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561b0bec | 1 | /* Minimal /bin/sh for in-container use. |
d614a753 | 2 | Copyright (C) 2018-2020 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]; | |
96 | int sfd, dfd; | |
97 | struct stat st; | |
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)); | |
111 | return 1; | |
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)); | |
119 | return 1; | |
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)); | |
126 | return 1; | |
127 | } | |
128 | ||
129 | close (sfd); | |
130 | close (dfd); | |
131 | ||
132 | chmod (dname, st.st_mode & 0777); | |
133 | ||
134 | return 0; | |
135 | ||
136 | } | |
137 | ||
5a5a3a32 AZ |
138 | /* Emulate the 'exit' builtin. The exit value is optional. */ |
139 | static int | |
140 | exit_func (char **argv) | |
141 | { | |
142 | int exit_val = 0; | |
143 | ||
144 | if (argv[0] != 0) | |
145 | exit_val = atoi (argv[0]) & 0xff; | |
146 | exit (exit_val); | |
147 | return 0; | |
148 | } | |
149 | ||
561b0bec DD |
150 | /* This is a list of all the built-in commands we understand. */ |
151 | static struct { | |
152 | const char *name; | |
153 | int (*func) (char **argv); | |
154 | } builtin_funcs[] = { | |
155 | { "true", true_func }, | |
156 | { "echo", echo_func }, | |
157 | { "cp", copy_func }, | |
5a5a3a32 | 158 | { "exit", exit_func }, |
561b0bec DD |
159 | { NULL, NULL } |
160 | }; | |
161 | ||
162 | /* Run one tokenized command. argv[0] is the command. argv is | |
163 | NULL-terminated. */ | |
164 | static void | |
165 | run_command_array (char **argv) | |
166 | { | |
167 | int i, j; | |
168 | pid_t pid; | |
169 | int status; | |
170 | int (*builtin_func) (char **args); | |
171 | ||
172 | if (argv[0] == NULL) | |
173 | return; | |
174 | ||
175 | builtin_func = NULL; | |
176 | ||
177 | int new_stdin = 0; | |
178 | int new_stdout = 1; | |
179 | int new_stderr = 2; | |
180 | ||
181 | dprintf (stderr, "run_command_array starting\n"); | |
182 | for (i = 0; argv[i]; i++) | |
183 | dprintf (stderr, " argv [%d] `%s'\n", i, argv[i]); | |
184 | ||
185 | for (j = i = 0; argv[i]; i++) | |
186 | { | |
187 | if (strcmp (argv[i], "<") == 0 && argv[i + 1]) | |
188 | { | |
189 | new_stdin = open (argv[i + 1], O_WRONLY|O_CREAT|O_TRUNC, 0777); | |
190 | ++i; | |
191 | continue; | |
192 | } | |
193 | if (strcmp (argv[i], ">") == 0 && argv[i + 1]) | |
194 | { | |
195 | new_stdout = open (argv[i + 1], O_WRONLY|O_CREAT|O_TRUNC, 0777); | |
196 | ++i; | |
197 | continue; | |
198 | } | |
199 | if (strcmp (argv[i], ">>") == 0 && argv[i + 1]) | |
200 | { | |
201 | new_stdout = open (argv[i + 1], O_WRONLY|O_CREAT|O_APPEND, 0777); | |
202 | ++i; | |
203 | continue; | |
204 | } | |
205 | if (strcmp (argv[i], "2>") == 0 && argv[i + 1]) | |
206 | { | |
207 | new_stderr = open (argv[i + 1], O_WRONLY|O_CREAT|O_TRUNC, 0777); | |
208 | ++i; | |
209 | continue; | |
210 | } | |
211 | argv[j++] = argv[i]; | |
212 | } | |
213 | argv[j] = NULL; | |
214 | ||
215 | ||
216 | for (i = 0; builtin_funcs[i].name != NULL; i++) | |
217 | if (strcmp (argv[0], builtin_funcs[i].name) == 0) | |
218 | builtin_func = builtin_funcs[i].func; | |
219 | ||
220 | dprintf (stderr, "builtin %p argv0 `%s'\n", builtin_func, argv[0]); | |
221 | ||
222 | pid = fork (); | |
223 | if (pid < 0) | |
224 | { | |
225 | fprintf (stderr, "sh: fork failed\n"); | |
226 | exit (1); | |
227 | } | |
228 | ||
229 | if (pid == 0) | |
230 | { | |
231 | if (new_stdin != 0) | |
232 | { | |
233 | dup2 (new_stdin, 0); | |
234 | close (new_stdin); | |
235 | } | |
236 | if (new_stdout != 1) | |
237 | { | |
238 | dup2 (new_stdout, 1); | |
239 | close (new_stdout); | |
240 | } | |
241 | if (new_stderr != 2) | |
242 | { | |
243 | dup2 (new_stderr, 2); | |
542160f0 | 244 | close (new_stderr); |
561b0bec DD |
245 | } |
246 | ||
247 | if (builtin_func != NULL) | |
248 | exit (builtin_func (argv + 1)); | |
249 | ||
250 | execvp (argv[0], argv); | |
251 | ||
252 | fprintf (stderr, "sh: execing %s failed: %s", | |
253 | argv[0], strerror (errno)); | |
5fce0e09 | 254 | exit (127); |
561b0bec DD |
255 | } |
256 | ||
257 | waitpid (pid, &status, 0); | |
258 | ||
259 | dprintf (stderr, "exiting run_command_array\n"); | |
260 | ||
261 | if (WIFEXITED (status)) | |
262 | { | |
263 | int rv = WEXITSTATUS (status); | |
264 | if (rv) | |
265 | exit (rv); | |
266 | } | |
267 | else | |
268 | exit (1); | |
269 | } | |
270 | ||
271 | /* Run one command-as-a-string, by tokenizing it. Limited to | |
272 | MAX_ARG_COUNT arguments. Simple substitution is done of $1 to $9 | |
273 | (as whole separate tokens) from iargs[]. Quoted strings work if | |
274 | the quotes wrap whole tokens; i.e. "foo bar" but not foo" bar". */ | |
275 | static void | |
276 | run_command_string (const char *cmdline, const char **iargs) | |
277 | { | |
278 | char *args[MAX_ARG_COUNT+1]; | |
279 | int ap = 0; | |
280 | const char *start, *end; | |
281 | int nargs; | |
282 | ||
283 | for (nargs = 0; iargs[nargs] != NULL; ++nargs) | |
284 | ; | |
285 | ||
286 | dprintf (stderr, "run_command_string starting: '%s'\n", cmdline); | |
287 | ||
288 | while (ap < MAX_ARG_COUNT) | |
289 | { | |
290 | /* If the argument is quoted, this is the quote character, else NUL. */ | |
291 | int in_quote = 0; | |
292 | ||
293 | /* Skip whitespace up to the next token. */ | |
294 | while (*cmdline && isspace (*cmdline)) | |
295 | cmdline ++; | |
296 | if (*cmdline == 0) | |
297 | break; | |
298 | ||
299 | start = cmdline; | |
300 | /* Check for quoted argument. */ | |
301 | in_quote = (*cmdline == '\'' || *cmdline == '"') ? *cmdline : 0; | |
302 | ||
303 | /* Skip to end of token; either by whitespace or matching quote. */ | |
304 | dprintf (stderr, "in_quote %d\n", in_quote); | |
305 | while (*cmdline | |
306 | && (!isspace (*cmdline) || in_quote)) | |
307 | { | |
308 | if (*cmdline == in_quote | |
309 | && cmdline != start) | |
310 | in_quote = 0; | |
311 | dprintf (stderr, "[%c]%d ", *cmdline, in_quote); | |
312 | cmdline ++; | |
313 | } | |
314 | dprintf (stderr, "\n"); | |
315 | ||
316 | /* Allocate space for this token and store it in args[]. */ | |
317 | end = cmdline; | |
318 | dprintf (stderr, "start<%s> end<%s>\n", start, end); | |
319 | args[ap] = (char *) xmalloc (end - start + 1); | |
320 | memcpy (args[ap], start, end - start); | |
321 | args[ap][end - start] = 0; | |
322 | ||
323 | /* Strip off quotes, if found. */ | |
324 | dprintf (stderr, "args[%d] = <%s>\n", ap, args[ap]); | |
325 | if (args[ap][0] == '\'' | |
326 | && args[ap][strlen (args[ap])-1] == '\'') | |
327 | { | |
328 | args[ap][strlen (args[ap])-1] = 0; | |
329 | args[ap] ++; | |
330 | } | |
331 | ||
332 | else if (args[ap][0] == '"' | |
333 | && args[ap][strlen (args[ap])-1] == '"') | |
334 | { | |
335 | args[ap][strlen (args[ap])-1] = 0; | |
336 | args[ap] ++; | |
337 | } | |
338 | ||
339 | /* Replace positional parameters like $4. */ | |
340 | else if (args[ap][0] == '$' | |
341 | && isdigit (args[ap][1]) | |
342 | && args[ap][2] == 0) | |
343 | { | |
344 | int a = args[ap][1] - '1'; | |
345 | if (0 <= a && a < nargs) | |
346 | args[ap] = strdup (iargs[a]); | |
347 | } | |
348 | ||
349 | ap ++; | |
350 | ||
351 | if (*cmdline == 0) | |
352 | break; | |
353 | } | |
354 | ||
355 | /* Lastly, NULL terminate the array and run it. */ | |
356 | args[ap] = NULL; | |
357 | run_command_array (args); | |
358 | } | |
359 | ||
360 | /* Run a script by reading lines and passing them to the above | |
361 | function. */ | |
362 | static void | |
363 | run_script (const char *filename, const char **args) | |
364 | { | |
365 | char line[MAX_LINE_LENGTH + 1]; | |
366 | dprintf (stderr, "run_script starting: '%s'\n", filename); | |
367 | FILE *f = fopen (filename, "r"); | |
368 | if (f == NULL) | |
369 | { | |
370 | fprintf (stderr, "sh: %s: %s\n", filename, strerror (errno)); | |
371 | exit (1); | |
372 | } | |
373 | while (fgets (line, sizeof (line), f) != NULL) | |
374 | { | |
375 | if (line[0] == '#') | |
376 | { | |
377 | dprintf (stderr, "comment: %s\n", line); | |
378 | continue; | |
379 | } | |
380 | run_command_string (line, args); | |
381 | } | |
382 | fclose (f); | |
383 | } | |
384 | ||
385 | int | |
386 | main (int argc, const char **argv) | |
387 | { | |
388 | int i; | |
389 | ||
390 | if (strcmp (argv[1], "--debug") == 0) | |
391 | { | |
392 | debug_mode = 1; | |
393 | --argc; | |
394 | ++argv; | |
395 | } | |
396 | ||
397 | dprintf (stderr, "container-sh starting:\n"); | |
398 | for (i = 0; i < argc; i++) | |
399 | dprintf (stderr, " argv[%d] is `%s'\n", i, argv[i]); | |
400 | ||
401 | if (strcmp (argv[1], "-c") == 0) | |
402 | run_command_string (argv[2], argv+3); | |
403 | else | |
404 | run_script (argv[1], argv+2); | |
405 | ||
406 | dprintf (stderr, "normal exit 0\n"); | |
407 | return 0; | |
408 | } |