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1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ | |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2010 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU Lesser General Public License as published by | |
10 | the Free Software Foundation; either version 2.1 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | Lesser General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU Lesser General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
22 | #include <fcntl.h> | |
23 | #include <stdlib.h> | |
24 | #include <unistd.h> | |
25 | #include <string.h> | |
26 | #include <sys/prctl.h> | |
27 | ||
28 | #include "pager.h" | |
29 | #include "util.h" | |
30 | #include "process-util.h" | |
31 | #include "macro.h" | |
32 | #include "terminal-util.h" | |
33 | #include "signal-util.h" | |
34 | #include "copy.h" | |
35 | ||
36 | static pid_t pager_pid = 0; | |
37 | ||
38 | noreturn static void pager_fallback(void) { | |
39 | int r; | |
40 | ||
41 | r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, (off_t) -1, false); | |
42 | if (r < 0) { | |
43 | log_error_errno(r, "Internal pager failed: %m"); | |
44 | _exit(EXIT_FAILURE); | |
45 | } | |
46 | ||
47 | _exit(EXIT_SUCCESS); | |
48 | } | |
49 | ||
50 | int pager_open(bool jump_to_end) { | |
51 | int fd[2]; | |
52 | const char *pager; | |
53 | pid_t parent_pid; | |
54 | int r; | |
55 | ||
56 | if (pager_pid > 0) | |
57 | return 1; | |
58 | ||
59 | if ((pager = getenv("SYSTEMD_PAGER")) || (pager = getenv("PAGER"))) | |
60 | if (!*pager || streq(pager, "cat")) | |
61 | return 0; | |
62 | ||
63 | if (!on_tty()) | |
64 | return 0; | |
65 | ||
66 | /* Determine and cache number of columns before we spawn the | |
67 | * pager so that we get the value from the actual tty */ | |
68 | columns(); | |
69 | ||
70 | if (pipe(fd) < 0) | |
71 | return log_error_errno(errno, "Failed to create pager pipe: %m"); | |
72 | ||
73 | parent_pid = getpid(); | |
74 | ||
75 | pager_pid = fork(); | |
76 | if (pager_pid < 0) { | |
77 | r = -errno; | |
78 | log_error_errno(errno, "Failed to fork pager: %m"); | |
79 | safe_close_pair(fd); | |
80 | return r; | |
81 | } | |
82 | ||
83 | /* In the child start the pager */ | |
84 | if (pager_pid == 0) { | |
85 | const char* less_opts; | |
86 | ||
87 | (void) reset_all_signal_handlers(); | |
88 | (void) reset_signal_mask(); | |
89 | ||
90 | dup2(fd[0], STDIN_FILENO); | |
91 | safe_close_pair(fd); | |
92 | ||
93 | less_opts = getenv("SYSTEMD_LESS"); | |
94 | if (!less_opts) | |
95 | less_opts = "FRSXMK"; | |
96 | if (jump_to_end) | |
97 | less_opts = strjoina(less_opts, " +G"); | |
98 | setenv("LESS", less_opts, 1); | |
99 | ||
100 | /* Make sure the pager goes away when the parent dies */ | |
101 | if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0) | |
102 | _exit(EXIT_FAILURE); | |
103 | ||
104 | /* Check whether our parent died before we were able | |
105 | * to set the death signal */ | |
106 | if (getppid() != parent_pid) | |
107 | _exit(EXIT_SUCCESS); | |
108 | ||
109 | if (pager) { | |
110 | execlp(pager, pager, NULL); | |
111 | execl("/bin/sh", "sh", "-c", pager, NULL); | |
112 | } | |
113 | ||
114 | /* Debian's alternatives command for pagers is | |
115 | * called 'pager'. Note that we do not call | |
116 | * sensible-pagers here, since that is just a | |
117 | * shell script that implements a logic that | |
118 | * is similar to this one anyway, but is | |
119 | * Debian-specific. */ | |
120 | execlp("pager", "pager", NULL); | |
121 | ||
122 | execlp("less", "less", NULL); | |
123 | execlp("more", "more", NULL); | |
124 | ||
125 | pager_fallback(); | |
126 | /* not reached */ | |
127 | } | |
128 | ||
129 | /* Return in the parent */ | |
130 | if (dup2(fd[1], STDOUT_FILENO) < 0) | |
131 | return log_error_errno(errno, "Failed to duplicate pager pipe: %m"); | |
132 | if (dup2(fd[1], STDERR_FILENO) < 0) | |
133 | return log_error_errno(errno, "Failed to duplicate pager pipe: %m"); | |
134 | ||
135 | safe_close_pair(fd); | |
136 | return 1; | |
137 | } | |
138 | ||
139 | void pager_close(void) { | |
140 | ||
141 | if (pager_pid <= 0) | |
142 | return; | |
143 | ||
144 | /* Inform pager that we are done */ | |
145 | fclose(stdout); | |
146 | stdout = NULL; | |
147 | ||
148 | fclose(stderr); | |
149 | stderr = NULL; | |
150 | ||
151 | kill(pager_pid, SIGCONT); | |
152 | (void) wait_for_terminate(pager_pid, NULL); | |
153 | pager_pid = 0; | |
154 | } | |
155 | ||
156 | bool pager_have(void) { | |
157 | return pager_pid > 0; | |
158 | } | |
159 | ||
160 | int show_man_page(const char *desc, bool null_stdio) { | |
161 | const char *args[4] = { "man", NULL, NULL, NULL }; | |
162 | char *e = NULL; | |
163 | pid_t pid; | |
164 | size_t k; | |
165 | int r; | |
166 | siginfo_t status; | |
167 | ||
168 | k = strlen(desc); | |
169 | ||
170 | if (desc[k-1] == ')') | |
171 | e = strrchr(desc, '('); | |
172 | ||
173 | if (e) { | |
174 | char *page = NULL, *section = NULL; | |
175 | ||
176 | page = strndupa(desc, e - desc); | |
177 | section = strndupa(e + 1, desc + k - e - 2); | |
178 | ||
179 | args[1] = section; | |
180 | args[2] = page; | |
181 | } else | |
182 | args[1] = desc; | |
183 | ||
184 | pid = fork(); | |
185 | if (pid < 0) | |
186 | return log_error_errno(errno, "Failed to fork: %m"); | |
187 | ||
188 | if (pid == 0) { | |
189 | /* Child */ | |
190 | ||
191 | (void) reset_all_signal_handlers(); | |
192 | (void) reset_signal_mask(); | |
193 | ||
194 | if (null_stdio) { | |
195 | r = make_null_stdio(); | |
196 | if (r < 0) { | |
197 | log_error_errno(r, "Failed to kill stdio: %m"); | |
198 | _exit(EXIT_FAILURE); | |
199 | } | |
200 | } | |
201 | ||
202 | execvp(args[0], (char**) args); | |
203 | log_error_errno(errno, "Failed to execute man: %m"); | |
204 | _exit(EXIT_FAILURE); | |
205 | } | |
206 | ||
207 | r = wait_for_terminate(pid, &status); | |
208 | if (r < 0) | |
209 | return r; | |
210 | ||
211 | log_debug("Exit code %i status %i", status.si_code, status.si_status); | |
212 | return status.si_status; | |
213 | } |