/*
* subst.c --- substitution program
*
* Subst is used as a quicky program to do @ substitutions
*
*/
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <utime.h>
#ifdef HAVE_GETOPT_H
#include <getopt.h>
#else
extern char *optarg;
extern int optind;
#endif
struct subst_entry {
char *name;
char *value;
struct subst_entry *next;
};
static struct subst_entry *subst_table = 0;
static int add_subst(char *name, char *value)
{
struct subst_entry *ent = 0;
ent = (struct subst_entry *) malloc(sizeof(struct subst_entry));
if (!ent)
goto fail;
ent->name = (char *) malloc(strlen(name)+1);
if (!ent->name)
goto fail;
ent->value = (char *) malloc(strlen(value)+1);
if (!ent->value)
goto fail;
strcpy(ent->name, name);
strcpy(ent->value, value);
ent->next = subst_table;
subst_table = ent;
return 0;
fail:
if (ent) {
free(ent->name);
free(ent);
}
return ENOMEM;
}
static struct subst_entry *fetch_subst_entry(char *name)
{
struct subst_entry *ent;
for (ent = subst_table; ent; ent = ent->next) {
if (strcmp(name, ent->name) == 0)
break;
}
return ent;
}
/*
* Given the starting and ending position of the replacement name,
* check to see if it is valid, and pull it out if it is.
*/
static char *get_subst_symbol(const char *begin, size_t len, char prefix)
{
static char replace_name[128];
char *cp, *start;
start = replace_name;
if (prefix)
*start++ = prefix;
if (len > sizeof(replace_name)-2)
return NULL;
memcpy(start, begin, len);
start[len] = 0;
/*
* The substitution variable must all be in the of [0-9A-Za-z_].
* If it isn't, this must be an invalid symbol name.
*/
for (cp = start; *cp; cp++) {
if (!(*cp >= 'a' && *cp <= 'z') &&
!(*cp >= 'A' && *cp <= 'Z') &&
!(*cp >= '0' && *cp <= '9') &&
!(*cp == '_'))
return NULL;
}
return (replace_name);
}
static void replace_string(char *begin, char *end, char *newstr)
{
int replace_len, len;
replace_len = strlen(newstr);
len = end - begin;
if (replace_len == 0)
memmove(begin, end+1, strlen(end)+1);
else if (replace_len != len+1)
memmove(end+(replace_len-len-1), end,
strlen(end)+1);
memcpy(begin, newstr, replace_len);
}
static void substitute_line(char *line)
{
char *ptr, *name_ptr, *end_ptr;
struct subst_entry *ent;
char *replace_name;
size_t len;
/*
* Expand all @FOO@ substitutions
*/
ptr = line;
while (ptr) {
name_ptr = strchr(ptr, '@');
if (!name_ptr)
break; /* No more */
if (*(++name_ptr) == '@') {
/*
* Handle tytso@@mit.edu --> tytso@mit.edu
*/
memmove(name_ptr-1, name_ptr, strlen(name_ptr)+1);
ptr = name_ptr+1;
continue;
}
end_ptr = strchr(name_ptr, '@');
if (!end_ptr)
break;
len = end_ptr - name_ptr;
replace_name = get_subst_symbol(name_ptr, len, 0);
if (!replace_name) {
ptr = name_ptr;
continue;
}
ent = fetch_subst_entry(replace_name);
if (!ent) {
fprintf(stderr, "Unfound expansion: '%s'\n",
replace_name);
ptr = end_ptr + 1;
continue;
}
#if 0
fprintf(stderr, "Replace name = '%s' with '%s'\n",
replace_name, ent->value);
#endif
ptr = name_ptr-1;
replace_string(ptr, end_ptr, ent->value);
if ((ent->value[0] == '@') &&
(strlen(replace_name) == strlen(ent->value)-2) &&
!strncmp(replace_name, ent->value+1,
strlen(ent->value)-2))
/* avoid an infinite loop */
ptr += strlen(ent->value);
}
/*
* Now do a second pass to expand ${FOO}
*/
ptr = line;
while (ptr) {
name_ptr = strchr(ptr, '$');
if (!name_ptr)
break; /* No more */
if (*(++name_ptr) != '{') {
ptr = name_ptr;
continue;
}
name_ptr++;
end_ptr = strchr(name_ptr, '}');
if (!end_ptr)
break;
len = end_ptr - name_ptr;
replace_name = get_subst_symbol(name_ptr, len, '$');
if (!replace_name) {
ptr = name_ptr;
continue;
}
ent = fetch_subst_entry(replace_name);
if (!ent) {
ptr = end_ptr + 1;
continue;
}
#if 0
fprintf(stderr, "Replace name = '%s' with '%s'\n",
replace_name, ent->value);
#endif
ptr = name_ptr-2;
replace_string(ptr, end_ptr, ent->value);
}
}
static void parse_config_file(FILE *f)
{
char line[2048];
char *cp, *ptr;
while (!feof(f)) {
memset(line, 0, sizeof(line));
if (fgets(line, sizeof(line), f) == NULL)
break;
/*
* Strip newlines and comments.
*/
cp = strchr(line, '\n');
if (cp)
*cp = 0;
cp = strchr(line, '#');
if (cp)
*cp = 0;
/*
* Skip trailing and leading whitespace
*/
for (cp = line + strlen(line) - 1; cp >= line; cp--) {
if (*cp == ' ' || *cp == '\t')
*cp = 0;
else
break;
}
cp = line;
while (*cp && isspace(*cp))
cp++;
ptr = cp;
/*
* Skip empty lines
*/
if (*ptr == 0)
continue;
/*
* Ignore future extensions
*/
if (*ptr == '@')
continue;
/*
* Parse substitutions
*/
for (cp = ptr; *cp; cp++)
if (isspace(*cp))
break;
*cp = 0;
for (cp++; *cp; cp++)
if (!isspace(*cp))
break;
#if 0
printf("Substitute: '%s' for '%s'\n", ptr, cp ? cp : "<NULL>");
#endif
add_subst(ptr, cp);
}
}
/*
* Return 0 if the files are different, 1 if the files are the same.
*/
static int compare_file(const char *outfn, const char *newfn)
{
FILE *old_f, *new_f;
char oldbuf[2048], newbuf[2048], *oldcp, *newcp;
int retval;
old_f = fopen(outfn, "r");
if (!old_f)
return 0;
new_f = fopen(newfn, "r");
if (!new_f) {
fclose(old_f);
return 0;
}
while (1) {
oldcp = fgets(oldbuf, sizeof(oldbuf), old_f);
newcp = fgets(newbuf, sizeof(newbuf), new_f);
if (!oldcp && !newcp) {
retval = 1;
break;
}
if (!oldcp || !newcp || strcmp(oldbuf, newbuf)) {
retval = 0;
break;
}
}
fclose(old_f);
fclose(new_f);
return retval;
}
int main(int argc, char **argv)
{
char line[2048];
int c;
FILE *in, *out;
char *outfn = NULL, *newfn = NULL;
int verbose = 0;
int adjust_timestamp = 0;
struct stat stbuf;
struct utimbuf ut;
while ((c = getopt (argc, argv, "f:tv")) != EOF) {
switch (c) {
case 'f':
in = fopen(optarg, "r");
if (!in) {
perror(optarg);
exit(1);
}
parse_config_file(in);
fclose(in);
break;
case 't':
adjust_timestamp++;
break;
case 'v':
verbose++;
break;
default:
fprintf(stderr, "%s: [-f config-file] [file]\n",
argv[0]);
break;
}
}
if (optind < argc) {
in = fopen(argv[optind], "r");
if (!in) {
perror(argv[optind]);
exit(1);
}
optind++;
} else
in = stdin;
if (optind < argc) {
outfn = argv[optind];
newfn = (char *) malloc(strlen(outfn)+20);
if (!newfn) {
fprintf(stderr, "Memory error! Exiting.\n");
exit(1);
}
strcpy(newfn, outfn);
strcat(newfn, ".new");
out = fopen(newfn, "w");
if (!out) {
perror(newfn);
exit(1);
}
} else {
out = stdout;
outfn = 0;
}
while (!feof(in)) {
if (fgets(line, sizeof(line), in) == NULL)
break;
substitute_line(line);
fputs(line, out);
}
fclose(in);
fclose(out);
if (outfn) {
struct stat st;
if (compare_file(outfn, newfn)) {
if (verbose)
printf("No change, keeping %s.\n", outfn);
if (adjust_timestamp) {
if (stat(outfn, &stbuf) == 0) {
if (verbose)
printf("Updating modtime for %s\n", outfn);
ut.actime = stbuf.st_atime;
ut.modtime = time(0);
if (utime(outfn, &ut) < 0)
perror("utime");
}
}
unlink(newfn);
} else {
if (verbose)
printf("Creating or replacing %s.\n", outfn);
rename(newfn, outfn);
}
/* set read-only to alert user it is a generated file */
if (stat(outfn, &st) == 0)
chmod(outfn, st.st_mode & ~0222);
}
return (0);
}