cgls: add pager support to systemd-cgls

Makefile.am

@@ -1118,7 +1118,8 @@ systemctl_SOURCES = \
 	src/cgroup-show.c \
 	src/cgroup-util.c \
 	src/exit-status.c \
-	src/unit-name.c
+	src/unit-name.c \
+        src/pager.c
 
 systemctl_CFLAGS = \
 	$(AM_CFLAGS) \
@@ -1177,7 +1178,8 @@ systemd_readahead_replay_LDADD = \
 systemd_cgls_SOURCES = \
 	src/cgls.c \
 	src/cgroup-show.c \
-	src/cgroup-util.c
+	src/cgroup-util.c \
+        src/pager.c
 
 systemd_cgls_CFLAGS = \
 	$(AM_CFLAGS)

src/cgls.c

@@ -30,19 +30,28 @@
 #include "cgroup-util.h"
 #include "log.h"
 #include "util.h"
+#include "pager.h"
+
+static bool arg_no_pager = false;
 
 static void help(void) {
 
         printf("%s [OPTIONS...] [CGROUP...]\n\n"
                "Recursively show control group contents.\n\n"
-               "  -h --help         Show this help\n",
+               "  -h --help         Show this help\n"
+               "     --no-pager       Do not pipe output into a pager.\n",
                program_invocation_short_name);
 }
 
 static int parse_argv(int argc, char *argv[]) {
 
+        enum {
+                ARG_NO_PAGER = 0x100
+        };
+
         static const struct option options[] = {
                 { "help",      no_argument,       NULL, 'h'          },
+                { "no-pager",  no_argument,       NULL, ARG_NO_PAGER },
                 { NULL,        0,                 NULL, 0            }
         };
 
@@ -59,6 +68,10 @@ static int parse_argv(int argc, char *argv[]) {
                         help();
                         return 0;
 
+                case ARG_NO_PAGER:
+                        arg_no_pager = true;
+                        break;
+
                 case '?':
                         return -EINVAL;
 
@@ -84,6 +97,9 @@ int main(int argc, char *argv[]) {
                 goto finish;
         }
 
+        if (!arg_no_pager)
+                pager_open();
+
         if (optind < argc) {
                 unsigned i;
 
@@ -132,6 +148,7 @@ int main(int argc, char *argv[]) {
         retval = EXIT_SUCCESS;
 
 finish:
+        pager_close();
 
         return retval;
 }

src/pager.c

@@ -0,0 +1,122 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd 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.
+
+  systemd 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.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/types.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/prctl.h>
+
+#include "pager.h"
+#include "util.h"
+#include "macro.h"
+
+static pid_t pager_pid = 0;
+
+void pager_open(void) {
+        int fd[2];
+        const char *pager;
+        pid_t parent_pid;
+
+        if (pager_pid > 0)
+                return;
+
+        if (isatty(STDOUT_FILENO) <= 0)
+                return;
+
+        if ((pager = getenv("SYSTEMD_PAGER")) || (pager = getenv("PAGER")))
+                if (!*pager || streq(pager, "cat"))
+                        return;
+
+        /* Determine and cache number of columns before we spawn the
+         * pager so that we get the value from the actual tty */
+        columns();
+
+        if (pipe(fd) < 0) {
+                log_error("Failed to create pager pipe: %m");
+                return;
+        }
+
+        parent_pid = getpid();
+
+        pager_pid = fork();
+        if (pager_pid < 0) {
+                log_error("Failed to fork pager: %m");
+                close_pipe(fd);
+                return;
+        }
+
+        /* In the child start the pager */
+        if (pager_pid == 0) {
+
+                dup2(fd[0], STDIN_FILENO);
+                close_pipe(fd);
+
+                setenv("LESS", "FRSX", 0);
+
+                /* Make sure the pager goes away when the parent dies */
+                if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
+                        _exit(EXIT_FAILURE);
+
+                /* Check whether our parent died before we were able
+                 * to set the death signal */
+                if (getppid() != parent_pid)
+                        _exit(EXIT_SUCCESS);
+
+                if (pager) {
+                        execlp(pager, pager, NULL);
+                        execl("/bin/sh", "sh", "-c", pager, NULL);
+                }
+
+                /* Debian's alternatives command for pagers is
+                 * called 'pager'. Note that we do not call
+                 * sensible-pagers here, since that is just a
+                 * shell script that implements a logic that
+                 * is similar to this one anyway, but is
+                 * Debian-specific. */
+                execlp("pager", "pager", NULL);
+
+                execlp("less", "less", NULL);
+                execlp("more", "more", NULL);
+                execlp("cat", "cat", NULL);
+
+                log_error("Unable to execute pager: %m");
+                _exit(EXIT_FAILURE);
+        }
+
+        /* Return in the parent */
+        if (dup2(fd[1], STDOUT_FILENO) < 0)
+                log_error("Failed to duplicate pager pipe: %m");
+
+        close_pipe(fd);
+}
+
+void pager_close(void) {
+
+        if (pager_pid <= 0)
+                return;
+
+        /* Inform pager that we are done */
+        fclose(stdout);
+        kill(pager_pid, SIGCONT);
+        wait_for_terminate(pager_pid, NULL);
+        pager_pid = 0;
+}

src/pager.h

@@ -0,0 +1,28 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#ifndef foopagerhfoo
+#define foopagerhfoo
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd 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.
+
+  systemd 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.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+void pager_open(void);
+void pager_close(void);
+
+#endif

src/systemctl.c

@@ -56,6 +56,7 @@
 #include "bus-errors.h"
 #include "build.h"
 #include "unit-name.h"
+#include "pager.h"
 
 static const char *arg_type = NULL;
 static char **arg_property = NULL;
@@ -118,11 +119,14 @@ static const char *arg_host = NULL;
 
 static bool private_bus = false;
 
-static pid_t pager_pid = 0;
 static pid_t agent_pid = 0;
 
 static int daemon_reload(DBusConnection *bus, char **args, unsigned n);
-static void pager_open(void);
+
+static void pager_open_if_enabled(void) {
+        if (!arg_no_pager)
+                pager_open();
+}
 
 static bool on_tty(void) {
         static int t = -1;
@@ -475,7 +479,7 @@ static int list_units(DBusConnection *bus, char **args, unsigned n) {
 
         assert(bus);
 
-        pager_open();
+        pager_open_if_enabled();
 
         if (!(m = dbus_message_new_method_call(
                               "org.freedesktop.systemd1",
@@ -825,7 +829,7 @@ static int list_jobs(DBusConnection *bus, char **args, unsigned n) {
 
         assert(bus);
 
-        pager_open();
+        pager_open_if_enabled();
 
         if (!(m = dbus_message_new_method_call(
                               "org.freedesktop.systemd1",
@@ -2652,7 +2656,7 @@ static int show(DBusConnection *bus, char **args, unsigned n) {
         show_properties = !streq(args[0], "status");
 
         if (show_properties)
-                pager_open();
+                pager_open_if_enabled();
 
         if (show_properties && n <= 1) {
                 /* If not argument is specified inspect the manager
@@ -3048,7 +3052,7 @@ static int dump(DBusConnection *bus, char **args, unsigned n) {
 
         dbus_error_init(&error);
 
-        pager_open();
+        pager_open_if_enabled();
 
         if (!(m = dbus_message_new_method_call(
                               "org.freedesktop.systemd1",
@@ -3419,7 +3423,7 @@ static int show_enviroment(DBusConnection *bus, char **args, unsigned n) {
 
         dbus_error_init(&error);
 
-        pager_open();
+        pager_open_if_enabled();
 
         if (!(m = dbus_message_new_method_call(
                               "org.freedesktop.systemd1",
@@ -5602,96 +5606,6 @@ static int runlevel_main(void) {
         return 0;
 }
 
-static void pager_open(void) {
-        int fd[2];
-        const char *pager;
-        pid_t parent_pid;
-
-        if (pager_pid > 0)
-                return;
-
-        if (!on_tty() || arg_no_pager)
-                return;
-
-        if ((pager = getenv("SYSTEMD_PAGER")) || (pager = getenv("PAGER")))
-                if (!*pager || streq(pager, "cat"))
-                        return;
-
-        /* Determine and cache number of columns before we spawn the
-         * pager so that we get the value from the actual tty */
-        columns();
-
-        if (pipe(fd) < 0) {
-                log_error("Failed to create pager pipe: %m");
-                return;
-        }
-
-        parent_pid = getpid();
-
-        pager_pid = fork();
-        if (pager_pid < 0) {
-                log_error("Failed to fork pager: %m");
-                close_pipe(fd);
-                return;
-        }
-
-        /* In the child start the pager */
-        if (pager_pid == 0) {
-
-                dup2(fd[0], STDIN_FILENO);
-                close_pipe(fd);
-
-                setenv("LESS", "FRSX", 0);
-
-                /* Make sure the pager goes away when the parent dies */
-                if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
-                        _exit(EXIT_FAILURE);
-
-                /* Check whether our parent died before we were able
-                 * to set the death signal */
-                if (getppid() != parent_pid)
-                        _exit(EXIT_SUCCESS);
-
-                if (pager) {
-                        execlp(pager, pager, NULL);
-                        execl("/bin/sh", "sh", "-c", pager, NULL);
-                } else {
-                        /* Debian's alternatives command for pagers is
-                         * called 'pager'. Note that we do not call
-                         * sensible-pagers here, since that is just a
-                         * shell script that implements a logic that
-                         * is similar to this one anyway, but is
-                         * Debian-specific. */
-                        execlp("pager", "pager", NULL);
-
-                        execlp("less", "less", NULL);
-                        execlp("more", "more", NULL);
-                }
-
-                log_error("Unable to execute pager: %m");
-                _exit(EXIT_FAILURE);
-        }
-
-        /* Return in the parent */
-        if (dup2(fd[1], STDOUT_FILENO) < 0)
-                log_error("Failed to duplicate pager pipe: %m");
-
-        close_pipe(fd);
-}
-
-static void pager_close(void) {
-        siginfo_t dummy;
-
-        if (pager_pid <= 0)
-                return;
-
-        /* Inform pager that we are done */
-        fclose(stdout);
-        kill(pager_pid, SIGCONT);
-        wait_for_terminate(pager_pid, &dummy);
-        pager_pid = 0;
-}
-
 static void agent_close(void) {
         siginfo_t dummy;
 

src/util.c

@@ -3866,8 +3866,12 @@ char *normalize_env_assignment(const char *s) {
 }
 
 int wait_for_terminate(pid_t pid, siginfo_t *status) {
+        siginfo_t dummy;
+
         assert(pid >= 1);
-        assert(status);
+
+        if (!status)
+                status = &dummy;
 
         for (;;) {
                 zero(*status);