Rework the append_buf function
It won't overflow the buffer and will allocate new buffers sufficiently large to
hold new strings longer than the expansion factor.
@@ -48,28 +48,38 @@ const OPTIONS engine_options[] = {
static int append_buf(char **buf, int *size, const char *s)
{
- if (*buf == NULL) {
- *size = 256;
- *buf = app_malloc(*size, "engine buffer");
- **buf = '\0';
- }
+ const int expand = 256;
+ int len = strlen(s) + 1;
+ char *p = *buf;
+
+ if (p == NULL) {
+ *size = ((len + expand - 1) / expand) * expand;
+ p = *buf = app_malloc(*size, "engine buffer");
+ } else {
+ const int blen = strlen(p);
- if (strlen(*buf) + strlen(s) >= (unsigned int)*size) {
- char *tmp;
- *size += 256;
- tmp = OPENSSL_realloc(*buf, *size);
- if (tmp == NULL) {
+ if (blen > 0)
+ len += 2 + blen;
+
+ if (len > *size) {
+ *size = ((len + expand - 1) / expand) * expand;
+ p = OPENSSL_realloc(p, *size);
+ if (p == NULL) {
OPENSSL_free(*buf);
*buf = NULL;
return 0;
}
- *buf = tmp;
+ *buf = p;
}
- if (**buf != '\0')
- strcat(*buf, ", ");
- strcat(*buf, s);
+ if (blen > 0) {
+ p += blen;
+ *p++ = ',';
+ *p++ = ' ';
+ }
+ }
+ strcpy(p, s);
return 1;
}
