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561b0bec | 1 | /* Minimal /bin/sh for in-container use. |
2b778ceb | 2 | Copyright (C) 2018-2021 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 DD |
18 | |
19 | #define _FILE_OFFSET_BITS 64 | |
20 | ||
21 | #include <stdio.h> | |
22 | #include <stdlib.h> | |
23 | #include <string.h> | |
24 | #include <sched.h> | |
25 | #include <sys/syscall.h> | |
26 | #include <unistd.h> | |
27 | #include <sys/types.h> | |
28 | #include <dirent.h> | |
29 | #include <string.h> | |
30 | #include <sys/stat.h> | |
31 | #include <sys/fcntl.h> | |
32 | #include <sys/file.h> | |
33 | #include <sys/wait.h> | |
34 | #include <stdarg.h> | |
35 | #include <sys/sysmacros.h> | |
36 | #include <ctype.h> | |
37 | #include <utime.h> | |
38 | #include <errno.h> | |
39 | #include <error.h> | |
40 | ||
41 | #include <support/support.h> | |
42 | ||
43 | /* Design considerations | |
44 | ||
45 | General rule: optimize for developer time, not run time. | |
46 | ||
47 | Specifically: | |
48 | ||
49 | * Don't worry about slow algorithms | |
50 | * Don't worry about free'ing memory | |
51 | * Don't implement anything the testsuite doesn't need. | |
52 | * Line and argument counts are limited, see below. | |
53 | ||
54 | */ | |
55 | ||
56 | #define MAX_ARG_COUNT 100 | |
57 | #define MAX_LINE_LENGTH 1000 | |
58 | ||
59 | /* Debugging is enabled via --debug, which must be the first argument. */ | |
60 | static int debug_mode = 0; | |
61 | #define dprintf if (debug_mode) fprintf | |
62 | ||
63 | /* Emulate the "/bin/true" command. Arguments are ignored. */ | |
64 | static int | |
65 | true_func (char **argv) | |
66 | { | |
67 | return 0; | |
68 | } | |
69 | ||
70 | /* Emulate the "/bin/echo" command. Options are ignored, arguments | |
71 | are printed to stdout. */ | |
72 | static int | |
73 | echo_func (char **argv) | |
74 | { | |
75 | int i; | |
76 | ||
77 | for (i = 0; argv[i]; i++) | |
78 | { | |
79 | if (i > 0) | |
80 | putchar (' '); | |
81 | fputs (argv[i], stdout); | |
82 | } | |
83 | putchar ('\n'); | |
84 | ||
85 | return 0; | |
86 | } | |
87 | ||
88 | /* Emulate the "/bin/cp" command. Options are ignored. Only copies | |
89 | one source file to one destination file. Directory destinations | |
90 | are not supported. */ | |
91 | static int | |
92 | copy_func (char **argv) | |
93 | { | |
94 | char *sname = argv[0]; | |
95 | char *dname = argv[1]; | |
75fe6d1a | 96 | int sfd = -1, dfd = -1; |
561b0bec | 97 | struct stat st; |
75fe6d1a | 98 | int ret = 1; |
561b0bec DD |
99 | |
100 | sfd = open (sname, O_RDONLY); | |
101 | if (sfd < 0) | |
102 | { | |
103 | fprintf (stderr, "cp: unable to open %s for reading: %s\n", | |
104 | sname, strerror (errno)); | |
105 | return 1; | |
106 | } | |
107 | ||
108 | if (fstat (sfd, &st) < 0) | |
109 | { | |
110 | fprintf (stderr, "cp: unable to fstat %s: %s\n", | |
111 | sname, strerror (errno)); | |
75fe6d1a | 112 | goto out; |
561b0bec DD |
113 | } |
114 | ||
115 | dfd = open (dname, O_WRONLY | O_TRUNC | O_CREAT, 0600); | |
116 | if (dfd < 0) | |
117 | { | |
118 | fprintf (stderr, "cp: unable to open %s for writing: %s\n", | |
119 | dname, strerror (errno)); | |
75fe6d1a | 120 | goto out; |
561b0bec DD |
121 | } |
122 | ||
6e36266c | 123 | if (support_copy_file_range (sfd, 0, dfd, 0, st.st_size, 0) != st.st_size) |
561b0bec DD |
124 | { |
125 | fprintf (stderr, "cp: cannot copy file %s to %s: %s\n", | |
126 | sname, dname, strerror (errno)); | |
75fe6d1a | 127 | goto out; |
561b0bec DD |
128 | } |
129 | ||
75fe6d1a | 130 | ret = 0; |
561b0bec DD |
131 | chmod (dname, st.st_mode & 0777); |
132 | ||
75fe6d1a SP |
133 | out: |
134 | if (sfd >= 0) | |
135 | close (sfd); | |
136 | if (dfd >= 0) | |
137 | close (dfd); | |
138 | ||
139 | return ret; | |
561b0bec DD |
140 | |
141 | } | |
142 | ||
5a5a3a32 AZ |
143 | /* Emulate the 'exit' builtin. The exit value is optional. */ |
144 | static int | |
145 | exit_func (char **argv) | |
146 | { | |
147 | int exit_val = 0; | |
148 | ||
149 | if (argv[0] != 0) | |
150 | exit_val = atoi (argv[0]) & 0xff; | |
151 | exit (exit_val); | |
152 | return 0; | |
153 | } | |
154 | ||
1c17100c AZ |
155 | /* Emulate the "/bin/kill" command. Options are ignored. */ |
156 | static int | |
157 | kill_func (char **argv) | |
158 | { | |
159 | int signum = SIGTERM; | |
160 | int i; | |
161 | ||
162 | for (i = 0; argv[i]; i++) | |
163 | { | |
164 | pid_t pid; | |
165 | if (strcmp (argv[i], "$$") == 0) | |
166 | pid = getpid (); | |
167 | else | |
168 | pid = atoi (argv[i]); | |
169 | kill (pid, signum); | |
170 | } | |
171 | return 0; | |
172 | } | |
173 | ||
561b0bec DD |
174 | /* This is a list of all the built-in commands we understand. */ |
175 | static struct { | |
176 | const char *name; | |
177 | int (*func) (char **argv); | |
178 | } builtin_funcs[] = { | |
179 | { "true", true_func }, | |
180 | { "echo", echo_func }, | |
181 | { "cp", copy_func }, | |
5a5a3a32 | 182 | { "exit", exit_func }, |
1c17100c | 183 | { "kill", kill_func }, |
561b0bec DD |
184 | { NULL, NULL } |
185 | }; | |
186 | ||
187 | /* Run one tokenized command. argv[0] is the command. argv is | |
188 | NULL-terminated. */ | |
189 | static void | |
190 | run_command_array (char **argv) | |
191 | { | |
192 | int i, j; | |
193 | pid_t pid; | |
194 | int status; | |
195 | int (*builtin_func) (char **args); | |
196 | ||
197 | if (argv[0] == NULL) | |
198 | return; | |
199 | ||
200 | builtin_func = NULL; | |
201 | ||
202 | int new_stdin = 0; | |
203 | int new_stdout = 1; | |
204 | int new_stderr = 2; | |
205 | ||
206 | dprintf (stderr, "run_command_array starting\n"); | |
207 | for (i = 0; argv[i]; i++) | |
208 | dprintf (stderr, " argv [%d] `%s'\n", i, argv[i]); | |
209 | ||
210 | for (j = i = 0; argv[i]; i++) | |
211 | { | |
212 | if (strcmp (argv[i], "<") == 0 && argv[i + 1]) | |
213 | { | |
214 | new_stdin = open (argv[i + 1], O_WRONLY|O_CREAT|O_TRUNC, 0777); | |
215 | ++i; | |
216 | continue; | |
217 | } | |
218 | if (strcmp (argv[i], ">") == 0 && argv[i + 1]) | |
219 | { | |
220 | new_stdout = open (argv[i + 1], O_WRONLY|O_CREAT|O_TRUNC, 0777); | |
221 | ++i; | |
222 | continue; | |
223 | } | |
224 | if (strcmp (argv[i], ">>") == 0 && argv[i + 1]) | |
225 | { | |
226 | new_stdout = open (argv[i + 1], O_WRONLY|O_CREAT|O_APPEND, 0777); | |
227 | ++i; | |
228 | continue; | |
229 | } | |
230 | if (strcmp (argv[i], "2>") == 0 && argv[i + 1]) | |
231 | { | |
232 | new_stderr = open (argv[i + 1], O_WRONLY|O_CREAT|O_TRUNC, 0777); | |
233 | ++i; | |
234 | continue; | |
235 | } | |
236 | argv[j++] = argv[i]; | |
237 | } | |
238 | argv[j] = NULL; | |
239 | ||
240 | ||
241 | for (i = 0; builtin_funcs[i].name != NULL; i++) | |
242 | if (strcmp (argv[0], builtin_funcs[i].name) == 0) | |
243 | builtin_func = builtin_funcs[i].func; | |
244 | ||
245 | dprintf (stderr, "builtin %p argv0 `%s'\n", builtin_func, argv[0]); | |
246 | ||
247 | pid = fork (); | |
248 | if (pid < 0) | |
249 | { | |
250 | fprintf (stderr, "sh: fork failed\n"); | |
251 | exit (1); | |
252 | } | |
253 | ||
254 | if (pid == 0) | |
255 | { | |
256 | if (new_stdin != 0) | |
257 | { | |
258 | dup2 (new_stdin, 0); | |
259 | close (new_stdin); | |
260 | } | |
261 | if (new_stdout != 1) | |
262 | { | |
263 | dup2 (new_stdout, 1); | |
264 | close (new_stdout); | |
265 | } | |
266 | if (new_stderr != 2) | |
267 | { | |
268 | dup2 (new_stderr, 2); | |
542160f0 | 269 | close (new_stderr); |
561b0bec DD |
270 | } |
271 | ||
272 | if (builtin_func != NULL) | |
273 | exit (builtin_func (argv + 1)); | |
274 | ||
275 | execvp (argv[0], argv); | |
276 | ||
277 | fprintf (stderr, "sh: execing %s failed: %s", | |
278 | argv[0], strerror (errno)); | |
5fce0e09 | 279 | exit (127); |
561b0bec DD |
280 | } |
281 | ||
282 | waitpid (pid, &status, 0); | |
283 | ||
284 | dprintf (stderr, "exiting run_command_array\n"); | |
285 | ||
286 | if (WIFEXITED (status)) | |
287 | { | |
288 | int rv = WEXITSTATUS (status); | |
289 | if (rv) | |
290 | exit (rv); | |
291 | } | |
1c17100c AZ |
292 | else if (WIFSIGNALED (status)) |
293 | { | |
294 | int sig = WTERMSIG (status); | |
295 | raise (sig); | |
296 | } | |
561b0bec DD |
297 | else |
298 | exit (1); | |
299 | } | |
300 | ||
301 | /* Run one command-as-a-string, by tokenizing it. Limited to | |
302 | MAX_ARG_COUNT arguments. Simple substitution is done of $1 to $9 | |
303 | (as whole separate tokens) from iargs[]. Quoted strings work if | |
304 | the quotes wrap whole tokens; i.e. "foo bar" but not foo" bar". */ | |
305 | static void | |
306 | run_command_string (const char *cmdline, const char **iargs) | |
307 | { | |
308 | char *args[MAX_ARG_COUNT+1]; | |
309 | int ap = 0; | |
310 | const char *start, *end; | |
311 | int nargs; | |
312 | ||
313 | for (nargs = 0; iargs[nargs] != NULL; ++nargs) | |
314 | ; | |
315 | ||
316 | dprintf (stderr, "run_command_string starting: '%s'\n", cmdline); | |
317 | ||
318 | while (ap < MAX_ARG_COUNT) | |
319 | { | |
320 | /* If the argument is quoted, this is the quote character, else NUL. */ | |
321 | int in_quote = 0; | |
322 | ||
323 | /* Skip whitespace up to the next token. */ | |
324 | while (*cmdline && isspace (*cmdline)) | |
325 | cmdline ++; | |
326 | if (*cmdline == 0) | |
327 | break; | |
328 | ||
329 | start = cmdline; | |
330 | /* Check for quoted argument. */ | |
331 | in_quote = (*cmdline == '\'' || *cmdline == '"') ? *cmdline : 0; | |
332 | ||
333 | /* Skip to end of token; either by whitespace or matching quote. */ | |
334 | dprintf (stderr, "in_quote %d\n", in_quote); | |
335 | while (*cmdline | |
336 | && (!isspace (*cmdline) || in_quote)) | |
337 | { | |
338 | if (*cmdline == in_quote | |
339 | && cmdline != start) | |
340 | in_quote = 0; | |
341 | dprintf (stderr, "[%c]%d ", *cmdline, in_quote); | |
342 | cmdline ++; | |
343 | } | |
344 | dprintf (stderr, "\n"); | |
345 | ||
346 | /* Allocate space for this token and store it in args[]. */ | |
347 | end = cmdline; | |
348 | dprintf (stderr, "start<%s> end<%s>\n", start, end); | |
349 | args[ap] = (char *) xmalloc (end - start + 1); | |
350 | memcpy (args[ap], start, end - start); | |
351 | args[ap][end - start] = 0; | |
352 | ||
353 | /* Strip off quotes, if found. */ | |
354 | dprintf (stderr, "args[%d] = <%s>\n", ap, args[ap]); | |
355 | if (args[ap][0] == '\'' | |
356 | && args[ap][strlen (args[ap])-1] == '\'') | |
357 | { | |
358 | args[ap][strlen (args[ap])-1] = 0; | |
359 | args[ap] ++; | |
360 | } | |
361 | ||
362 | else if (args[ap][0] == '"' | |
363 | && args[ap][strlen (args[ap])-1] == '"') | |
364 | { | |
365 | args[ap][strlen (args[ap])-1] = 0; | |
366 | args[ap] ++; | |
367 | } | |
368 | ||
369 | /* Replace positional parameters like $4. */ | |
370 | else if (args[ap][0] == '$' | |
371 | && isdigit (args[ap][1]) | |
372 | && args[ap][2] == 0) | |
373 | { | |
374 | int a = args[ap][1] - '1'; | |
375 | if (0 <= a && a < nargs) | |
376 | args[ap] = strdup (iargs[a]); | |
377 | } | |
378 | ||
379 | ap ++; | |
380 | ||
381 | if (*cmdline == 0) | |
382 | break; | |
383 | } | |
384 | ||
385 | /* Lastly, NULL terminate the array and run it. */ | |
386 | args[ap] = NULL; | |
387 | run_command_array (args); | |
388 | } | |
389 | ||
390 | /* Run a script by reading lines and passing them to the above | |
391 | function. */ | |
392 | static void | |
393 | run_script (const char *filename, const char **args) | |
394 | { | |
395 | char line[MAX_LINE_LENGTH + 1]; | |
396 | dprintf (stderr, "run_script starting: '%s'\n", filename); | |
397 | FILE *f = fopen (filename, "r"); | |
398 | if (f == NULL) | |
399 | { | |
400 | fprintf (stderr, "sh: %s: %s\n", filename, strerror (errno)); | |
401 | exit (1); | |
402 | } | |
403 | while (fgets (line, sizeof (line), f) != NULL) | |
404 | { | |
405 | if (line[0] == '#') | |
406 | { | |
407 | dprintf (stderr, "comment: %s\n", line); | |
408 | continue; | |
409 | } | |
410 | run_command_string (line, args); | |
411 | } | |
412 | fclose (f); | |
413 | } | |
414 | ||
415 | int | |
416 | main (int argc, const char **argv) | |
417 | { | |
418 | int i; | |
419 | ||
420 | if (strcmp (argv[1], "--debug") == 0) | |
421 | { | |
422 | debug_mode = 1; | |
423 | --argc; | |
424 | ++argv; | |
425 | } | |
426 | ||
427 | dprintf (stderr, "container-sh starting:\n"); | |
428 | for (i = 0; i < argc; i++) | |
429 | dprintf (stderr, " argv[%d] is `%s'\n", i, argv[i]); | |
430 | ||
431 | if (strcmp (argv[1], "-c") == 0) | |
432 | run_command_string (argv[2], argv+3); | |
433 | else | |
434 | run_script (argv[1], argv+2); | |
435 | ||
436 | dprintf (stderr, "normal exit 0\n"); | |
437 | return 0; | |
438 | } |