <cutils/klog.h>
+#include <log/log.h>
+#include <logwrap/logwrap.h>
+
+static pthread_mutex_t fd_mutex = PTHREAD_MUTEX_INITIALIZER;
+// Protected by fd_mutex. These signals must be blocked while modifying as well.
+static pid_t child_pid;
+static struct sigaction old_int;
+static struct sigaction old_quit;
+static struct sigaction old_hup;
+
+#define ERROR(fmt, args...) \
+ do { \
+ fprintf(stderr, fmt, ##args); \
+ ALOG(LOG_ERROR, "logwrapper", fmt, ##args); \
+ } while (0)
+
+#define FATAL_CHILD(fmt, args...) \
+ do { \
+ ERROR(fmt, ##args); \
+ _exit(-1); \
+ } while (0)
+
+#define MAX_KLOG_TAG 16
+
+/* This is a simple buffer that holds up to the first beginning_buf->buf_size
+ * bytes of output from a command.
+ */
+#define BEGINNING_BUF_SIZE 0x1000
+struct beginning_buf {
+ char* buf;
+ size_t alloc_len;
+ /* buf_size is the usable space, which is one less than the allocated size */
+ size_t buf_size;
+ size_t used_len;
+};
+
+/* This is a circular buf that holds up to the last ending_buf->buf_size bytes
+ * of output from a command after the first beginning_buf->buf_size bytes
+ * (which are held in beginning_buf above).
+ */
+#define ENDING_BUF_SIZE 0x1000
+struct ending_buf {
+ char* buf;
+ ssize_t alloc_len;
+ /* buf_size is the usable space, which is one less than the allocated size */
+ ssize_t buf_size;
+ ssize_t used_len;
+ /* read and write offsets into the circular buffer */
+ int read;
+ int write;
+};
+
+/* A structure to hold all the abbreviated buf data */
+struct abbr_buf {
+ struct beginning_buf b_buf;
+ struct ending_buf e_buf;
+ int beginning_buf_full;
+};
+
+/* Collect all the various bits of info needed for logging in one place. */
+struct log_info {
+ int log_target;
+ char klog_fmt[MAX_KLOG_TAG * 2];
+ const char* btag;
+ bool abbreviated;
+ FILE* fp;
+ struct abbr_buf a_buf;
+};
+
+/* Forware declaration */
+static void add_line_to_abbr_buf(struct abbr_buf* a_buf, char* linebuf, int linelen);
+
+/* Return 0 on success, and 1 when full */
+static int add_line_to_linear_buf(struct beginning_buf* b_buf, char* line, ssize_t line_len) {
+ int full = 0;
+
+ if ((line_len + b_buf->used_len) > b_buf->buf_size) {
+ full = 1;
+ } else {
+ /* Add to the end of the buf */
+ memcpy(b_buf->buf + b_buf->used_len, line, line_len);
+ b_buf->used_len += line_len;
+ }
+
+ return full;
+}
+
+static void add_line_to_circular_buf(struct ending_buf* e_buf, char* line, ssize_t line_len) {
+ ssize_t free_len;
+ ssize_t needed_space;
+ int cnt;
+
+ if (e_buf->buf == nullptr) {
+ return;
+ }
+
+ if (line_len > e_buf->buf_size) {
+ return;
+ }
+
+ free_len = e_buf->buf_size - e_buf->used_len;
+
+ if (line_len > free_len) {
+ /* remove oldest entries at read, and move read to make
+ * room for the new string */
+ needed_space = line_len - free_len;
+ e_buf->read = (e_buf->read + needed_space) % e_buf->buf_size;
+ e_buf->used_len -= needed_space;
+ }
+
+ /* Copy the line into the circular buffer, dealing with possible
+ * wraparound.
+ */
+ cnt = std::min(line_len, e_buf->buf_size - e_buf->write);
+ memcpy(e_buf->buf + e_buf->write, line, cnt);
+ if (cnt < line_len) {
+ memcpy(e_buf->buf, line + cnt, line_len - cnt);
+ }
+ e_buf->used_len += line_len;
+ e_buf->write = (e_buf->write + line_len) % e_buf->buf_size;
+}
+
+/* Log directly to the specified log */
+static void do_log_line(struct log_info* log_info, const char* line) {
+ if (log_info->log_target & LOG_KLOG) {
+ klog_write(6, log_info->klog_fmt, line);
+ }
+ if (log_info->log_target & LOG_ALOG) {
+ ALOG(LOG_INFO, log_info->btag, "%s", line);
+ }
+ if (log_info->log_target & LOG_FILE) {
+ fprintf(log_info->fp, "%s\n", line);
+ }
+}
+
+/* Log to either the abbreviated buf, or directly to the specified log
+ * via do_log_line() above.
+ */
+static void log_line(struct log_info* log_info, char* line, int len) {
+ if (log_info->abbreviated) {
+ add_line_to_abbr_buf(&log_info->a_buf, line, len);
+ } else {
+ do_log_line(log_info, line);
+ }
+}
+
+/*
+ * The kernel will take a maximum of 1024 bytes in any single write to
+ * the kernel logging device file, so find and print each line one at
+ * a time. The allocated size for buf should be at least 1 byte larger
+ * than buf_size (the usable size of the buffer) to make sure there is
+ * room to temporarily stuff a null byte to terminate a line for logging.
+ */
+static void print_buf_lines(struct log_info* log_info, char* buf, int buf_size) {
+ char* line_start;
+ char c;
+ int i;
+
+ line_start = buf;
+ for (i = 0; i < buf_size; i++) {
+ if (*(buf + i) == '\n') {
+ /* Found a line ending, print the line and compute new line_start */
+ /* Save the next char and replace with \0 */
+ c = *(buf + i + 1);
+ *(buf + i + 1) = '\0';
+ do_log_line(log_info, line_start);
+ /* Restore the saved char */
+ *(buf + i + 1) = c;
+ line_start = buf + i + 1;
+ } else if (*(buf + i) == '\0') {
+ /* The end of the buffer, print the last bit */
+ do_log_line(log_info, line_start);
+ break;
+ }
+ }
+ /* If the buffer was completely full, and didn't end with a newline, just
+ * ignore the partial last line.
+ */
+}
+
+static void init_abbr_buf(struct abbr_buf* a_buf) {
+ char* new_buf;
+
+ memset(a_buf, 0, sizeof(struct abbr_buf));
+ new_buf = static_cast<char*>(malloc(BEGINNING_BUF_SIZE));
+ if (new_buf) {
+ a_buf->b_buf.buf = new_buf;
+ a_buf->b_buf.alloc_len = BEGINNING_BUF_SIZE;
+ a_buf->b_buf.buf_size = BEGINNING_BUF_SIZE - 1;
+ }
+ new_buf = static_cast<char*>(malloc(ENDING_BUF_SIZE));
+ if (new_buf) {
+ a_buf->e_buf.buf = new_buf;
+ a_buf->e_buf.alloc_len = ENDING_BUF_SIZE;
+ a_buf->e_buf.buf_size = ENDING_BUF_SIZE - 1;
+ }
+}
+
+static void free_abbr_buf(struct abbr_buf* a_buf) {
+ free(a_buf->b_buf.buf);
+ free(a_buf->e_buf.buf);
+}
+
+static void add_line_to_abbr_buf(struct abbr_buf* a_buf, char* linebuf, int linelen) {
+ if (!a_buf->beginning_buf_full) {
+ a_buf->beginning_buf_full = add_line_to_linear_buf(&a_buf->b_buf, linebuf, linelen);
+ }
+ if (a_buf->beginning_buf_full) {
+ add_line_to_circular_buf(&a_buf->e_buf, linebuf, linelen);
+ }
+}
+
+static void print_abbr_buf(struct log_info* log_info) {
+ struct abbr_buf* a_buf = &log_info->a_buf;
+
+ /* Add the abbreviated output to the kernel log */
+ if (a_buf->b_buf.alloc_len) {
+ print_buf_lines(log_info, a_buf->b_buf.buf, a_buf->b_buf.used_len);
+ }
+
+ /* Print an ellipsis to indicate that the buffer has wrapped or
+ * is full, and some data was not logged.
+ */
+ if (a_buf->e_buf.used_len == a_buf->e_buf.buf_size) {
+ do_log_line(log_info, "...\n");
+ }
+
+ if (a_buf->e_buf.used_len == 0) {
+ return;
+ }
+
+ /* Simplest way to print the circular buffer is allocate a second buf
+ * of the same size, and memcpy it so it's a simple linear buffer,
+ * and then cal print_buf_lines on it */
+ if (a_buf->e_buf.read < a_buf->e_buf.write) {
+ /* no wrap around, just print it */
+ print_buf_lines(log_info, a_buf->e_buf.buf + a_buf->e_buf.read, a_buf->e_buf.used_len);
+ } else {
+ /* The circular buffer will always have at least 1 byte unused,
+ * so by allocating alloc_len here we will have at least
+ * 1 byte of space available as required by print_buf_lines().
+ */
+ char* nbuf = static_cast<char*>(malloc(a_buf->e_buf.alloc_len));
+ if (!nbuf) {
+ return;
+ }
+ int first_chunk_len = a_buf->e_buf.buf_size - a_buf->e_buf.read;
+ memcpy(nbuf, a_buf->e_buf.buf + a_buf->e_buf.read, first_chunk_len);
+ /* copy second chunk */
+ memcpy(nbuf + first_chunk_len, a_buf->e_buf.buf, a_buf->e_buf.write);
+ print_buf_lines(log_info, nbuf, first_chunk_len + a_buf->e_buf.write);
+ free(nbuf);
+ }
+}
+
+static void signal_handler(int signal_num);
+
+static void block_signals(sigset_t* oldset) {
+ sigset_t blockset;
+
+ sigemptyset(&blockset);
+ sigaddset(&blockset, SIGINT);
+ sigaddset(&blockset, SIGQUIT);
+ sigaddset(&blockset, SIGHUP);
+ pthread_sigmask(SIG_BLOCK, &blockset, oldset);
+}
+
+static void unblock_signals(sigset_t* oldset) {
+ pthread_sigmask(SIG_SETMASK, oldset, nullptr);
+}
+
+static void setup_signal_handlers(pid_t pid) {
+ struct sigaction handler = {.sa_handler = signal_handler};
+
+ child_pid = pid;
+ sigaction(SIGINT, &handler, &old_int);
+ sigaction(SIGQUIT, &handler, &old_quit);
+ sigaction(SIGHUP, &handler, &old_hup);
+}
+
+static void restore_signal_handlers() {
+ sigaction(SIGINT, &old_int, nullptr);
+ sigaction(SIGQUIT, &old_quit, nullptr);
+ sigaction(SIGHUP, &old_hup, nullptr);
+ child_pid = 0;
+}
+
+static void signal_handler(int signal_num) {
+ if (child_pid == 0 || kill(child_pid, signal_num) != 0) {
+ restore_signal_handlers();
+ raise(signal_num);
+ }
+}
+
+static int parent(const char* tag, int parent_read, pid_t pid, int* chld_sts, int log_target,
+ bool abbreviated, const char* file_path, bool forward_signals) {
+ int status = 0;
+ char buffer[4096];
+ struct pollfd poll_fds[] = {
+ {
+ .fd = parent_read,
+ .events = POLLIN,
+ },
+ };
+ int rc = 0;
+ int fd;
+
+ struct log_info log_info;
+
+ int a = 0; // start index of unprocessed data
+ int b = 0; // end index of unprocessed data
+ int sz;
+ bool found_child = false;
+ // There is a very small chance that opening child_ptty in the child will fail, but in this case
+ // POLLHUP will not be generated below. Therefore, we use a 1 second timeout for poll() until
+ // we receive a message from child_ptty. If this times out, we call waitpid() with WNOHANG to
+ // check the status of the child process and exit appropriately if it has terminated.
+ bool received_messages = false;
+ char tmpbuf[256];
+
+ log_info.btag = basename(tag);
+ if (!log_info.btag) {
+ log_info.btag = tag;
+ }
+
+ if (abbreviated && (log_target == LOG_NONE)) {
+ abbreviated = 0;
+ }
+ if (abbreviated) {
+ init_abbr_buf(&log_info.a_buf);
+ }
+
+ if (log_target & LOG_KLOG) {
+ snprintf(log_info.klog_fmt, sizeof(log_info.klog_fmt), "<6>%.*s: %%s\n", MAX_KLOG_TAG,
+ log_info.btag);
+ }
+
+ if ((log_target & LOG_FILE) && !file_path) {
+ /* No file_path specified, clear the LOG_FILE bit */
+ log_target &= ~LOG_FILE;
+ }
+
+ if (log_target & LOG_FILE) {
+ fd = open(file_path, O_WRONLY | O_CREAT, 0664);
+ if (fd < 0) {
+ ERROR("Cannot log to file %s\n", file_path);
+ log_target &= ~LOG_FILE;
+ } else {
+ lseek(fd, 0, SEEK_END);
+ log_info.fp = fdopen(fd, "a");
+ }
+ }
+
+ log_info.log_target = log_target;
+ log_info.abbreviated = abbreviated;
+
+ while (!found_child) {
+ int timeout = received_messages ? -1 : 1000;
+ if (TEMP_FAILURE_RETRY(poll(poll_fds, arraysize(poll_fds), timeout)) < 0) {
+ ERROR("poll failed\n");
+ rc = -1;
+ goto err_poll;
+ }
+
+ if (poll_fds[0].revents & POLLIN) {
+ received_messages = true;
+ sz = TEMP_FAILURE_RETRY(read(parent_read, &buffer[b], sizeof(buffer) - 1 - b));
+
+ sz += b;
+ // Log one line at a time
+ for (b = 0; b < sz; b++) {
+ if (buffer[b] == '\r') {
+ if (abbreviated) {
+ /* The abbreviated logging code uses newline as
+ * the line separator. Lucikly, the pty layer
+ * helpfully cooks the output of the command
+ * being run and inserts a CR before NL. So
+ * I just change it to NL here when doing
+ * abbreviated logging.
+ */
+ buffer[b] = '\n';
+ } else {
+ buffer[b] = '\0';
+ }
+ } else if (buffer[b] == '\n') {
+ buffer[b] = '\0';
+ log_line(&log_info, &buffer[a], b - a);
+ a = b + 1;
+ }
+ }
+
+ if (a == 0 && b == sizeof(buffer) - 1) {
+ // buffer is full, flush
+ buffer[b] = '\0';
+ log_line(&log_info, &buffer[a], b - a);
+ b = 0;
+ } else if (a != b) {
+ // Keep left-overs
+ b -= a;
+ memmove(buffer, &buffer[a], b);
+ a = 0;
+ } else {
+ a = 0;
+ b = 0;
+ }
+ }
+
+ if (!received_messages || (poll_fds[0].revents & POLLHUP)) {
+ int ret;
+ sigset_t oldset;
+
+ if (forward_signals) {
+ // Our signal handlers forward these signals to 'child_pid', but waitpid() may reap
+ // the child, so we must block these signals until we either 1) conclude that the
+ // child is still running or 2) determine the child has been reaped and we have
+ // reset the signals to their original disposition.
+ block_signals(&oldset);
+ }
+
+ int flags = (poll_fds[0].revents & POLLHUP) ? 0 : WNOHANG;
+ ret = TEMP_FAILURE_RETRY(waitpid(pid, &status, flags));
+ if (ret < 0) {
+ rc = errno;
+ ALOG(LOG_ERROR, "logwrap", "waitpid failed with %s\n", strerror(errno));
+ goto err_waitpid;
+ }
+ if (ret > 0) {
+ found_child = true;
+ }
+
+ if (forward_signals) {
+ if (found_child) {
+ restore_signal_handlers();
+ }
+ unblock_signals(&oldset);
+ }
+ }
+ }
+
+ if (chld_sts != nullptr) {
+ *chld_sts = status;
+ } else {
+ if (WIFEXITED(status))
+ rc = WEXITSTATUS(status);
+ else
+ rc = -ECHILD;
+ }
+
+ // Flush remaining data
+ if (a != b) {
+ buffer[b] = '\0';
+ log_line(&log_info, &buffer[a], b - a);
+ }
+
+ /* All the output has been processed, time to dump the abbreviated output */
+ if (abbreviated) {
+ print_abbr_buf(&log_info);
+ }
+
+ if (WIFEXITED(status)) {
+ if (WEXITSTATUS(status)) {
+ snprintf(tmpbuf, sizeof(tmpbuf), "%s terminated by exit(%d)\n", log_info.btag,
+ WEXITSTATUS(status));
+ do_log_line(&log_info, tmpbuf);
+ }
+ } else {
+ if (WIFSIGNALED(status)) {
+ snprintf(tmpbuf, sizeof(tmpbuf), "%s terminated by signal %d\n", log_info.btag,
+ WTERMSIG(status));
+ do_log_line(&log_info, tmpbuf);
+ } else if (WIFSTOPPED(status)) {
+ snprintf(tmpbuf, sizeof(tmpbuf), "%s stopped by signal %d\n", log_info.btag,
+ WSTOPSIG(status));
+ do_log_line(&log_info, tmpbuf);
+ }
+ }
+
+err_waitpid:
+err_poll:
+ if (log_target & LOG_FILE) {
+ fclose(log_info.fp); /* Also closes underlying fd */
+ }
+ if (abbreviated) {
+ free_abbr_buf(&log_info.a_buf);
+ }
+ return rc;
+}
+
+static void child(int argc, const char* const* argv) {
+ // create null terminated argv_child array
+ char* argv_child[argc + 1];
+ memcpy(argv_child, argv, argc * sizeof(char*));
+ argv_child[argc] = nullptr;
+
+ if (execvp(argv_child[0], argv_child)) {
+ FATAL_CHILD("executing %s failed: %s\n", argv_child[0], strerror(errno));
+ }
+}
+
+int logwrap_fork_execvp(int argc, const char* const* argv, int* status, bool forward_signals,
+ int log_target, bool abbreviated, const char* file_path) {
+ pid_t pid;
+ int parent_ptty;
+ sigset_t oldset;
+ int rc = 0;
+
+ rc = pthread_mutex_lock(&fd_mutex);
+ if (rc) {
+ ERROR("failed to lock signal_fd mutex\n");
+ goto err_lock;
+ }
+
+ /* Use ptty instead of socketpair so that STDOUT is not buffered */
+ parent_ptty = TEMP_FAILURE_RETRY(posix_openpt(O_RDWR | O_CLOEXEC));
+ if (parent_ptty < 0) {
+ ERROR("Cannot create parent ptty\n");
+ rc = -1;
+ goto err_open;
+ }
+
+ char child_devname[64];
+ if (grantpt(parent_ptty) || unlockpt(parent_ptty) ||
+ ptsname_r(parent_ptty, child_devname, sizeof(child_devname)) != 0) {
+ ERROR("Problem with /dev/ptmx\n");
+ rc = -1;
+ goto err_ptty;
+ }
+
+ if (forward_signals) {
+ // Block these signals until we have the child pid and our signal handlers set up.
+ block_signals(&oldset);
+ }
+
+ pid = fork();
+ if (pid < 0) {
+ ERROR("Failed to fork\n");
+ rc = -1;
+ goto err_fork;
+ } else if (pid == 0) {
+ pthread_mutex_unlock(&fd_mutex);
+ if (forward_signals) {
+ unblock_signals(&oldset);
+ }
+
+ setsid();
+
+ int child_ptty = TEMP_FAILURE_RETRY(open(child_devname, O_RDWR | O_CLOEXEC));
+ if (child_ptty < 0) {
+ FATAL_CHILD("Cannot open child_ptty: %s\n", strerror(errno));
+ }
+ close(parent_ptty);
+
+ dup2(child_ptty, 1);
+ dup2(child_ptty, 2);
+ close(child_ptty);
+
+ child(argc, argv);
+ } else {
+ if (forward_signals) {
+ setup_signal_handlers(pid);
+ unblock_signals(&oldset);
+ }
+
+ rc = parent(argv[0], parent_ptty, pid, status, log_target, abbreviated, file_path,
+ forward_signals);
+
+ if (forward_signals) {
+ restore_signal_handlers();
+ }
+ }
+
+err_fork:
+ if (forward_signals) {
+ unblock_signals(&oldset);
+ }
+err_ptty:
+ close(parent_ptty);
+err_open:
+ pthread_mutex_unlock(&fd_mutex);
+err_lock:
+ return rc;
+}