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authorRoberto Ierusalimschy <roberto@inf.puc-rio.br>2023-11-13 13:12:33 -0300
committerRoberto Ierusalimschy <roberto@inf.puc-rio.br>2023-11-13 13:12:33 -0300
commit6d042a178fba32d10ec23c98fb2fd284397ccddc (patch)
treef68f9c48a5c3832e929f1317bfd83750ca13b17d /lauxlib.c
parenteabf425c76e0089eb88e102e2a44d8c8a37bc213 (diff)
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Auxiliary buffer uses external strings
The buffer system from the auxiliary library reuses its buffer as external memory when closing long strings.
Diffstat (limited to 'lauxlib.c')
-rw-r--r--lauxlib.c54
1 files changed, 38 insertions, 16 deletions
diff --git a/lauxlib.c b/lauxlib.c
index 555a5976..73190975 100644
--- a/lauxlib.c
+++ b/lauxlib.c
@@ -470,18 +470,27 @@ typedef struct UBox {
470} UBox; 470} UBox;
471 471
472 472
473/* Resize the buffer used by a box. Optimize for the common case of
474** resizing to the old size. (For instance, __gc will resize the box
475** to 0 even after it was closed. 'pushresult' may also resize it to a
476** final size that is equal to the one set when the buffer was created.)
477*/
473static void *resizebox (lua_State *L, int idx, size_t newsize) { 478static void *resizebox (lua_State *L, int idx, size_t newsize) {
474 void *ud;
475 lua_Alloc allocf = lua_getallocf(L, &ud);
476 UBox *box = (UBox *)lua_touserdata(L, idx); 479 UBox *box = (UBox *)lua_touserdata(L, idx);
477 void *temp = allocf(ud, box->box, box->bsize, newsize); 480 if (box->bsize == newsize) /* not changing size? */
478 if (l_unlikely(temp == NULL && newsize > 0)) { /* allocation error? */ 481 return box->box; /* keep the buffer */
479 lua_pushliteral(L, "not enough memory"); 482 else {
480 lua_error(L); /* raise a memory error */ 483 void *ud;
484 lua_Alloc allocf = lua_getallocf(L, &ud);
485 void *temp = allocf(ud, box->box, box->bsize, newsize);
486 if (l_unlikely(temp == NULL && newsize > 0)) { /* allocation error? */
487 lua_pushliteral(L, "not enough memory");
488 lua_error(L); /* raise a memory error */
489 }
490 box->box = temp;
491 box->bsize = newsize;
492 return temp;
481 } 493 }
482 box->box = temp;
483 box->bsize = newsize;
484 return temp;
485} 494}
486 495
487 496
@@ -526,15 +535,15 @@ static void newbox (lua_State *L) {
526 535
527/* 536/*
528** Compute new size for buffer 'B', enough to accommodate extra 'sz' 537** Compute new size for buffer 'B', enough to accommodate extra 'sz'
529** bytes. (The test for "not big enough" also gets the case when the 538** bytes plus one for a terminating zero. (The test for "not big enough"
530** computation of 'newsize' overflows.) 539** also gets the case when the computation of 'newsize' overflows.)
531*/ 540*/
532static size_t newbuffsize (luaL_Buffer *B, size_t sz) { 541static size_t newbuffsize (luaL_Buffer *B, size_t sz) {
533 size_t newsize = (B->size / 2) * 3; /* buffer size * 1.5 */ 542 size_t newsize = (B->size / 2) * 3; /* buffer size * 1.5 */
534 if (l_unlikely(MAX_SIZET - sz < B->n)) /* overflow in (B->n + sz)? */ 543 if (l_unlikely(MAX_SIZET - sz - 1 < B->n)) /* overflow in (B->n + sz + 1)? */
535 return luaL_error(B->L, "buffer too large"); 544 return luaL_error(B->L, "buffer too large");
536 if (newsize < B->n + sz) /* not big enough? */ 545 if (newsize < B->n + sz + 1) /* not big enough? */
537 newsize = B->n + sz; 546 newsize = B->n + sz + 1;
538 return newsize; 547 return newsize;
539} 548}
540 549
@@ -594,9 +603,22 @@ LUALIB_API void luaL_addstring (luaL_Buffer *B, const char *s) {
594LUALIB_API void luaL_pushresult (luaL_Buffer *B) { 603LUALIB_API void luaL_pushresult (luaL_Buffer *B) {
595 lua_State *L = B->L; 604 lua_State *L = B->L;
596 checkbufferlevel(B, -1); 605 checkbufferlevel(B, -1);
597 lua_pushlstring(L, B->b, B->n); 606 if (!buffonstack(B)) /* using static buffer? */
598 if (buffonstack(B)) 607 lua_pushlstring(L, B->b, B->n); /* save result as regular string */
608 else { /* reuse buffer already allocated */
609 UBox *box = (UBox *)lua_touserdata(L, -1);
610 void *ud;
611 lua_Alloc allocf = lua_getallocf(L, &ud); /* function to free buffer */
612 size_t len = B->n; /* final string length */
613 char *s;
614 resizebox(L, -1, len + 1); /* adjust box size to content size */
615 s = (char*)box->box; /* final buffer address */
616 s[len] = '\0'; /* add ending zero */
617 /* clear box, as 'lua_pushextlstring' will take control over buffer */
618 box->bsize = 0; box->box = NULL;
619 lua_pushextlstring(L, s, len, allocf, ud);
599 lua_closeslot(L, -2); /* close the box */ 620 lua_closeslot(L, -2); /* close the box */
621 }
600 lua_remove(L, -2); /* remove box or placeholder from the stack */ 622 lua_remove(L, -2); /* remove box or placeholder from the stack */
601} 623}
602 624