process: Provide an abstraction to spawn child processes with redirected I/O

src/libstrongswan/Android.mk

@@ -37,7 +37,7 @@ selectors/traffic_selector.c settings/settings.c settings/settings_types.c \
 settings/settings_parser.c settings/settings_lexer.c \
 utils/utils.c utils/chunk.c utils/debug.c utils/enum.c utils/identification.c \
 utils/lexparser.c utils/optionsfrom.c utils/capabilities.c utils/backtrace.c \
-utils/parser_helper.c utils/test.c utils/utils/strerror.c
+utils/parser_helper.c utils/test.c utils/process.c utils/utils/strerror.c
 
 libstrongswan_la_SOURCES += \
     threading/thread.c \

src/libstrongswan/Makefile.am

@@ -35,7 +35,7 @@ selectors/traffic_selector.c settings/settings.c settings/settings_types.c \
 settings/settings_parser.y settings/settings_lexer.l \
 utils/utils.c utils/chunk.c utils/debug.c utils/enum.c utils/identification.c \
 utils/lexparser.c utils/optionsfrom.c utils/capabilities.c utils/backtrace.c \
-utils/parser_helper.c utils/test.c utils/utils/strerror.c
+utils/parser_helper.c utils/test.c utils/process.c utils/utils/strerror.c
 
 if !USE_WINDOWS
   libstrongswan_la_SOURCES += \
@@ -102,7 +102,7 @@ utils/lexparser.h utils/optionsfrom.h utils/capabilities.h utils/backtrace.h \
 utils/leak_detective.h utils/printf_hook/printf_hook.h \
 utils/printf_hook/printf_hook_vstr.h utils/printf_hook/printf_hook_builtin.h \
 utils/parser_helper.h utils/test.h utils/integrity_checker.h utils/windows.h \
-utils/utils/strerror.h
+utils/process.h utils/utils/strerror.h
 endif
 
 library.lo :	$(top_builddir)/config.status

src/libstrongswan/tests/Makefile.am

@@ -30,6 +30,7 @@ tests_SOURCES = tests.h tests.c \
   suites/test_hashtable.c \
   suites/test_identification.c \
   suites/test_threading.c \
+  suites/test_process.c \
   suites/test_watcher.c \
   suites/test_stream.c \
   suites/test_fetch_http.c \

src/libstrongswan/tests/suites/test_process.c

@@ -0,0 +1,173 @@
+/*
+ * Copyright (C) 2014 Martin Willi
+ * Copyright (C) 2014 revosec AG
+ *
+ * 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.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "test_suite.h"
+
+#include <unistd.h>
+
+#include <utils/process.h>
+
+START_TEST(test_retval_true)
+{
+	process_t *process;
+	char *argv[] = {
+		"/bin/true",
+		NULL
+	};
+	int retval;
+
+	process = process_start(argv, NULL, NULL, NULL, NULL, TRUE);
+	ck_assert(process != NULL);
+	ck_assert(process->wait(process, &retval));
+	ck_assert_int_eq(retval, 0);
+}
+END_TEST
+
+START_TEST(test_retval_false)
+{
+	process_t *process;
+	char *argv[] = {
+		"/bin/false",
+		NULL
+	};
+	int retval;
+
+	process = process_start(argv, NULL, NULL, NULL, NULL, TRUE);
+	ck_assert(process != NULL);
+	ck_assert(process->wait(process, &retval));
+	ck_assert(retval != 0);
+}
+END_TEST
+
+START_TEST(test_not_found)
+{
+	process_t *process;
+	char *argv[] = {
+		"/bin/does-not-exist",
+		NULL
+	};
+
+	process = process_start(argv, NULL, NULL, NULL, NULL, TRUE);
+	/* both is acceptable behavior */
+	ck_assert(process == NULL || !process->wait(process, NULL));
+}
+END_TEST
+
+START_TEST(test_echo)
+{
+	process_t *process;
+	char *argv[] = {
+		"/bin/cat",
+		NULL
+	};
+	int retval, in, out;
+	char *msg = "test";
+	char buf[strlen(msg) + 1];
+
+	memset(buf, 0, strlen(msg) + 1);
+
+	process = process_start(argv, NULL, &in, &out, NULL, TRUE);
+	ck_assert(process != NULL);
+	ck_assert_int_eq(write(in, msg, strlen(msg)), strlen(msg));
+	ck_assert(close(in) == 0);
+	ck_assert_int_eq(read(out, buf, strlen(msg) + 1), strlen(msg));
+	ck_assert_str_eq(buf, msg);
+	ck_assert(close(out) == 0);
+	ck_assert(process->wait(process, &retval));
+	ck_assert_int_eq(retval, 0);
+}
+END_TEST
+
+START_TEST(test_echo_err)
+{
+	process_t *process;
+	char *argv[] = {
+		"/bin/sh",
+		"-c",
+		"1>&2 /bin/cat",
+		NULL
+	};
+	int retval, in, err;
+	char *msg = "a longer test message";
+	char buf[strlen(msg) + 1];
+
+	memset(buf, 0, strlen(msg) + 1);
+
+	process = process_start(argv, NULL, &in, NULL, &err, TRUE);
+	ck_assert(process != NULL);
+	ck_assert_int_eq(write(in, msg, strlen(msg)), strlen(msg));
+	ck_assert(close(in) == 0);
+	ck_assert_int_eq(read(err, buf, strlen(msg) + 1), strlen(msg));
+	ck_assert_str_eq(buf, msg);
+	ck_assert(close(err) == 0);
+	ck_assert(process->wait(process, &retval));
+	ck_assert_int_eq(retval, 0);
+}
+END_TEST
+
+START_TEST(test_env)
+{
+	process_t *process;
+	char *argv[] = {
+		"/bin/sh",
+		"-c",
+		"echo -n $A $B",
+		NULL
+	};
+	char *envp[] = {
+		"A=atest",
+		"B=bstring",
+		NULL
+	};
+	int retval, out;
+	char buf[64] = {};
+
+	process = process_start(argv, envp, NULL, &out, NULL, TRUE);
+	ck_assert(process != NULL);
+	ck_assert(read(out, buf, sizeof(buf)) > 0);
+	ck_assert_str_eq(buf, "atest bstring");
+	ck_assert(close(out) == 0);
+	ck_assert(process->wait(process, &retval));
+	ck_assert_int_eq(retval, 0);
+}
+END_TEST
+
+Suite *process_suite_create()
+{
+	Suite *s;
+	TCase *tc;
+
+	s = suite_create("process");
+
+	tc = tcase_create("return values");
+	tcase_add_test(tc, test_retval_true);
+	tcase_add_test(tc, test_retval_false);
+	suite_add_tcase(s, tc);
+
+	tc = tcase_create("not found");
+	tcase_add_test(tc, test_not_found);
+	suite_add_tcase(s, tc);
+
+	tc = tcase_create("echo");
+	tcase_add_test(tc, test_echo);
+	tcase_add_test(tc, test_echo_err);
+	suite_add_tcase(s, tc);
+
+	tc = tcase_create("env");
+	tcase_add_test(tc, test_env);
+	suite_add_tcase(s, tc);
+
+	return s;
+}

src/libstrongswan/tests/tests.h

@@ -24,6 +24,7 @@ TEST_SUITE(hashtable_suite_create)
 TEST_SUITE(array_suite_create)
 TEST_SUITE(identification_suite_create)
 TEST_SUITE(threading_suite_create)
+TEST_SUITE(process_suite_create)
 TEST_SUITE(watcher_suite_create)
 TEST_SUITE(stream_suite_create)
 TEST_SUITE(utils_suite_create)

src/libstrongswan/utils/process.c

@@ -0,0 +1,232 @@
+/*
+ * Copyright (C) 2014 Martin Willi
+ * Copyright (C) 2014 revosec AG
+ *
+ * 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.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "process.h"
+
+#include <utils/debug.h>
+
+#include <fcntl.h>
+
+typedef struct private_process_t private_process_t;
+
+/**
+ * Ends of a pipe()
+ */
+enum {
+	PIPE_READ = 0,
+	PIPE_WRITE = 1,
+	PIPE_ENDS,
+};
+
+#ifndef WIN32
+
+#include <unistd.h>
+#include <errno.h>
+#include <sys/wait.h>
+
+/**
+ * Private data of an process_t object.
+ */
+struct private_process_t {
+
+	/**
+	 * Public process_t interface.
+	 */
+	process_t public;
+
+	/**
+	 * child stdin pipe
+	 */
+	int in[PIPE_ENDS];
+
+	/**
+	 * child stdout pipe
+	 */
+	int out[PIPE_ENDS];
+
+	/**
+	 * child stderr pipe
+	 */
+	int err[PIPE_ENDS];
+
+	/**
+	 * child process
+	 */
+	int pid;
+};
+
+/**
+ * Close a file descriptor if it is not -1
+ */
+static void close_if(int *fd)
+{
+	if (*fd != -1)
+	{
+		close(*fd);
+		*fd = -1;
+	}
+}
+
+/**
+ * Destroy a process structure, close all pipes
+ */
+static void process_destroy(private_process_t *this)
+{
+	close_if(&this->in[PIPE_READ]);
+	close_if(&this->in[PIPE_WRITE]);
+	close_if(&this->out[PIPE_READ]);
+	close_if(&this->out[PIPE_WRITE]);
+	close_if(&this->err[PIPE_READ]);
+	close_if(&this->err[PIPE_WRITE]);
+	free(this);
+}
+
+METHOD(process_t, wait_, bool,
+	private_process_t *this, int *code)
+{
+	int status, ret;
+
+	ret = waitpid(this->pid, &status, 0);
+	process_destroy(this);
+	if (ret == -1)
+	{
+		return FALSE;
+	}
+	if (!WIFEXITED(status))
+	{
+		return FALSE;
+	}
+	if (code)
+	{
+		*code = WEXITSTATUS(status);
+	}
+	return TRUE;
+}
+
+/**
+ * See header
+ */
+process_t* process_start(char *const argv[], char *const envp[],
+						 int *in, int *out, int *err, bool close_all)
+{
+	private_process_t *this;
+	char *empty[] = { NULL };
+
+	INIT(this,
+		.public = {
+			.wait = _wait_,
+		},
+		.in = { -1, -1 },
+		.out = { -1, -1 },
+		.err = { -1, -1 },
+	);
+
+	if (in && pipe(this->in) != 0)
+	{
+		DBG1(DBG_LIB, "creating stdin pipe failed: %s", strerror(errno));
+		process_destroy(this);
+		return NULL;
+	}
+	if (out && pipe(this->out) != 0)
+	{
+		DBG1(DBG_LIB, "creating stdout pipe failed: %s", strerror(errno));
+		process_destroy(this);
+		return NULL;
+	}
+	if (err && pipe(this->err) != 0)
+	{
+		DBG1(DBG_LIB, "creating stderr pipe failed: %s", strerror(errno));
+		process_destroy(this);
+		return NULL;
+	}
+
+	this->pid = fork();
+	switch (this->pid)
+	{
+		case -1:
+			DBG1(DBG_LIB, "forking process failed: %s", strerror(errno));
+			process_destroy(this);
+			return NULL;
+		case 0:
+			/* child */
+			close_if(&this->in[PIPE_WRITE]);
+			close_if(&this->out[PIPE_READ]);
+			close_if(&this->err[PIPE_READ]);
+			if (this->in[PIPE_READ] != -1)
+			{
+				if (dup2(this->in[PIPE_READ], 0) == -1)
+				{
+					raise(SIGKILL);
+				}
+			}
+			if (this->out[PIPE_WRITE] != -1)
+			{
+				if (dup2(this->out[PIPE_WRITE], 1) == -1)
+				{
+					raise(SIGKILL);
+				}
+			}
+			if (this->err[PIPE_WRITE] != -1)
+			{
+				if (dup2(this->err[PIPE_WRITE], 2) == -1)
+				{
+					raise(SIGKILL);
+				}
+			}
+			if (close_all)
+			{
+				closefrom(3);
+			}
+			if (execve(argv[0], argv, envp ?: empty) == -1)
+			{
+				raise(SIGKILL);
+			}
+			/* not reached */
+		default:
+			/* parent */
+			close_if(&this->in[PIPE_READ]);
+			close_if(&this->out[PIPE_WRITE]);
+			close_if(&this->err[PIPE_WRITE]);
+			if (in)
+			{
+				*in = this->in[PIPE_WRITE];
+				this->in[PIPE_WRITE] = -1;
+			}
+			if (out)
+			{
+				*out = this->out[PIPE_READ];
+				this->out[PIPE_READ] = -1;
+			}
+			if (err)
+			{
+				*err = this->err[PIPE_READ];
+				this->err[PIPE_READ] = -1;
+			}
+			return &this->public;
+	}
+}
+
+#else /* WIN32 */
+
+/**
+ * See header
+ */
+process_t* process_start(char *const argv[], char *const envp[],
+						 int *in, int *out, int *err, bool close_all)
+{
+	return NULL;
+}
+
+#endif /* WIN32 */

src/libstrongswan/utils/process.h

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2014 Martin Willi
+ * Copyright (C) 2014 revosec AG
+ *
+ * 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.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup process process
+ * @{ @ingroup utils
+ */
+
+#ifndef PROCESS_H_
+#define PROCESS_H_
+
+#include <utils/utils.h>
+
+typedef struct process_t process_t;
+
+/**
+ * Child process spawning abstraction
+ */
+struct process_t {
+
+	/**
+	 * Wait for a started process to terminate.
+	 *
+	 * The process object gets destroyed by this call, regardless of the
+	 * return value.
+	 *
+	 * The returned code is the exit code, not the status returned by waitpid().
+	 * If the program could not be executed or has terminated abnormally
+	 * (by signals etc.), FALSE is returned.
+	 *
+	 * @param code	process exit code, set only if TRUE returned
+	 * @return		TRUE if program exited normally through exit()
+	 */
+	bool (*wait)(process_t *this, int *code);
+};
+
+/**
+ * Spawn a child process with redirected I/O.
+ *
+ * Forks the current process, optionally redirects stdin/out/err to the current
+ * process, and executes the provided program with arguments.
+ *
+ * The process to execute is specified as argv[0], followed by the process
+ * arguments, followed by NULL. envp[] has a NULL terminated list of arguments
+ * to invoke the process with.
+ *
+ * If any of in/out/err is given, stdin/out/err from the child process get
+ * connected over pipe()s to the caller. If close_all is TRUE, all other
+ * open file descriptors get closed, regardless of any CLOEXEC setting.
+ *
+ * A caller must close all of the returned file descriptors to avoid file
+ * descriptor leaks.
+ *
+ * A non-NULL return value does not guarantee that the process has been
+ * invoked successfully.
+ *
+ * @param argv		NULL terminated process arguments, with argv[0] as program
+ * @param envp		NULL terminated list of environment variables
+ * @param in		pipe fd returned for redirecting data to child stdin
+ * @param out		pipe fd returned to redirect child stdout data to
+ * @param err		pipe fd returned to redirect child stderr data to
+ * @param close_all	close all open file descriptors above 2 before execve()
+ * @return			process, NULL on failure
+ */
+process_t* process_start(char *const argv[], char *const envp[],
+						 int *in, int *out, int *err, bool close_all);
+
+#endif /** PROCESS_H_ @}*/