attach: move pty allocation into api

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

doc/lxc-attach.sgml.in

@@ -58,7 +58,6 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
       <arg choice="opt">-R, --remount-sys-proc</arg>
       <arg choice="opt">--keep-env</arg>
       <arg choice="opt">--clear-env</arg>
-      <arg choice="opt">-L, --pty-log <replaceable>file</replaceable></arg>
       <arg choice="opt">-v, --set-var <replaceable>variable</replaceable></arg>
       <arg choice="opt">--keep-var <replaceable>variable</replaceable></arg>
       <arg choice="opt">-- <replaceable>command</replaceable></arg>
@@ -256,22 +255,6 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 	</listitem>
       </varlistentry>
 
-      <varlistentry>
-	<term>
-	  <option>-L, --pty-log <replaceable>file</replaceable></option>
-	</term>
-	<listitem>
-	  <para>
-	Specify a file where the output of <command>lxc-attach</command> will be
-	logged.
-	  </para>
-	  <para>
-	    <emphasis>Important:</emphasis>  When a standard file descriptor
-	    does not refer to a pty output produced on it will not be logged.
-	  </para>
-	</listitem>
-      </varlistentry>
-
       <varlistentry>
 	<term>
 	  <option>-v, --set-var <replaceable>variable</replaceable></option>

src/lxc/attach.c

@@ -66,6 +66,7 @@
 #include "lsm/lsm.h"
 #include "lxclock.h"
 #include "lxcseccomp.h"
+#include "mainloop.h"
 #include "namespace.h"
 #include "utils.h"
 
@@ -819,12 +820,30 @@ static signed long get_personality(const char *name, const char *lxcpath)
 
 struct attach_clone_payload {
 	int ipc_socket;
+	int pty_fd;
 	lxc_attach_options_t *options;
 	struct lxc_proc_context_info *init_ctx;
 	lxc_attach_exec_t exec_function;
 	void *exec_payload;
 };
 
+static void lxc_put_attach_clone_payload(struct attach_clone_payload *p)
+{
+	if (p->ipc_socket >= 0) {
+		shutdown(p->ipc_socket, SHUT_RDWR);
+		close(p->ipc_socket);
+		p->ipc_socket = -EBADF;
+	}
+
+	if (p->pty_fd >= 0) {
+		close(p->pty_fd);
+		p->pty_fd = -EBADF;
+	}
+
+	if (p->init_ctx)
+		lxc_proc_put_context_info(p->init_ctx);
+}
+
 static int attach_child_main(struct attach_clone_payload *payload)
 {
 	int fd, lsm_fd, ret;
@@ -961,7 +980,8 @@ static int attach_child_main(struct attach_clone_payload *payload)
 	}
 	shutdown(payload->ipc_socket, SHUT_RDWR);
 	close(payload->ipc_socket);
-	payload->ipc_socket = -1;
+	payload->ipc_socket = -EBADF;
+	lxc_proc_put_context_info(init_ctx);
 
 	/* The following is done after the communication socket is shut down.
 	 * That way, all errors that might (though unlikely) occur up until this
@@ -1011,19 +1031,107 @@ static int attach_child_main(struct attach_clone_payload *payload)
 		}
 	}
 
+	if (options->attach_flags & LXC_ATTACH_ALLOCATE_PTY) {
+		ret = lxc_login_pty(payload->pty_fd);
+		if (ret < 0) {
+			SYSERROR("Failed to prepare pty file descriptor %d", payload->pty_fd);
+			goto on_error;
+		}
+		TRACE("Prepared pty file descriptor %d", payload->pty_fd);
+	}
+
 	/* We're done, so we can now do whatever the user intended us to do. */
 	rexit(payload->exec_function(payload->exec_payload));
 
 on_error:
-	if (payload->ipc_socket >= 0) {
+	lxc_put_attach_clone_payload(payload);
-		shutdown(payload->ipc_socket, SHUT_RDWR);
-		close(payload->ipc_socket);
-		payload->ipc_socket = -1;
-	}
-	lxc_proc_put_context_info(init_ctx);
 	rexit(EXIT_FAILURE);
 }
 
+static int lxc_attach_pty(struct lxc_conf *conf, struct lxc_console *pty)
+{
+	int ret;
+
+	lxc_pty_init(pty);
+
+	ret = lxc_pty_create(pty);
+	if (ret < 0) {
+		SYSERROR("Failed to create pty");
+		return -1;
+	}
+
+	/* Shift ttys to container. */
+	ret = lxc_pty_map_ids(conf, pty);
+	if (ret < 0) {
+		ERROR("Failed to shift pty");
+		goto on_error;
+	}
+
+	return 0;
+
+on_error:
+	lxc_console_delete(pty);
+	lxc_pty_conf_free(pty);
+	return -1;
+}
+
+static int lxc_attach_pty_mainloop_init(struct lxc_console *pty,
+					struct lxc_epoll_descr *descr)
+{
+	int ret;
+
+	ret = lxc_mainloop_open(descr);
+	if (ret < 0) {
+		ERROR("Failed to create mainloop");
+		return -1;
+	}
+
+	ret = lxc_console_mainloop_add(descr, pty);
+	if (ret < 0) {
+		ERROR("Failed to add handlers to mainloop");
+		lxc_mainloop_close(descr);
+		return -1;
+	}
+
+	return 0;
+}
+
+static inline void lxc_attach_pty_close_master(struct lxc_console *pty)
+{
+	if (pty->master < 0)
+		return;
+
+	close(pty->master);
+	pty->master = -EBADF;
+}
+
+static inline void lxc_attach_pty_close_slave(struct lxc_console *pty)
+{
+	if (pty->slave < 0)
+		return;
+
+	close(pty->slave);
+	pty->slave = -EBADF;
+}
+
+static inline void lxc_attach_pty_close_peer(struct lxc_console *pty)
+{
+	if (pty->peer < 0)
+		return;
+
+	close(pty->peer);
+	pty->peer = -EBADF;
+}
+
+static inline void lxc_attach_pty_close_log(struct lxc_console *pty)
+{
+	if (pty->log_fd < 0)
+		return;
+
+	close(pty->log_fd);
+	pty->log_fd = -EBADF;
+}
+
 int lxc_attach(const char *name, const char *lxcpath,
 	       lxc_attach_exec_t exec_function, void *exec_payload,
 	       lxc_attach_options_t *options, pid_t *attached_process)
@@ -1032,8 +1140,9 @@ int lxc_attach(const char *name, const char *lxcpath,
 	int ipc_sockets[2];
 	char *cwd, *new_cwd;
 	signed long personality;
-	pid_t attached_pid, expected, init_pid, pid;
+	pid_t attached_pid, init_pid, pid;
 	struct lxc_proc_context_info *init_ctx;
+	struct lxc_console pty;
 	struct attach_clone_payload payload = {0};
 
 	ret = access("/proc/self/ns", X_OK);
@@ -1150,6 +1259,18 @@ int lxc_attach(const char *name, const char *lxcpath,
 		return -1;
 	}
 
+	if (options->attach_flags & LXC_ATTACH_ALLOCATE_PTY) {
+		ret = lxc_attach_pty(init_ctx->container->lxc_conf, &pty);
+		if (ret < 0) {
+			ERROR("Failed to allocate pty");
+			free(cwd);
+			lxc_proc_put_context_info(init_ctx);
+			return -1;
+		}
+
+		pty.log_fd = options->log_fd;
+	}
+
 	/* Create a socket pair for IPC communication; set SOCK_CLOEXEC in order
 	 * to make sure we don't irritate other threads that want to fork+exec
 	 * away
@@ -1210,13 +1331,16 @@ int lxc_attach(const char *name, const char *lxcpath,
 	}
 
 	if (pid) {
+		int ret_parent = -1;
 		pid_t to_cleanup_pid = pid;
+		struct lxc_epoll_descr descr = {0};
 
-		/* Initial thread, we close the socket that is for the
+		/* close unneeded file descriptors */
-		 * subprocesses.
-		 */
 		close(ipc_sockets[1]);
 		free(cwd);
+		lxc_proc_close_ns_fd(init_ctx);
+		if (options->attach_flags & LXC_ATTACH_ALLOCATE_PTY)
+			lxc_attach_pty_close_slave(&pty);
 
 		/* Attach to cgroup, if requested. */
 		if (options->attach_flags & LXC_ATTACH_MOVE_TO_CGROUP) {
@@ -1227,21 +1351,30 @@ int lxc_attach(const char *name, const char *lxcpath,
 		}
 
 		/* Setup resource limits */
-		if (!lxc_list_empty(&init_ctx->container->lxc_conf->limits))
+		if (!lxc_list_empty(&init_ctx->container->lxc_conf->limits)) {
-			if (setup_resource_limits(&init_ctx->container->lxc_conf->limits, pid) < 0)
+			ret = setup_resource_limits(&init_ctx->container->lxc_conf->limits, pid);
+			if (ret < 0)
 				goto on_error;
+		}
+
+		if (options->attach_flags & LXC_ATTACH_ALLOCATE_PTY) {
+			ret = lxc_attach_pty_mainloop_init(&pty, &descr);
+			if (ret < 0)
+				goto on_error;
+			TRACE("Initalized pty mainloop");
+		}
 
 		/* Let the child process know to go ahead. */
 		status = 0;
 		ret = lxc_write_nointr(ipc_sockets[0], &status, sizeof(status));
 		if (ret != sizeof(status))
-			goto on_error;
+			goto close_mainloop;
 		TRACE("Told intermediate process to start initializing");
 
 		/* Get pid of attached process from intermediate process. */
 		ret = lxc_read_nointr(ipc_sockets[0], &attached_pid, sizeof(attached_pid));
 		if (ret != sizeof(attached_pid))
-			goto on_error;
+			goto close_mainloop;
 		TRACE("Received pid %d of attached process in parent pid namespace", attached_pid);
 
 		/* Ignore SIGKILL (CTRL-C) and SIGQUIT (CTRL-\) - issue #313. */
@@ -1253,7 +1386,7 @@ int lxc_attach(const char *name, const char *lxcpath,
 		/* Reap intermediate process. */
 		ret = wait_for_pid(pid);
 		if (ret < 0)
-			goto on_error;
+			goto close_mainloop;
 		TRACE("Intermediate process %d exited", pid);
 
 		/* We will always have to reap the attached process now. */
@@ -1269,7 +1402,7 @@ int lxc_attach(const char *name, const char *lxcpath,
 			on_exec = options->attach_flags & LXC_ATTACH_LSM_EXEC ? 1 : 0;
 			labelfd = lsm_open(attached_pid, on_exec);
 			if (labelfd < 0)
-				goto on_error;
+				goto close_mainloop;
 			TRACE("Opened LSM label file descriptor %d", labelfd);
 
 			/* Send child fd of the LSM security module to write to. */
@@ -1277,45 +1410,66 @@ int lxc_attach(const char *name, const char *lxcpath,
 			close(labelfd);
 			if (ret <= 0) {
 				SYSERROR("%d", (int)ret);
-				goto on_error;
+				goto close_mainloop;
 			}
 			TRACE("Sent LSM label file descriptor %d to child", labelfd);
 		}
 
-		/* Now shut down communication with child, we're done. */
-		shutdown(ipc_sockets[0], SHUT_RDWR);
-		close(ipc_sockets[0]);
-		lxc_proc_put_context_info(init_ctx);
-
 		/* We're done, the child process should now execute whatever it
 		 * is that the user requested. The parent can now track it with
 		 * waitpid() or similar.
 		 */
 
 		*attached_process = attached_pid;
-		return 0;
 
-	on_error:
+		/* Now shut down communication with child, we're done. */
-		/* First shut down the socket, then wait for the pid, otherwise
-		 * the pid we're waiting for may never exit.
-		 */
 		shutdown(ipc_sockets[0], SHUT_RDWR);
 		close(ipc_sockets[0]);
-		if (to_cleanup_pid)
+		ipc_sockets[0] = -1;
-			(void)wait_for_pid(to_cleanup_pid);
+
-		lxc_proc_put_context_info(init_ctx);
+		ret_parent = 0;
-		return -1;
+		to_cleanup_pid = -1;
+		if (options->attach_flags & LXC_ATTACH_ALLOCATE_PTY) {
+			ret = lxc_mainloop(&descr, -1);
+			if (ret < 0) {
+				ret_parent = -1;
+				to_cleanup_pid = attached_pid;
+			}
 		}
 
-	/* First subprocess begins here, we close the socket that is for the
+	close_mainloop:
-	 * initial thread.
+		if (options->attach_flags & LXC_ATTACH_ALLOCATE_PTY)
-	 */
+			lxc_mainloop_close(&descr);
+
+	on_error:
+		if (ipc_sockets[0] >= 0) {
+			shutdown(ipc_sockets[0], SHUT_RDWR);
 			close(ipc_sockets[0]);
+		}
+
+		if (to_cleanup_pid > 0)
+			(void)wait_for_pid(to_cleanup_pid);
+
+		if (options->attach_flags & LXC_ATTACH_ALLOCATE_PTY) {
+			lxc_console_delete(&pty);
+			lxc_pty_conf_free(&pty);
+		}
+		lxc_proc_put_context_info(init_ctx);
+		return ret_parent;
+	}
+
+	/* close unneeded file descriptors */
+	close(ipc_sockets[0]);
+	ipc_sockets[0] = -EBADF;
+	if (options->attach_flags & LXC_ATTACH_ALLOCATE_PTY) {
+		lxc_attach_pty_close_master(&pty);
+		lxc_attach_pty_close_peer(&pty);
+		lxc_attach_pty_close_log(&pty);
+	}
 
 	/* Wait for the parent to have setup cgroups. */
-	expected = 0;
 	ret = lxc_read_nointr(ipc_sockets[1], &status, sizeof(status));
-	if (ret != sizeof(status) || status != expected) {
+	if (ret != sizeof(status)) {
 		shutdown(ipc_sockets[1], SHUT_RDWR);
 		lxc_proc_put_context_info(init_ctx);
 		rexit(-1);
@@ -1351,6 +1505,7 @@ int lxc_attach(const char *name, const char *lxcpath,
 	payload.ipc_socket = ipc_sockets[1];
 	payload.options = options;
 	payload.init_ctx = init_ctx;
+	payload.pty_fd = pty.slave;
 	payload.exec_function = exec_function;
 	payload.exec_payload = exec_payload;
 
@@ -1368,6 +1523,8 @@ int lxc_attach(const char *name, const char *lxcpath,
 			ERROR("Failed to exec");
 		_exit(EXIT_FAILURE);
 	}
+	if (options->attach_flags & LXC_ATTACH_ALLOCATE_PTY)
+		lxc_attach_pty_close_slave(&pty);
 
 	/* Tell grandparent the pid of the pid of the newly created child. */
 	ret = lxc_write_nointr(ipc_sockets[1], &pid, sizeof(pid));

src/lxc/attach_options.h

@@ -51,6 +51,7 @@ enum {
 	LXC_ATTACH_LSM_NOW               = 0x00020000, /*!< FIXME: unknown */
 	/* Set PR_SET_NO_NEW_PRIVS to block execve() gainable privileges. */
 	LXC_ATTACH_NO_NEW_PRIVS		 = 0x00040000, /*!< PR_SET_NO_NEW_PRIVS */
+	LXC_ATTACH_ALLOCATE_PTY          = 0x00080000, /*!< Allocate new pty for attached process. */
 
 	/* We have 16 bits for things that are on by default and 16 bits that
 	 * are off by default, that should be sufficient to keep binary

src/lxc/tools/lxc_attach.c

@@ -27,11 +27,12 @@
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <sys/ioctl.h>
-#include <sys/types.h>
-#include <sys/wait.h>
 #include <termios.h>
 #include <unistd.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 
 #include <lxc/lxccontainer.h>
 
@@ -46,12 +47,6 @@
 #include "mainloop.h"
 #include "utils.h"
 
-#if HAVE_PTY_H
-#include <pty.h>
-#else
-#include <../include/openpty.h>
-#endif
-
 static const struct option my_longopts[] = {
 	{"elevated-privileges", optional_argument, 0, 'e'},
 	{"arch", required_argument, 0, 'a'},
@@ -241,155 +236,29 @@ Options :\n\
 	.checker  = NULL,
 };
 
-struct wrapargs {
+static bool stdfd_is_pty(void)
-	lxc_attach_options_t *options;
-	lxc_attach_command_t *command;
-	struct lxc_console *console;
-	int ptyfd;
-};
-
-/* Minimalistic login_tty() implementation. */
-static int login_pty(int fd)
-{
-	setsid();
-	if (ioctl(fd, TIOCSCTTY, NULL) < 0)
-		return -1;
-	if (lxc_console_set_stdfds(fd) < 0)
-		return -1;
-	if (fd > STDERR_FILENO)
-		close(fd);
-	return 0;
-}
-
-static int get_pty_on_host_callback(void *p)
-{
-	struct wrapargs *wrap = p;
-
-	close(wrap->console->master);
-	if (login_pty(wrap->console->slave) < 0)
-		return -1;
-
-	if (wrap->command->program)
-		lxc_attach_run_command(wrap->command);
-	else
-		lxc_attach_run_shell(NULL);
-	return -1;
-}
-
-static int get_pty_on_host(struct lxc_container *c, struct wrapargs *wrap, int *pid)
-{
-	struct lxc_epoll_descr descr;
-	struct lxc_conf *conf;
-	struct lxc_tty_state *ts;
-	int ret = -1;
-	struct wrapargs *args = wrap;
-
-	if (!isatty(args->ptyfd)) {
-		fprintf(stderr, "Standard file descriptor does not refer to a pty\n");
-		return -1;
-	}
-
-	if (c->lxc_conf) {
-		conf = c->lxc_conf;
-	} else {
-		/* If the container is not defined and the user didn't specify a
-		 * config file to load we will simply init a dummy config here.
-		 */
-		conf = lxc_conf_init();
-		if (!conf) {
-			fprintf(stderr, "Failed to allocate dummy config file for the container\n");
-			return -1;
-		}
-
-		/* We also need a dummy rootfs path otherwise
-		 * lxc_console_create() will not let us create a console. Note,
-		 * I don't want this change to make it into
-		 * lxc_console_create()'s since this function will only be
-		 * responsible for proper /dev/{console,tty<n>} devices.
-		 * lxc-attach is just abusing it to also handle the pty case
-		 * because it is very similar. However, with LXC 3.0 lxc-attach
-		 * will need to move away from using lxc_console_create() since
-		 * this is actually an internal symbol and we only want the
-		 * tools to use the API with LXC 3.0.
-		 */
-		conf->rootfs.path = strdup("dummy");
-		if (!conf->rootfs.path)
-			return -1;
-	}
-	free(conf->console.log_path);
-	if (my_args.console_log)
-		conf->console.log_path = strdup(my_args.console_log);
-	else
-		conf->console.log_path = NULL;
-
-	/* In the case of lxc-attach our peer pty will always be the current
-	 * controlling terminal. We clear whatever was set by the user for
-	 * lxc.console.path here and set it NULL. lxc_console_peer_default()
-	 * will then try to open /dev/tty. If the process doesn't have a
-	 * controlling terminal we should still proceed.
-	 */
-	free(conf->console.path);
-	conf->console.path = NULL;
-
-	/* Create pty on the host. */
-	if (lxc_console_create(conf) < 0)
-		return -1;
-	ts = conf->console.tty_state;
-	conf->console.descr = &descr;
-
-	/* Shift ttys to container. */
-	ret = lxc_pty_map_ids(conf, &conf->console);
-	if (ret < 0) {
-		fprintf(stderr, "Failed to shift tty into container\n");
-		goto err1;
-	}
-
-	/* Send wrapper function on its way. */
-	wrap->console = &conf->console;
-	if (c->attach(c, get_pty_on_host_callback, wrap, wrap->options, pid) < 0)
-		goto err1;
-	close(conf->console.slave); /* Close slave side. */
-	conf->console.slave = -1;
-
-	ret = lxc_mainloop_open(&descr);
-	if (ret) {
-		fprintf(stderr, "failed to create mainloop\n");
-		goto err2;
-	}
-
-	if (lxc_console_mainloop_add(&descr, &conf->console) < 0) {
-		fprintf(stderr, "Failed to add handlers to lxc mainloop.\n");
-		goto err3;
-	}
-
-	ret = lxc_mainloop(&descr, -1);
-	if (ret) {
-		fprintf(stderr, "mainloop returned an error\n");
-		goto err3;
-	}
-	ret = 0;
-
-err3:
-	lxc_mainloop_close(&descr);
-err2:
-	if (ts && ts->sigfd != -1)
-		lxc_console_signal_fini(ts);
-err1:
-	lxc_console_delete(&conf->console);
-
-	return ret;
-}
-
-static int stdfd_is_pty(void)
 {
 	if (isatty(STDIN_FILENO))
-		return STDIN_FILENO;
+		return true;
 	if (isatty(STDOUT_FILENO))
-		return STDOUT_FILENO;
+		return true;
 	if (isatty(STDERR_FILENO))
-		return STDERR_FILENO;
+		return true;
 
+	return false;
+}
+
+int lxc_attach_create_log_file(const char *log_file)
+{
+	int fd;
+
+	fd = open(log_file, O_CLOEXEC | O_RDWR | O_CREAT | O_APPEND, 0600);
+	if (fd < 0) {
+		fprintf(stderr, "Failed to open log file \"%s\"\n", log_file);
 		return -1;
+	}
+
+	return fd;
 }
 
 int main(int argc, char *argv[])
@@ -463,6 +332,8 @@ int main(int argc, char *argv[])
 		attach_options.attach_flags |= LXC_ATTACH_REMOUNT_PROC_SYS;
 	if (elevated_privileges)
 		attach_options.attach_flags &= ~(elevated_privileges);
+	if (stdfd_is_pty())
+		attach_options.attach_flags |= LXC_ATTACH_ALLOCATE_PTY;
 	attach_options.namespaces = namespace_flags;
 	attach_options.personality = new_personality;
 	attach_options.env_policy = env_policy;
@@ -474,28 +345,16 @@ int main(int argc, char *argv[])
 		command.argv = (char**)my_args.argv;
 	}
 
-	struct wrapargs wrap = (struct wrapargs){
-		.command = &command,
-		.options = &attach_options
-	};
-
-	wrap.ptyfd = stdfd_is_pty();
-	if (wrap.ptyfd >= 0) {
-		if ((!isatty(STDOUT_FILENO) || !isatty(STDERR_FILENO)) && my_args.console_log) {
-			fprintf(stderr, "-L/--pty-log can only be used when stdout and stderr refer to a pty.\n");
-			goto out;
-		}
-		ret = get_pty_on_host(c, &wrap, &pid);
-	} else {
 	if (my_args.console_log) {
-			fprintf(stderr, "-L/--pty-log can only be used when stdout and stderr refer to a pty.\n");
+		attach_options.log_fd = lxc_attach_create_log_file(my_args.console_log);
+		if (attach_options.log_fd < 0)
 			goto out;
 	}
+
 	if (command.program)
 		ret = c->attach(c, lxc_attach_run_command, &command, &attach_options, &pid);
 	else
 		ret = c->attach(c, lxc_attach_run_shell, NULL, &attach_options, &pid);
-	}
 
 	if (ret < 0)
 		goto out;

src/tests/attach.c

@@ -19,16 +19,18 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include <lxc/lxccontainer.h>
+#include <errno.h>
-#include "lxc/utils.h"
-#include "lxc/lsm/lsm.h"
-
-#include <sys/types.h>
 #include <string.h>
 #include <unistd.h>
 #include <sys/stat.h>
 #include <sys/syscall.h>
-#include <errno.h>
+#include <sys/types.h>
+
+#include "lxctest.h"
+#include "utils.h"
+#include "lsm/lsm.h"
+
+#include <lxc/lxccontainer.h>
 
 #define TSTNAME    "lxc-attach-test"
 #define TSTOUT(fmt, ...) do { \
@@ -392,19 +394,60 @@ err1:
 
 int main(int argc, char *argv[])
 {
-	int ret;
+	int i, ret;
+	struct lxc_log log;
+	char template[sizeof(P_tmpdir"/attach_XXXXXX")];
+	int fret = EXIT_FAILURE;
+
+	strcpy(template, P_tmpdir"/attach_XXXXXX");
+	i = lxc_make_tmpfile(template, false);
+	if (i < 0) {
+		lxc_error("Failed to create temporary log file for container %s\n", TSTNAME);
+		exit(EXIT_FAILURE);
+	} else {
+		lxc_debug("Using \"%s\" as temporary log file for container %s\n", template, TSTNAME);
+		close(i);
+	}
+
+	log.name = TSTNAME;
+	log.file = template;
+	log.level = "TRACE";
+	log.prefix = "attach";
+	log.quiet = false;
+	log.lxcpath = NULL;
+	if (lxc_log_init(&log))
+		goto on_error;
 
 	test_lsm_detect();
 	ret = test_attach(NULL, TSTNAME, "busybox");
 	if (ret < 0)
-		return EXIT_FAILURE;
+		goto on_error;
 
 	TSTOUT("\n");
 	ret = test_attach(LXCPATH "/alternate-path-test", TSTNAME, "busybox");
 	if (ret < 0)
-		return EXIT_FAILURE;
+		goto on_error;
 
-	(void)rmdir(LXCPATH "/alternate-path-test");
 	TSTOUT("All tests passed\n");
-	return EXIT_SUCCESS;
+	fret = EXIT_SUCCESS;
+
+on_error:
+	if (fret != EXIT_SUCCESS) {
+		int fd;
+
+		fd = open(template, O_RDONLY);
+		if (fd >= 0) {
+			char buf[4096];
+			ssize_t buflen;
+			while ((buflen = read(fd, buf, 1024)) > 0) {
+				buflen = write(STDERR_FILENO, buf, buflen);
+				if (buflen <= 0)
+					break;
+			}
+			close(fd);
+		}
+	}
+	(void)rmdir(LXCPATH "/alternate-path-test");
+	(void)unlink(template);
+	exit(fret);
 }

src/tests/lxc-test-lxc-attach

@@ -190,17 +190,6 @@ fi
 
 rm -f $out $err
 
-if [ $allocate_pty = "pty" ]; then
-	# Test whether logging pty output to a file works.
-	trap "rm -f /tmp/ptylog" EXIT INT QUIT PIPE
-	lxc-attach -n busy -L /tmp/ptylog -- hostname || FAIL "to allocate or setup pty"
-	if [ ! -s /tmp/ptylog ]; then
-		FAIL "lxc-attach -n busy -L /tmp/ptylog -- hostname"
-	fi
-
-	rm -f /tmp/ptylog
-fi
-
 lxc-destroy -n busy -f
 
 exit 0