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                 if ((ent->value[0] == '@') &&
 169                     (strlen(replace_name) == strlen(ent->value)-2) &&
 170                     !strncmp(replace_name, ent->value+1,
 171                              strlen(ent->value)-2))
 172                         /* avoid an infinite loop */
 173                         ptr += strlen(ent->value);
 174         }
 175         /*
 176          * Now do a second pass to expand ${FOO}
 177          */
 178         ptr = line;
 179         while (ptr) {
 180                 name_ptr = strchr(ptr, '$');
 181                 if (!name_ptr)
 182                         break;  /* No more */
 183                 if (*(++name_ptr) != '{') {
 184                         ptr = name_ptr;
 185                         continue;
 186                 }
 187                 name_ptr++;
 188                 end_ptr = strchr(name_ptr, '}');
 189                 if (!end_ptr)
 190                         break;
 191                 len = end_ptr - name_ptr;
 192                 replace_name = get_subst_symbol(name_ptr, len, '$');
 193                 if (!replace_name) {
 194                         ptr = name_ptr;
 195                         continue;
 196                 }
 197                 ent = fetch_subst_entry(replace_name);
 198                 if (!ent) {
 199                         ptr = end_ptr + 1;
 200                         continue;
 201                 }
 202 #if 0
 203                 fprintf(stderr, "Replace name = '%s' with '%s'\n",
 204                        replace_name, ent->value);
 205 #endif
 206                 ptr = name_ptr-2;
 207                 replace_string(ptr, end_ptr, ent->value);
 208         }
 209 }
 210
 211 static void parse_config_file(FILE *f)
 212 {
 213         char    line[2048];
 214         char    *cp, *ptr;
 215
 216         while (!feof(f)) {
 217                 memset(line, 0, sizeof(line));
 218                 if (fgets(line, sizeof(line), f) == NULL)
 219                         break;
 220                 /*
 221                  * Strip newlines and comments.
 222                  */
 223                 cp = strchr(line, '\n');
 224                 if (cp)
 225                         *cp = 0;
 226                 cp = strchr(line, '#');
 227                 if (cp)
 228                         *cp = 0;
 229                 /*
 230                  * Skip trailing and leading whitespace
 231                  */
 232                 for (cp = line + strlen(line) - 1; cp >= line; cp--) {
 233                         if (*cp == ' ' || *cp == '\t')
 234                                 *cp = 0;
 235                         else
 236                                 break;
 237                 }
 238                 cp = line;
 239                 while (*cp && isspace(*cp))
 240                         cp++;
 241                 ptr = cp;
 242                 /*
 243                  * Skip empty lines
 244                  */
 245                 if (*ptr == 0)
 246                         continue;
 247                 /*
 248                  * Ignore future extensions
 249                  */
 250                 if (*ptr == '@')
 251                         continue;
 252                 /*
 253                  * Parse substitutions
 254                  */
 255                 for (cp = ptr; *cp; cp++)
 256                         if (isspace(*cp))
 257                                 break;
 258                 *cp = 0;
 259                 for (cp++; *cp; cp++)
 260                         if (!isspace(*cp))
 261                                 break;
 262 #if 0
 263                 printf("Substitute: '%s' for '%s'\n", ptr, cp ? cp : "<NULL>");
 264 #endif
 265                 add_subst(ptr, cp);
 266         }
 267 }
 268
 269 /*
 270  * Return 0 if the files are different, 1 if the files are the same.
 271  */
 272 static int compare_file(const char *outfn, const char *newfn)
 273 {
 274         FILE    *old_f, *new_f;
 275         char    oldbuf[2048], newbuf[2048], *oldcp, *newcp;
 276         int     retval;
 277
 278         old_f = fopen(outfn, "r");
 279         if (!old_f)
 280                 return 0;
 281         new_f = fopen(newfn, "r");
 282         if (!new_f) {
 283                 fclose(old_f);
 284                 return 0;
 285         }
 286
 287         while (1) {
 288                 oldcp = fgets(oldbuf, sizeof(oldbuf), old_f);
 289                 newcp = fgets(newbuf, sizeof(newbuf), new_f);
 290                 if (!oldcp && !newcp) {
 291                         retval = 1;
 292                         break;
 293                 }
 294                 if (!oldcp || !newcp || strcmp(oldbuf, newbuf)) {
 295                         retval = 0;
 296                         break;
 297                 }
 298         }
 299         fclose(old_f);
 300         fclose(new_f);
 301         return retval;
 302 }
 303
 304
 305
 306 int main(int argc, char **argv)
 307 {
 308         char    line[2048];
 309         int     c;
 310         FILE    *in, *out;
 311         char    *outfn = NULL, *newfn = NULL;
 312         int     verbose = 0;
 313         int     adjust_timestamp = 0;
 314         struct stat stbuf;
 315         struct utimbuf ut;
 316
 317         while ((c = getopt (argc, argv, "f:tv")) != EOF) {
 318                 switch (c) {
 319                 case 'f':
 320                         in = fopen(optarg, "r");
 321                         if (!in) {
 322                                 perror(optarg);
 323                                 exit(1);
 324                         }
 325                         parse_config_file(in);
 326                         fclose(in);
 327                         break;
 328                 case 't':
 329                         adjust_timestamp++;
 330                         break;
 331                 case 'v':
 332                         verbose++;
 333                         break;
 334                 default:
 335                         fprintf(stderr, "%s: [-f config-file] [file]\n",
 336                                 argv[0]);
 337                         break;
 338                 }
 339         }
 340         if (optind < argc) {
 341                 in = fopen(argv[optind], "r");
 342                 if (!in) {
 343                         perror(argv[optind]);
 344                         exit(1);
 345                 }
 346                 optind++;
 347         } else
 348                 in = stdin;
 349
 350         if (optind < argc) {
 351                 outfn = argv[optind];
 352                 newfn = (char *) malloc(strlen(outfn)+20);
 353                 if (!newfn) {
 354                         fprintf(stderr, "Memory error!  Exiting.\n");
 355                         exit(1);
 356                 }
 357                 strcpy(newfn, outfn);
 358                 strcat(newfn, ".new");
 359                 out = fopen(newfn, "w");
 360                 if (!out) {
 361                         perror(newfn);
 362                         exit(1);
 363                 }
 364         } else {
 365                 out = stdout;
 366                 outfn = 0;
 367         }
 368
 369         while (!feof(in)) {
 370                 if (fgets(line, sizeof(line), in) == NULL)
 371                         break;
 372                 substitute_line(line);
 373                 fputs(line, out);
 374         }
 375         fclose(in);
 376         fclose(out);
 377         if (outfn) {
 378                 struct stat st;
 379                 if (compare_file(outfn, newfn)) {
 380                         if (verbose)
 381                                 printf("No change, keeping %s.\n", outfn);
 382                         if (adjust_timestamp) {
 383                                 if (stat(outfn, &stbuf) == 0) {
 384                                         if (verbose)
 385                                                 printf("Updating modtime for %s\n", outfn);
 386                                         ut.actime = stbuf.st_atime;
 387                                         ut.modtime = time(0);
 388                                         if (utime(outfn, &ut) < 0)
 389                                                 perror("utime");
 390                                 }
 391                         }
 392                         unlink(newfn);
 393                 } else {
 394                         if (verbose)
 395                                 printf("Creating or replacing %s.\n", outfn);
 396                         rename(newfn, outfn);
 397                 }
 398                 /* set read-only to alert user it is a generated file */
 399                 if (stat(outfn, &st) == 0)
 400                         chmod(outfn, st.st_mode & ~0222);
 401         }
 402         return (0);
 403 }
 404
 405