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 #ifdef HAVE_CONFIG_H
   9 #include "config.h"
  10 #endif
  11 #include <stdio.h>
  12 #include <errno.h>
  13 #include <stdlib.h>
  14 #include <unistd.h>
  15 #include <string.h>
  16 #include <ctype.h>
  17 #ifdef HAVE_SYS_TIME_H
  18 #include <sys/time.h>
  19 #endif
  20 #include <sys/types.h>
  21 #include <sys/stat.h>
  22 #include <fcntl.h>
  23 #include <time.h>
  24 #include <utime.h>
  25
  26 #ifdef HAVE_GETOPT_H
  27 #include <getopt.h>
  28 #else
  29 extern char *optarg;
  30 extern int optind;
  31 #endif
  32
  33
  34 struct subst_entry {
  35         char *name;
  36         char *value;
  37         struct subst_entry *next;
  38 };
  39
  40 static struct subst_entry *subst_table = 0;
  41
  42 static int add_subst(char *name, char *value)
  43 {
  44         struct subst_entry      *ent = 0;
  45
  46         ent = (struct subst_entry *) malloc(sizeof(struct subst_entry));
  47         if (!ent)
  48                 goto fail;
  49         ent->name = (char *) malloc(strlen(name)+1);
  50         if (!ent->name)
  51                 goto fail;
  52         ent->value = (char *) malloc(strlen(value)+1);
  53         if (!ent->value)
  54                 goto fail;
  55         strcpy(ent->name, name);
  56         strcpy(ent->value, value);
  57         ent->next = subst_table;
  58         subst_table = ent;
  59         return 0;
  60 fail:
  61         if (ent) {
  62                 free(ent->name);
  63                 free(ent);
  64         }
  65         return ENOMEM;
  66 }
  67
  68 static struct subst_entry *fetch_subst_entry(char *name)
  69 {
  70         struct subst_entry *ent;
  71
  72         for (ent = subst_table; ent; ent = ent->next) {
  73                 if (strcmp(name, ent->name) == 0)
  74                         break;
  75         }
  76         return ent;
  77 }
  78
  79 /*
  80  * Given the starting and ending position of the replacement name,
  81  * check to see if it is valid, and pull it out if it is.
  82  */
  83 static char *get_subst_symbol(const char *begin, size_t len, char prefix)
  84 {
  85         static char replace_name[128];
  86         char *cp, *start;
  87
  88         start = replace_name;
  89         if (prefix)
  90                 *start++ = prefix;
  91
  92         if (len > sizeof(replace_name)-2)
  93                 return NULL;
  94         memcpy(start, begin, len);
  95         start[len] = 0;
  96
  97         /*
  98          * The substitution variable must all be in the of [0-9A-Za-z_].
  99          * If it isn't, this must be an invalid symbol name.
 100          */
 101         for (cp = start; *cp; cp++) {
 102                 if (!(*cp >= 'a' && *cp <= 'z') &&
 103                     !(*cp >= 'A' && *cp <= 'Z') &&
 104                     !(*cp >= '0' && *cp <= '9') &&
 105                     !(*cp == '_'))
 106                         return NULL;
 107         }
 108         return (replace_name);
 109 }
 110
 111 static void replace_string(char *begin, char *end, char *newstr)
 112 {
 113         int     replace_len, len;
 114
 115         replace_len = strlen(newstr);
 116         len = end - begin;
 117         if (replace_len == 0)
 118                 memmove(begin, end+1, strlen(end)+1);
 119         else if (replace_len != len+1)
 120                 memmove(end+(replace_len-len-1), end,
 121                         strlen(end)+1);
 122         memcpy(begin, newstr, replace_len);
 123 }
 124
 125 static void substitute_line(char *line)
 126 {
 127         char    *ptr, *name_ptr, *end_ptr;
 128         struct subst_entry *ent;
 129         char    *replace_name;
 130         size_t  len;
 131
 132         /*
 133          * Expand all @FOO@ substitutions
 134          */
 135         ptr = line;
 136         while (ptr) {
 137                 name_ptr = strchr(ptr, '@');
 138                 if (!name_ptr)
 139                         break;  /* No more */
 140                 if (*(++name_ptr) == '@') {
 141                         /*
 142                          * Handle tytso@@mit.edu --> tytso@mit.edu
 143                          */
 144                         memmove(name_ptr-1, name_ptr, strlen(name_ptr)+1);
 145                         ptr = name_ptr+1;
 146                         continue;
 147                 }
 148                 end_ptr = strchr(name_ptr, '@');
 149                 if (!end_ptr)
 150                         break;
 151                 len = end_ptr - name_ptr;
 152                 replace_name = get_subst_symbol(name_ptr, len, 0);
 153                 if (!replace_name) {
 154                         ptr = name_ptr;
 155                         continue;
 156                 }
 157                 ent = fetch_subst_entry(replace_name);
 158                 if (!ent) {
 159                         fprintf(stderr, "Unfound expansion: '%s'\n",
 160                                 replace_name);
 161                         ptr = end_ptr + 1;
 162                         continue;
 163                 }
 164 #if 0
 165                 fprintf(stderr, "Replace name = '%s' with '%s'\n",
 166                        replace_name, ent->value);
 167 #endif
 168                 ptr = name_ptr-1;
 169                 replace_string(ptr, end_ptr, ent->value);
 170                 if ((ent->value[0] == '@') &&
 171                     (strlen(replace_name) == strlen(ent->value)-2) &&
 172                     !strncmp(replace_name, ent->value+1,
 173                              strlen(ent->value)-2))
 174                         /* avoid an infinite loop */
 175                         ptr += strlen(ent->value);
 176         }
 177         /*
 178          * Now do a second pass to expand ${FOO}
 179          */
 180         ptr = line;
 181         while (ptr) {
 182                 name_ptr = strchr(ptr, '$');
 183                 if (!name_ptr)
 184                         break;  /* No more */
 185                 if (*(++name_ptr) != '{') {
 186                         ptr = name_ptr;
 187                         continue;
 188                 }
 189                 name_ptr++;
 190                 end_ptr = strchr(name_ptr, '}');
 191                 if (!end_ptr)
 192                         break;
 193                 len = end_ptr - name_ptr;
 194                 replace_name = get_subst_symbol(name_ptr, len, '$');
 195                 if (!replace_name) {
 196                         ptr = name_ptr;
 197                         continue;
 198                 }
 199                 ent = fetch_subst_entry(replace_name);
 200                 if (!ent) {
 201                         ptr = end_ptr + 1;
 202                         continue;
 203                 }
 204 #if 0
 205                 fprintf(stderr, "Replace name = '%s' with '%s'\n",
 206                        replace_name, ent->value);
 207 #endif
 208                 ptr = name_ptr-2;
 209                 replace_string(ptr, end_ptr, ent->value);
 210         }
 211 }
 212
 213 static void parse_config_file(FILE *f)
 214 {
 215         char    line[2048];
 216         char    *cp, *ptr;
 217
 218         while (!feof(f)) {
 219                 memset(line, 0, sizeof(line));
 220                 if (fgets(line, sizeof(line), f) == NULL)
 221                         break;
 222                 /*
 223                  * Strip newlines and comments.
 224                  */
 225                 cp = strchr(line, '\n');
 226                 if (cp)
 227                         *cp = 0;
 228                 cp = strchr(line, '#');
 229                 if (cp)
 230                         *cp = 0;
 231                 /*
 232                  * Skip trailing and leading whitespace
 233                  */
 234                 for (cp = line + strlen(line) - 1; cp >= line; cp--) {
 235                         if (*cp == ' ' || *cp == '\t')
 236                                 *cp = 0;
 237                         else
 238                                 break;
 239                 }
 240                 cp = line;
 241                 while (*cp && isspace(*cp))
 242                         cp++;
 243                 ptr = cp;
 244                 /*
 245                  * Skip empty lines
 246                  */
 247                 if (*ptr == 0)
 248                         continue;
 249                 /*
 250                  * Ignore future extensions
 251                  */
 252                 if (*ptr == '@')
 253                         continue;
 254                 /*
 255                  * Parse substitutions
 256                  */
 257                 for (cp = ptr; *cp; cp++)
 258                         if (isspace(*cp))
 259                                 break;
 260                 *cp = 0;
 261                 for (cp++; *cp; cp++)
 262                         if (!isspace(*cp))
 263                                 break;
 264 #if 0
 265                 printf("Substitute: '%s' for '%s'\n", ptr, cp ? cp : "<NULL>");
 266 #endif
 267                 add_subst(ptr, cp);
 268         }
 269 }
 270
 271 /*
 272  * Return 0 if the files are different, 1 if the files are the same.
 273  */
 274 static int compare_file(FILE *old_f, FILE *new_f)
 275 {
 276         char    oldbuf[2048], newbuf[2048], *oldcp, *newcp;
 277         int     retval;
 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         return retval;
 292 }
 293
 294
 295
 296 int main(int argc, char **argv)
 297 {
 298         char    line[2048];
 299         int     c;
 300         int     fd;
 301         FILE    *in, *out, *old = NULL;
 302         char    *outfn = NULL, *newfn = NULL;
 303         int     verbose = 0;
 304         int     adjust_timestamp = 0;
 305         int     got_atime = 0;
 306         struct stat stbuf;
 307         struct timeval tv[2];
 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                 fd = open(newfn, O_CREAT|O_TRUNC|O_RDWR, 0444);
 352                 if (fd < 0) {
 353                         perror(newfn);
 354                         exit(1);
 355                 }
 356                 out = fdopen(fd, "w+");
 357                 if (!out) {
 358                         perror("fdopen");
 359                         exit(1);
 360                 }
 361
 362                 fd = open(outfn, O_RDONLY);
 363                 if (fd > 0) {
 364                         /* save the original atime, if possible */
 365                         if (fstat(fd, &stbuf) == 0) {
 366 #if HAVE_STRUCT_STAT_ST_ATIM
 367                                 tv[0].tv_sec = stbuf.st_atim.tv_sec;
 368                                 tv[0].tv_usec = stbuf.st_atim.tv_nsec / 1000;
 369 #else
 370                                 tv[0].tv_sec = stbuf.st_atime;
 371                                 tv[0].tv_usec = 0;
 372 #endif
 373                                 got_atime = 1;
 374                         }
 375                         old = fdopen(fd, "r");
 376                         if (!old)
 377                                 close(fd);
 378                 }
 379         } else {
 380                 out = stdout;
 381                 outfn = 0;
 382         }
 383
 384         while (!feof(in)) {
 385                 if (fgets(line, sizeof(line), in) == NULL)
 386                         break;
 387                 substitute_line(line);
 388                 fputs(line, out);
 389         }
 390         fclose(in);
 391         if (outfn) {
 392                 fflush(out);
 393                 rewind(out);
 394                 if (old && compare_file(old, out)) {
 395                         if (verbose)
 396                                 printf("No change, keeping %s.\n", outfn);
 397                         if (adjust_timestamp) {
 398                                 if (verbose)
 399                                         printf("Updating modtime for %s\n", outfn);
 400                                 if (gettimeofday(&tv[1], NULL) < 0) {
 401                                         perror("gettimeofday");
 402                                         exit(1);
 403                                 }
 404                                 if (got_atime == 0)
 405                                         tv[0] = tv[1];
 406                                 else if (verbose)
 407                                         printf("Using original atime\n");
 408 #ifdef HAVE_FUTIMES
 409                                 if (futimes(fileno(old), tv) < 0)
 410                                         perror("futimes");
 411 #else
 412                                 if (utimes(outfn, tv) < 0)
 413                                         perror("utimes");
 414 #endif
 415                         }
 416                         fclose(out);
 417                         if (unlink(newfn) < 0)
 418                                 perror("unlink");
 419                 } else {
 420                         if (verbose)
 421                                 printf("Creating or replacing %s.\n", outfn);
 422                         fclose(out);
 423                         if (old)
 424                                 fclose(old);
 425                         old = NULL;
 426                         if (rename(newfn, outfn) < 0) {
 427                                 perror("rename");
 428                                 exit(1);
 429                         }
 430                 }
 431         }
 432         if (old)
 433                 fclose(old);
 434         return (0);
 435 }
 436
 437