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-rw-r--r--src/libshared/pager.c223
1 files changed, 223 insertions, 0 deletions
diff --git a/src/libshared/pager.c b/src/libshared/pager.c
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index 0000000000..05b2b15e40
--- /dev/null
+++ b/src/libshared/pager.c
@@ -0,0 +1,223 @@
+/***
+ 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 Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <signal.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/prctl.h>
+#include <unistd.h>
+
+#include "copy.h"
+#include "fd-util.h"
+#include "locale-util.h"
+#include "log.h"
+#include "macro.h"
+#include "pager.h"
+#include "process-util.h"
+#include "signal-util.h"
+#include "string-util.h"
+#include "terminal-util.h"
+
+static pid_t pager_pid = 0;
+
+noreturn static void pager_fallback(void) {
+ int r;
+
+ r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, (uint64_t) -1, false);
+ if (r < 0) {
+ log_error_errno(r, "Internal pager failed: %m");
+ _exit(EXIT_FAILURE);
+ }
+
+ _exit(EXIT_SUCCESS);
+}
+
+int pager_open(bool jump_to_end) {
+ _cleanup_close_pair_ int fd[2] = { -1, -1 };
+ const char *pager;
+ pid_t parent_pid;
+
+ if (pager_pid > 0)
+ return 1;
+
+ if (!on_tty())
+ return 0;
+
+ pager = getenv("SYSTEMD_PAGER");
+ if (!pager)
+ pager = getenv("PAGER");
+
+ /* If the pager is explicitly turned off, honour it */
+ if (pager && (pager[0] == 0 || streq(pager, "cat")))
+ return 0;
+
+ /* Determine and cache number of columns before we spawn the
+ * pager so that we get the value from the actual tty */
+ (void) columns();
+
+ if (pipe(fd) < 0)
+ return log_error_errno(errno, "Failed to create pager pipe: %m");
+
+ parent_pid = getpid();
+
+ pager_pid = fork();
+ if (pager_pid < 0)
+ return log_error_errno(errno, "Failed to fork pager: %m");
+
+ /* In the child start the pager */
+ if (pager_pid == 0) {
+ const char* less_opts, *less_charset;
+
+ (void) reset_all_signal_handlers();
+ (void) reset_signal_mask();
+
+ (void) dup2(fd[0], STDIN_FILENO);
+ safe_close_pair(fd);
+
+ /* Initialize a good set of less options */
+ less_opts = getenv("SYSTEMD_LESS");
+ if (!less_opts)
+ less_opts = "FRSXMK";
+ if (jump_to_end)
+ less_opts = strjoina(less_opts, " +G");
+ setenv("LESS", less_opts, 1);
+
+ /* Initialize a good charset for less. This is
+ * particularly important if we output UTF-8
+ * characters. */
+ less_charset = getenv("SYSTEMD_LESSCHARSET");
+ if (!less_charset && is_locale_utf8())
+ less_charset = "utf-8";
+ if (less_charset)
+ setenv("LESSCHARSET", less_charset, 1);
+
+ /* 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);
+
+ pager_fallback();
+ /* not reached */
+ }
+
+ /* Return in the parent */
+ if (dup2(fd[1], STDOUT_FILENO) < 0)
+ return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
+ if (dup2(fd[1], STDERR_FILENO) < 0)
+ return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
+
+ return 1;
+}
+
+void pager_close(void) {
+
+ if (pager_pid <= 0)
+ return;
+
+ /* Inform pager that we are done */
+ stdout = safe_fclose(stdout);
+ stderr = safe_fclose(stderr);
+
+ (void) kill(pager_pid, SIGCONT);
+ (void) wait_for_terminate(pager_pid, NULL);
+ pager_pid = 0;
+}
+
+bool pager_have(void) {
+ return pager_pid > 0;
+}
+
+int show_man_page(const char *desc, bool null_stdio) {
+ const char *args[4] = { "man", NULL, NULL, NULL };
+ char *e = NULL;
+ pid_t pid;
+ size_t k;
+ int r;
+ siginfo_t status;
+
+ k = strlen(desc);
+
+ if (desc[k-1] == ')')
+ e = strrchr(desc, '(');
+
+ if (e) {
+ char *page = NULL, *section = NULL;
+
+ page = strndupa(desc, e - desc);
+ section = strndupa(e + 1, desc + k - e - 2);
+
+ args[1] = section;
+ args[2] = page;
+ } else
+ args[1] = desc;
+
+ pid = fork();
+ if (pid < 0)
+ return log_error_errno(errno, "Failed to fork: %m");
+
+ if (pid == 0) {
+ /* Child */
+
+ (void) reset_all_signal_handlers();
+ (void) reset_signal_mask();
+
+ if (null_stdio) {
+ r = make_null_stdio();
+ if (r < 0) {
+ log_error_errno(r, "Failed to kill stdio: %m");
+ _exit(EXIT_FAILURE);
+ }
+ }
+
+ execvp(args[0], (char**) args);
+ log_error_errno(errno, "Failed to execute man: %m");
+ _exit(EXIT_FAILURE);
+ }
+
+ r = wait_for_terminate(pid, &status);
+ if (r < 0)
+ return r;
+
+ log_debug("Exit code %i status %i", status.si_code, status.si_status);
+ return status.si_status;
+}