pipecmd: reverse order of args to match documentation; add pipecmd_preserve.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/pipecmd/_info

@@ -32,7 +32,7 @@
  *			exit(1);
  *		exit(0);
  *	}
- *	child = pipecmd(&outputfd, NULL, NULL, argv[0], "ignoredarg", NULL);
+ *	child = pipecmd(NULL, &outputfd, NULL, argv[0], "ignoredarg", NULL);
  *	if (child < 0)
  *		err(1, "Creating child");
  *	if (read(outputfd, input, sizeof(input)) != sizeof(input))

ccan/pipecmd/pipecmd.c

@@ -6,6 +6,8 @@
 #include <unistd.h>
 #include <fcntl.h>
 
+int pipecmd_preserve;
+
 static char **gather_args(const char *arg0, va_list ap)
 {
 	size_t n = 1;
@@ -26,7 +28,7 @@ static char **gather_args(const char *arg0, va_list ap)
 	return arr;
 }
 
-pid_t pipecmdv(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
+pid_t pipecmdv(int *fd_tochild, int *fd_fromchild, int *fd_errfromchild,
 	       const char *cmd, va_list ap)
 {
 	char **arr = gather_args(cmd, ap);
@@ -36,12 +38,12 @@ pid_t pipecmdv(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
 		errno = ENOMEM;
 		return -1;
 	}
-	ret = pipecmdarr(fd_fromchild, fd_tochild, fd_errfromchild, arr);
+	ret = pipecmdarr(fd_tochild, fd_fromchild, fd_errfromchild, arr);
 	free_noerr(arr);
 	return ret;
 }
 
-pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
+pid_t pipecmdarr(int *fd_tochild, int *fd_fromchild, int *fd_errfromchild,
 		 char *const *arr)
 {
 	int tochild[2], fromchild[2], errfromchild[2], execfail[2];
@@ -49,7 +51,10 @@ pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
 	int err;
 
 	if (fd_tochild) {
-		if (pipe(tochild) != 0)
+		if (fd_tochild == &pipecmd_preserve) {
+			tochild[0] = STDIN_FILENO;
+			fd_tochild = NULL;
+		} else if (pipe(tochild) != 0)
 			goto fail;
 	} else {
 		tochild[0] = open("/dev/null", O_RDONLY);
@@ -57,7 +62,10 @@ pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
 			goto fail;
 	}
 	if (fd_fromchild) {
-		if (pipe(fromchild) != 0)
+		if (fd_fromchild == &pipecmd_preserve) {
+			fromchild[1] = STDOUT_FILENO;
+			fd_fromchild = NULL;
+		} else if (pipe(fromchild) != 0)
 			goto close_tochild_fail;
 	} else {
 		fromchild[1] = open("/dev/null", O_WRONLY);
@@ -65,7 +73,10 @@ pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
 			goto close_tochild_fail;
 	}
 	if (fd_errfromchild) {
-		if (fd_errfromchild == fd_fromchild) {
+		if (fd_errfromchild == &pipecmd_preserve) {
+			errfromchild[1] = STDERR_FILENO;
+			fd_errfromchild = NULL;
+		} else if (fd_errfromchild == fd_fromchild) {
 			errfromchild[0] = fromchild[0];
 			errfromchild[1] = fromchild[1];
 		} else {
@@ -77,7 +88,7 @@ pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
 		if (errfromchild[1] < 0)
 			goto close_fromchild_fail;
 	}
-		
+
 	if (pipe(execfail) != 0)
 		goto close_errfromchild_fail;
 
@@ -168,14 +179,14 @@ fail:
 	return -1;
 }
 
-pid_t pipecmd(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
+pid_t pipecmd(int *fd_tochild, int *fd_fromchild, int *fd_errfromchild,
 	      const char *cmd, ...)
 {
 	pid_t childpid;
 
 	va_list ap;
 	va_start(ap, cmd);
-	childpid = pipecmdv(fd_fromchild, fd_tochild, fd_errfromchild, cmd, ap);
+	childpid = pipecmdv(fd_tochild, fd_fromchild, fd_errfromchild, cmd, ap);
 	va_end(ap);
 
 	return childpid;

ccan/pipecmd/pipecmd.h

@@ -18,6 +18,7 @@
  * If @errfd is NULL, the child's stderr is (write-only) /dev/null.
  *
  * If @errfd == @outfd (and non-NULL) they will be shared.
+ * If @infd, @outfd or @errfd is &pipecmd_preserve, it is unchanged.
  *
  * The return value is the pid of the child, or -1.
  */
@@ -41,4 +42,10 @@ pid_t pipecmdv(int *infd, int *outfd, int *errfd, const char *cmd, va_list ap);
  * @arr: NULL-terminated array for arguments (first is program to run).
  */
 pid_t pipecmdarr(int *infd, int *outfd, int *errfd, char *const *arr);
+
+/**
+ * pipecmd_preserve - special value for fds to indicate it is unchanged
+ */
+extern int pipecmd_preserve;
+
 #endif /* CCAN_PIPECMD_H */

ccan/pipecmd/test/run-fdleak.c

@@ -21,7 +21,7 @@ int main(int argc, char *argv[])
 
 	/* This is how many tests you plan to run */
 	plan_tests(13);
-	child = pipecmd(&outfd, NULL, NULL, argv[0], "out", NULL);
+	child = pipecmd(NULL, &outfd, NULL, argv[0], "out", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(read(outfd, buf, sizeof(buf)) == sizeof(buf));

ccan/pipecmd/test/run-preserve.c

+#include <ccan/pipecmd/pipecmd.h>
+/* Include the C files directly. */
+#include <ccan/pipecmd/pipecmd.c>
+#include <ccan/tap/tap.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+int main(int argc, char *argv[])
+{
+	pid_t child;
+	int fd, oldfd, status;
+	char buf[5] = "test";
+	char template[] = "/tmp/run-preserve.XXXXXX";
+
+	/* We call ourselves, to test pipe. */
+	if (argc == 2) {
+		if (strcmp(argv[1], "out") == 0) {
+			if (write(STDOUT_FILENO, buf, sizeof(buf)) != sizeof(buf))
+				exit(2);
+		} else if (strcmp(argv[1], "in") == 0) {
+			if (read(STDIN_FILENO, buf, sizeof(buf)) != sizeof(buf))
+				exit(3);
+			if (memcmp(buf, "test", sizeof(buf)) != 0)
+				exit(4);
+		} else if (strcmp(argv[1], "err") == 0) {
+			if (write(STDERR_FILENO, buf, sizeof(buf)) != sizeof(buf))
+				exit(5);
+		} else
+			abort();
+		exit(0);
+	}
+
+	/* This is how many tests you plan to run */
+	plan_tests(25);
+
+	/* Preserve stdin test. */
+	fd = mkstemp(template);
+	ok1(write(fd, buf, sizeof(buf)) == sizeof(buf));
+	ok1(fd >= 0);
+	ok1(dup2(fd, STDIN_FILENO) == STDIN_FILENO);
+	ok1(lseek(STDIN_FILENO, 0, SEEK_SET) == 0);
+	child = pipecmd(&pipecmd_preserve, NULL, NULL, argv[0], "in", NULL);
+	if (!ok1(child > 0))
+		exit(1);
+	ok1(waitpid(child, &status, 0) == child);
+	ok1(WIFEXITED(status));
+	ok1(WEXITSTATUS(status) == 0);
+
+	close(STDIN_FILENO);
+
+	/* Preserve stdout test */
+	fd = open(template, O_WRONLY|O_TRUNC);
+	ok1(fd >= 0);
+	oldfd = dup(STDOUT_FILENO);
+	/* Can't use OK after this, since we mug stdout */
+	if (dup2(fd, STDOUT_FILENO) != STDOUT_FILENO)
+		exit(1);
+	child = pipecmd(NULL, &pipecmd_preserve, NULL, argv[0], "out", NULL);
+	if (child == -1)
+		exit(1);
+	/* Restore stdout */
+	dup2(oldfd, STDOUT_FILENO);
+	close(oldfd);
+	ok1(waitpid(child, &status, 0) == child);
+	ok1(WIFEXITED(status));
+	ok1(WEXITSTATUS(status) == 0);
+
+	fd = open(template, O_RDONLY);
+	ok1(read(fd, buf, sizeof(buf)) == sizeof(buf));
+	ok1(close(fd) == 0);
+	ok1(memcmp(buf, "test", sizeof(buf)) == 0);
+
+	/* Preserve stderr test. */
+	fd = open(template, O_WRONLY|O_TRUNC);
+	ok1(fd >= 0);
+	oldfd = dup(STDERR_FILENO);
+	ok1(dup2(fd, STDERR_FILENO) == STDERR_FILENO);
+	child = pipecmd(NULL, NULL, &pipecmd_preserve, argv[0], "err", NULL);
+	if (!ok1(child > 0))
+		exit(1);
+
+	/* Restore stderr. */
+	ok1(dup2(oldfd, STDERR_FILENO));
+	ok1(waitpid(child, &status, 0) == child);
+	ok1(WIFEXITED(status));
+	ok1(WEXITSTATUS(status) == 0);
+	close(oldfd);
+
+	fd = open(template, O_RDONLY);
+	ok1(read(fd, buf, sizeof(buf)) == sizeof(buf));
+	ok1(close(fd) == 0);
+	ok1(memcmp(buf, "test", sizeof(buf)) == 0);
+	unlink(template);
+
+	/* This exits depending on whether all tests passed */
+	return exit_status();
+}

ccan/pipecmd/test/run.c

@@ -48,7 +48,7 @@ int main(int argc, char *argv[])
 	
 	/* This is how many tests you plan to run */
 	plan_tests(67);
-	child = pipecmd(&outfd, &infd, &errfd, argv[0], "inout", NULL);
+	child = pipecmd(&infd, &outfd, &errfd, argv[0], "inout", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(write(infd, buf, sizeof(buf)) == sizeof(buf));
@@ -63,7 +63,7 @@ int main(int argc, char *argv[])
 	ok1(WIFEXITED(status));
 	ok1(WEXITSTATUS(status) == 0);
 
-	child = pipecmd(NULL, &infd, NULL, argv[0], "in", NULL);
+	child = pipecmd(&infd, NULL, NULL, argv[0], "in", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(write(infd, buf, sizeof(buf)) == sizeof(buf));
@@ -72,7 +72,7 @@ int main(int argc, char *argv[])
 	ok1(WIFEXITED(status));
 	ok1(WEXITSTATUS(status) == 0);
 
-	child = pipecmd(&outfd, NULL, NULL, argv[0], "out", NULL);
+	child = pipecmd(NULL, &outfd, NULL, argv[0], "out", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(read(outfd, buf, sizeof(buf)) == sizeof(buf));
@@ -94,7 +94,7 @@ int main(int argc, char *argv[])
 	ok1(WEXITSTATUS(status) == 0);
 
 	/* errfd == outfd should work with both. */
-	child = pipecmd(&errfd, NULL, &errfd, argv[0], "err", NULL);
+	child = pipecmd(NULL, &errfd, &errfd, argv[0], "err", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(read(errfd, buf, sizeof(buf)) == sizeof(buf));
@@ -104,7 +104,7 @@ int main(int argc, char *argv[])
 	ok1(WIFEXITED(status));
 	ok1(WEXITSTATUS(status) == 0);
 
-	child = pipecmd(&outfd, NULL, &outfd, argv[0], "out", NULL);
+	child = pipecmd(NULL, &outfd, &outfd, argv[0], "out", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(read(outfd, buf, sizeof(buf)) == sizeof(buf));