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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <errno.h>
#include <stddef.h>
#include <stdlib.h>
#include "alloc-util.h"
#include "macro.h"
#include "replace-var.h"
#include "string-util.h"
/*
* Generic infrastructure for replacing @FOO@ style variables in
* strings. Will call a callback for each replacement.
*/
static int get_variable(const char *b, char **r) {
size_t k;
char *t;
assert(b);
assert(r);
if (*b != '@')
return 0;
k = strspn(b + 1, UPPERCASE_LETTERS "_");
if (k <= 0 || b[k+1] != '@')
return 0;
t = strndup(b + 1, k);
if (!t)
return -ENOMEM;
*r = t;
return 1;
}
char* replace_var(const char *text, char *(*lookup)(const char *variable, void *userdata), void *userdata) {
char *r, *t;
const char *f;
size_t l;
assert(text);
assert(lookup);
l = strlen(text);
r = new(char, l+1);
if (!r)
return NULL;
f = text;
t = r;
while (*f) {
_cleanup_free_ char *v = NULL, *n = NULL;
char *a;
int k;
size_t skip, d, nl;
k = get_variable(f, &v);
if (k < 0)
goto oom;
if (k == 0) {
*(t++) = *(f++);
continue;
}
n = lookup(v, userdata);
if (!n)
goto oom;
skip = strlen(v) + 2;
d = t - r;
nl = l - skip + strlen(n);
a = realloc(r, nl + 1);
if (!a)
goto oom;
l = nl;
r = a;
t = r + d;
t = stpcpy(t, n);
f += skip;
}
*t = 0;
return r;
oom:
return mfree(r);
}
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