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/selinux.cpp b/init/selinux.cpp
index 1f211dd..e191b60 100644
--- a/init/selinux.cpp
+++ b/init/selinux.cpp
@@ -111,97 +111,6 @@
     return true;
 }
 
-// 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;
-    }
-}
-
 bool ReadFirstLine(const char* file, std::string* line) {
     line->clear();
 
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
diff --git a/init/util.h b/init/util.h
index 2d02182..aa24123 100644
--- a/init/util.h
+++ b/init/util.h
@@ -117,5 +117,10 @@
 // (.rc == .0rc for ranking purposes)
 std::vector<std::string> FilterVersionedConfigs(const std::vector<std::string>& configs,
                                                   int active_sdk);
+
+// 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[]);
+
 }  // namespace init
 }  // namespace android