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1 | /* -*-c-*- |
2 | * |
436d5c73 |
3 | * $Id: sw_env.c,v 1.2 1999/07/27 13:38:27 mdw Exp $ |
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4 | * |
5 | * Mangling of environment variables |
6 | * |
7 | * (c) 1999 EBI |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of sw-tools. |
13 | * |
14 | * sw-tools is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * sw-tools is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with sw-tools; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: sw_env.c,v $ |
436d5c73 |
32 | * Revision 1.2 1999/07/27 13:38:27 mdw |
33 | * Cauterized out the low-level environment operations and put them in |
34 | * mLib. |
35 | * |
36 | * Revision 1.1.1.1 1999/06/02 16:53:35 mdw |
37 | * Initial import. |
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38 | * |
39 | */ |
40 | |
41 | /*----- Header files ------------------------------------------------------*/ |
42 | |
43 | #include "config.h" |
44 | |
45 | #include <ctype.h> |
46 | #include <errno.h> |
47 | #include <stdio.h> |
48 | #include <stdlib.h> |
49 | #include <string.h> |
50 | |
51 | #include <unistd.h> |
52 | #include <sys/wait.h> |
53 | |
54 | #ifndef DECL_ENVIRON |
55 | extern char **environ; |
56 | #endif |
57 | |
58 | #include <mLib/alloc.h> |
59 | #include <mLib/dstr.h> |
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60 | #include <mLib/env.h> |
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61 | #include <mLib/report.h> |
62 | #include <mLib/sym.h> |
63 | |
64 | #include "sw_env.h" |
65 | |
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66 | /*----- Main code ---------------------------------------------------------*/ |
67 | |
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68 | /* --- @env_error@ --- * |
69 | * |
70 | * Arguments: @int e@ = error code |
71 | * |
72 | * Returns: String representation of error. |
73 | * |
74 | * Use: Transforms an error into something a user can understand. |
75 | */ |
76 | |
77 | const char *env_error(int e) |
78 | { |
79 | const char *tab[] = { |
80 | "Everything is fine", |
81 | "Unexpected end-of-file", |
82 | "Bad character in variable name", |
83 | "Bad parameter substitution", |
84 | "Mismatched quote", |
85 | "Missing or spurious `}'", |
86 | "<see errno>", |
87 | "Internal error" |
88 | }; |
89 | if (e == ENV_SYSTEM) |
90 | return (strerror(errno)); |
91 | else |
92 | return (tab[e]); |
93 | } |
94 | |
95 | /* --- @peek@ --- * |
96 | * |
97 | * Arguments: @FILE *fp@ = stream to read from |
98 | * |
99 | * Returns: Next nonwhitespace character. |
100 | * |
101 | * Use: Advances the file position past whitespace characters, and |
102 | * returns the following nonwhitespace character. The character |
103 | * is not `read'. |
104 | */ |
105 | |
106 | static int peek(FILE *fp) |
107 | { |
108 | int ch; |
109 | |
110 | do { |
111 | ch = getc(fp); |
112 | if (ch == EOF) |
113 | return (EOF); |
114 | } while (isspace((unsigned char)ch)); |
115 | ungetc(ch, fp); |
116 | return (ch); |
117 | } |
118 | |
119 | /* --- @env_var@ --- * |
120 | * |
121 | * Arguments: @sym_table *t@ = pointer to symbol table |
122 | * @FILE *fp@ = pointer to stream to read from |
123 | * @dstr *d@ = pointer to output variable |
124 | * |
125 | * Returns: One of the @ENV_@ constants. |
126 | * |
127 | * Use: Scans a variable name from the input stream. |
128 | */ |
129 | |
130 | int env_var(sym_table *t, FILE *fp, dstr *d) |
131 | { |
132 | int ch = getc(fp); |
133 | |
134 | if (ch == EOF) |
135 | return (ENV_EOF); |
136 | if (ch != '_' && !isalpha((unsigned char)ch)) |
137 | return (ENV_VCHAR); |
138 | for (;;) { |
139 | DPUTC(d, ch); |
140 | ch = getc(fp); |
141 | if (ch == EOF || (ch != '_' && !isalnum((unsigned char)ch))) |
142 | break; |
143 | } |
144 | ungetc(ch, fp); |
145 | DPUTZ(d); |
146 | return (ENV_OK); |
147 | } |
148 | |
149 | /* --- @cmdsubst@ --- * |
150 | * |
151 | * Arguments: @sym_table *t@ = pointer to symbol table |
152 | * @FILE *fp@ = pointer to stream to read from |
153 | * @dstr *d@ = pointer to output variable |
154 | * @unsigned f@ = interesting flags |
155 | * |
156 | * Returns: An @ENV_@ magic code. |
157 | * |
158 | * Use: Rips a command line out of the input stream and writes the |
159 | * output of the command to the variable. The parsing has some |
160 | * bizarre artifacts, but it's fairly serviceable. |
161 | */ |
162 | |
163 | static int cmdsubst(sym_table *t, FILE *fp, dstr *d, unsigned f) |
164 | { |
165 | int term = (f & EVF_BACKTICK) ? '`' : ')'; |
166 | int argc = 1; |
167 | size_t l = d->len; |
168 | pid_t kid; |
169 | int fd[2]; |
170 | int e; |
171 | char **argv; |
172 | |
173 | /* --- Snarfle the arguments --- */ |
174 | |
175 | f &= ~EVF_INCSPC; |
176 | while (peek(fp) != term) { |
177 | if ((e = env_value(t, fp, d, f)) != ENV_OK) |
178 | return (e); |
179 | DPUTC(d, 0); |
180 | argc++; |
181 | } |
182 | getc(fp); |
183 | if (argc == 1) { |
184 | d->len = l; |
185 | return (ENV_OK); |
186 | } |
187 | |
188 | /* --- Make the @argv@ array --- */ |
189 | |
190 | { |
191 | char *p = d->buf + l; |
192 | char *lim = d->buf + d->len; |
193 | char **v; |
194 | |
195 | v = argv = xmalloc(argc * sizeof(char *)); |
196 | while (p < lim) { |
197 | *v++ = p; |
198 | while (*p) { |
199 | p++; |
200 | if (p >= lim) |
201 | goto done; |
202 | } |
203 | p++; |
204 | } |
205 | done:; |
206 | *v++ = 0; |
207 | } |
208 | |
209 | /* --- Do the fork/exec thing --- */ |
210 | |
211 | if (pipe(fd)) |
212 | goto fail_0; |
213 | if ((kid = fork()) < 0) |
214 | goto fail_1; |
215 | |
216 | if (kid == 0) { |
217 | close(fd[0]); |
218 | if (fd[1] != 1) { |
219 | dup2(fd[1], 1); |
220 | close(fd[1]); |
221 | } |
222 | environ = env_export(t); |
223 | execvp(argv[0], argv); |
224 | _exit(127); |
225 | } |
226 | |
227 | d->len = l; |
228 | close(fd[1]); |
229 | for (;;) { |
230 | char buf[4096]; |
231 | ssize_t n = read(fd[0], buf, sizeof(buf)); |
232 | if (n <= 0) |
233 | break; |
234 | DPUTM(d, buf, n); |
235 | } |
236 | close(fd[0]); |
237 | waitpid(kid, 0, 0); |
238 | l = d->len; |
239 | while (l > 0 && d->buf[l - 1] == '\n') |
240 | l--; |
241 | d->len = l; |
242 | free(argv); |
243 | return (ENV_OK); |
244 | |
245 | fail_1: |
246 | close(fd[0]); |
247 | close(fd[1]); |
248 | fail_0: |
249 | free(argv); |
250 | return (ENV_SYSTEM); |
251 | } |
252 | |
253 | /* --- @env_value@ --- * |
254 | * |
255 | * Arguments: @sym_table *t@ = pointer to symbol table |
256 | * @FILE *fp@ = pointer to stream to read from |
257 | * @dstr *d@ = pointer to output variable |
258 | * @unsigned f@ = various interesting flags |
259 | * |
260 | * Returns: 0 if OK, @EOF@ if end-of-file encountered, or >0 on error. |
261 | * |
262 | * Use: Scans a value from the input stream. The value read may be |
263 | * quoted in a Bourne-shell sort of a way, and contain Bourne- |
264 | * shell-like parameter substitutions. Some substitutions |
265 | * aren't available because they're too awkward to implement. |
266 | */ |
267 | |
268 | int env_value(sym_table *t, FILE *fp, dstr *d, unsigned f) |
269 | { |
270 | enum { Q_NONE, Q_SINGLE, Q_DOUBLE, Q_BACK } qt = Q_NONE; |
271 | int ch; |
272 | |
273 | do { |
274 | ch = getc(fp); |
275 | if (ch == EOF) |
276 | return (ENV_EOF); |
277 | } while ((f & EVF_INITSPC) && isspace((unsigned char)ch)); |
278 | |
279 | for (;; ch = getc(fp)) { |
280 | |
281 | /* --- Sort out the current character --- */ |
282 | |
283 | if (ch == EOF) break; |
284 | |
285 | /* --- A backslash escapes the next character --- */ |
286 | |
287 | if (ch == '\\') { |
288 | if ((ch = getc(fp)) == EOF) break; |
289 | else if (ch != '\n') |
290 | DPUTC(d, ch); |
291 | continue; |
292 | } |
293 | |
294 | /* --- A single quote starts single-quoting, unless quoted --- * |
295 | * |
296 | * Do the single-quoted snarf here rather than fiddling with anything |
297 | * else. |
298 | */ |
299 | |
300 | if (ch == '\'' && qt == Q_NONE) { |
301 | qt = Q_SINGLE; |
302 | for (;;) { |
303 | if ((ch = getc(fp)) == EOF) goto done; |
304 | if (ch == '\'') break; |
305 | DPUTC(d, ch); |
306 | } |
307 | qt = Q_NONE; |
308 | continue; |
309 | } |
310 | |
311 | /* --- A backtick does the obvious thing --- */ |
312 | |
313 | if (ch == '`' && !(f & EVF_BACKTICK)) { |
314 | int e; |
315 | if ((e = cmdsubst(t, fp, d, f | EVF_BACKTICK)) != ENV_OK) |
316 | return (e); |
317 | continue; |
318 | } |
319 | |
320 | /* --- Handle double-quoted text --- */ |
321 | |
322 | if (ch == '\"') { |
323 | if (qt == Q_DOUBLE) |
324 | qt = Q_NONE; |
325 | else if (qt == Q_NONE) |
326 | qt = Q_DOUBLE; |
327 | else |
328 | return (ENV_INTERNAL); |
329 | continue; |
330 | } |
331 | |
332 | /* --- Handle variable references and similar magic --- */ |
333 | |
334 | if (ch == '$') { |
335 | size_t l = d->len; |
336 | int e; |
337 | char *v; |
338 | char *vn; |
339 | |
340 | /* --- Read one character ahead --- */ |
341 | |
342 | if ((ch = getc(fp)) == EOF) goto done; |
343 | |
344 | /* --- An alphabetic means this is a direct reference --- */ |
345 | |
346 | if (ch == '_' || isalpha(ch)) { |
347 | ungetc(ch, fp); |
348 | if ((e = env_var(t, fp, d)) != ENV_OK) return (e); |
349 | d->len = l; |
350 | if ((v = env_get(t, d->buf + l)) != 0) |
351 | DPUTS(d, v); |
352 | } |
353 | |
354 | /* --- A brace means this is a more complex substitution --- */ |
355 | |
356 | else if (ch == '{') { |
357 | if ((e = env_var(t, fp, d)) != ENV_OK) |
358 | return (e); |
359 | d->len = l; |
360 | v = env_get(t, d->buf + l); |
361 | |
362 | again: |
363 | ch = getc(fp); |
364 | switch (ch) { |
365 | |
366 | case EOF: |
367 | goto done; |
368 | |
369 | case '}': |
370 | if (v) |
371 | DPUTS(d, v); |
372 | ungetc(ch, fp); |
373 | break; |
374 | |
375 | case ':': |
376 | if (v && !*v) |
377 | v = 0; |
378 | goto again; /* `::' and `:}' should be errors */ |
379 | |
380 | case '+': |
381 | if (v) |
382 | v = 0; |
383 | else |
384 | v = ""; |
385 | /* Drop through hackily */ |
386 | |
387 | case '-': |
388 | if (v) { |
389 | DPUTS(d, v); |
390 | l = d->len; |
391 | } |
392 | if ((e = env_value(t, fp, d, EVF_INCSPC)) != ENV_OK) |
393 | return (e); |
394 | if (v) |
395 | d->len = l; |
396 | break; |
397 | |
398 | case '=': |
399 | if (v) { |
400 | DPUTS(d, v); |
401 | l = d->len; |
402 | if ((e = env_value(t, fp, d, EVF_INCSPC)) != ENV_OK) |
403 | return (e); |
404 | d->len = l; |
405 | } else { |
406 | vn = xstrdup(d->buf + l); |
407 | if ((e = env_value(t, fp, d, EVF_INCSPC)) != ENV_OK) |
408 | return (e); |
409 | if (!(f & EVF_SKIP)) |
410 | env_put(t, vn, d->buf + l); |
411 | free(vn); |
412 | } |
413 | break; |
414 | |
415 | default: |
416 | return (ENV_SUBST); |
417 | } |
418 | if (getc(fp) != '}') |
419 | return (ENV_BRACE); |
420 | } |
421 | |
422 | /* --- Handle `$(...)'-style command substitution --- */ |
423 | |
424 | else if (ch == '(') { |
425 | if ((e = cmdsubst(t, fp, d, f & ~EVF_BACKTICK)) != ENV_OK) |
426 | return (e); |
427 | } |
428 | |
429 | /* --- No other `$...' tricks implemented yet --- * |
430 | * |
431 | * Other ideas: `$((...))' arithmetic. |
432 | */ |
433 | |
434 | else |
435 | return (ENV_SUBST); |
436 | continue; |
437 | } |
438 | |
439 | /* --- At this point, anything else double-quoted is munched --- */ |
440 | |
441 | if (qt == Q_DOUBLE) { |
442 | DPUTC(d, ch); |
443 | continue; |
444 | } |
445 | |
446 | /* --- Some characters just aren't allowed unquoted --- * |
447 | * |
448 | * They're not an error; they just mean I should stop parsing. They're |
449 | * probably interesting to the next level up. |
450 | */ |
451 | |
452 | switch (ch) { |
453 | case '(': case ')': |
454 | case '{': case '}': |
455 | case ';': |
456 | ungetc(ch, fp); |
457 | goto done; |
458 | case '`': |
459 | if (f & EVF_BACKTICK) { |
460 | ungetc(ch, fp); |
461 | goto done; |
462 | } |
463 | break; |
464 | } |
465 | |
466 | /* --- Whitespace characters --- * |
467 | * |
468 | * I might snarf them myself anyway, according to flags. Or I might |
469 | * stop, and skip any following whitespace |
470 | */ |
471 | |
472 | if (isspace((unsigned char)ch) && (f & EVF_INCSPC) == 0) { |
473 | do |
474 | ch = getc(fp); |
475 | while (ch != EOF && isspace((unsigned char)ch)); |
476 | ungetc(ch, fp); |
477 | break; |
478 | } |
479 | |
480 | /* --- Get a new character and go around again --- */ |
481 | |
482 | DPUTC(d, ch); |
483 | } |
484 | |
485 | /* --- Tidying --- */ |
486 | |
487 | done: |
488 | DPUTZ(d); |
489 | return (qt == Q_NONE ? ENV_OK : ENV_QUOTE); |
490 | } |
491 | |
492 | /* --- @env_read@ --- * |
493 | * |
494 | * Arguments: @sym_table *t@ = pointer to symbol table |
495 | * @FILE *fp@ = file handle to read |
496 | * @unsigned f@ = various flags |
497 | * |
498 | * Returns: Zero if OK, @EOF@ for end-of-file, or error code. |
499 | * |
500 | * Use: Reads the environment assignment statements in the file. |
501 | */ |
502 | |
503 | int env_read(sym_table *t, FILE *fp, unsigned f) |
504 | { |
505 | dstr n = DSTR_INIT, v = DSTR_INIT; |
506 | int e = ENV_OK, ch; |
507 | |
508 | for (;;) { |
509 | ch = peek(fp); |
510 | |
511 | if (ch == ':') { |
512 | getc(fp); |
513 | peek(fp); |
514 | if ((e = env_value(t, fp, &v, f)) != ENV_OK) |
515 | goto done; |
516 | } |
517 | |
518 | else if (ch == '#') |
519 | do ch = getc(fp); while (ch != EOF && ch != '\n'); |
520 | |
521 | else if (peek(fp) == '}' || |
522 | (e = env_var(t, fp, &n)) != ENV_OK) |
523 | goto done; |
524 | |
525 | else if (strcmp(n.buf, "include") == 0) { |
526 | peek(fp); |
527 | if ((e = env_value(t, fp, &v, f)) != ENV_OK) |
528 | goto done; |
529 | if (!(f & EVF_SKIP)) |
530 | env_file(t, v.buf); |
531 | } |
532 | |
533 | else if (strcmp(n.buf, "arch") == 0) { |
534 | peek(fp); |
535 | if ((e = env_value(t, fp, &v, f)) != ENV_OK) |
536 | goto done; |
537 | if (peek(fp) != '{') { |
538 | e = ENV_BRACE; |
539 | goto done; |
540 | } |
541 | getc(fp); |
542 | e = env_read(t, fp, strcmp(v.buf, ARCH) ? f | EVF_SKIP : f); |
543 | if (e != ENV_OK) |
544 | goto done; |
545 | if (getc(fp) != '}') { |
546 | e = ENV_BRACE; |
547 | goto done; |
548 | } |
549 | } |
550 | |
551 | else if (strcmp(n.buf, "unset") == 0) { |
552 | peek(fp); |
553 | if ((e = env_var(t, fp, &v)) != ENV_OK) |
554 | goto done; |
555 | env_put(t, v.buf, 0); |
556 | } |
557 | |
558 | else { |
559 | if (strcmp(n.buf, "set") == 0) { |
560 | DRESET(&n); |
561 | peek(fp); |
562 | if ((e = env_var(t, fp, &n)) != ENV_OK) |
563 | goto done; |
564 | } |
565 | if (peek(fp) == '=') { |
566 | getc(fp); |
567 | peek(fp); |
568 | } |
569 | if ((e = env_value(t, fp, &v, f)) != ENV_OK) |
570 | goto done; |
571 | |
572 | if (!(f & EVF_SKIP)) |
573 | env_put(t, n.buf, v.buf); |
574 | } |
575 | |
576 | if (peek(fp) == ';') |
577 | getc(fp); |
578 | DRESET(&n); |
579 | DRESET(&v); |
580 | } |
581 | |
582 | done: |
583 | dstr_destroy(&n); |
584 | dstr_destroy(&v); |
585 | return (e); |
586 | } |
587 | |
588 | /* --- @env_file@ --- * |
589 | * |
590 | * Arguments: @sym_table *t@ = pointer to symbol table |
591 | * @const char *name@ = pointer to filename |
592 | * |
593 | * Returns: Zero if OK, or an error code. |
594 | * |
595 | * Use: Reads a named file of environment assignments. |
596 | */ |
597 | |
598 | int env_file(sym_table *t, const char *name) |
599 | { |
600 | FILE *fp; |
601 | int e; |
602 | |
603 | if ((fp = fopen(name, "r")) == 0) |
604 | return (ENV_SYSTEM); |
605 | e = env_read(t, fp, 0); |
606 | fclose(fp); |
607 | if (e == ENV_EOF) |
608 | e = ENV_OK; |
609 | else if (e == ENV_OK) |
610 | e = ENV_BRACE; |
611 | return (e); |
612 | } |
613 | |
614 | /*----- That's all, folks -------------------------------------------------*/ |