1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2005 - Garance Alistair Drosehn <gad@FreeBSD.org>.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * The views and conclusions contained in the software and documentation
29 * are those of the authors and should not be interpreted as representing
30 * official policies, either expressed or implied, of the FreeBSD Project.
31 */
32
33 #include <sys/cdefs.h>
34 #include <sys/stat.h>
35 #include <sys/param.h>
36 #include <err.h>
37 #include <errno.h>
38 #include <ctype.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <unistd.h>
43
44 #include "envopts.h"
45
46 static const char *
47 expand_vars(int in_thisarg, char **thisarg_p, char **dest_p,
48 const char **src_p);
49 static int is_there(char *candidate);
50
51 /*
52 * The is*() routines take a parameter of 'int', but expect values in the range
53 * of unsigned char. Define some wrappers which take a value of type 'char',
54 * whether signed or unsigned, and ensure the value ends up in the right range.
55 */
56 #define isalnumch(Anychar) isalnum((u_char)(Anychar))
57 #define isalphach(Anychar) isalpha((u_char)(Anychar))
58 #define isspacech(Anychar) isspace((u_char)(Anychar))
59
60 /*
61 * Routine to determine if a given fully-qualified filename is executable.
62 * This is copied almost verbatim from FreeBSD's usr.bin/which/which.c.
63 */
64 static int
is_there(char * candidate)65 is_there(char *candidate)
66 {
67 struct stat fin;
68
69 /* XXX work around access(2) false positives for superuser */
70 if (access(candidate, X_OK) == 0 &&
71 stat(candidate, &fin) == 0 &&
72 S_ISREG(fin.st_mode) &&
73 (getuid() != 0 ||
74 (fin.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) != 0)) {
75 if (env_verbosity > 1)
76 fprintf(stderr, "#env matched:\t'%s'\n", candidate);
77 return (1);
78 }
79 return (0);
80 }
81
82 /**
83 * Routine to search through an alternate path-list, looking for a given
84 * filename to execute. If the file is found, replace the original
85 * unqualified name with a fully-qualified path. This allows `env' to
86 * execute programs from a specific strict list of possible paths, without
87 * changing the value of PATH seen by the program which will be executed.
88 * E.G.:
89 * #!/usr/bin/env -S-P/usr/local/bin:/usr/bin perl
90 * will execute /usr/local/bin/perl or /usr/bin/perl (whichever is found
91 * first), no matter what the current value of PATH is, and without
92 * changing the value of PATH that the script will see when it runs.
93 *
94 * This is similar to the print_matches() routine in usr.bin/which/which.c.
95 */
96 void
search_paths(char * path,char ** argv)97 search_paths(char *path, char **argv)
98 {
99 char candidate[PATH_MAX];
100 const char *d;
101 char *filename, *fqname;
102
103 /* If the file has a `/' in it, then no search is done */
104 filename = *argv;
105 if (strchr(filename, '/') != NULL)
106 return;
107
108 if (env_verbosity > 1) {
109 fprintf(stderr, "#env Searching:\t'%s'\n", path);
110 fprintf(stderr, "#env for file:\t'%s'\n", filename);
111 }
112
113 fqname = NULL;
114 while ((d = strsep(&path, ":")) != NULL) {
115 if (*d == '\0')
116 d = ".";
117 if (snprintf(candidate, sizeof(candidate), "%s/%s", d,
118 filename) >= (int)sizeof(candidate))
119 continue;
120 if (is_there(candidate)) {
121 fqname = candidate;
122 break;
123 }
124 }
125
126 if (fqname == NULL) {
127 errno = ENOENT;
128 err(127, "%s", filename);
129 }
130 *argv = strdup(candidate);
131 }
132
133 /**
134 * Routine to split a string into multiple parameters, while recognizing a
135 * few special characters. It recognizes both single and double-quoted
136 * strings. This processing is designed entirely for the benefit of the
137 * parsing of "#!"-lines (aka "shebang" lines == the first line of an
138 * executable script). Different operating systems parse that line in very
139 * different ways, and this split-on-spaces processing is meant to provide
140 * ways to specify arbitrary arguments on that line, no matter how the OS
141 * parses it.
142 *
143 * Within a single-quoted string, the two characters "\'" are treated as
144 * a literal "'" character to add to the string, and "\\" are treated as
145 * a literal "\" character to add. Other than that, all characters are
146 * copied until the processing gets to a terminating "'".
147 *
148 * Within a double-quoted string, many more "\"-style escape sequences
149 * are recognized, mostly copied from what is recognized in the `printf'
150 * command. Some OS's will not allow a literal blank character to be
151 * included in the one argument that they recognize on a shebang-line,
152 * so a few additional escape-sequences are defined to provide ways to
153 * specify blanks.
154 *
155 * Within a double-quoted string "\_" is turned into a literal blank.
156 * (Inside of a single-quoted string, the two characters are just copied)
157 * Outside of a quoted string, "\_" is treated as both a blank, and the
158 * end of the current argument. So with a shelbang-line of:
159 * #!/usr/bin/env -SA=avalue\_perl
160 * the -S value would be broken up into arguments "A=avalue" and "perl".
161 */
162 void
split_spaces(const char * str,int * origind,int * origc,char *** origv)163 split_spaces(const char *str, int *origind, int *origc, char ***origv)
164 {
165 static const char *nullarg = "";
166 const char *bq_src, *copystr, *src;
167 char *dest, **newargv, *newstr, **nextarg, **oldarg;
168 int addcount, bq_destlen, copychar, found_sep, in_arg, in_dq, in_sq;
169
170 /*
171 * Ignore leading space on the string, and then malloc enough room
172 * to build a copy of it. The copy might end up shorter than the
173 * original, due to quoted strings and '\'-processing.
174 */
175 while (isspacech(*str))
176 str++;
177 if (*str == '\0')
178 return;
179 newstr = malloc(strlen(str) + 1);
180
181 /*
182 * Allocate plenty of space for the new array of arg-pointers,
183 * and start that array off with the first element of the old
184 * array.
185 */
186 newargv = malloc((*origc + (strlen(str) / 2) + 2) * sizeof(char *));
187 nextarg = newargv;
188 *nextarg++ = **origv;
189
190 /* Come up with the new args by splitting up the given string. */
191 addcount = 0;
192 bq_destlen = in_arg = in_dq = in_sq = 0;
193 bq_src = NULL;
194 for (src = str, dest = newstr; *src != '\0'; src++) {
195 /*
196 * This switch will look at a character in *src, and decide
197 * what should be copied to *dest. It only decides what
198 * character(s) to copy, it should not modify *dest. In some
199 * cases, it will look at multiple characters from *src.
200 */
201 copychar = found_sep = 0;
202 copystr = NULL;
203 switch (*src) {
204 case '"':
205 if (in_sq)
206 copychar = *src;
207 else if (in_dq)
208 in_dq = 0;
209 else {
210 /*
211 * Referencing nullarg ensures that a new
212 * argument is created, even if this quoted
213 * string ends up with zero characters.
214 */
215 copystr = nullarg;
216 in_dq = 1;
217 bq_destlen = dest - *(nextarg - 1);
218 bq_src = src;
219 }
220 break;
221 case '$':
222 if (in_sq)
223 copychar = *src;
224 else {
225 copystr = expand_vars(in_arg, (nextarg - 1),
226 &dest, &src);
227 }
228 break;
229 case '\'':
230 if (in_dq)
231 copychar = *src;
232 else if (in_sq)
233 in_sq = 0;
234 else {
235 /*
236 * Referencing nullarg ensures that a new
237 * argument is created, even if this quoted
238 * string ends up with zero characters.
239 */
240 copystr = nullarg;
241 in_sq = 1;
242 bq_destlen = dest - *(nextarg - 1);
243 bq_src = src;
244 }
245 break;
246 case '\\':
247 if (in_sq) {
248 /*
249 * Inside single-quoted strings, only the
250 * "\'" and "\\" are recognized as special
251 * strings.
252 */
253 copychar = *(src + 1);
254 if (copychar == '\'' || copychar == '\\')
255 src++;
256 else
257 copychar = *src;
258 break;
259 }
260 src++;
261 switch (*src) {
262 case '"':
263 case '#':
264 case '$':
265 case '\'':
266 case '\\':
267 copychar = *src;
268 break;
269 case '_':
270 /*
271 * Alternate way to get a blank, which allows
272 * that blank be used to separate arguments
273 * when it is not inside a quoted string.
274 */
275 if (in_dq)
276 copychar = ' ';
277 else {
278 found_sep = 1;
279 src++;
280 }
281 break;
282 case 'c':
283 /*
284 * Ignore remaining characters in the -S string.
285 * This would not make sense if found in the
286 * middle of a quoted string.
287 */
288 if (in_dq)
289 errx(1, "Sequence '\\%c' is not allowed"
290 " in quoted strings", *src);
291 goto str_done;
292 case 'f':
293 copychar = '\f';
294 break;
295 case 'n':
296 copychar = '\n';
297 break;
298 case 'r':
299 copychar = '\r';
300 break;
301 case 't':
302 copychar = '\t';
303 break;
304 case 'v':
305 copychar = '\v';
306 break;
307 default:
308 if (isspacech(*src))
309 copychar = *src;
310 else
311 errx(1, "Invalid sequence '\\%c' in -S",
312 *src);
313 }
314 break;
315 default:
316 if ((in_dq || in_sq) && in_arg)
317 copychar = *src;
318 else if (isspacech(*src))
319 found_sep = 1;
320 else {
321 /*
322 * If the first character of a new argument
323 * is `#', then ignore the remaining chars.
324 */
325 if (!in_arg && *src == '#')
326 goto str_done;
327 copychar = *src;
328 }
329 }
330 /*
331 * Now that the switch has determined what (if anything)
332 * needs to be copied, copy whatever that is to *dest.
333 */
334 if (copychar || copystr != NULL) {
335 if (!in_arg) {
336 /* This is the first byte of a new argument */
337 *nextarg++ = dest;
338 addcount++;
339 in_arg = 1;
340 }
341 if (copychar)
342 *dest++ = (char)copychar;
343 else if (copystr != NULL)
344 while (*copystr != '\0')
345 *dest++ = *copystr++;
346 } else if (found_sep) {
347 *dest++ = '\0';
348 while (isspacech(*src))
349 src++;
350 --src;
351 in_arg = 0;
352 }
353 }
354 str_done:
355 *dest = '\0';
356 *nextarg = NULL;
357 if (in_dq || in_sq) {
358 errx(1, "No terminating quote for string: %.*s%s",
359 bq_destlen, *(nextarg - 1), bq_src);
360 }
361 if (env_verbosity > 1) {
362 fprintf(stderr, "#env split -S:\t'%s'\n", str);
363 oldarg = newargv + 1;
364 fprintf(stderr, "#env into:\t'%s'\n", *oldarg);
365 for (oldarg++; *oldarg; oldarg++)
366 fprintf(stderr, "#env &\t'%s'\n", *oldarg);
367 }
368
369 /* Copy the unprocessed arg-pointers from the original array */
370 for (oldarg = *origv + *origind; *oldarg; oldarg++)
371 *nextarg++ = *oldarg;
372 *nextarg = NULL;
373
374 /* Update optind/argc/argv in the calling routine */
375 *origc += addcount - *origind + 1;
376 *origv = newargv;
377 *origind = 1;
378 }
379
380 /**
381 * Routine to split expand any environment variables referenced in the string
382 * that -S is processing. For now it only supports the form ${VARNAME}. It
383 * explicitly does not support $VARNAME, and obviously can not handle special
384 * shell-variables such as $?, $*, $1, etc. It is called with *src_p pointing
385 * at the initial '$', and if successful it will update *src_p, *dest_p, and
386 * possibly *thisarg_p in the calling routine.
387 */
388 static const char *
expand_vars(int in_thisarg,char ** thisarg_p,char ** dest_p,const char ** src_p)389 expand_vars(int in_thisarg, char **thisarg_p, char **dest_p, const char **src_p)
390 {
391 const char *vbegin, *vend, *vvalue;
392 char *newstr, *vname;
393 int bad_reference;
394 size_t namelen, newlen;
395
396 bad_reference = 1;
397 vbegin = vend = (*src_p) + 1;
398 if (*vbegin++ == '{')
399 if (*vbegin == '_' || isalphach(*vbegin)) {
400 vend = vbegin + 1;
401 while (*vend == '_' || isalnumch(*vend))
402 vend++;
403 if (*vend == '}')
404 bad_reference = 0;
405 }
406 if (bad_reference)
407 errx(1, "Only ${VARNAME} expansion is supported, error at: %s",
408 *src_p);
409
410 /*
411 * We now know we have a valid environment variable name, so update
412 * the caller's source-pointer to the last character in that reference,
413 * and then pick up the matching value. If the variable is not found,
414 * or if it has a null value, then our work here is done.
415 */
416 *src_p = vend;
417 namelen = vend - vbegin + 1;
418 vname = malloc(namelen);
419 strlcpy(vname, vbegin, namelen);
420 vvalue = getenv(vname);
421 if (vvalue == NULL || *vvalue == '\0') {
422 if (env_verbosity > 2)
423 fprintf(stderr,
424 "#env replacing ${%s} with null string\n",
425 vname);
426 free(vname);
427 return (NULL);
428 }
429
430 if (env_verbosity > 2)
431 fprintf(stderr, "#env expanding ${%s} into '%s'\n", vname,
432 vvalue);
433
434 /*
435 * There is some value to copy to the destination. If the value is
436 * shorter than the ${VARNAME} reference that it replaces, then our
437 * caller can just copy the value to the existing destination.
438 */
439 if (strlen(vname) + 3 >= strlen(vvalue)) {
440 free(vname);
441 return (vvalue);
442 }
443
444 /*
445 * The value is longer than the string it replaces, which means the
446 * present destination area is too small to hold it. Create a new
447 * destination area, and update the caller's 'dest' variable to match.
448 * If the caller has already started copying some info for 'thisarg'
449 * into the present destination, then the new destination area must
450 * include a copy of that data, and the pointer to 'thisarg' must also
451 * be updated. Note that it is still the caller which copies this
452 * vvalue to the new *dest.
453 */
454 newlen = strlen(vvalue) + strlen(*src_p) + 1;
455 if (in_thisarg) {
456 **dest_p = '\0'; /* Provide terminator for 'thisarg' */
457 newlen += strlen(*thisarg_p);
458 newstr = malloc(newlen);
459 strcpy(newstr, *thisarg_p);
460 *thisarg_p = newstr;
461 } else {
462 newstr = malloc(newlen);
463 *newstr = '\0';
464 }
465 *dest_p = strchr(newstr, '\0');
466 free(vname);
467 return (vvalue);
468 }
469