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-rw-r--r--src/basic/meson.build2
-rw-r--r--src/basic/pager.c208
-rw-r--r--src/basic/pager.h14
3 files changed, 224 insertions, 0 deletions
diff --git a/src/basic/meson.build b/src/basic/meson.build
index 0161aba76..27d6ace45 100644
--- a/src/basic/meson.build
+++ b/src/basic/meson.build
@@ -297,6 +297,8 @@ basic_sources = files('''
mkdir-label.c
mount-util.c
mount-util.h
+ pager.c
+ pager.h
parse-printf-format.c
parse-printf-format.h
parse-util.c
diff --git a/src/basic/pager.c b/src/basic/pager.c
new file mode 100644
index 000000000..c0ad0bb3b
--- /dev/null
+++ b/src/basic/pager.c
@@ -0,0 +1,208 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#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 "strv.h"
+#include "terminal-util.h"
+
+static pid_t pager_pid = 0;
+
+static int stored_stdout = -1;
+static int stored_stderr = -1;
+static bool stdout_redirected = false;
+static bool stderr_redirected = false;
+
+_noreturn_ static void pager_fallback(void) {
+ int r;
+
+ r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, (uint64_t) -1, 0);
+ if (r < 0) {
+ log_error_errno(r, "Internal pager failed: %m");
+ _exit(EXIT_FAILURE);
+ }
+
+ _exit(EXIT_SUCCESS);
+}
+
+int pager_open(bool no_pager, bool jump_to_end) {
+ _cleanup_close_pair_ int fd[2] = { -1, -1 };
+ const char *pager;
+ int r;
+
+ if (no_pager)
+ return 0;
+
+ if (pager_pid > 0)
+ return 1;
+
+ if (terminal_is_dumb())
+ return 0;
+
+ if (!is_main_thread())
+ return -EPERM;
+
+ pager = getenv("SYSTEMD_PAGER");
+ if (!pager)
+ pager = getenv("PAGER");
+
+ /* If the pager is explicitly turned off, honour it */
+ if (pager && STR_IN_SET(pager, "", "cat"))
+ return 0;
+
+ /* Determine and cache number of columns/lines before we spawn the pager so that we get the value from the
+ * actual tty */
+ (void) columns();
+ (void) lines();
+
+ if (pipe2(fd, O_CLOEXEC) < 0)
+ return log_error_errno(errno, "Failed to create pager pipe: %m");
+
+ r = safe_fork("(pager)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_LOG, &pager_pid);
+ if (r < 0)
+ return r;
+ if (r == 0) {
+ const char* less_opts, *less_charset;
+
+ /* In the child start the pager */
+
+ (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");
+ if (setenv("LESS", less_opts, 1) < 0)
+ _exit(EXIT_FAILURE);
+
+ /* 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) < 0)
+ _exit(EXIT_FAILURE);
+
+ 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 */
+ stored_stdout = fcntl(STDOUT_FILENO, F_DUPFD_CLOEXEC, 3);
+ if (dup2(fd[1], STDOUT_FILENO) < 0) {
+ stored_stdout = safe_close(stored_stdout);
+ return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
+ }
+ stdout_redirected = true;
+
+ stored_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3);
+ if (dup2(fd[1], STDERR_FILENO) < 0) {
+ stored_stderr = safe_close(stored_stderr);
+ return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
+ }
+ stderr_redirected = true;
+
+ return 1;
+}
+
+void pager_close(void) {
+
+ if (pager_pid <= 0)
+ return;
+
+ /* Inform pager that we are done */
+ (void) fflush(stdout);
+ if (stdout_redirected)
+ if (stored_stdout < 0 || dup2(stored_stdout, STDOUT_FILENO) < 0)
+ (void) close(STDOUT_FILENO);
+ stored_stdout = safe_close(stored_stdout);
+ (void) fflush(stderr);
+ if (stderr_redirected)
+ if (stored_stderr < 0 || dup2(stored_stderr, STDERR_FILENO) < 0)
+ (void) close(STDERR_FILENO);
+ stored_stderr = safe_close(stored_stderr);
+ stdout_redirected = stderr_redirected = false;
+
+ (void) kill(pager_pid, SIGCONT);
+ (void) wait_for_terminate(pager_pid, NULL);
+ pager_pid = 0;
+}
+
+bool pager_have(void) {
+ return pager_pid > 0;
+}
+
+#if 0 /// UNNEEDED by elogind
+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;
+
+ 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;
+
+ r = safe_fork("(man)", FORK_RESET_SIGNALS|FORK_DEATHSIG|(null_stdio ? FORK_NULL_STDIO : 0)|FORK_LOG, &pid);
+ if (r < 0)
+ return r;
+ if (r == 0) {
+ /* Child */
+ execvp(args[0], (char**) args);
+ log_error_errno(errno, "Failed to execute man: %m");
+ _exit(EXIT_FAILURE);
+ }
+
+ return wait_for_terminate_and_check(NULL, pid, 0);
+}
+#endif // 0
diff --git a/src/basic/pager.h b/src/basic/pager.h
new file mode 100644
index 000000000..edeae3a11
--- /dev/null
+++ b/src/basic/pager.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#include <stdbool.h>
+
+#include "macro.h"
+
+int pager_open(bool no_pager, bool jump_to_end);
+void pager_close(void);
+bool pager_have(void) _pure_;
+
+#if 0 /// UNNEEDED by elogind
+int show_man_page(const char *page, bool null_stdio);
+#endif // 0