| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: sw_env.c,v 1.2 1999/07/27 13:38:27 mdw Exp $ |
| 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 $ |
| 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. |
| 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> |
| 60 | #include <mLib/env.h> |
| 61 | #include <mLib/report.h> |
| 62 | #include <mLib/sym.h> |
| 63 | |
| 64 | #include "sw_env.h" |
| 65 | |
| 66 | /*----- Main code ---------------------------------------------------------*/ |
| 67 | |
| 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 -------------------------------------------------*/ |