2 * subst.c --- substitution program
4 * Subst is used as a quicky program to do @ substitutions
17 #ifdef HAVE_SYS_TIME_H
20 #include <sys/types.h>
25 #ifdef HAVE_SYS_TIME_H
40 struct subst_entry *next;
43 static struct subst_entry *subst_table = 0;
45 static int add_subst(char *name, char *value)
47 struct subst_entry *ent = 0;
49 ent = (struct subst_entry *) malloc(sizeof(struct subst_entry));
52 ent->name = (char *) malloc(strlen(name)+1);
55 ent->value = (char *) malloc(strlen(value)+1);
58 strcpy(ent->name, name);
59 strcpy(ent->value, value);
60 ent->next = subst_table;
71 static struct subst_entry *fetch_subst_entry(char *name)
73 struct subst_entry *ent;
75 for (ent = subst_table; ent; ent = ent->next) {
76 if (strcmp(name, ent->name) == 0)
83 * Given the starting and ending position of the replacement name,
84 * check to see if it is valid, and pull it out if it is.
86 static char *get_subst_symbol(const char *begin, size_t len, char prefix)
88 static char replace_name[128];
95 if (len > sizeof(replace_name)-2)
97 memcpy(start, begin, len);
101 * The substitution variable must all be in the of [0-9A-Za-z_].
102 * If it isn't, this must be an invalid symbol name.
104 for (cp = start; *cp; cp++) {
105 if (!(*cp >= 'a' && *cp <= 'z') &&
106 !(*cp >= 'A' && *cp <= 'Z') &&
107 !(*cp >= '0' && *cp <= '9') &&
111 return (replace_name);
114 static void replace_string(char *begin, char *end, char *newstr)
116 int replace_len, len;
118 replace_len = strlen(newstr);
120 if (replace_len == 0)
121 memmove(begin, end+1, strlen(end)+1);
122 else if (replace_len != len+1)
123 memmove(end+(replace_len-len-1), end,
125 memcpy(begin, newstr, replace_len);
128 static void substitute_line(char *line)
130 char *ptr, *name_ptr, *end_ptr;
131 struct subst_entry *ent;
136 * Expand all @FOO@ substitutions
140 name_ptr = strchr(ptr, '@');
143 if (*(++name_ptr) == '@') {
145 * Handle tytso@@mit.edu --> tytso@mit.edu
147 memmove(name_ptr-1, name_ptr, strlen(name_ptr)+1);
151 end_ptr = strchr(name_ptr, '@');
154 len = end_ptr - name_ptr;
155 replace_name = get_subst_symbol(name_ptr, len, 0);
160 ent = fetch_subst_entry(replace_name);
162 fprintf(stderr, "Unfound expansion: '%s'\n",
168 fprintf(stderr, "Replace name = '%s' with '%s'\n",
169 replace_name, ent->value);
172 replace_string(ptr, end_ptr, ent->value);
173 if ((ent->value[0] == '@') &&
174 (strlen(replace_name) == strlen(ent->value)-2) &&
175 !strncmp(replace_name, ent->value+1,
176 strlen(ent->value)-2))
177 /* avoid an infinite loop */
178 ptr += strlen(ent->value);
181 * Now do a second pass to expand ${FOO}
185 name_ptr = strchr(ptr, '$');
188 if (*(++name_ptr) != '{') {
193 end_ptr = strchr(name_ptr, '}');
196 len = end_ptr - name_ptr;
197 replace_name = get_subst_symbol(name_ptr, len, '$');
202 ent = fetch_subst_entry(replace_name);
208 fprintf(stderr, "Replace name = '%s' with '%s'\n",
209 replace_name, ent->value);
212 replace_string(ptr, end_ptr, ent->value);
216 static void parse_config_file(FILE *f)
222 memset(line, 0, sizeof(line));
223 if (fgets(line, sizeof(line), f) == NULL)
226 * Strip newlines and comments.
228 cp = strchr(line, '\n');
231 cp = strchr(line, '#');
235 * Skip trailing and leading whitespace
237 for (cp = line + strlen(line) - 1; cp >= line; cp--) {
238 if (*cp == ' ' || *cp == '\t')
244 while (*cp && isspace(*cp))
253 * Ignore future extensions
258 * Parse substitutions
260 for (cp = ptr; *cp; cp++)
264 for (cp++; *cp; cp++)
268 printf("Substitute: '%s' for '%s'\n", ptr, cp ? cp : "<NULL>");
275 * Return 0 if the files are different, 1 if the files are the same.
277 static int compare_file(FILE *old_f, FILE *new_f)
279 char oldbuf[2048], newbuf[2048], *oldcp, *newcp;
283 oldcp = fgets(oldbuf, sizeof(oldbuf), old_f);
284 newcp = fgets(newbuf, sizeof(newbuf), new_f);
285 if (!oldcp && !newcp) {
289 if (!oldcp || !newcp || strcmp(oldbuf, newbuf)) {
299 int main(int argc, char **argv)
304 FILE *in, *out, *old = NULL;
305 char *outfn = NULL, *newfn = NULL;
307 int adjust_timestamp = 0;
310 struct timeval tv[2];
312 while ((c = getopt (argc, argv, "f:tv")) != EOF) {
315 in = fopen(optarg, "r");
320 parse_config_file(in);
330 fprintf(stderr, "%s: [-f config-file] [file]\n",
336 in = fopen(argv[optind], "r");
338 perror(argv[optind]);
346 outfn = argv[optind];
347 newfn = (char *) malloc(strlen(outfn)+20);
349 fprintf(stderr, "Memory error! Exiting.\n");
352 strcpy(newfn, outfn);
353 strcat(newfn, ".new");
354 fd = open(newfn, O_CREAT|O_TRUNC|O_RDWR, 0444);
359 out = fdopen(fd, "w+");
365 fd = open(outfn, O_RDONLY);
367 /* save the original atime, if possible */
368 if (fstat(fd, &stbuf) == 0) {
369 #if HAVE_STRUCT_STAT_ST_ATIM
370 tv[0].tv_sec = stbuf.st_atim.tv_sec;
371 tv[0].tv_usec = stbuf.st_atim.tv_nsec / 1000;
373 tv[0].tv_sec = stbuf.st_atime;
378 old = fdopen(fd, "r");
388 if (fgets(line, sizeof(line), in) == NULL)
390 substitute_line(line);
397 if (old && compare_file(old, out)) {
399 printf("No change, keeping %s.\n", outfn);
400 if (adjust_timestamp) {
402 printf("Updating modtime for %s\n", outfn);
403 if (gettimeofday(&tv[1], NULL) < 0) {
404 perror("gettimeofday");
410 printf("Using original atime\n");
412 if (futimes(fileno(old), tv) < 0)
415 if (utimes(outfn, tv) < 0)
420 if (unlink(newfn) < 0)
424 printf("Creating or replacing %s.\n", outfn);
429 if (rename(newfn, outfn) < 0) {