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QProcess::startDetached/Unix: simplify handling of the pipes

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Use a structure that will automatically close them for us. This doesn't
apply to startProcess() because the pipes there are long-lived (though
each of them in QProcessPrivate could be an AutoPipe...).

The destructor only runs in the parent process, so the child processes
don't need to worry about setting file descriptors to -1.

Pick-to: 6.1
Change-Id: Ic90d8429a0eb4837971dfffd1664ed98f3d74d1c
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
This commit is contained in:
Thiago Macieira 2021-02-18 11:16:47 -08:00
parent 089bcb0074
commit f0ce50d335
1 changed files with 26 additions and 21 deletions
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47
src/corelib/io/qprocess_unix.cpp
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@ -148,6 +148,26 @@ QProcessEnvironment QProcessEnvironment::systemEnvironment()
#if QT_CONFIG(process)
namespace {
struct AutoPipe
{
int pipe[2] = { -1, -1 };
AutoPipe(int flags = 0)
{
qt_safe_pipe(pipe, flags);
}
~AutoPipe()
{
for (int fd : pipe) {
if (fd >= 0)
qt_safe_close(fd);
}
}
explicit operator bool() const { return pipe[0] >= 0; }
int &operator[](int idx) { return pipe[idx]; }
int operator[](int idx) const { return pipe[idx]; }
};
struct QProcessPoller
{
QProcessPoller(const QProcessPrivate &proc);
@ -882,30 +902,18 @@ bool QProcessPrivate::startDetached(qint64 *pid)
{
QByteArray encodedWorkingDirectory = QFile::encodeName(workingDirectory);
// To catch the startup of the child
int startedPipe[2];
if (qt_safe_pipe(startedPipe) != 0) {
// To catch the startup of the child and communicate its pid
AutoPipe startedPipe, pidPipe;
if (!startedPipe || !pidPipe) {
setErrorAndEmit(QProcess::FailedToStart, QLatin1String("pipe: ") + qt_error_string(errno));
return false;
}
// To communicate the pid of the child
int pidPipe[2];
if (qt_safe_pipe(pidPipe) != 0) {
setErrorAndEmit(QProcess::FailedToStart, QLatin1String("pipe: ") + qt_error_string(errno));
qt_safe_close(startedPipe[0]);
qt_safe_close(startedPipe[1]);
return false;
}
if (!openChannelsForDetached()) {
// openChannel sets the error string
closeChannel(&stdinChannel);
closeChannel(&stdoutChannel);
closeChannel(&stderrChannel);
qt_safe_close(pidPipe[0]);
qt_safe_close(pidPipe[1]);
qt_safe_close(startedPipe[0]);
qt_safe_close(startedPipe[1]);
return false;
}
@ -976,20 +984,18 @@ bool QProcessPrivate::startDetached(qint64 *pid)
closeChannel(&stdinChannel);
closeChannel(&stdoutChannel);
closeChannel(&stderrChannel);
qt_safe_close(startedPipe[1]);
qt_safe_close(pidPipe[1]);
if (childPid == -1) {
qt_safe_close(startedPipe[0]);
qt_safe_close(pidPipe[0]);
setErrorAndEmit(QProcess::FailedToStart, QLatin1String("fork: ") + qt_error_string(savedErrno));
return false;
}
qt_safe_close(startedPipe[1]);
startedPipe[1] = -1;
char reply = '\0';
int startResult = qt_safe_read(startedPipe[0], &reply, 1);
int result;
qt_safe_close(startedPipe[0]);
qt_safe_waitpid(childPid, &result, 0);
bool success = (startResult != -1 && reply == '\0');
@ -1003,7 +1009,6 @@ bool QProcessPrivate::startDetached(qint64 *pid)
*pid = -1;
setErrorAndEmit(QProcess::FailedToStart);
}
qt_safe_close(pidPipe[0]);
return success;
}