Add popen3 based on popenRWE (http://www.jukie.net/bart/blog/popenRWE)HEADmaster

3 files changed, 133 insertions, 0 deletions

diff --git a/popen3/README b/popen3/README
new file mode 100644
index 0000000..e614fc4
--- /dev/null
+++ b/popen3/README
@@ -0,0 +1,20 @@
+example usage:
+
+	#include <unistd.h>
+	#include "popen3.h"
+
+	int pipes[3];
+	pid_t pid;
+	int ret;
+
+	const char *cmd = "cat -n";
+
+	pid = popen3(cmd, pipes);
+
+	/*
+	 *  - write to pipes[0] will go to stdin of cat
+	 *  - read from pipes[1] to get stdout of cat
+	 *  - read from pipes[2] to get stderr of ct
+	 */
+
+	ret = pclose3(pid, pipes);
diff --git a/popen3/popen3.c b/popen3/popen3.c
new file mode 100644
index 0000000..121ee95
--- /dev/null
+++ b/popen3/popen3.c
@@ -0,0 +1,106 @@
+/*
+ * popen() for stdin, stdout and stderr.
+ *
+ * Based on popenRWE() by Bart Trojanowski.
+ *
+ * Copyright (C) 2012 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2009-2010 Bart Trojanowski <bart@jukie.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/**
+ * Pipe stream to an application (like popen() but for std{in,out,err}).
+ *
+ * After successful return:
+ *  - write to pipes[0] will go to stdin of the child
+ *  - read from pipes[1] to get stdout of the child
+ *  - read from pipes[2] to get stderr of the child
+ *
+ * @param cmd    external command to execute
+ * @param pipes  int array of three to write FDs for std{in,out,err} to
+ * @return       PID of the executed application on success, -1 otherwise
+ */
+pid_t popen3(const char *cmd, int *pipes)
+{
+	int in[2], out[2], err[2];
+	pid_t pid;
+	int ret;
+
+	/* Open pipes to stdin, stdout, stderr */
+	ret = pipe(in);
+	if (ret < 0)
+		goto err_in;
+
+	ret = pipe(out);
+	if (ret < 0)
+		goto err_out;
+
+	ret = pipe(err);
+	if (ret < 0)
+		goto err_err;
+
+	pid = fork();
+	if (pid > 0) {          /* parent */
+		close(in[0]);
+		close(out[1]);
+		close(err[1]);
+		pipes[0] = in[1];
+		pipes[1] = out[0];
+		pipes[2] = err[0];
+		return pid;
+	} else if (pid == 0) {  /* child */
+		close(in[1]);
+		close(out[0]);
+		close(err[0]);
+		dup2(in[0], 0);
+		dup2(out[1], 1);
+		dup2(err[1], 2);
+
+		/* just emulate what popen() does */
+		execl("/bin/sh", "sh", "-c", cmd, NULL);
+		exit(EXIT_FAILURE);
+	} else
+		goto err_fork;
+
+	return pid;
+
+err_fork:
+	close(err[0]);
+	close(err[1]);
+err_err:
+	close(out[0]);
+	close(out[1]);
+err_out:
+	close(in[0]);
+	close(in[1]);
+err_in:
+	return ret;
+}
+
+/**
+ * Close pipes previously opened with popen3.
+ *
+ * @param pid
+ * @param pipes
+ * @return
+ */
+int pclose3(pid_t pid, int *pipes)
+{
+	int ret, status;
+	close(pipes[0]);
+	close(pipes[1]);
+	close(pipes[2]);
+	ret = waitpid(pid, &status, 0);
+	if (ret == 0)
+		return status;
+	else
+		return ret;
+}
diff --git a/popen3/popen3.h b/popen3/popen3.h
new file mode 100644
index 0000000..d39266a
--- /dev/null
+++ b/popen3/popen3.h
@@ -0,0 +1,7 @@
+#ifndef _POPEN3_H
+#define _POPEN3_H
+
+extern pid_t popen3(const char *cmd, int *pipes);
+extern int pclose3(pid_t pid, int *pipes);
+
+#endif /* _POPEN3_H */