util/subst.c

   1 /*
   2  * subst.c --- substitution program
   3  *
   4  * Subst is used as a quicky program to do @ substitutions
   5  *
   6  */
   7
   8 #include <stdio.h>
   9 #include <errno.h>
  10 #include <stdlib.h>
  11 #include <unistd.h>
  12 #include <string.h>
  13 #include <ctype.h>
  14 #include <sys/types.h>
  15 #include <sys/stat.h>
  16 #include <time.h>
  17 #include <utime.h>
  18
  19 #ifdef HAVE_GETOPT_H
  20 #include <getopt.h>
  21 #else
  22 extern char *optarg;
  23 extern int optind;
  24 #endif
  25
  26
  27 struct subst_entry {
  28         char *name;
  29         char *value;
  30         struct subst_entry *next;
  31 };
  32
  33 struct subst_entry *subst_table = 0;
  34
  35 static int add_subst(char *name, char *value)
  36 {
  37         struct subst_entry      *ent = 0;
  38         int     retval;
  39
  40         retval = ENOMEM;
  41         ent = (struct subst_entry *) malloc(sizeof(struct subst_entry));
  42         if (!ent)
  43                 goto fail;
  44         ent->name = (char *) malloc(strlen(name)+1);
  45         if (!ent->name)
  46                 goto fail;
  47         ent->value = (char *) malloc(strlen(value)+1);
  48         if (!ent->value)
  49                 goto fail;
  50         strcpy(ent->name, name);
  51         strcpy(ent->value, value);
  52         ent->next = subst_table;
  53         subst_table = ent;
  54         return 0;
  55 fail:
  56         if (ent) {
  57                 free(ent->name);
  58                 free(ent->value);
  59                 free(ent);
  60         }
  61         return retval;
  62 }
  63
  64 static struct subst_entry *fetch_subst_entry(char *name)
  65 {
  66         struct subst_entry *ent;
  67
  68         for (ent = subst_table; ent; ent = ent->next) {
  69                 if (strcmp(name, ent->name) == 0)
  70                         break;
  71         }
  72         return ent;
  73 }
  74
  75 /*
  76  * Given the starting and ending position of the replacement name,
  77  * check to see if it is valid, and pull it out if it is.
  78  */
  79 static char *get_subst_symbol(const char *begin, size_t len, char prefix)
  80 {
  81         static char replace_name[128];
  82         char *cp, *start;
  83
  84         start = replace_name;
  85         if (prefix)
  86                 *start++ = prefix;
  87
  88         if (len > sizeof(replace_name)-2)
  89                 return NULL;
  90         memcpy(start, begin, len);
  91         start[len] = 0;
  92
  93         /*
  94          * The substitution variable must all be in the of [0-9A-Za-z_].
  95          * If it isn't, this must be an invalid symbol name.
  96          */
  97         for (cp = start; *cp; cp++) {
  98                 if (!(*cp >= 'a' && *cp <= 'z') &&
  99                     !(*cp >= 'A' && *cp <= 'Z') &&
 100                     !(*cp >= '0' && *cp <= '9') &&
 101                     !(*cp == '_'))
 102                         return NULL;
 103         }
 104         return (replace_name);
 105 }
 106
 107 static void replace_string(char *begin, char *end, char *newstr)
 108 {
 109         int     replace_len, len;
 110
 111         replace_len = strlen(newstr);
 112         len = end - begin;
 113         if (replace_len == 0)
 114                 memmove(begin, end+1, strlen(end)+1);
 115         else if (replace_len != len+1)
 116                 memmove(end+(replace_len-len-1), end,
 117                         strlen(end)+1);
 118         memcpy(begin, newstr, replace_len);
 119 }
 120
 121 static void substitute_line(char *line)
 122 {
 123         char    *ptr, *name_ptr, *end_ptr;
 124         struct subst_entry *ent;
 125         char    *replace_name;
 126         size_t  len;
 127
 128         /*
 129          * Expand all @FOO@ substitutions
 130          */
 131         ptr = line;
 132         while (ptr) {
 133                 name_ptr = strchr(ptr, '@');
 134                 if (!name_ptr)
 135                         break;  /* No more */
 136                 if (*(++name_ptr) == '@') {
 137                         /*
 138                          * Handle tytso@@mit.edu --> tytso@mit.edu
 139                          */
 140                         memmove(name_ptr-1, name_ptr, strlen(name_ptr)+1);
 141                         ptr = name_ptr+1;
 142                         continue;
 143                 }
 144                 end_ptr = strchr(name_ptr, '@');
 145                 if (!end_ptr)
 146                         break;
 147                 len = end_ptr - name_ptr;
 148                 replace_name = get_subst_symbol(name_ptr, len, 0);
 149                 if (!replace_name) {
 150                         ptr = name_ptr;
 151                         continue;
 152                 }
 153                 ent = fetch_subst_entry(replace_name);
 154                 if (!ent) {
 155                         fprintf(stderr, "Unfound expansion: '%s'\n",
 156                                 replace_name);
 157                         ptr = end_ptr + 1;
 158                         continue;
 159                 }
 160 #if 0
 161                 fprintf(stderr, "Replace name = '%s' with '%s'\n",
 162                        replace_name, ent->value);
 163 #endif
 164                 ptr = name_ptr-1;
 165                 replace_string(ptr, end_ptr, ent->value);
 166                 if ((ent->value[0] == '@') &&
 167                     (strlen(replace_name) == strlen(ent->value)-2) &&
 168                     !strncmp(replace_name, ent->value+1,
 169                              strlen(ent->value)-2))
 170                         /* avoid an infinite loop */
 171                         ptr += strlen(ent->value);
 172         }
 173         /*
 174          * Now do a second pass to expand ${FOO}
 175          */
 176         ptr = line;
 177         while (ptr) {
 178                 name_ptr = strchr(ptr, '$');
 179                 if (!name_ptr)
 180                         break;  /* No more */
 181                 if (*(++name_ptr) != '{') {
 182                         ptr = name_ptr;
 183                         continue;
 184                 }
 185                 name_ptr++;
 186                 end_ptr = strchr(name_ptr, '}');
 187                 if (!end_ptr)
 188                         break;
 189                 len = end_ptr - name_ptr;
 190                 replace_name = get_subst_symbol(name_ptr, len, '$');
 191                 if (!replace_name) {
 192                         ptr = name_ptr;
 193                         continue;
 194                 }
 195                 ent = fetch_subst_entry(replace_name);
 196                 if (!ent) {
 197                         ptr = end_ptr + 1;
 198                         continue;
 199                 }
 200 #if 0
 201                 fprintf(stderr, "Replace name = '%s' with '%s'\n",
 202                        replace_name, ent->value);
 203 #endif
 204                 ptr = name_ptr-2;
 205                 replace_string(ptr, end_ptr, ent->value);
 206         }
 207 }
 208
 209 static void parse_config_file(FILE *f)
 210 {
 211         char    line[2048];
 212         char    *cp, *ptr;
 213
 214         while (!feof(f)) {
 215                 memset(line, 0, sizeof(line));
 216                 if (fgets(line, sizeof(line), f) == NULL)
 217                         break;
 218                 /*
 219                  * Strip newlines and comments.
 220                  */
 221                 cp = strchr(line, '\n');
 222                 if (cp)
 223                         *cp = 0;
 224                 cp = strchr(line, '#');
 225                 if (cp)
 226                         *cp = 0;
 227                 /*
 228                  * Skip trailing and leading whitespace
 229                  */
 230                 for (cp = line + strlen(line) - 1; cp >= line; cp--) {
 231                         if (*cp == ' ' || *cp == '\t')
 232                                 *cp = 0;
 233                         else
 234                                 break;
 235                 }
 236                 cp = line;
 237                 while (*cp && isspace(*cp))
 238                         cp++;
 239                 ptr = cp;
 240                 /*
 241                  * Skip empty lines
 242                  */
 243                 if (*ptr == 0)
 244                         continue;
 245                 /*
 246                  * Ignore future extensions
 247                  */
 248                 if (*ptr == '@')
 249                         continue;
 250                 /*
 251                  * Parse substitutions
 252                  */
 253                 for (cp = ptr; *cp; cp++)
 254                         if (isspace(*cp))
 255                                 break;
 256                 *cp = 0;
 257                 for (cp++; *cp; cp++)
 258                         if (!isspace(*cp))
 259                                 break;
 260 #if 0
 261                 printf("Substitute: '%s' for '%s'\n", ptr, cp ? cp : "<NULL>");
 262 #endif
 263                 add_subst(ptr, cp);
 264         }
 265 }
 266
 267 /*
 268  * Return 0 if the files are different, 1 if the files are the same.
 269  */
 270 static int compare_file(const char *outfn, const char *newfn)
 271 {
 272         FILE    *old_f, *new_f;
 273         char    oldbuf[2048], newbuf[2048], *oldcp, *newcp;
 274         int     retval;
 275
 276         old_f = fopen(outfn, "r");
 277         if (!old_f)
 278                 return 0;
 279         new_f = fopen(newfn, "r");
 280         if (!new_f) {
 281                 fclose(old_f);
 282                 return 0;
 283         }
 284
 285         while (1) {
 286                 oldcp = fgets(oldbuf, sizeof(oldbuf), old_f);
 287                 newcp = fgets(newbuf, sizeof(newbuf), new_f);
 288                 if (!oldcp && !newcp) {
 289                         retval = 1;
 290                         break;
 291                 }
 292                 if (!oldcp || !newcp || strcmp(oldbuf, newbuf)) {
 293                         retval = 0;
 294                         break;
 295                 }
 296         }
 297         fclose(old_f);
 298         fclose(new_f);
 299         return retval;
 300 }
 301
 302
 303
 304 int main(int argc, char **argv)
 305 {
 306         char    line[2048];
 307         int     c;
 308         FILE    *in, *out;
 309         char    *outfn = NULL, *newfn = NULL;
 310         int     verbose = 0;
 311         int     adjust_timestamp = 0;
 312         struct stat stbuf;
 313         struct utimbuf ut;
 314
 315         while ((c = getopt (argc, argv, "f:tv")) != EOF) {
 316                 switch (c) {
 317                 case 'f':
 318                         in = fopen(optarg, "r");
 319                         if (!in) {
 320                                 perror(optarg);
 321                                 exit(1);
 322                         }
 323                         parse_config_file(in);
 324                         fclose(in);
 325                         break;
 326                 case 't':
 327                         adjust_timestamp++;
 328                         break;
 329                 case 'v':
 330                         verbose++;
 331                         break;
 332                 default:
 333                         fprintf(stderr, "%s: [-f config-file] [file]\n",
 334                                 argv[0]);
 335                         break;
 336                 }
 337         }
 338         if (optind < argc) {
 339                 in = fopen(argv[optind], "r");
 340                 if (!in) {
 341                         perror(argv[optind]);
 342                         exit(1);
 343                 }
 344                 optind++;
 345         } else
 346                 in = stdin;
 347
 348         if (optind < argc) {
 349                 outfn = argv[optind];
 350                 newfn = (char *) malloc(strlen(outfn)+20);
 351                 if (!newfn) {
 352                         fprintf(stderr, "Memory error!  Exiting.\n");
 353                         exit(1);
 354                 }
 355                 strcpy(newfn, outfn);
 356                 strcat(newfn, ".new");
 357                 out = fopen(newfn, "w");
 358                 if (!out) {
 359                         perror(newfn);
 360                         exit(1);
 361                 }
 362         } else {
 363                 out = stdout;
 364                 outfn = 0;
 365         }
 366
 367         while (!feof(in)) {
 368                 if (fgets(line, sizeof(line), in) == NULL)
 369                         break;
 370                 substitute_line(line);
 371                 fputs(line, out);
 372         }
 373         fclose(in);
 374         fclose(out);
 375         if (outfn) {
 376                 struct stat st;
 377                 if (compare_file(outfn, newfn)) {
 378                         if (verbose)
 379                                 printf("No change, keeping %s.\n", outfn);
 380                         if (adjust_timestamp) {
 381                                 if (stat(outfn, &stbuf) == 0) {
 382                                         if (verbose)
 383                                                 printf("Updating modtime for %s\n", outfn);
 384                                         ut.actime = stbuf.st_atime;
 385                                         ut.modtime = time(0);
 386                                         if (utime(outfn, &ut) < 0)
 387                                                 perror("utime");
 388                                 }
 389                         }
 390                         unlink(newfn);
 391                 } else {
 392                         if (verbose)
 393                                 printf("Creating or replacing %s.\n", outfn);
 394                         rename(newfn, outfn);
 395                 }
 396                 /* set read-only to alert user it is a generated file */
 397                 if (stat(outfn, &st) == 0)
 398                         chmod(outfn, st.st_mode & ~0222);
 399         }
 400         return (0);
 401 }
 402
 403