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Commit | Line | Data |
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561b0bec | 1 | /* Minimal /bin/sh for in-container use. |
dff8da6b | 2 | Copyright (C) 2018-2024 Free Software Foundation, Inc. |
561b0bec DD |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
16 | License along with the GNU C Library; if not, see | |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
561b0bec | 18 | |
561b0bec DD |
19 | #include <stdio.h> |
20 | #include <stdlib.h> | |
21 | #include <string.h> | |
22 | #include <sched.h> | |
23 | #include <sys/syscall.h> | |
24 | #include <unistd.h> | |
25 | #include <sys/types.h> | |
26 | #include <dirent.h> | |
27 | #include <string.h> | |
28 | #include <sys/stat.h> | |
29 | #include <sys/fcntl.h> | |
30 | #include <sys/file.h> | |
31 | #include <sys/wait.h> | |
32 | #include <stdarg.h> | |
33 | #include <sys/sysmacros.h> | |
34 | #include <ctype.h> | |
35 | #include <utime.h> | |
36 | #include <errno.h> | |
37 | #include <error.h> | |
38 | ||
39 | #include <support/support.h> | |
436a604b | 40 | #include <support/timespec.h> |
561b0bec DD |
41 | |
42 | /* Design considerations | |
43 | ||
44 | General rule: optimize for developer time, not run time. | |
45 | ||
46 | Specifically: | |
47 | ||
48 | * Don't worry about slow algorithms | |
49 | * Don't worry about free'ing memory | |
50 | * Don't implement anything the testsuite doesn't need. | |
51 | * Line and argument counts are limited, see below. | |
52 | ||
53 | */ | |
54 | ||
55 | #define MAX_ARG_COUNT 100 | |
56 | #define MAX_LINE_LENGTH 1000 | |
57 | ||
58 | /* Debugging is enabled via --debug, which must be the first argument. */ | |
59 | static int debug_mode = 0; | |
60 | #define dprintf if (debug_mode) fprintf | |
61 | ||
62 | /* Emulate the "/bin/true" command. Arguments are ignored. */ | |
63 | static int | |
64 | true_func (char **argv) | |
65 | { | |
66 | return 0; | |
67 | } | |
68 | ||
69 | /* Emulate the "/bin/echo" command. Options are ignored, arguments | |
70 | are printed to stdout. */ | |
71 | static int | |
72 | echo_func (char **argv) | |
73 | { | |
74 | int i; | |
75 | ||
76 | for (i = 0; argv[i]; i++) | |
77 | { | |
78 | if (i > 0) | |
79 | putchar (' '); | |
80 | fputs (argv[i], stdout); | |
81 | } | |
82 | putchar ('\n'); | |
83 | ||
84 | return 0; | |
85 | } | |
86 | ||
87 | /* Emulate the "/bin/cp" command. Options are ignored. Only copies | |
88 | one source file to one destination file. Directory destinations | |
89 | are not supported. */ | |
90 | static int | |
91 | copy_func (char **argv) | |
92 | { | |
93 | char *sname = argv[0]; | |
94 | char *dname = argv[1]; | |
75fe6d1a | 95 | int sfd = -1, dfd = -1; |
561b0bec | 96 | struct stat st; |
75fe6d1a | 97 | int ret = 1; |
561b0bec DD |
98 | |
99 | sfd = open (sname, O_RDONLY); | |
100 | if (sfd < 0) | |
101 | { | |
102 | fprintf (stderr, "cp: unable to open %s for reading: %s\n", | |
103 | sname, strerror (errno)); | |
104 | return 1; | |
105 | } | |
106 | ||
107 | if (fstat (sfd, &st) < 0) | |
108 | { | |
109 | fprintf (stderr, "cp: unable to fstat %s: %s\n", | |
110 | sname, strerror (errno)); | |
75fe6d1a | 111 | goto out; |
561b0bec DD |
112 | } |
113 | ||
114 | dfd = open (dname, O_WRONLY | O_TRUNC | O_CREAT, 0600); | |
115 | if (dfd < 0) | |
116 | { | |
117 | fprintf (stderr, "cp: unable to open %s for writing: %s\n", | |
118 | dname, strerror (errno)); | |
75fe6d1a | 119 | goto out; |
561b0bec DD |
120 | } |
121 | ||
6e36266c | 122 | if (support_copy_file_range (sfd, 0, dfd, 0, st.st_size, 0) != st.st_size) |
561b0bec DD |
123 | { |
124 | fprintf (stderr, "cp: cannot copy file %s to %s: %s\n", | |
125 | sname, dname, strerror (errno)); | |
75fe6d1a | 126 | goto out; |
561b0bec DD |
127 | } |
128 | ||
75fe6d1a | 129 | ret = 0; |
561b0bec DD |
130 | chmod (dname, st.st_mode & 0777); |
131 | ||
75fe6d1a SP |
132 | out: |
133 | if (sfd >= 0) | |
134 | close (sfd); | |
135 | if (dfd >= 0) | |
136 | close (dfd); | |
137 | ||
138 | return ret; | |
561b0bec DD |
139 | |
140 | } | |
141 | ||
5a5a3a32 AZ |
142 | /* Emulate the 'exit' builtin. The exit value is optional. */ |
143 | static int | |
144 | exit_func (char **argv) | |
145 | { | |
146 | int exit_val = 0; | |
147 | ||
148 | if (argv[0] != 0) | |
149 | exit_val = atoi (argv[0]) & 0xff; | |
150 | exit (exit_val); | |
151 | return 0; | |
152 | } | |
153 | ||
1c17100c AZ |
154 | /* Emulate the "/bin/kill" command. Options are ignored. */ |
155 | static int | |
156 | kill_func (char **argv) | |
157 | { | |
158 | int signum = SIGTERM; | |
159 | int i; | |
160 | ||
161 | for (i = 0; argv[i]; i++) | |
162 | { | |
163 | pid_t pid; | |
164 | if (strcmp (argv[i], "$$") == 0) | |
165 | pid = getpid (); | |
166 | else | |
167 | pid = atoi (argv[i]); | |
168 | kill (pid, signum); | |
169 | } | |
170 | return 0; | |
171 | } | |
172 | ||
436a604b AY |
173 | /* Emulate the "/bin/sleep" command. No suffix support. Options are |
174 | ignored. */ | |
175 | static int | |
176 | sleep_func (char **argv) | |
177 | { | |
178 | if (argv[0] == NULL) | |
179 | { | |
180 | fprintf (stderr, "sleep: missing operand\n"); | |
181 | return 1; | |
182 | } | |
183 | char *endptr = NULL; | |
184 | double sec = strtod (argv[0], &endptr); | |
185 | if (endptr == argv[0] || errno == ERANGE || sec < 0) | |
186 | { | |
187 | fprintf (stderr, "sleep: invalid time interval '%s'\n", argv[0]); | |
188 | return 1; | |
189 | } | |
190 | struct timespec ts = dtotimespec (sec); | |
191 | if (nanosleep (&ts, NULL) < 0) | |
192 | { | |
193 | fprintf (stderr, "sleep: failed to nanosleep: %s\n", strerror (errno)); | |
194 | return 1; | |
195 | } | |
196 | return 0; | |
197 | } | |
198 | ||
561b0bec DD |
199 | /* This is a list of all the built-in commands we understand. */ |
200 | static struct { | |
201 | const char *name; | |
202 | int (*func) (char **argv); | |
203 | } builtin_funcs[] = { | |
204 | { "true", true_func }, | |
205 | { "echo", echo_func }, | |
206 | { "cp", copy_func }, | |
5a5a3a32 | 207 | { "exit", exit_func }, |
1c17100c | 208 | { "kill", kill_func }, |
436a604b | 209 | { "sleep", sleep_func }, |
561b0bec DD |
210 | { NULL, NULL } |
211 | }; | |
212 | ||
213 | /* Run one tokenized command. argv[0] is the command. argv is | |
214 | NULL-terminated. */ | |
215 | static void | |
216 | run_command_array (char **argv) | |
217 | { | |
218 | int i, j; | |
219 | pid_t pid; | |
220 | int status; | |
221 | int (*builtin_func) (char **args); | |
222 | ||
223 | if (argv[0] == NULL) | |
224 | return; | |
225 | ||
226 | builtin_func = NULL; | |
227 | ||
228 | int new_stdin = 0; | |
229 | int new_stdout = 1; | |
230 | int new_stderr = 2; | |
231 | ||
232 | dprintf (stderr, "run_command_array starting\n"); | |
233 | for (i = 0; argv[i]; i++) | |
234 | dprintf (stderr, " argv [%d] `%s'\n", i, argv[i]); | |
235 | ||
236 | for (j = i = 0; argv[i]; i++) | |
237 | { | |
238 | if (strcmp (argv[i], "<") == 0 && argv[i + 1]) | |
239 | { | |
240 | new_stdin = open (argv[i + 1], O_WRONLY|O_CREAT|O_TRUNC, 0777); | |
241 | ++i; | |
242 | continue; | |
243 | } | |
244 | if (strcmp (argv[i], ">") == 0 && argv[i + 1]) | |
245 | { | |
246 | new_stdout = open (argv[i + 1], O_WRONLY|O_CREAT|O_TRUNC, 0777); | |
247 | ++i; | |
248 | continue; | |
249 | } | |
250 | if (strcmp (argv[i], ">>") == 0 && argv[i + 1]) | |
251 | { | |
252 | new_stdout = open (argv[i + 1], O_WRONLY|O_CREAT|O_APPEND, 0777); | |
253 | ++i; | |
254 | continue; | |
255 | } | |
256 | if (strcmp (argv[i], "2>") == 0 && argv[i + 1]) | |
257 | { | |
258 | new_stderr = open (argv[i + 1], O_WRONLY|O_CREAT|O_TRUNC, 0777); | |
259 | ++i; | |
260 | continue; | |
261 | } | |
262 | argv[j++] = argv[i]; | |
263 | } | |
264 | argv[j] = NULL; | |
265 | ||
266 | ||
267 | for (i = 0; builtin_funcs[i].name != NULL; i++) | |
268 | if (strcmp (argv[0], builtin_funcs[i].name) == 0) | |
269 | builtin_func = builtin_funcs[i].func; | |
270 | ||
271 | dprintf (stderr, "builtin %p argv0 `%s'\n", builtin_func, argv[0]); | |
272 | ||
273 | pid = fork (); | |
274 | if (pid < 0) | |
275 | { | |
276 | fprintf (stderr, "sh: fork failed\n"); | |
277 | exit (1); | |
278 | } | |
279 | ||
280 | if (pid == 0) | |
281 | { | |
282 | if (new_stdin != 0) | |
283 | { | |
284 | dup2 (new_stdin, 0); | |
285 | close (new_stdin); | |
286 | } | |
287 | if (new_stdout != 1) | |
288 | { | |
289 | dup2 (new_stdout, 1); | |
290 | close (new_stdout); | |
291 | } | |
292 | if (new_stderr != 2) | |
293 | { | |
294 | dup2 (new_stderr, 2); | |
542160f0 | 295 | close (new_stderr); |
561b0bec DD |
296 | } |
297 | ||
298 | if (builtin_func != NULL) | |
299 | exit (builtin_func (argv + 1)); | |
300 | ||
301 | execvp (argv[0], argv); | |
302 | ||
303 | fprintf (stderr, "sh: execing %s failed: %s", | |
304 | argv[0], strerror (errno)); | |
5fce0e09 | 305 | exit (127); |
561b0bec DD |
306 | } |
307 | ||
308 | waitpid (pid, &status, 0); | |
309 | ||
310 | dprintf (stderr, "exiting run_command_array\n"); | |
311 | ||
312 | if (WIFEXITED (status)) | |
313 | { | |
314 | int rv = WEXITSTATUS (status); | |
315 | if (rv) | |
316 | exit (rv); | |
317 | } | |
1c17100c AZ |
318 | else if (WIFSIGNALED (status)) |
319 | { | |
320 | int sig = WTERMSIG (status); | |
321 | raise (sig); | |
322 | } | |
561b0bec DD |
323 | else |
324 | exit (1); | |
325 | } | |
326 | ||
327 | /* Run one command-as-a-string, by tokenizing it. Limited to | |
328 | MAX_ARG_COUNT arguments. Simple substitution is done of $1 to $9 | |
329 | (as whole separate tokens) from iargs[]. Quoted strings work if | |
330 | the quotes wrap whole tokens; i.e. "foo bar" but not foo" bar". */ | |
331 | static void | |
332 | run_command_string (const char *cmdline, const char **iargs) | |
333 | { | |
334 | char *args[MAX_ARG_COUNT+1]; | |
335 | int ap = 0; | |
336 | const char *start, *end; | |
337 | int nargs; | |
338 | ||
339 | for (nargs = 0; iargs[nargs] != NULL; ++nargs) | |
340 | ; | |
341 | ||
342 | dprintf (stderr, "run_command_string starting: '%s'\n", cmdline); | |
343 | ||
344 | while (ap < MAX_ARG_COUNT) | |
345 | { | |
346 | /* If the argument is quoted, this is the quote character, else NUL. */ | |
347 | int in_quote = 0; | |
348 | ||
349 | /* Skip whitespace up to the next token. */ | |
350 | while (*cmdline && isspace (*cmdline)) | |
351 | cmdline ++; | |
352 | if (*cmdline == 0) | |
353 | break; | |
354 | ||
355 | start = cmdline; | |
356 | /* Check for quoted argument. */ | |
357 | in_quote = (*cmdline == '\'' || *cmdline == '"') ? *cmdline : 0; | |
358 | ||
359 | /* Skip to end of token; either by whitespace or matching quote. */ | |
360 | dprintf (stderr, "in_quote %d\n", in_quote); | |
361 | while (*cmdline | |
362 | && (!isspace (*cmdline) || in_quote)) | |
363 | { | |
364 | if (*cmdline == in_quote | |
365 | && cmdline != start) | |
366 | in_quote = 0; | |
367 | dprintf (stderr, "[%c]%d ", *cmdline, in_quote); | |
368 | cmdline ++; | |
369 | } | |
370 | dprintf (stderr, "\n"); | |
371 | ||
372 | /* Allocate space for this token and store it in args[]. */ | |
373 | end = cmdline; | |
374 | dprintf (stderr, "start<%s> end<%s>\n", start, end); | |
375 | args[ap] = (char *) xmalloc (end - start + 1); | |
376 | memcpy (args[ap], start, end - start); | |
377 | args[ap][end - start] = 0; | |
378 | ||
379 | /* Strip off quotes, if found. */ | |
380 | dprintf (stderr, "args[%d] = <%s>\n", ap, args[ap]); | |
381 | if (args[ap][0] == '\'' | |
382 | && args[ap][strlen (args[ap])-1] == '\'') | |
383 | { | |
384 | args[ap][strlen (args[ap])-1] = 0; | |
385 | args[ap] ++; | |
386 | } | |
387 | ||
388 | else if (args[ap][0] == '"' | |
389 | && args[ap][strlen (args[ap])-1] == '"') | |
390 | { | |
391 | args[ap][strlen (args[ap])-1] = 0; | |
392 | args[ap] ++; | |
393 | } | |
394 | ||
395 | /* Replace positional parameters like $4. */ | |
396 | else if (args[ap][0] == '$' | |
397 | && isdigit (args[ap][1]) | |
398 | && args[ap][2] == 0) | |
399 | { | |
400 | int a = args[ap][1] - '1'; | |
401 | if (0 <= a && a < nargs) | |
402 | args[ap] = strdup (iargs[a]); | |
403 | } | |
404 | ||
405 | ap ++; | |
406 | ||
407 | if (*cmdline == 0) | |
408 | break; | |
409 | } | |
410 | ||
411 | /* Lastly, NULL terminate the array and run it. */ | |
412 | args[ap] = NULL; | |
413 | run_command_array (args); | |
414 | } | |
415 | ||
416 | /* Run a script by reading lines and passing them to the above | |
417 | function. */ | |
418 | static void | |
419 | run_script (const char *filename, const char **args) | |
420 | { | |
421 | char line[MAX_LINE_LENGTH + 1]; | |
422 | dprintf (stderr, "run_script starting: '%s'\n", filename); | |
423 | FILE *f = fopen (filename, "r"); | |
424 | if (f == NULL) | |
425 | { | |
426 | fprintf (stderr, "sh: %s: %s\n", filename, strerror (errno)); | |
427 | exit (1); | |
428 | } | |
429 | while (fgets (line, sizeof (line), f) != NULL) | |
430 | { | |
431 | if (line[0] == '#') | |
432 | { | |
433 | dprintf (stderr, "comment: %s\n", line); | |
434 | continue; | |
435 | } | |
436 | run_command_string (line, args); | |
437 | } | |
438 | fclose (f); | |
439 | } | |
440 | ||
441 | int | |
442 | main (int argc, const char **argv) | |
443 | { | |
444 | int i; | |
445 | ||
446 | if (strcmp (argv[1], "--debug") == 0) | |
447 | { | |
448 | debug_mode = 1; | |
449 | --argc; | |
450 | ++argv; | |
451 | } | |
452 | ||
453 | dprintf (stderr, "container-sh starting:\n"); | |
454 | for (i = 0; i < argc; i++) | |
455 | dprintf (stderr, " argv[%d] is `%s'\n", i, argv[i]); | |
456 | ||
457 | if (strcmp (argv[1], "-c") == 0) | |
868506eb JST |
458 | { |
459 | if (strcmp (argv[2], "--") == 0) | |
460 | run_command_string (argv[3], argv+4); | |
461 | else | |
462 | run_command_string (argv[2], argv+3); | |
463 | } | |
561b0bec DD |
464 | else |
465 | run_script (argv[1], argv+2); | |
466 | ||
467 | dprintf (stderr, "normal exit 0\n"); | |
468 | return 0; | |
469 | } |