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Unified Diff: runtime/bin/process_linux.cc

Issue 798743004: Add support for starting a detached process (Closed) Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart
Patch Set: Minor fixes + rebase Created 5 years, 11 months ago
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Index: runtime/bin/process_linux.cc
diff --git a/runtime/bin/process_linux.cc b/runtime/bin/process_linux.cc
index e7bcd80df74f35d35f6410bad5ee4f7c1001abeb..d0a107119a31bb235dc2054faf88af377ce5abac 100644
--- a/runtime/bin/process_linux.cc
+++ b/runtime/bin/process_linux.cc
@@ -256,12 +256,24 @@ static void ReportChildError(int exec_control_fd) {
}
+static void ReportPid(int exec_control_fd, int pid) {
+ // In the case of starting a detached process the actual pid of that process
+ // is communicated using the exec control pipe.
+ int bytes_written =
+ FDUtils::WriteToBlocking(
+ exec_control_fd, &pid, sizeof(pid));
kustermann 2015/01/16 16:11:03 doesn't this fit on the previous line?
Søren Gjesse 2015/01/21 12:32:34 Done.
+ ASSERT(bytes_written == sizeof(int));
+ USE(bytes_written);
+}
+
+
int Process::Start(const char* path,
char* arguments[],
intptr_t arguments_length,
const char* working_directory,
char* environment[],
intptr_t environment_length,
+ bool detached,
intptr_t* in,
intptr_t* out,
intptr_t* err,
@@ -269,70 +281,61 @@ int Process::Start(const char* path,
intptr_t* exit_event,
char** os_error_message) {
pid_t pid;
- int read_in[2]; // Pipe for stdout to child process.
- int read_err[2]; // Pipe for stderr to child process.
- int write_out[2]; // Pipe for stdin to child process.
- int exec_control[2]; // Pipe to get the result from exec.
+ int read_in[2] = {-1, -1}; // Pipe for stdout to child process.
+ int read_err[2] = {-1, -1}; // Pipe for stderr to child process.
+ int write_out[2] = {-1, -1}; // Pipe for stdin to child process.
+ int exec_control[2] = {-1, -1}; // Pipe to get the result from exec.
int result;
- result = pipe(read_in);
- if (result < 0) {
- SetChildOsErrorMessage(os_error_message);
- Log::PrintErr("Error pipe creation failed: %s\n", *os_error_message);
- return errno;
- }
- FDUtils::SetCloseOnExec(read_in[0]);
-
- result = pipe(read_err);
- if (result < 0) {
- SetChildOsErrorMessage(os_error_message);
- VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
- Log::PrintErr("Error pipe creation failed: %s\n", *os_error_message);
- return errno;
- }
- FDUtils::SetCloseOnExec(read_err[0]);
-
- result = pipe(write_out);
- if (result < 0) {
- SetChildOsErrorMessage(os_error_message);
- VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
- Log::PrintErr("Error pipe creation failed: %s\n", *os_error_message);
- return errno;
- }
- FDUtils::SetCloseOnExec(write_out[1]);
-
result = pipe(exec_control);
if (result < 0) {
SetChildOsErrorMessage(os_error_message);
- VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
- VOID_TEMP_FAILURE_RETRY(close(write_out[0]));
- VOID_TEMP_FAILURE_RETRY(close(write_out[1]));
Log::PrintErr("Error pipe creation failed: %s\n", *os_error_message);
return errno;
}
FDUtils::SetCloseOnExec(exec_control[0]);
FDUtils::SetCloseOnExec(exec_control[1]);
+ // For a detached process the pipe to connect stdout is still used for
+ // signaling when to do the first fork.
+ result = pipe(read_in);
if (result < 0) {
SetChildOsErrorMessage(os_error_message);
- VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
- VOID_TEMP_FAILURE_RETRY(close(write_out[0]));
- VOID_TEMP_FAILURE_RETRY(close(write_out[1]));
VOID_TEMP_FAILURE_RETRY(close(exec_control[0]));
VOID_TEMP_FAILURE_RETRY(close(exec_control[1]));
- Log::PrintErr("fcntl failed: %s\n", *os_error_message);
+ Log::PrintErr("Error pipe creation failed: %s\n", *os_error_message);
return errno;
}
+ FDUtils::SetCloseOnExec(read_in[0]);
+
+ // For detached processes the pipe to connect stderr and stdin are not used.
+ if (!detached) {
+ result = pipe(read_err);
+ if (result < 0) {
+ SetChildOsErrorMessage(os_error_message);
+ VOID_TEMP_FAILURE_RETRY(close(exec_control[0]));
+ VOID_TEMP_FAILURE_RETRY(close(exec_control[1]));
+ VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
+ VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
+ Log::PrintErr("Error pipe creation failed: %s\n", *os_error_message);
+ return errno;
+ }
+ FDUtils::SetCloseOnExec(read_err[0]);
+
+ result = pipe(write_out);
+ if (result < 0) {
+ SetChildOsErrorMessage(os_error_message);
+ VOID_TEMP_FAILURE_RETRY(close(exec_control[0]));
+ VOID_TEMP_FAILURE_RETRY(close(exec_control[1]));
+ VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
+ VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
+ VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
+ VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
+ Log::PrintErr("Error pipe creation failed: %s\n", *os_error_message);
+ return errno;
+ }
+ FDUtils::SetCloseOnExec(write_out[1]);
+ }
char** program_arguments = new char*[arguments_length + 2];
program_arguments[0] = const_cast<char*>(path);
@@ -354,14 +357,16 @@ int Process::Start(const char* path,
if (pid < 0) {
SetChildOsErrorMessage(os_error_message);
delete[] program_arguments;
- VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
- VOID_TEMP_FAILURE_RETRY(close(write_out[0]));
- VOID_TEMP_FAILURE_RETRY(close(write_out[1]));
VOID_TEMP_FAILURE_RETRY(close(exec_control[0]));
VOID_TEMP_FAILURE_RETRY(close(exec_control[1]));
+ VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
+ VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
+ if (!detached) {
+ VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
+ VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
+ VOID_TEMP_FAILURE_RETRY(close(write_out[0]));
+ VOID_TEMP_FAILURE_RETRY(close(write_out[1]));
+ }
return errno;
} else if (pid == 0) {
// Wait for parent process before setting up the child process.
@@ -371,38 +376,91 @@ int Process::Start(const char* path,
perror("Failed receiving notification message");
exit(1);
}
+ if (detached) {
+ // For a detached process the pipe to connect stdout is only used for
+ // signaling when to do the first fork.
+ VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
+ VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
+ // Fork once more to start a new session.
+ pid = TEMP_FAILURE_RETRY(fork());
+ if (pid < 0) {
+ ReportChildError(exec_control[1]);
+ } else if (pid == 0) {
+ // Start a new session.
+ if (TEMP_FAILURE_RETRY(setsid()) == -1) {
+ ReportChildError(exec_control[1]);
+ } else {
+ // Do a final fork to not be the session leader.
+ pid = TEMP_FAILURE_RETRY(fork());
+ if (pid < 0) {
+ ReportChildError(exec_control[1]);
+ } else if (pid == 0) {
+ // Close all open file descriptors except for exec_control[1].
+ int max_fds = sysconf(_SC_OPEN_MAX);
+ if (max_fds == -1) max_fds = _POSIX_OPEN_MAX;
+ for (int fd = 0; fd < max_fds; fd++) {
+ if (fd != exec_control[1]) {
+ VOID_TEMP_FAILURE_RETRY(close(fd));
+ }
+ }
- VOID_TEMP_FAILURE_RETRY(close(write_out[1]));
- VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
- VOID_TEMP_FAILURE_RETRY(close(exec_control[0]));
+ // Re-open stdin, stdout and stderr and connect them to /dev/null.
+ VOID_TEMP_FAILURE_RETRY(close(STDIN_FILENO));
kustermann 2015/01/16 16:11:03 That one should be included by the loop above.
Søren Gjesse 2015/01/21 12:32:35 Done, and added comment.
+ int fd = TEMP_FAILURE_RETRY(open("/dev/null", O_RDWR));
+ if (fd != STDIN_FILENO) {
+ ReportChildError(exec_control[1]);
+ }
+ if (dup2(STDIN_FILENO, STDOUT_FILENO) != STDOUT_FILENO) {
+ ReportChildError(exec_control[1]);
+ }
+ if (dup2(STDIN_FILENO, STDERR_FILENO) != STDERR_FILENO) {
+ ReportChildError(exec_control[1]);
+ }
- if (TEMP_FAILURE_RETRY(dup2(write_out[0], STDIN_FILENO)) == -1) {
- ReportChildError(exec_control[1]);
- }
- VOID_TEMP_FAILURE_RETRY(close(write_out[0]));
+ // Report the final PID and do the exec.
+ ReportPid(exec_control[1], getpid()); // getpid cannot fail.
+ execvp(path, const_cast<char* const*>(program_arguments));
+ ReportChildError(exec_control[1]);
+ } else {
+ exit(0);
+ }
+ }
+ } else {
+ exit(0);
+ }
+ } else {
+ VOID_TEMP_FAILURE_RETRY(close(write_out[1]));
+ VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
+ VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
+ VOID_TEMP_FAILURE_RETRY(close(exec_control[0]));
- if (TEMP_FAILURE_RETRY(dup2(read_in[1], STDOUT_FILENO)) == -1) {
- ReportChildError(exec_control[1]);
- }
- VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
+ if (TEMP_FAILURE_RETRY(dup2(write_out[0], STDIN_FILENO)) == -1) {
+ ReportChildError(exec_control[1]);
+ }
+ VOID_TEMP_FAILURE_RETRY(close(write_out[0]));
- if (TEMP_FAILURE_RETRY(dup2(read_err[1], STDERR_FILENO)) == -1) {
- ReportChildError(exec_control[1]);
- }
- VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
+ if (TEMP_FAILURE_RETRY(dup2(read_in[1], STDOUT_FILENO)) == -1) {
+ ReportChildError(exec_control[1]);
+ }
+ VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
- if (working_directory != NULL && chdir(working_directory) == -1) {
- ReportChildError(exec_control[1]);
- }
+ if (TEMP_FAILURE_RETRY(dup2(read_err[1], STDERR_FILENO)) == -1) {
+ ReportChildError(exec_control[1]);
+ }
+ VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
- if (program_environment != NULL) {
- environ = program_environment;
- }
+ if (working_directory != NULL && chdir(working_directory) == -1) {
+ ReportChildError(exec_control[1]);
+ }
- execvp(path, const_cast<char* const*>(program_arguments));
+ if (program_environment != NULL) {
+ environ = program_environment;
+ }
+
+ execvp(path, const_cast<char* const*>(program_arguments));
- ReportChildError(exec_control[1]);
+ ReportChildError(exec_control[1]);
+ }
}
// Be sure to listen for exit-codes, now we have a child-process.
@@ -413,25 +471,27 @@ int Process::Start(const char* path,
delete[] program_arguments;
delete[] program_environment;
- int event_fds[2];
- result = pipe(event_fds);
- if (result < 0) {
- SetChildOsErrorMessage(os_error_message);
- VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
- VOID_TEMP_FAILURE_RETRY(close(write_out[0]));
- VOID_TEMP_FAILURE_RETRY(close(write_out[1]));
- Log::PrintErr("Error pipe creation failed: %s\n", *os_error_message);
- return errno;
- }
- FDUtils::SetCloseOnExec(event_fds[0]);
- FDUtils::SetCloseOnExec(event_fds[1]);
+ if (!detached) {
+ int event_fds[2];
+ result = pipe(event_fds);
+ if (result < 0) {
+ SetChildOsErrorMessage(os_error_message);
+ VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
+ VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
+ VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
+ VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
+ VOID_TEMP_FAILURE_RETRY(close(write_out[0]));
+ VOID_TEMP_FAILURE_RETRY(close(write_out[1]));
+ Log::PrintErr("Error pipe creation failed: %s\n", *os_error_message);
+ return errno;
+ }
+ FDUtils::SetCloseOnExec(event_fds[0]);
+ FDUtils::SetCloseOnExec(event_fds[1]);
- ProcessInfoList::AddProcess(pid, event_fds[1]);
- *exit_event = event_fds[0];
- FDUtils::SetNonBlocking(event_fds[0]);
+ ProcessInfoList::AddProcess(pid, event_fds[1]);
+ *exit_event = event_fds[0];
+ FDUtils::SetNonBlocking(event_fds[0]);
+ }
// Notify child process to start.
char msg = '1';
@@ -440,43 +500,71 @@ int Process::Start(const char* path,
perror("Failed sending notification message");
}
- // Read exec result from child. If no data is returned the exec was
- // successful and the exec call closed the pipe. Otherwise the errno
- // is written to the pipe.
VOID_TEMP_FAILURE_RETRY(close(exec_control[1]));
+ bool failed = false;
int child_errno;
int bytes_read = -1;
ASSERT(sizeof(child_errno) == sizeof(errno));
- bytes_read =
- FDUtils::ReadFromBlocking(
- exec_control[0], &child_errno, sizeof(child_errno));
- if (bytes_read == sizeof(child_errno)) {
- static const int kMaxMessageSize = 256;
- char* message = static_cast<char*>(malloc(kMaxMessageSize));
- bytes_read = FDUtils::ReadFromBlocking(exec_control[0],
- message,
- kMaxMessageSize);
- message[kMaxMessageSize - 1] = '\0';
- *os_error_message = message;
+ if (!detached) {
+ // Read exec result from child. If no data is returned the exec was
+ // successful and the exec call closed the pipe. Otherwise the errno
+ // is written to the pipe.
+ bytes_read =
+ FDUtils::ReadFromBlocking(
+ exec_control[0], &child_errno, sizeof(child_errno));
+ if (bytes_read == sizeof(child_errno)) {
+ static const int kMaxMessageSize = 256;
+ char* message = static_cast<char*>(malloc(kMaxMessageSize));
kustermann 2015/01/16 16:11:03 The malloc() can potentially return NULL.
Søren Gjesse 2015/01/21 12:32:35 Added check and return a fixed error if malloc fai
+ bytes_read = FDUtils::ReadFromBlocking(exec_control[0],
+ message,
+ kMaxMessageSize);
+ message[kMaxMessageSize - 1] = '\0';
+ *os_error_message = message;
+ failed = true;
+ }
+ } else {
+ // Read exec result from child. If only pid data is returned the exec was
+ // successful and the exec call closed the pipe. Otherwise the errno
+ // is written to the pipe as well.
+ int result[2];
+ ASSERT(sizeof(int) == sizeof(child_errno));
kustermann 2015/01/16 16:11:03 That is a tautology because child_errno is defined
Søren Gjesse 2015/01/21 12:32:35 Yes, it is mainly there to document the checks for
+ bytes_read =
+ FDUtils::ReadFromBlocking(
+ exec_control[0], result, sizeof(result));
+ if (bytes_read == sizeof(int)) {
+ pid = result[0];
+ } else if (bytes_read == 2 * sizeof(int)) {
+ pid = result[0];
+ child_errno = result[1];
+ static const int kMaxMessageSize = 256;
+ char* message = static_cast<char*>(malloc(kMaxMessageSize));
kustermann 2015/01/16 16:11:03 ditto.
Søren Gjesse 2015/01/21 12:32:35 ditto.
+ bytes_read = FDUtils::ReadFromBlocking(exec_control[0],
+ message,
+ kMaxMessageSize);
+ message[kMaxMessageSize - 1] = '\0';
+ *os_error_message = message;
+ failed = true;
+ }
}
VOID_TEMP_FAILURE_RETRY(close(exec_control[0]));
// Return error code if any failures.
- if (bytes_read != 0) {
- VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
- VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
- VOID_TEMP_FAILURE_RETRY(close(write_out[0]));
- VOID_TEMP_FAILURE_RETRY(close(write_out[1]));
-
- // Since exec() failed, we're not interested in the exit code.
- // We close the reading side of the exit code pipe here.
- // GetProcessExitCodes will get a broken pipe error when it tries to write
- // to the writing side of the pipe and it will ignore the error.
- VOID_TEMP_FAILURE_RETRY(close(*exit_event));
- *exit_event = -1;
-
+ if (failed) {
+ if (!detached) {
+ VOID_TEMP_FAILURE_RETRY(close(read_in[0]));
+ VOID_TEMP_FAILURE_RETRY(close(read_in[1]));
+ VOID_TEMP_FAILURE_RETRY(close(read_err[0]));
+ VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
+ VOID_TEMP_FAILURE_RETRY(close(write_out[0]));
+ VOID_TEMP_FAILURE_RETRY(close(write_out[1]));
+
+ // Since exec() failed, we're not interested in the exit code.
+ // We close the reading side of the exit code pipe here.
+ // GetProcessExitCodes will get a broken pipe error when it tries to write
+ // to the writing side of the pipe and it will ignore the error.
+ VOID_TEMP_FAILURE_RETRY(close(*exit_event));
+ *exit_event = -1;
+ }
if (bytes_read == -1) {
return errno; // Read failed.
} else {
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