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2cd8c160 | 1 | /* env - manipulate environment and execute a program in that environment |
be06db9a | 2 | Copyright (C) 1986, 1994 Free Software Foundation, Inc. |
2cd8c160 JB |
3 | |
4 | This program is free software; you can redistribute it and/or modify | |
5 | it under the terms of the GNU General Public License as published by | |
6 | the Free Software Foundation; either version 2, or (at your option) | |
7 | any later version. | |
8 | ||
9 | This program is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | GNU General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU General Public License | |
15 | along with this program; if not, write to the Free Software | |
16 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
17 | ||
18 | /* Mly 861126 */ | |
19 | ||
20 | /* If first argument is "-", then a new environment is constructed | |
21 | from scratch; otherwise the environment is inherited from the parent | |
22 | process, except as modified by other options. | |
23 | ||
24 | So, "env - foo" will invoke the "foo" program in a null environment, | |
25 | whereas "env foo" would invoke "foo" in the same environment as that | |
26 | passed to "env" itself. | |
27 | ||
28 | Subsequent arguments are interpreted as follows: | |
29 | ||
30 | * "variable=value" (i.e., an arg containing a "=" character) | |
31 | means to set the specified environment variable to that value. | |
32 | `value' may be of zero length ("variable="). Note that setting | |
33 | a variable to a zero-length value is different from unsetting it. | |
34 | ||
35 | * "-u variable" or "-unset variable" | |
36 | means to unset that variable. | |
37 | If that variable isn't set, does nothing. | |
38 | ||
39 | * "-s variable value" or "-set variable value" | |
40 | same as "variable=value". | |
41 | ||
42 | * "-" or "--" | |
43 | are used to indicate that the following argument is the program | |
44 | to invoke. This is only necessary when the program's name | |
45 | begins with "-" or contains a "=". | |
46 | ||
47 | * anything else | |
48 | The first remaining argument specifies a program to invoke | |
49 | (it is searched for according to the specification of the PATH | |
50 | environment variable) and any arguments following that are | |
51 | passed as arguments to that program. | |
52 | ||
53 | If no program-name is specified following the environment | |
54 | specifications, the resulting environment is printed. | |
55 | This is like specifying a program-name of "printenv". | |
56 | ||
57 | Examples: | |
58 | If the environment passed to "env" is | |
59 | { USER=rms EDITOR=emacs PATH=.:/gnubin:/hacks } | |
60 | ||
61 | * "env DISPLAY=gnu:0 nemacs" | |
be06db9a | 62 | calls "nemacs" in the environment |
2cd8c160 JB |
63 | { USER=rms EDITOR=emacs PATH=.:/gnubin:/hacks DISPLAY=gnu:0 } |
64 | ||
65 | * "env - USER=foo /hacks/hack bar baz" | |
66 | calls the "hack" program on arguments "bar" and "baz" | |
67 | in an environment in which the only variable is "USER". | |
68 | Note that the "-" option clears out the PATH variable, | |
69 | so one should be careful to specify in which directory | |
70 | to find the program to call. | |
71 | ||
72 | * "env -u EDITOR USER=foo PATH=/energy -- e=mc2 bar baz" | |
73 | The program "/energy/e=mc2" is called with environment | |
74 | { USER=foo PATH=/energy } | |
75 | */ | |
76 | ||
77 | #ifdef EMACS | |
78 | #define NO_SHORTNAMES | |
79 | #include "../src/config.h" | |
80 | #endif /* EMACS */ | |
81 | ||
82 | #include <stdio.h> | |
83 | ||
84 | extern int execvp (); | |
85 | ||
86 | char *xmalloc (), *xrealloc (); | |
87 | char *concat (); | |
88 | ||
89 | extern char **environ; | |
90 | ||
91 | char **nenv; | |
92 | int nenv_size; | |
93 | ||
94 | char *progname; | |
95 | void setenv (); | |
96 | void fatal (); | |
97 | char *myindex (); | |
98 | ||
03c71d89 RM |
99 | extern char *strerror (); |
100 | ||
101 | ||
2cd8c160 JB |
102 | main (argc, argv, envp) |
103 | register int argc; | |
104 | register char **argv; | |
105 | char **envp; | |
106 | { | |
107 | register char *tem; | |
108 | ||
109 | progname = argv[0]; | |
110 | argc--; | |
111 | argv++; | |
112 | ||
113 | nenv_size = 100; | |
114 | nenv = (char **) xmalloc (nenv_size * sizeof (char *)); | |
115 | *nenv = (char *) 0; | |
116 | ||
117 | /* "-" flag means to not inherit parent's environment */ | |
118 | if (argc && !strcmp (*argv, "-")) | |
119 | { | |
120 | argc--; | |
121 | argv++; | |
122 | } | |
123 | else | |
124 | /* Else pass on existing env vars. */ | |
125 | for (; *envp; envp++) | |
126 | { | |
127 | tem = myindex (*envp, '='); | |
128 | if (tem) | |
129 | { | |
130 | *tem = '\000'; | |
131 | setenv (*envp, tem + 1); | |
132 | } | |
133 | } | |
134 | ||
135 | while (argc > 0) | |
136 | { | |
137 | tem = myindex (*argv, '='); | |
138 | if (tem) | |
139 | /* If arg contains a "=" it specifies to set a variable */ | |
140 | { | |
141 | *tem = '\000'; | |
142 | setenv (*argv, tem + 1); | |
143 | argc--; | |
144 | argv++; | |
145 | continue; | |
146 | } | |
147 | ||
148 | if (**argv != '-') | |
149 | /* Remaining args are program name and args to pass it */ | |
150 | break; | |
151 | ||
152 | if (argc < 2) | |
153 | fatal ("no argument for `%s' option", *argv); | |
154 | if (!strcmp (*argv, "-u") | |
155 | || !strcmp (*argv, "-unset")) | |
156 | /* Unset a variable */ | |
157 | { | |
158 | argc--; | |
159 | argv++; | |
160 | setenv (*argv, (char *) 0); | |
161 | argc--; | |
162 | argv++; | |
163 | } | |
164 | else if (!strcmp (*argv, "-s") || | |
165 | !strcmp (*argv, "-set")) | |
166 | /* Set a variable */ | |
167 | { | |
168 | argc--; | |
169 | argv++; | |
170 | tem = *argv; | |
171 | if (argc < 2) | |
172 | fatal ("no value specified for variable \"%s\"", tem); | |
173 | argc--; | |
174 | argv++; | |
175 | setenv (tem, *argv); | |
176 | argc--; | |
177 | argv++; | |
178 | } | |
179 | else if (!strcmp (*argv, "-") || !strcmp (*argv, "--")) | |
180 | { | |
181 | argc--; | |
182 | argv++; | |
183 | break; | |
184 | } | |
185 | else | |
186 | { | |
187 | fatal ("unrecognized option `%s'", *argv); | |
188 | } | |
189 | } | |
190 | ||
191 | /* If no program specified print the environment and exit */ | |
192 | if (argc <= 0) | |
193 | { | |
194 | while (*nenv) | |
195 | printf ("%s\n", *nenv++); | |
196 | exit (0); | |
197 | } | |
198 | else | |
199 | { | |
be06db9a RM |
200 | extern int errno; |
201 | extern char *strerror (); | |
2cd8c160 JB |
202 | |
203 | environ = nenv; | |
204 | (void) execvp (*argv, argv); | |
205 | ||
be06db9a RM |
206 | fprintf (stderr, "%s: cannot execute `%s': %s\n", |
207 | progname, *argv, strerror (errno)); | |
2cd8c160 JB |
208 | exit (errno != 0 ? errno : 1); |
209 | } | |
210 | } | |
211 | ||
212 | void | |
213 | setenv (var, val) | |
214 | register char *var, *val; | |
215 | { | |
216 | register char **e; | |
217 | int len = strlen (var); | |
218 | ||
219 | { | |
220 | register char *tem = myindex (var, '='); | |
221 | if (tem) | |
222 | fatal ("environment variable names can not contain `=': %s", var); | |
223 | else if (*var == '\000') | |
224 | fatal ("zero-length environment variable name specified"); | |
225 | } | |
226 | ||
227 | for (e = nenv; *e; e++) | |
228 | if (!strncmp (var, *e, len) && (*e)[len] == '=') | |
229 | { | |
230 | if (val) | |
231 | goto set; | |
232 | else | |
233 | do | |
234 | { | |
235 | *e = *(e + 1); | |
236 | } while (*e++); | |
237 | return; | |
238 | } | |
239 | ||
240 | if (!val) | |
241 | return; /* Nothing to unset */ | |
242 | ||
243 | len = e - nenv; | |
244 | if (len + 1 >= nenv_size) | |
245 | { | |
246 | nenv_size += 100; | |
247 | nenv = (char **) xrealloc (nenv, nenv_size * sizeof (char *)); | |
248 | e = nenv + len; | |
249 | } | |
250 | ||
251 | set: | |
252 | val = concat (var, "=", val); | |
253 | if (*e) | |
254 | free (*e); | |
255 | else | |
256 | *(e + 1) = (char *) 0; | |
257 | *e = val; | |
258 | return; | |
259 | } | |
260 | ||
261 | void | |
262 | fatal (msg, arg1, arg2) | |
263 | char *msg, *arg1, *arg2; | |
264 | { | |
265 | fprintf (stderr, "%s: ", progname); | |
266 | fprintf (stderr, msg, arg1, arg2); | |
267 | putc ('\n', stderr); | |
268 | exit (1); | |
269 | } | |
270 | \f | |
271 | ||
272 | extern char *malloc (), *realloc (); | |
273 | ||
274 | void | |
275 | memory_fatal () | |
276 | { | |
277 | fatal ("virtual memory exhausted"); | |
278 | } | |
279 | ||
280 | char * | |
281 | xmalloc (size) | |
282 | int size; | |
283 | { | |
284 | register char *value; | |
285 | value = (char *) malloc (size); | |
286 | if (!value) | |
287 | memory_fatal (); | |
288 | return (value); | |
289 | } | |
290 | ||
291 | char * | |
292 | xrealloc (ptr, size) | |
293 | char *ptr; | |
294 | int size; | |
295 | { | |
296 | register char *value; | |
297 | value = (char *) realloc (ptr, size); | |
298 | if (!value) | |
299 | memory_fatal (); | |
300 | return (value); | |
301 | } | |
302 | ||
303 | /* Return a newly-allocated string whose contents concatenate | |
304 | those of S1, S2, S3. */ | |
305 | ||
306 | char * | |
307 | concat (s1, s2, s3) | |
308 | char *s1, *s2, *s3; | |
309 | { | |
310 | int len1 = strlen (s1), len2 = strlen (s2), len3 = strlen (s3); | |
311 | char *result = (char *) xmalloc (len1 + len2 + len3 + 1); | |
312 | ||
313 | strcpy (result, s1); | |
314 | strcpy (result + len1, s2); | |
315 | strcpy (result + len1 + len2, s3); | |
316 | result[len1 + len2 + len3] = 0; | |
317 | ||
318 | return result; | |
319 | } | |
320 | ||
321 | /* Return a pointer to the first occurrence in STR of C, | |
322 | or 0 if C does not occur. */ | |
323 | ||
324 | char * | |
325 | myindex (str, c) | |
326 | char *str; | |
327 | char c; | |
328 | { | |
329 | char *s = str; | |
330 | ||
331 | while (*s) | |
332 | { | |
333 | if (*s == c) | |
334 | return s; | |
335 | s++; | |
336 | } | |
337 | return 0; | |
338 | } | |
27711600 RM |
339 | \f |
340 | #ifndef HAVE_STRERROR | |
341 | char * | |
342 | strerror (errnum) | |
343 | int errnum; | |
344 | { | |
345 | extern char *sys_errlist[]; | |
346 | extern int sys_nerr; | |
347 | ||
348 | if (errnum >= 0 && errnum < sys_nerr) | |
349 | return sys_errlist[errnum]; | |
350 | return (char *) "Unknown error"; | |
351 | } | |
352 | ||
353 | #endif /* ! HAVE_STRERROR */ |