* { "%%", "%"},
* }
*
- * Returns 1 on a successful substitution pass that fits in result,
- * Returns 0 on a failed or overflowing substitution pass.
+ * Returns the length of the substituted string (not including the final \0).
+ * Like with snprintf, if the result is >= reslen, then it overflowed.
*/
-int interpolate(char *result, int reslen,
+unsigned long interpolate(char *result, unsigned long reslen,
const char *orig,
const struct interp *interps, int ninterps)
{
const char *src = orig;
char *dest = result;
- int newlen = 0;
+ unsigned long newlen = 0;
const char *name, *value;
- int namelen, valuelen;
+ unsigned long namelen, valuelen;
int i;
char c;
- memset(result, 0, reslen);
-
- while ((c = *src) && newlen < reslen - 1) {
+ while ((c = *src)) {
if (c == '%') {
/* Try to match an interpolation string. */
for (i = 0; i < ninterps; i++) {
name = interps[i].name;
namelen = strlen(name);
- if (strncmp(src, name, namelen) == 0) {
+ if (strncmp(src, name, namelen) == 0)
break;
- }
}
/* Check for valid interpolation. */
if (i < ninterps) {
value = interps[i].value;
- valuelen = strlen(value);
+ if (!value) {
+ src += namelen;
+ continue;
+ }
- if (newlen + valuelen < reslen - 1) {
+ valuelen = strlen(value);
+ if (newlen + valuelen < reslen) {
/* Substitute. */
- strncpy(dest, value, valuelen);
- newlen += valuelen;
+ memcpy(dest, value, valuelen);
dest += valuelen;
- src += namelen;
- } else {
- /* Something's not fitting. */
- return 0;
}
-
- } else {
- /* Skip bogus interpolation. */
- *dest++ = *src++;
- newlen++;
+ newlen += valuelen;
+ src += namelen;
+ continue;
}
-
- } else {
- /* Straight copy one non-interpolation character. */
- *dest++ = *src++;
- newlen++;
}
+ /* Straight copy one non-interpolation character. */
+ if (newlen + 1 < reslen)
+ *dest++ = *src;
+ src++;
+ newlen++;
}
- return newlen < reslen - 1;
+ /* XXX: the previous loop always keep room for the ending NUL,
+ we just need to check if there was room for a NUL in the first place */
+ if (reslen > 0)
+ *dest = '\0';
+ return newlen;
}