pipecmd: add stderr fd arg.

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

ccan/pipecmd/_info

@@ -31,7 +31,7 @@
  *		write(STDOUT_FILENO, "hello world\n", 12);
  *		exit(0);
  *	}
- *	child = pipecmd(&outputfd, NULL, argv[0], "ignoredarg", NULL);
+ *	child = pipecmd(&outputfd, NULL, NULL, argv[0], "ignoredarg", NULL);
  *	if (child < 0)
  *		err(1, "Creating child");
  *	if (read(outputfd, input, sizeof(input)) != sizeof(input))

ccan/pipecmd/pipecmd.c

@@ -23,7 +23,8 @@ static char **gather_args(const char *arg0, va_list ap)
 	return arr;
 }
 
-pid_t pipecmdv(int *fd_fromchild, int *fd_tochild, const char *cmd, va_list ap)
+pid_t pipecmdv(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
+	       const char *cmd, va_list ap)
 {
 	char **arr = gather_args(cmd, ap);
 	pid_t ret;
@@ -32,14 +33,15 @@ pid_t pipecmdv(int *fd_fromchild, int *fd_tochild, const char *cmd, va_list ap)
 		errno = ENOMEM;
 		return -1;
 	}
-	ret = pipecmdarr(fd_fromchild, fd_tochild, arr);
+	ret = pipecmdarr(fd_fromchild, fd_tochild, fd_errfromchild, arr);
 	free_noerr(arr);
 	return ret;
 }
 
-pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, char *const *arr)
+pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
+		 char *const *arr)
 {
-	int tochild[2], fromchild[2], execfail[2];
+	int tochild[2], fromchild[2], errfromchild[2], execfail[2];
 	pid_t childpid;
 	int err;
 
@@ -59,8 +61,22 @@ pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, char *const *arr)
 		if (fromchild[1] < 0)
 			goto close_tochild_fail;
 	}
-	if (pipe(execfail) != 0)
+	if (fd_errfromchild) {
+		if (fd_errfromchild == fd_fromchild) {
+			errfromchild[0] = fromchild[0];
+			errfromchild[1] = fromchild[1];
+		} else {
+			if (pipe(errfromchild) != 0)
+				goto close_fromchild_fail;
+		}
+	} else {
+		errfromchild[1] = open("/dev/null", O_WRONLY);
+		if (errfromchild[1] < 0)
 			goto close_fromchild_fail;
+	}
+		
+	if (pipe(execfail) != 0)
+		goto close_errfromchild_fail;
 
 	if (fcntl(execfail[1], F_SETFD, fcntl(execfail[1], F_GETFD)
 		  | FD_CLOEXEC) < 0)
@@ -75,6 +91,9 @@ pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, char *const *arr)
 			close(tochild[1]);
 		if (fd_fromchild)
 			close(fromchild[0]);
+		if (fd_errfromchild && fd_errfromchild != fd_fromchild)
+			close(errfromchild[0]);
+
 		close(execfail[0]);
 
 		// Child runs command.
@@ -88,6 +107,14 @@ pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, char *const *arr)
 				goto child_errno_fail;
 			close(fromchild[1]);
 		}
+		if (fd_errfromchild && fd_errfromchild == fd_fromchild) {
+			if (dup2(STDOUT_FILENO, STDERR_FILENO) == -1)
+				goto child_errno_fail;
+		} else if (errfromchild[1] != STDERR_FILENO) {
+			if (dup2(errfromchild[1], STDERR_FILENO) == -1)
+				goto child_errno_fail;
+			close(errfromchild[1]);
+		}
 		execvp(arr[0], arr);
 
 	child_errno_fail:
@@ -98,6 +125,7 @@ pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, char *const *arr)
 
 	close(tochild[0]);
 	close(fromchild[1]);
+	close(errfromchild[1]);
 	close(execfail[1]);
 	/* Child will close this without writing on successful exec. */
 	if (read(execfail[0], &err, sizeof(err)) == sizeof(err)) {
@@ -111,11 +139,17 @@ pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, char *const *arr)
 		*fd_tochild = tochild[1];
 	if (fd_fromchild)
 		*fd_fromchild = fromchild[0];
+	if (fd_errfromchild)
+		*fd_errfromchild = errfromchild[0];
 	return childpid;
 
 close_execfail_fail:
 	close_noerr(execfail[0]);
 	close_noerr(execfail[1]);
+close_errfromchild_fail:
+	if (fd_errfromchild)
+		close_noerr(errfromchild[0]);
+	close_noerr(errfromchild[1]);
 close_fromchild_fail:
 	if (fd_fromchild)
 		close_noerr(fromchild[0]);
@@ -128,13 +162,14 @@ fail:
 	return -1;
 }
 
-pid_t pipecmd(int *fd_fromchild, int *fd_tochild, const char *cmd, ...)
+pid_t pipecmd(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
+	      const char *cmd, ...)
 {
 	pid_t childpid;
 
 	va_list ap;
 	va_start(ap, cmd);
-	childpid = pipecmdv(fd_fromchild, fd_tochild, cmd, ap);
+	childpid = pipecmdv(fd_fromchild, fd_tochild, fd_errfromchild, cmd, ap);
 	va_end(ap);
 
 	return childpid;

ccan/pipecmd/pipecmd.h

@@ -10,29 +10,35 @@
  * pipecmd - run a command, optionally connect pipes.
  * @infd: input fd to write to child (if non-NULL)
  * @outfd: output fd to read from child (if non-NULL)
+ * @errfd: error-output fd to read from child (if non-NULL)
  * @cmd...: NULL-terminate list of command and arguments.
  *
  * If @infd is NULL, the child's input is (read-only) /dev/null.
  * If @outfd is NULL, the child's output is (write-only) /dev/null.
+ * If @errfd is NULL, the child's stderr is (write-only) /dev/null.
+ *
+ * If @errfd == @outfd (and non-NULL) they will be shared.
  *
  * The return value is the pid of the child, or -1.
  */
-pid_t pipecmd(int *infd, int *outfd, const char *cmd, ...);
+pid_t pipecmd(int *infd, int *outfd, int *errfd, const char *cmd, ...);
 
 /**
  * pipecmdv - run a command, optionally connect pipes (stdarg version)
  * @infd: input fd to write to child (if non-NULL)
  * @outfd: output fd to read from child (if non-NULL)
+ * @errfd: error-output fd to read from child (if non-NULL)
  * @cmd: command to run.
  * @ap: argument list for arguments.
  */
-pid_t pipecmdv(int *infd, int *outfd, const char *cmd, va_list ap);
+pid_t pipecmdv(int *infd, int *outfd, int *errfd, const char *cmd, va_list ap);
 
 /**
  * pipecmdarr - run a command, optionally connect pipes (char arry version)
  * @infd: input fd to write to child (if non-NULL)
  * @outfd: output fd to read from child (if non-NULL)
+ * @errfd: error-output fd to read from child (if non-NULL)
  * @arr: NULL-terminated array for arguments (first is program to run).
  */
-pid_t pipecmdarr(int *infd, int *outfd, char *const *arr);
+pid_t pipecmdarr(int *infd, int *outfd, int *errfd, char *const *arr);
 #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, argv[0], "out", NULL);
+	child = pipecmd(&outfd, NULL, NULL, argv[0], "out", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(read(outfd, buf, sizeof(buf)) == sizeof(buf));

ccan/pipecmd/test/run.c

@@ -9,7 +9,7 @@
 int main(int argc, char *argv[])
 {
 	pid_t child;
-	int infd, outfd, status;
+	int infd, outfd, errfd, status;
 	char buf[5] = "test";
 
 	/* We call ourselves, to test pipe. */
@@ -28,43 +28,94 @@ int main(int argc, char *argv[])
 			buf[0]++;
 			if (write(STDOUT_FILENO, buf, sizeof(buf)) != sizeof(buf))
 				exit(1);
+		} else if (strcmp(argv[1], "err") == 0) {
+			if (write(STDERR_FILENO, buf, sizeof(buf)) != sizeof(buf))
+				exit(1);
 		} else
 			abort();
 		exit(0);
 	}
 
+	/* We assume no fd leaks, so close them now. */
+	close(3);
+	close(4);
+	close(5);
+	close(6);
+	close(7);
+	close(8);
+	close(9);
+	close(10);
+	
 	/* This is how many tests you plan to run */
-	plan_tests(28);
-	child = pipecmd(&outfd, &infd, argv[0], "inout", NULL);
+	plan_tests(67);
+	child = pipecmd(&outfd, &infd, &errfd, argv[0], "inout", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(write(infd, buf, sizeof(buf)) == sizeof(buf));
 	ok1(read(outfd, buf, sizeof(buf)) == sizeof(buf));
+	ok1(read(errfd, buf, sizeof(buf)) == 0);
+	ok1(close(infd) == 0);
+	ok1(close(outfd) == 0);
+	ok1(close(errfd) == 0);
 	buf[0]--;
 	ok1(memcmp(buf, "test", sizeof(buf)) == 0);
 	ok1(waitpid(child, &status, 0) == child);
 	ok1(WIFEXITED(status));
 	ok1(WEXITSTATUS(status) == 0);
 
-	child = pipecmd(NULL, &infd, argv[0], "in", NULL);
+	child = pipecmd(NULL, &infd, NULL, argv[0], "in", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(write(infd, buf, sizeof(buf)) == sizeof(buf));
+	ok1(close(infd) == 0);
 	ok1(waitpid(child, &status, 0) == child);
 	ok1(WIFEXITED(status));
 	ok1(WEXITSTATUS(status) == 0);
 
-	child = pipecmd(&outfd, NULL, argv[0], "out", NULL);
+	child = pipecmd(&outfd, NULL, NULL, argv[0], "out", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(read(outfd, buf, sizeof(buf)) == sizeof(buf));
+	ok1(close(outfd) == 0);
+	ok1(memcmp(buf, "test", sizeof(buf)) == 0);
+	ok1(waitpid(child, &status, 0) == child);
+	ok1(WIFEXITED(status));
+	ok1(WEXITSTATUS(status) == 0);
+
+	/* Errfd only should be fine. */
+	child = pipecmd(NULL, NULL, &errfd, argv[0], "err", NULL);
+	if (!ok1(child > 0))
+		exit(1);
+	ok1(read(errfd, buf, sizeof(buf)) == sizeof(buf));
+	ok1(close(errfd) == 0);
+	ok1(memcmp(buf, "test", sizeof(buf)) == 0);
+	ok1(waitpid(child, &status, 0) == child);
+	ok1(WIFEXITED(status));
+	ok1(WEXITSTATUS(status) == 0);
+
+	/* errfd == outfd should work with both. */
+	child = pipecmd(&errfd, NULL, &errfd, argv[0], "err", NULL);
+	if (!ok1(child > 0))
+		exit(1);
+	ok1(read(errfd, buf, sizeof(buf)) == sizeof(buf));
+	ok1(close(errfd) == 0);
+	ok1(memcmp(buf, "test", sizeof(buf)) == 0);
+	ok1(waitpid(child, &status, 0) == child);
+	ok1(WIFEXITED(status));
+	ok1(WEXITSTATUS(status) == 0);
+
+	child = pipecmd(&outfd, NULL, &outfd, argv[0], "out", NULL);
+	if (!ok1(child > 0))
+		exit(1);
+	ok1(read(outfd, buf, sizeof(buf)) == sizeof(buf));
+	ok1(close(outfd) == 0);
 	ok1(memcmp(buf, "test", sizeof(buf)) == 0);
 	ok1(waitpid(child, &status, 0) == child);
 	ok1(WIFEXITED(status));
 	ok1(WEXITSTATUS(status) == 0);
 
 	// Writing to /dev/null should be fine.
-	child = pipecmd(NULL, NULL, argv[0], "out", NULL);
+	child = pipecmd(NULL, NULL, NULL, argv[0], "out", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(waitpid(child, &status, 0) == child);
@@ -72,18 +123,35 @@ int main(int argc, char *argv[])
 	ok1(WEXITSTATUS(status) == 0);
 
 	// Reading should fail.
-	child = pipecmd(NULL, NULL, argv[0], "in", NULL);
+	child = pipecmd(NULL, NULL, NULL, argv[0], "in", NULL);
 	if (!ok1(child > 0))
 		exit(1);
 	ok1(waitpid(child, &status, 0) == child);
 	ok1(WIFEXITED(status));
 	ok1(WEXITSTATUS(status) == 1);
 
+	child = pipecmd(NULL, NULL, NULL, argv[0], "err", NULL);
+	if (!ok1(child > 0))
+		exit(1);
+	ok1(waitpid(child, &status, 0) == child);
+	ok1(WIFEXITED(status));
+	ok1(WEXITSTATUS(status) == 0);
+
 	// Can't run non-existent file, but errno set correctly.
-	child = pipecmd(NULL, NULL, "/doesnotexist", "in", NULL);
+	child = pipecmd(NULL, NULL, NULL, "/doesnotexist", "in", NULL);
 	ok1(errno == ENOENT);
 	ok1(child < 0);
 
+	/* No fd leaks! */
+	ok1(close(3) == -1 && errno == EBADF);
+	ok1(close(4) == -1 && errno == EBADF);
+	ok1(close(5) == -1 && errno == EBADF);
+	ok1(close(6) == -1 && errno == EBADF);
+	ok1(close(7) == -1 && errno == EBADF);
+	ok1(close(8) == -1 && errno == EBADF);
+	ok1(close(9) == -1 && errno == EBADF);
+	ok1(close(10) == -1 && errno == EBADF);
+
 	/* This exits depending on whether all tests passed */
 	return exit_status();
 }