Subprocess: Close all unused file descriptors.
This patch extends Subprocess::ExecFlags() method with a list of
file descriptors that should be kept open on the child process and
mapped to a pipe() in the parent. The remaining file descriptors
will be closed.
Bug: 27880754
TEST=Added unittests for this functionality.
Change-Id: Id96fb6a72f7805a0bfacfbc85422dc7d44750d93
diff --git a/common/subprocess.h b/common/subprocess.h
index 6b952dc..b655fb7 100644
--- a/common/subprocess.h
+++ b/common/subprocess.h
@@ -64,15 +64,26 @@
void Init(brillo::AsynchronousSignalHandlerInterface* async_signal_handler);
// Launches a process in the background and calls the passed |callback| when
- // the process exits.
+ // the process exits. The file descriptors specified in |output_pipes| will
+ // be available in the child as the writer end of a pipe. Use GetPipeFd() to
+ // know the reader end in the parent. Only stdin, stdout, stderr and the file
+ // descriptors in |output_pipes| will be open in the child.
// Returns the process id of the new launched process or 0 in case of failure.
pid_t Exec(const std::vector<std::string>& cmd, const ExecCallback& callback);
pid_t ExecFlags(const std::vector<std::string>& cmd,
uint32_t flags,
+ const std::vector<int>& output_pipes,
const ExecCallback& callback);
// Kills the running process with SIGTERM and ignores the callback.
- void KillExec(pid_t tag);
+ void KillExec(pid_t pid);
+
+ // Return the parent end of the pipe mapped onto |fd| in the child |pid|. This
+ // file descriptor is available until the callback for the child |pid|
+ // returns. After that the file descriptor will be closed. The passed |fd|
+ // must be one of the file descriptors passed to ExecFlags() in
+ // |output_pipes|, otherwise returns -1.
+ int GetPipeFd(pid_t pid, int fd) const;
// Executes a command synchronously. Returns true on success. If |stdout| is
// non-null, the process output is stored in it, otherwise the output is
