Move ForkExecveAndWaitForCompletion to util.h
In the follow up patch this function will also be used in
first_stage_init.
Bug: 287593065
Test: m
Change-Id: Id805f8523596c26ed262d89aa652b27184b612c1
diff --git a/init/util.cpp b/init/util.cpp
index e760a59..e5efc7d 100644
--- a/init/util.cpp
+++ b/init/util.cpp
@@ -27,6 +27,7 @@
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
+#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
@@ -747,5 +748,96 @@
return filtered_configs;
}
+// Forks, executes the provided program in the child, and waits for the completion in the parent.
+// Child's stderr is captured and logged using LOG(ERROR).
+bool ForkExecveAndWaitForCompletion(const char* filename, char* const argv[]) {
+ // Create a pipe used for redirecting child process's output.
+ // * pipe_fds[0] is the FD the parent will use for reading.
+ // * pipe_fds[1] is the FD the child will use for writing.
+ int pipe_fds[2];
+ if (pipe(pipe_fds) == -1) {
+ PLOG(ERROR) << "Failed to create pipe";
+ return false;
+ }
+
+ pid_t child_pid = fork();
+ if (child_pid == -1) {
+ PLOG(ERROR) << "Failed to fork for " << filename;
+ return false;
+ }
+
+ if (child_pid == 0) {
+ // fork succeeded -- this is executing in the child process
+
+ // Close the pipe FD not used by this process
+ close(pipe_fds[0]);
+
+ // Redirect stderr to the pipe FD provided by the parent
+ if (TEMP_FAILURE_RETRY(dup2(pipe_fds[1], STDERR_FILENO)) == -1) {
+ PLOG(ERROR) << "Failed to redirect stderr of " << filename;
+ _exit(127);
+ return false;
+ }
+ close(pipe_fds[1]);
+
+ if (execv(filename, argv) == -1) {
+ PLOG(ERROR) << "Failed to execve " << filename;
+ return false;
+ }
+ // Unreachable because execve will have succeeded and replaced this code
+ // with child process's code.
+ _exit(127);
+ return false;
+ } else {
+ // fork succeeded -- this is executing in the original/parent process
+
+ // Close the pipe FD not used by this process
+ close(pipe_fds[1]);
+
+ // Log the redirected output of the child process.
+ // It's unfortunate that there's no standard way to obtain an istream for a file descriptor.
+ // As a result, we're buffering all output and logging it in one go at the end of the
+ // invocation, instead of logging it as it comes in.
+ const int child_out_fd = pipe_fds[0];
+ std::string child_output;
+ if (!android::base::ReadFdToString(child_out_fd, &child_output)) {
+ PLOG(ERROR) << "Failed to capture full output of " << filename;
+ }
+ close(child_out_fd);
+ if (!child_output.empty()) {
+ // Log captured output, line by line, because LOG expects to be invoked for each line
+ std::istringstream in(child_output);
+ std::string line;
+ while (std::getline(in, line)) {
+ LOG(ERROR) << filename << ": " << line;
+ }
+ }
+
+ // Wait for child to terminate
+ int status;
+ if (TEMP_FAILURE_RETRY(waitpid(child_pid, &status, 0)) != child_pid) {
+ PLOG(ERROR) << "Failed to wait for " << filename;
+ return false;
+ }
+
+ if (WIFEXITED(status)) {
+ int status_code = WEXITSTATUS(status);
+ if (status_code == 0) {
+ return true;
+ } else {
+ LOG(ERROR) << filename << " exited with status " << status_code;
+ }
+ } else if (WIFSIGNALED(status)) {
+ LOG(ERROR) << filename << " killed by signal " << WTERMSIG(status);
+ } else if (WIFSTOPPED(status)) {
+ LOG(ERROR) << filename << " stopped by signal " << WSTOPSIG(status);
+ } else {
+ LOG(ERROR) << "waitpid for " << filename << " returned unexpected status: " << status;
+ }
+
+ return false;
+ }
+}
+
} // namespace init
} // namespace android