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.
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3847)
diff --git a/apps/engine.c b/apps/engine.c
index 61fb758..5d47082 100644
--- a/apps/engine.c
+++ b/apps/engine.c
@@ -48,28 +48,38 @@
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 (strlen(*buf) + strlen(s) >= (unsigned int)*size) {
- char *tmp;
- *size += 256;
- tmp = OPENSSL_realloc(*buf, *size);
- if (tmp == NULL) {
- OPENSSL_free(*buf);
- *buf = NULL;
- return 0;
+ if (p == NULL) {
+ *size = ((len + expand - 1) / expand) * expand;
+ p = *buf = app_malloc(*size, "engine buffer");
+ } else {
+ const int blen = strlen(p);
+
+ 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 = p;
}
- *buf = tmp;
+
+ if (blen > 0) {
+ p += blen;
+ *p++ = ',';
+ *p++ = ' ';
+ }
}
- if (**buf != '\0')
- strcat(*buf, ", ");
- strcat(*buf, s);
-
+ strcpy(p, s);
return 1;
}
