New implementation for 'luaL_addvalue'
The function 'luaL_addvalue' (from the buffer system) was rewritten
so that it does not change the position of the box (if present)
in the stack.
diff --git a/lauxlib.c b/lauxlib.c
index 78dfb4e..68842a9 100644
--- a/lauxlib.c
+++ b/lauxlib.c
@@ -27,6 +27,12 @@
#include "lauxlib.h"
+#if !defined(MAX_SIZET)
+/* maximum value for size_t */
+#define MAX_SIZET ((size_t)(~(size_t)0))
+#endif
+
+
/*
** {======================================================
** Traceback
@@ -501,34 +507,56 @@
/*
-** returns a pointer to a free area with at least 'sz' bytes
+** Compute new size for buffer 'B', enough to accommodate extra 'sz'
+** bytes.
*/
-LUALIB_API char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz) {
- lua_State *L = B->L;
- if (B->size - B->n < sz) { /* not enough space? */
+static size_t newbuffsize (luaL_Buffer *B, size_t sz) {
+ size_t newsize = B->size * 2; /* double buffer size */
+ if (MAX_SIZET - sz < B->n) /* overflow in (B->n + sz)? */
+ return luaL_error(B->L, "buffer too large");
+ if (newsize < B->n + sz) /* double is not big enough? */
+ newsize = B->n + sz;
+ return newsize;
+}
+
+
+/*
+** Returns a pointer to a free area with at least 'sz' bytes in buffer
+** 'B'. 'boxidx' is the position in the stack where the buffer's box is
+** or should be.
+*/
+static char *prepbuffsize (luaL_Buffer *B, size_t sz, int boxidx) {
+ if (B->size - B->n >= sz) /* enough space? */
+ return B->b + B->n;
+ else {
+ lua_State *L = B->L;
char *newbuff;
- size_t newsize = B->size * 2; /* double buffer size */
- if (newsize - B->n < sz) /* not big enough? */
- newsize = B->n + sz;
- if (newsize < B->n || newsize - B->n < sz)
- luaL_error(L, "buffer too large");
+ size_t newsize = newbuffsize(B, sz);
/* create larger buffer */
- if (buffonstack(B))
- newbuff = (char *)resizebox(L, -1, newsize);
- else { /* no buffer yet */
- newbuff = (char *)newbox(L, newsize);
+ if (buffonstack(B)) /* buffer already has a box? */
+ newbuff = (char *)resizebox(L, boxidx, newsize); /* resize it */
+ else { /* no box yet */
+ newbuff = (char *)newbox(L, newsize); /* create a new box */
memcpy(newbuff, B->b, B->n * sizeof(char)); /* copy original content */
+ lua_insert(L, boxidx); /* move box to its intended position */
}
B->b = newbuff;
B->size = newsize;
+ return newbuff + B->n;
}
- return &B->b[B->n];
+}
+
+/*
+** returns a pointer to a free area with at least 'sz' bytes
+*/
+LUALIB_API char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz) {
+ return prepbuffsize(B, sz, -1);
}
LUALIB_API void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l) {
if (l > 0) { /* avoid 'memcpy' when 's' can be NULL */
- char *b = luaL_prepbuffsize(B, l);
+ char *b = prepbuffsize(B, l, -1);
memcpy(b, s, l * sizeof(char));
luaL_addsize(B, l);
}
@@ -556,14 +584,23 @@
}
+/*
+** 'luaL_addvalue' is the only function in the Buffer system where the
+** box (if existent) is not on the top of the stack. So, instead of
+** calling 'luaL_addlstring', it replicates the code using -2 as the
+** last argument to 'prepbuffsize', signaling that the box is (or will
+** be) bellow the string being added to the buffer. (Box creation can
+** trigger an emergency GC, so we should not remove the string from the
+** stack before we have the space guaranteed.)
+*/
LUALIB_API void luaL_addvalue (luaL_Buffer *B) {
lua_State *L = B->L;
- size_t l;
- const char *s = lua_tolstring(L, -1, &l);
- if (buffonstack(B))
- lua_insert(L, -2); /* put value below buffer */
- luaL_addlstring(B, s, l);
- lua_remove(L, (buffonstack(B)) ? -2 : -1); /* remove value */
+ size_t len;
+ const char *s = lua_tolstring(L, -1, &len);
+ char *b = prepbuffsize(B, len, -2);
+ memcpy(b, s, len * sizeof(char));
+ luaL_addsize(B, len);
+ lua_pop(L, 1); /* pop string */
}
@@ -577,7 +614,7 @@
LUALIB_API char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz) {
luaL_buffinit(L, B);
- return luaL_prepbuffsize(B, sz);
+ return prepbuffsize(B, sz, -1);
}
/* }====================================================== */
