diff options
Diffstat (limited to 'src/shared')
| -rw-r--r-- | src/shared/pager.c | 134 | ||||
| -rw-r--r-- | src/shared/pager.h | 28 |
2 files changed, 162 insertions, 0 deletions
diff --git a/src/shared/pager.c b/src/shared/pager.c new file mode 100644 index 0000000000..3fc81820e9 --- /dev/null +++ b/src/shared/pager.c @@ -0,0 +1,134 @@ +/*-*- 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 <fcntl.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; + +_noreturn_ static void pager_fallback(void) { + ssize_t n; + do { + n = splice(STDIN_FILENO, NULL, STDOUT_FILENO, NULL, 64*1024, 0); + } while (n > 0); + if (n < 0) { + log_error("Internal pager failed: %m"); + _exit(EXIT_FAILURE); + } + _exit(EXIT_SUCCESS); +} + +void pager_open(void) { + int fd[2]; + const char *pager; + pid_t parent_pid; + + if (pager_pid > 0) + return; + + if ((pager = getenv("SYSTEMD_PAGER")) || (pager = getenv("PAGER"))) + if (!*pager || streq(pager, "cat")) + return; + + if (isatty(STDOUT_FILENO) <= 0) + 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); + + pager_fallback(); + /* not reached */ + } + + /* 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; +} diff --git a/src/shared/pager.h b/src/shared/pager.h new file mode 100644 index 0000000000..b5b4998445 --- /dev/null +++ b/src/shared/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 |