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