Implement fixed buffer vstrs; use them for import path.
diff --git a/py/vstr.c b/py/vstr.c
index b2e46c8..4d10dfb 100644
--- a/py/vstr.c
+++ b/py/vstr.c
@@ -1,6 +1,7 @@
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
+#include <assert.h>
#include "misc.h"
// returned value is always at least 1 greater than argument
@@ -16,10 +17,23 @@
}
vstr->buf[0] = 0;
vstr->had_error = false;
+ vstr->fixed_buf = false;
+}
+
+void vstr_init_fixed_buf(vstr_t *vstr, int alloc, char *buf) {
+ assert(alloc > 0); // need at least room for the null byte
+ vstr->alloc = alloc;
+ vstr->len = 0;
+ vstr->buf = buf;
+ vstr->buf[0] = 0;
+ vstr->had_error = false;
+ vstr->fixed_buf = true;
}
void vstr_clear(vstr_t *vstr) {
- m_del(char, vstr->buf, vstr->alloc);
+ if (!vstr->fixed_buf) {
+ m_del(char, vstr->buf, vstr->alloc);
+ }
vstr->buf = NULL;
}
@@ -43,7 +57,9 @@
void vstr_free(vstr_t *vstr) {
if (vstr != NULL) {
- m_del(char, vstr->buf, vstr->alloc);
+ if (!vstr->fixed_buf) {
+ m_del(char, vstr->buf, vstr->alloc);
+ }
m_del_obj(vstr_t, vstr);
}
}
@@ -73,7 +89,10 @@
}
// Extend vstr strictly to by requested size, return pointer to newly added chunk
-char *vstr_extend(vstr_t *vstr, int size) {
+char *vstr_extend(vstr_t *vstr, int size) {
+ if (vstr->fixed_buf) {
+ return NULL;
+ }
char *new_buf = m_renew(char, vstr->buf, vstr->alloc, vstr->alloc + size);
if (new_buf == NULL) {
vstr->had_error = true;
@@ -87,6 +106,9 @@
// Shrink vstr to be given size
bool vstr_set_size(vstr_t *vstr, int size) {
+ if (vstr->fixed_buf) {
+ return false;
+ }
char *new_buf = m_renew(char, vstr->buf, vstr->alloc, size);
if (new_buf == NULL) {
vstr->had_error = true;
@@ -102,8 +124,11 @@
return vstr_set_size(vstr, vstr->len);
}
-bool vstr_ensure_extra(vstr_t *vstr, int size) {
+static bool vstr_ensure_extra(vstr_t *vstr, int size) {
if (vstr->len + size + 1 > vstr->alloc) {
+ if (vstr->fixed_buf) {
+ return false;
+ }
int new_alloc = ROUND_ALLOC((vstr->len + size + 1) * 2);
char *new_buf = m_renew(char, vstr->buf, vstr->alloc, new_alloc);
if (new_buf == NULL) {
@@ -156,8 +181,15 @@
void vstr_add_strn(vstr_t *vstr, const char *str, int len) {
if (vstr->had_error || !vstr_ensure_extra(vstr, len)) {
+ // if buf is fixed, we got here because there isn't enough room left
+ // so just try to copy as much as we can, with room for null byte
+ if (vstr->fixed_buf && vstr->len + 1 < vstr->alloc) {
+ len = vstr->alloc - vstr->len - 1;
+ goto copy;
+ }
return;
}
+copy:
memmove(vstr->buf + vstr->len, str, len);
vstr->len += len;
vstr->buf[vstr->len] = 0;