diff options
Diffstat (limited to 'src/libshared/pager.c')
| -rw-r--r-- | src/libshared/pager.c | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/src/libshared/pager.c b/src/libshared/pager.c new file mode 100644 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; +} |