1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 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 * $FreeBSD: head/usr.bin/env/envopts.c 326276 2017-11-27 15:37:16Z pfg $ 33 */ 34 35 #include <sys/stat.h> 36 #include <sys/param.h> 37 #include <err.h> 38 #include <errno.h> 39 #include <ctype.h> 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include <string.h> 43 #include <unistd.h> 44 45 #include "envopts.h" 46 47 static const char * 48 expand_vars(int in_thisarg, char **thisarg_p, char **dest_p, 49 const char **src_p); 50 static int is_there(char *candidate); 51 52 /* 53 * The is*() routines take a parameter of 'int', but expect values in the range 54 * of unsigned char. Define some wrappers which take a value of type 'char', 55 * whether signed or unsigned, and ensure the value ends up in the right range. 56 */ 57 #define isalnumch(Anychar) isalnum((u_char)(Anychar)) 58 #define isalphach(Anychar) isalpha((u_char)(Anychar)) 59 #define isspacech(Anychar) isspace((u_char)(Anychar)) 60 61 /* 62 * Routine to determine if a given fully-qualified filename is executable. 63 * This is copied almost verbatim from FreeBSD's usr.bin/which/which.c. 64 */ 65 static int 66 is_there(char *candidate) 67 { 68 struct stat fin; 69 70 /* XXX work around access(2) false positives for superuser */ 71 if (access(candidate, X_OK) == 0 && 72 stat(candidate, &fin) == 0 && 73 S_ISREG(fin.st_mode) && 74 (getuid() != 0 || 75 (fin.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) != 0)) { 76 if (env_verbosity > 1) 77 fprintf(stderr, "#env matched:\t'%s'\n", candidate); 78 return (1); 79 } 80 return (0); 81 } 82 83 /** 84 * Routine to search through an alternate path-list, looking for a given 85 * filename to execute. If the file is found, replace the original 86 * unqualified name with a fully-qualified path. This allows `env' to 87 * execute programs from a specific strict list of possible paths, without 88 * changing the value of PATH seen by the program which will be executed. 89 * E.G.: 90 * #!/usr/bin/env -S-P/usr/local/bin:/usr/bin perl 91 * will execute /usr/local/bin/perl or /usr/bin/perl (whichever is found 92 * first), no matter what the current value of PATH is, and without 93 * changing the value of PATH that the script will see when it runs. 94 * 95 * This is similar to the print_matches() routine in usr.bin/which/which.c. 96 */ 97 void 98 search_paths(char *path, char **argv) 99 { 100 char candidate[PATH_MAX]; 101 const char *d; 102 char *filename, *fqname; 103 104 /* If the file has a `/' in it, then no search is done */ 105 filename = *argv; 106 if (strchr(filename, '/') != NULL) 107 return; 108 109 if (env_verbosity > 1) { 110 fprintf(stderr, "#env Searching:\t'%s'\n", path); 111 fprintf(stderr, "#env for file:\t'%s'\n", filename); 112 } 113 114 fqname = NULL; 115 while ((d = strsep(&path, ":")) != NULL) { 116 if (*d == '\0') 117 d = "."; 118 if (snprintf(candidate, sizeof(candidate), "%s/%s", d, 119 filename) >= (int)sizeof(candidate)) 120 continue; 121 if (is_there(candidate)) { 122 fqname = candidate; 123 break; 124 } 125 } 126 127 if (fqname == NULL) { 128 errno = ENOENT; 129 err(127, "%s", filename); 130 } 131 *argv = strdup(candidate); 132 } 133 134 /** 135 * Routine to split a string into multiple parameters, while recognizing a 136 * few special characters. It recognizes both single and double-quoted 137 * strings. This processing is designed entirely for the benefit of the 138 * parsing of "#!"-lines (aka "shebang" lines == the first line of an 139 * executable script). Different operating systems parse that line in very 140 * different ways, and this split-on-spaces processing is meant to provide 141 * ways to specify arbitrary arguments on that line, no matter how the OS 142 * parses it. 143 * 144 * Within a single-quoted string, the two characters "\'" are treated as 145 * a literal "'" character to add to the string, and "\\" are treated as 146 * a literal "\" character to add. Other than that, all characters are 147 * copied until the processing gets to a terminating "'". 148 * 149 * Within a double-quoted string, many more "\"-style escape sequences 150 * are recognized, mostly copied from what is recognized in the `printf' 151 * command. Some OS's will not allow a literal blank character to be 152 * included in the one argument that they recognize on a shebang-line, 153 * so a few additional escape-sequences are defined to provide ways to 154 * specify blanks. 155 * 156 * Within a double-quoted string "\_" is turned into a literal blank. 157 * (Inside of a single-quoted string, the two characters are just copied) 158 * Outside of a quoted string, "\_" is treated as both a blank, and the 159 * end of the current argument. So with a shelbang-line of: 160 * #!/usr/bin/env -SA=avalue\_perl 161 * the -S value would be broken up into arguments "A=avalue" and "perl". 162 */ 163 void 164 split_spaces(const char *str, int *origind, int *origc, char ***origv) 165 { 166 static const char *nullarg = ""; 167 const char *bq_src, *copystr, *src; 168 char *dest, **newargv, *newstr, **nextarg, **oldarg; 169 int addcount, bq_destlen, copychar, found_sep, in_arg, in_dq, in_sq; 170 171 /* 172 * Ignore leading space on the string, and then malloc enough room 173 * to build a copy of it. The copy might end up shorter than the 174 * original, due to quoted strings and '\'-processing. 175 */ 176 while (isspacech(*str)) 177 str++; 178 if (*str == '\0') 179 return; 180 newstr = malloc(strlen(str) + 1); 181 182 /* 183 * Allocate plenty of space for the new array of arg-pointers, 184 * and start that array off with the first element of the old 185 * array. 186 */ 187 newargv = malloc((*origc + (strlen(str) / 2) + 2) * sizeof(char *)); 188 nextarg = newargv; 189 *nextarg++ = **origv; 190 191 /* Come up with the new args by splitting up the given string. */ 192 addcount = 0; 193 bq_destlen = in_arg = in_dq = in_sq = 0; 194 bq_src = NULL; 195 for (src = str, dest = newstr; *src != '\0'; src++) { 196 /* 197 * This switch will look at a character in *src, and decide 198 * what should be copied to *dest. It only decides what 199 * character(s) to copy, it should not modify *dest. In some 200 * cases, it will look at multiple characters from *src. 201 */ 202 copychar = found_sep = 0; 203 copystr = NULL; 204 switch (*src) { 205 case '"': 206 if (in_sq) 207 copychar = *src; 208 else if (in_dq) 209 in_dq = 0; 210 else { 211 /* 212 * Referencing nullarg ensures that a new 213 * argument is created, even if this quoted 214 * string ends up with zero characters. 215 */ 216 copystr = nullarg; 217 in_dq = 1; 218 bq_destlen = dest - *(nextarg - 1); 219 bq_src = src; 220 } 221 break; 222 case '$': 223 if (in_sq) 224 copychar = *src; 225 else { 226 copystr = expand_vars(in_arg, (nextarg - 1), 227 &dest, &src); 228 } 229 break; 230 case '\'': 231 if (in_dq) 232 copychar = *src; 233 else if (in_sq) 234 in_sq = 0; 235 else { 236 /* 237 * Referencing nullarg ensures that a new 238 * argument is created, even if this quoted 239 * string ends up with zero characters. 240 */ 241 copystr = nullarg; 242 in_sq = 1; 243 bq_destlen = dest - *(nextarg - 1); 244 bq_src = src; 245 } 246 break; 247 case '\\': 248 if (in_sq) { 249 /* 250 * Inside single-quoted strings, only the 251 * "\'" and "\\" are recognized as special 252 * strings. 253 */ 254 copychar = *(src + 1); 255 if (copychar == '\'' || copychar == '\\') 256 src++; 257 else 258 copychar = *src; 259 break; 260 } 261 src++; 262 switch (*src) { 263 case '"': 264 case '#': 265 case '$': 266 case '\'': 267 case '\\': 268 copychar = *src; 269 break; 270 case '_': 271 /* 272 * Alternate way to get a blank, which allows 273 * that blank be used to separate arguments 274 * when it is not inside a quoted string. 275 */ 276 if (in_dq) 277 copychar = ' '; 278 else { 279 found_sep = 1; 280 src++; 281 } 282 break; 283 case 'c': 284 /* 285 * Ignore remaining characters in the -S string. 286 * This would not make sense if found in the 287 * middle of a quoted string. 288 */ 289 if (in_dq) 290 errx(1, "Sequence '\\%c' is not allowed" 291 " in quoted strings", *src); 292 goto str_done; 293 case 'f': 294 copychar = '\f'; 295 break; 296 case 'n': 297 copychar = '\n'; 298 break; 299 case 'r': 300 copychar = '\r'; 301 break; 302 case 't': 303 copychar = '\t'; 304 break; 305 case 'v': 306 copychar = '\v'; 307 break; 308 default: 309 if (isspacech(*src)) 310 copychar = *src; 311 else 312 errx(1, "Invalid sequence '\\%c' in -S", 313 *src); 314 } 315 break; 316 default: 317 if ((in_dq || in_sq) && in_arg) 318 copychar = *src; 319 else if (isspacech(*src)) 320 found_sep = 1; 321 else { 322 /* 323 * If the first character of a new argument 324 * is `#', then ignore the remaining chars. 325 */ 326 if (!in_arg && *src == '#') 327 goto str_done; 328 copychar = *src; 329 } 330 } 331 /* 332 * Now that the switch has determined what (if anything) 333 * needs to be copied, copy whatever that is to *dest. 334 */ 335 if (copychar || copystr != NULL) { 336 if (!in_arg) { 337 /* This is the first byte of a new argument */ 338 *nextarg++ = dest; 339 addcount++; 340 in_arg = 1; 341 } 342 if (copychar) 343 *dest++ = (char)copychar; 344 else if (copystr != NULL) 345 while (*copystr != '\0') 346 *dest++ = *copystr++; 347 } else if (found_sep) { 348 *dest++ = '\0'; 349 while (isspacech(*src)) 350 src++; 351 --src; 352 in_arg = 0; 353 } 354 } 355 str_done: 356 *dest = '\0'; 357 *nextarg = NULL; 358 if (in_dq || in_sq) { 359 errx(1, "No terminating quote for string: %.*s%s", 360 bq_destlen, *(nextarg - 1), bq_src); 361 } 362 if (env_verbosity > 1) { 363 fprintf(stderr, "#env split -S:\t'%s'\n", str); 364 oldarg = newargv + 1; 365 fprintf(stderr, "#env into:\t'%s'\n", *oldarg); 366 for (oldarg++; *oldarg; oldarg++) 367 fprintf(stderr, "#env &\t'%s'\n", *oldarg); 368 } 369 370 /* Copy the unprocessed arg-pointers from the original array */ 371 for (oldarg = *origv + *origind; *oldarg; oldarg++) 372 *nextarg++ = *oldarg; 373 *nextarg = NULL; 374 375 /* Update optind/argc/argv in the calling routine */ 376 *origc += addcount - *origind + 1; 377 *origv = newargv; 378 *origind = 1; 379 } 380 381 /** 382 * Routine to split expand any environment variables referenced in the string 383 * that -S is processing. For now it only supports the form ${VARNAME}. It 384 * explicitly does not support $VARNAME, and obviously can not handle special 385 * shell-variables such as $?, $*, $1, etc. It is called with *src_p pointing 386 * at the initial '$', and if successful it will update *src_p, *dest_p, and 387 * possibly *thisarg_p in the calling routine. 388 */ 389 static const char * 390 expand_vars(int in_thisarg, char **thisarg_p, char **dest_p, const char **src_p) 391 { 392 const char *vbegin, *vend, *vvalue; 393 char *newstr, *vname; 394 int bad_reference; 395 size_t namelen, newlen; 396 397 bad_reference = 1; 398 vbegin = vend = (*src_p) + 1; 399 if (*vbegin++ == '{') 400 if (*vbegin == '_' || isalphach(*vbegin)) { 401 vend = vbegin + 1; 402 while (*vend == '_' || isalnumch(*vend)) 403 vend++; 404 if (*vend == '}') 405 bad_reference = 0; 406 } 407 if (bad_reference) 408 errx(1, "Only ${VARNAME} expansion is supported, error at: %s", 409 *src_p); 410 411 /* 412 * We now know we have a valid environment variable name, so update 413 * the caller's source-pointer to the last character in that reference, 414 * and then pick up the matching value. If the variable is not found, 415 * or if it has a null value, then our work here is done. 416 */ 417 *src_p = vend; 418 namelen = vend - vbegin + 1; 419 vname = malloc(namelen); 420 strlcpy(vname, vbegin, namelen); 421 vvalue = getenv(vname); 422 if (vvalue == NULL || *vvalue == '\0') { 423 if (env_verbosity > 2) 424 fprintf(stderr, 425 "#env replacing ${%s} with null string\n", 426 vname); 427 free(vname); 428 return (NULL); 429 } 430 431 if (env_verbosity > 2) 432 fprintf(stderr, "#env expanding ${%s} into '%s'\n", vname, 433 vvalue); 434 435 /* 436 * There is some value to copy to the destination. If the value is 437 * shorter than the ${VARNAME} reference that it replaces, then our 438 * caller can just copy the value to the existing destination. 439 */ 440 if (strlen(vname) + 3 >= strlen(vvalue)) { 441 free(vname); 442 return (vvalue); 443 } 444 445 /* 446 * The value is longer than the string it replaces, which means the 447 * present destination area is too small to hold it. Create a new 448 * destination area, and update the caller's 'dest' variable to match. 449 * If the caller has already started copying some info for 'thisarg' 450 * into the present destination, then the new destination area must 451 * include a copy of that data, and the pointer to 'thisarg' must also 452 * be updated. Note that it is still the caller which copies this 453 * vvalue to the new *dest. 454 */ 455 newlen = strlen(vvalue) + strlen(*src_p) + 1; 456 if (in_thisarg) { 457 **dest_p = '\0'; /* Provide terminator for 'thisarg' */ 458 newlen += strlen(*thisarg_p); 459 newstr = malloc(newlen); 460 strcpy(newstr, *thisarg_p); 461 *thisarg_p = newstr; 462 } else { 463 newstr = malloc(newlen); 464 *newstr = '\0'; 465 } 466 *dest_p = strchr(newstr, '\0'); 467 free(vname); 468 return (vvalue); 469 } 470