2 * subst.c --- substitution program
4 * Subst is used as a quickie program to do @ substitutions
11 #define HAVE_SYS_TIME_H
19 #ifdef HAVE_SYS_TIME_H
22 #ifdef HAVE_SYS_TYPES_H
23 #include <sys/types.h>
25 #ifdef HAVE_SYS_STAT_H
31 #ifdef HAVE_SYS_TIME_H
46 struct subst_entry *next;
49 static struct subst_entry *subst_table = 0;
51 static int add_subst(char *name, char *value)
53 struct subst_entry *ent = 0;
55 ent = (struct subst_entry *) malloc(sizeof(struct subst_entry));
58 ent->name = (char *) malloc(strlen(name)+1);
61 ent->value = (char *) malloc(strlen(value)+1);
64 strcpy(ent->name, name);
65 strcpy(ent->value, value);
66 ent->next = subst_table;
77 static struct subst_entry *fetch_subst_entry(char *name)
79 struct subst_entry *ent;
81 for (ent = subst_table; ent; ent = ent->next) {
82 if (strcmp(name, ent->name) == 0)
89 * Given the starting and ending position of the replacement name,
90 * check to see if it is valid, and pull it out if it is.
92 static char *get_subst_symbol(const char *begin, size_t len, char prefix)
94 static char replace_name[128];
101 if (len > sizeof(replace_name)-2)
103 memcpy(start, begin, len);
107 * The substitution variable must all be in the of [0-9A-Za-z_].
108 * If it isn't, this must be an invalid symbol name.
110 for (cp = start; *cp; cp++) {
111 if (!(*cp >= 'a' && *cp <= 'z') &&
112 !(*cp >= 'A' && *cp <= 'Z') &&
113 !(*cp >= '0' && *cp <= '9') &&
117 return (replace_name);
120 static void replace_string(char *begin, char *end, char *newstr)
122 int replace_len, len;
124 replace_len = strlen(newstr);
126 if (replace_len == 0)
127 memmove(begin, end+1, strlen(end)+1);
128 else if (replace_len != len+1)
129 memmove(end+(replace_len-len-1), end,
131 memcpy(begin, newstr, replace_len);
134 static void substitute_line(char *line)
136 char *ptr, *name_ptr, *end_ptr;
137 struct subst_entry *ent;
142 * Expand all @FOO@ substitutions
146 name_ptr = strchr(ptr, '@');
149 if (*(++name_ptr) == '@') {
151 * Handle tytso@@mit.edu --> tytso@mit.edu
153 memmove(name_ptr-1, name_ptr, strlen(name_ptr)+1);
157 end_ptr = strchr(name_ptr, '@');
160 len = end_ptr - name_ptr;
161 replace_name = get_subst_symbol(name_ptr, len, 0);
166 ent = fetch_subst_entry(replace_name);
168 fprintf(stderr, "Unfound expansion: '%s'\n",
174 fprintf(stderr, "Replace name = '%s' with '%s'\n",
175 replace_name, ent->value);
178 replace_string(ptr, end_ptr, ent->value);
179 if ((ent->value[0] == '@') &&
180 (strlen(replace_name) == strlen(ent->value)-2) &&
181 !strncmp(replace_name, ent->value+1,
182 strlen(ent->value)-2))
183 /* avoid an infinite loop */
184 ptr += strlen(ent->value);
187 * Now do a second pass to expand ${FOO}
191 name_ptr = strchr(ptr, '$');
194 if (*(++name_ptr) != '{') {
199 end_ptr = strchr(name_ptr, '}');
202 len = end_ptr - name_ptr;
203 replace_name = get_subst_symbol(name_ptr, len, '$');
208 ent = fetch_subst_entry(replace_name);
214 fprintf(stderr, "Replace name = '%s' with '%s'\n",
215 replace_name, ent->value);
218 replace_string(ptr, end_ptr, ent->value);
222 static void parse_config_file(FILE *f)
228 memset(line, 0, sizeof(line));
229 if (fgets(line, sizeof(line), f) == NULL)
232 * Strip newlines and comments.
234 cp = strchr(line, '\n');
237 cp = strchr(line, '#');
241 * Skip trailing and leading whitespace
243 for (cp = line + strlen(line) - 1; cp >= line; cp--) {
244 if (*cp == ' ' || *cp == '\t')
250 while (*cp && isspace(*cp))
259 * Ignore future extensions
264 * Parse substitutions
266 for (cp = ptr; *cp; cp++)
270 for (cp++; *cp; cp++)
274 printf("Substitute: '%s' for '%s'\n", ptr, cp ? cp : "<NULL>");
281 * Return 0 if the files are different, 1 if the files are the same.
283 static int compare_file(FILE *old_f, FILE *new_f)
285 char oldbuf[2048], newbuf[2048], *oldcp, *newcp;
289 oldcp = fgets(oldbuf, sizeof(oldbuf), old_f);
290 newcp = fgets(newbuf, sizeof(newbuf), new_f);
291 if (!oldcp && !newcp) {
295 if (!oldcp || !newcp || strcmp(oldbuf, newbuf)) {
303 void set_utimes(const char *filename, int fd, const struct timeval times[2])
306 if (futimes(fd, times) < 0)
309 if (utimes(filename, times) < 0)
314 ut.actime = times[0].tv_sec;
315 ut.modtime = times[1].tv_sec;
316 if (utime(filename, &ut) < 0)
322 int main(int argc, char **argv)
327 FILE *in, *out, *old = NULL;
328 char *outfn = NULL, *newfn = NULL;
330 int adjust_timestamp = 0;
333 struct timeval tv[2];
335 while ((c = getopt (argc, argv, "f:tv")) != EOF) {
338 in = fopen(optarg, "r");
343 parse_config_file(in);
353 fprintf(stderr, "%s: [-f config-file] [file]\n",
359 in = fopen(argv[optind], "r");
361 perror(argv[optind]);
369 outfn = argv[optind];
370 newfn = (char *) malloc(strlen(outfn)+20);
372 fprintf(stderr, "Memory error! Exiting.\n");
375 strcpy(newfn, outfn);
376 strcat(newfn, ".new");
377 ofd = open(newfn, O_CREAT|O_TRUNC|O_RDWR, 0644);
382 out = fdopen(ofd, "w+");
388 fd = open(outfn, O_RDONLY);
390 /* save the original atime, if possible */
391 if (fstat(fd, &stbuf) == 0) {
392 #if HAVE_STRUCT_STAT_ST_ATIM
393 tv[0].tv_sec = stbuf.st_atim.tv_sec;
394 tv[0].tv_usec = stbuf.st_atim.tv_nsec / 1000;
396 tv[0].tv_sec = stbuf.st_atime;
401 old = fdopen(fd, "r");
411 if (fgets(line, sizeof(line), in) == NULL)
413 substitute_line(line);
420 if (old && compare_file(old, out)) {
422 printf("No change, keeping %s.\n", outfn);
423 if (adjust_timestamp) {
425 printf("Updating modtime for %s\n", outfn);
426 if (gettimeofday(&tv[1], NULL) < 0) {
427 perror("gettimeofday");
433 printf("Using original atime\n");
434 set_utimes(outfn, fileno(old), tv);
437 (void) fchmod(ofd, 0444);
439 if (unlink(newfn) < 0)
443 printf("Creating or replacing %s.\n", outfn);
445 (void) fchmod(ofd, 0444);
450 if (rename(newfn, outfn) < 0) {