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Commit | Line | Data |
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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
1968a360 | 2 | |
a8fbdf54 TA |
3 | #include <errno.h> |
4 | #include <signal.h> | |
5 | #include <stddef.h> | |
6 | #include <stdint.h> | |
7 | #include <stdio.h> | |
1968a360 | 8 | #include <stdlib.h> |
1968a360 LP |
9 | #include <string.h> |
10 | #include <sys/prctl.h> | |
07630cea | 11 | #include <unistd.h> |
1968a360 | 12 | |
07630cea | 13 | #include "copy.h" |
3ffd4af2 | 14 | #include "fd-util.h" |
6432da6a ZJS |
15 | #include "fileio.h" |
16 | #include "io-util.h" | |
8752c575 | 17 | #include "locale-util.h" |
a8fbdf54 | 18 | #include "log.h" |
1968a360 | 19 | #include "macro.h" |
3ffd4af2 | 20 | #include "pager.h" |
07630cea | 21 | #include "process-util.h" |
595225af | 22 | #include "rlimit-util.h" |
ce30c8dc | 23 | #include "signal-util.h" |
07630cea | 24 | #include "string-util.h" |
57c9e047 | 25 | #include "strv.h" |
07630cea | 26 | #include "terminal-util.h" |
ca78ad1d | 27 | #include "util.h" |
1968a360 LP |
28 | |
29 | static pid_t pager_pid = 0; | |
30 | ||
3f603952 LP |
31 | static int stored_stdout = -1; |
32 | static int stored_stderr = -1; | |
33 | static bool stdout_redirected = false; | |
34 | static bool stderr_redirected = false; | |
35 | ||
848e863a | 36 | _noreturn_ static void pager_fallback(void) { |
6a7c676c | 37 | int r; |
46e65dcc | 38 | |
1c876927 | 39 | r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, (uint64_t) -1, 0); |
6a7c676c LP |
40 | if (r < 0) { |
41 | log_error_errno(r, "Internal pager failed: %m"); | |
4a8e40eb MS |
42 | _exit(EXIT_FAILURE); |
43 | } | |
46e65dcc | 44 | |
4a8e40eb MS |
45 | _exit(EXIT_SUCCESS); |
46 | } | |
47 | ||
6432da6a ZJS |
48 | static int no_quit_on_interrupt(int exe_name_fd, const char *less_opts) { |
49 | _cleanup_fclose_ FILE *file = NULL; | |
50 | _cleanup_free_ char *line = NULL; | |
51 | int r; | |
52 | ||
53 | assert(exe_name_fd >= 0); | |
54 | assert(less_opts); | |
55 | ||
56 | /* This takes ownership of exe_name_fd */ | |
57 | file = fdopen(exe_name_fd, "r"); | |
58 | if (!file) { | |
59 | safe_close(exe_name_fd); | |
1d788908 | 60 | return log_error_errno(errno, "Failed to create FILE object: %m"); |
6432da6a ZJS |
61 | } |
62 | ||
63 | /* Find the last line */ | |
64 | for (;;) { | |
65 | _cleanup_free_ char *t = NULL; | |
66 | ||
67 | r = read_line(file, LONG_LINE_MAX, &t); | |
68 | if (r < 0) | |
1d788908 | 69 | return log_error_errno(r, "Failed to read from socket: %m"); |
6432da6a ZJS |
70 | if (r == 0) |
71 | break; | |
72 | ||
73 | free_and_replace(line, t); | |
74 | } | |
75 | ||
76 | /* We only treat "less" specially. | |
77 | * Return true whenever option K is *not* set. */ | |
78 | r = streq_ptr(line, "less") && !strchr(less_opts, 'K'); | |
79 | ||
80 | log_debug("Pager executable is \"%s\", options \"%s\", quit_on_interrupt: %s", | |
81 | strnull(line), less_opts, yes_no(!r)); | |
82 | return r; | |
83 | } | |
84 | ||
0221d68a | 85 | int pager_open(PagerFlags flags) { |
6432da6a | 86 | _cleanup_close_pair_ int fd[2] = { -1, -1 }, exe_name_pipe[2] = { -1, -1 }; |
43942e80 | 87 | _cleanup_strv_free_ char **pager_args = NULL; |
6432da6a | 88 | const char *pager, *less_opts; |
4c253ed1 | 89 | int r; |
1968a360 | 90 | |
0221d68a | 91 | if (flags & PAGER_DISABLE) |
ea4b98e6 AK |
92 | return 0; |
93 | ||
1968a360 | 94 | if (pager_pid > 0) |
f89a3b6f | 95 | return 1; |
1968a360 | 96 | |
ac96418b | 97 | if (terminal_is_dumb()) |
f89a3b6f | 98 | return 0; |
729e3769 | 99 | |
85afeae8 | 100 | if (!is_main_thread()) |
1d788908 | 101 | return log_error_errno(SYNTHETIC_ERRNO(EPERM), "Pager invoked from wrong thread."); |
85afeae8 | 102 | |
bcbd61db LP |
103 | pager = getenv("SYSTEMD_PAGER"); |
104 | if (!pager) | |
105 | pager = getenv("PAGER"); | |
106 | ||
43942e80 YW |
107 | if (pager) { |
108 | pager_args = strv_split(pager, WHITESPACE); | |
109 | if (!pager_args) | |
1d788908 | 110 | return log_oom(); |
43942e80 YW |
111 | |
112 | /* If the pager is explicitly turned off, honour it */ | |
113 | if (strv_isempty(pager_args) || strv_equal(pager_args, STRV_MAKE("cat"))) | |
114 | return 0; | |
115 | } | |
bcbd61db | 116 | |
d13b5227 LP |
117 | /* Determine and cache number of columns/lines before we spawn the pager so that we get the value from the |
118 | * actual tty */ | |
bcbd61db | 119 | (void) columns(); |
d13b5227 | 120 | (void) lines(); |
1968a360 | 121 | |
d262e99e | 122 | if (pipe2(fd, O_CLOEXEC) < 0) |
4a62c710 | 123 | return log_error_errno(errno, "Failed to create pager pipe: %m"); |
1968a360 | 124 | |
6432da6a ZJS |
125 | /* This is a pipe to feed the name of the executed pager binary into the parent */ |
126 | if (pipe2(exe_name_pipe, O_CLOEXEC) < 0) | |
127 | return log_error_errno(errno, "Failed to create exe_name pipe: %m"); | |
128 | ||
129 | /* Initialize a good set of less options */ | |
130 | less_opts = getenv("SYSTEMD_LESS"); | |
131 | if (!less_opts) | |
132 | less_opts = "FRSXMK"; | |
133 | if (flags & PAGER_JUMP_TO_END) | |
134 | less_opts = strjoina(less_opts, " +G"); | |
135 | ||
a81921e4 | 136 | r = safe_fork("(pager)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pager_pid); |
4c253ed1 | 137 | if (r < 0) |
b6e1fff1 | 138 | return r; |
4c253ed1 | 139 | if (r == 0) { |
6432da6a | 140 | const char *less_charset, *exe; |
1968a360 | 141 | |
4c253ed1 | 142 | /* In the child start the pager */ |
ce30c8dc | 143 | |
1d788908 LP |
144 | if (dup2(fd[0], STDIN_FILENO) < 0) { |
145 | log_error_errno(errno, "Failed to duplicate file descriptor to STDIN: %m"); | |
146 | _exit(EXIT_FAILURE); | |
147 | } | |
148 | ||
3d94f76c | 149 | safe_close_pair(fd); |
1968a360 | 150 | |
1d788908 LP |
151 | if (setenv("LESS", less_opts, 1) < 0) { |
152 | log_error_errno(errno, "Failed to set environment variable LESS: %m"); | |
0357fa0d | 153 | _exit(EXIT_FAILURE); |
1d788908 | 154 | } |
1968a360 | 155 | |
a1b4e6e9 LP |
156 | /* Initialize a good charset for less. This is |
157 | * particularly important if we output UTF-8 | |
158 | * characters. */ | |
159 | less_charset = getenv("SYSTEMD_LESSCHARSET"); | |
160 | if (!less_charset && is_locale_utf8()) | |
161 | less_charset = "utf-8"; | |
0357fa0d | 162 | if (less_charset && |
1d788908 LP |
163 | setenv("LESSCHARSET", less_charset, 1) < 0) { |
164 | log_error_errno(errno, "Failed to set environment variable LESSCHARSET: %m"); | |
0357fa0d | 165 | _exit(EXIT_FAILURE); |
1d788908 | 166 | } |
a1b4e6e9 | 167 | |
6432da6a | 168 | if (pager_args) { |
1d788908 LP |
169 | r = loop_write(exe_name_pipe[1], pager_args[0], strlen(pager_args[0]) + 1, false); |
170 | if (r < 0) { | |
171 | log_error_errno(r, "Failed to write pager name to socket: %m"); | |
6432da6a | 172 | _exit(EXIT_FAILURE); |
1d788908 | 173 | } |
6432da6a | 174 | |
43942e80 | 175 | execvp(pager_args[0], pager_args); |
1d788908 | 176 | log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno, |
118dccc9 | 177 | "Failed to execute '%s', using fallback pagers: %m", pager_args[0]); |
6432da6a | 178 | } |
1968a360 LP |
179 | |
180 | /* Debian's alternatives command for pagers is | |
181 | * called 'pager'. Note that we do not call | |
182 | * sensible-pagers here, since that is just a | |
183 | * shell script that implements a logic that | |
184 | * is similar to this one anyway, but is | |
185 | * Debian-specific. */ | |
6432da6a | 186 | FOREACH_STRING(exe, "pager", "less", "more") { |
1d788908 LP |
187 | r = loop_write(exe_name_pipe[1], exe, strlen(exe) + 1, false); |
188 | if (r < 0) { | |
189 | log_error_errno(r, "Failed to write pager name to socket: %m"); | |
6432da6a | 190 | _exit(EXIT_FAILURE); |
1d788908 | 191 | } |
6432da6a | 192 | execlp(exe, exe, NULL); |
1d788908 | 193 | log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno, |
118dccc9 | 194 | "Failed to execute '%s', using next fallback pager: %m", exe); |
6432da6a | 195 | } |
1968a360 | 196 | |
1d788908 LP |
197 | r = loop_write(exe_name_pipe[1], "(built-in)", strlen("(built-in") + 1, false); |
198 | if (r < 0) { | |
199 | log_error_errno(r, "Failed to write pager name to socket: %m"); | |
6432da6a | 200 | _exit(EXIT_FAILURE); |
1d788908 | 201 | } |
4a8e40eb MS |
202 | pager_fallback(); |
203 | /* not reached */ | |
1968a360 LP |
204 | } |
205 | ||
206 | /* Return in the parent */ | |
a45e7bb4 MS |
207 | stored_stdout = fcntl(STDOUT_FILENO, F_DUPFD_CLOEXEC, 3); |
208 | if (dup2(fd[1], STDOUT_FILENO) < 0) { | |
209 | stored_stdout = safe_close(stored_stdout); | |
4a62c710 | 210 | return log_error_errno(errno, "Failed to duplicate pager pipe: %m"); |
a45e7bb4 MS |
211 | } |
212 | stdout_redirected = true; | |
213 | ||
214 | stored_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3); | |
215 | if (dup2(fd[1], STDERR_FILENO) < 0) { | |
216 | stored_stderr = safe_close(stored_stderr); | |
8b5264aa | 217 | return log_error_errno(errno, "Failed to duplicate pager pipe: %m"); |
a45e7bb4 MS |
218 | } |
219 | stderr_redirected = true; | |
1968a360 | 220 | |
6432da6a ZJS |
221 | exe_name_pipe[1] = safe_close(exe_name_pipe[1]); |
222 | ||
223 | r = no_quit_on_interrupt(TAKE_FD(exe_name_pipe[0]), less_opts); | |
224 | if (r < 0) | |
225 | return r; | |
226 | if (r > 0) | |
227 | (void) ignore_signals(SIGINT, -1); | |
228 | ||
f89a3b6f | 229 | return 1; |
1968a360 LP |
230 | } |
231 | ||
232 | void pager_close(void) { | |
233 | ||
234 | if (pager_pid <= 0) | |
235 | return; | |
236 | ||
237 | /* Inform pager that we are done */ | |
a45e7bb4 | 238 | (void) fflush(stdout); |
77018a8c MS |
239 | if (stdout_redirected) |
240 | if (stored_stdout < 0 || dup2(stored_stdout, STDOUT_FILENO) < 0) | |
241 | (void) close(STDOUT_FILENO); | |
a45e7bb4 MS |
242 | stored_stdout = safe_close(stored_stdout); |
243 | (void) fflush(stderr); | |
77018a8c MS |
244 | if (stderr_redirected) |
245 | if (stored_stderr < 0 || dup2(stored_stderr, STDERR_FILENO) < 0) | |
246 | (void) close(STDERR_FILENO); | |
a45e7bb4 MS |
247 | stored_stderr = safe_close(stored_stderr); |
248 | stdout_redirected = stderr_redirected = false; | |
8b5264aa | 249 | |
74ca738f | 250 | (void) kill(pager_pid, SIGCONT); |
c73d180d | 251 | (void) wait_for_terminate(pager_pid, NULL); |
1968a360 LP |
252 | pager_pid = 0; |
253 | } | |
f89a3b6f LP |
254 | |
255 | bool pager_have(void) { | |
256 | return pager_pid > 0; | |
257 | } | |
78002a67 ZJS |
258 | |
259 | int show_man_page(const char *desc, bool null_stdio) { | |
260 | const char *args[4] = { "man", NULL, NULL, NULL }; | |
261 | char *e = NULL; | |
262 | pid_t pid; | |
263 | size_t k; | |
264 | int r; | |
78002a67 ZJS |
265 | |
266 | k = strlen(desc); | |
267 | ||
268 | if (desc[k-1] == ')') | |
269 | e = strrchr(desc, '('); | |
270 | ||
271 | if (e) { | |
272 | char *page = NULL, *section = NULL; | |
273 | ||
274 | page = strndupa(desc, e - desc); | |
275 | section = strndupa(e + 1, desc + k - e - 2); | |
276 | ||
277 | args[1] = section; | |
278 | args[2] = page; | |
279 | } else | |
280 | args[1] = desc; | |
281 | ||
0672e2c6 | 282 | r = safe_fork("(man)", FORK_RESET_SIGNALS|FORK_DEATHSIG|(null_stdio ? FORK_NULL_STDIO : 0)|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pid); |
4c253ed1 | 283 | if (r < 0) |
b6e1fff1 | 284 | return r; |
4c253ed1 | 285 | if (r == 0) { |
78002a67 | 286 | /* Child */ |
78002a67 | 287 | execvp(args[0], (char**) args); |
56f64d95 | 288 | log_error_errno(errno, "Failed to execute man: %m"); |
78002a67 ZJS |
289 | _exit(EXIT_FAILURE); |
290 | } | |
291 | ||
2e87a1fd | 292 | return wait_for_terminate_and_check(NULL, pid, 0); |
78002a67 | 293 | } |