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LUAI_MAXSTACK defined privately

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LUAI_MAXSTACK is limited to INT_MAX/2, so can use INT_MAX/2 to define
pseudo-indices (LUA_REGISTRYINDEX) in 'lua.h'. A change in the maximum
stack size does not need to change the Lua-C ABI.
This commit is contained in:
Roberto Ierusalimschy
2025-07-01 10:57:02 -03:00
parent cfce6f4b20
commit 59a1adf194
4 changed files with 17 additions and 18 deletions
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14
ldo.c
View File

@@ -174,6 +174,20 @@ TStatus luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
#define STACKERRSPACE 200
/*
** LUAI_MAXSTACK limits the size of the Lua stack.
** It must fit into INT_MAX/2.
*/
#if !defined(LUAI_MAXSTACK)
#if 1000000 < (INT_MAX / 2)
#define LUAI_MAXSTACK 1000000
#else
#define LUAI_MAXSTACK (INT_MAX / 2u)
#endif
#endif
/* maximum stack size that respects size_t */
#define MAXSTACK_BYSIZET ((MAX_SIZET / sizeof(StackValue)) - STACKERRSPACE)

1
ltests.h
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@@ -155,7 +155,6 @@ LUA_API void *debug_realloc (void *ud, void *block,
** Reduce maximum stack size to make stack-overflow tests run faster.
** (But value is still large enough to overflow smaller integers.)
*/
#undef LUAI_MAXSTACK
#define LUAI_MAXSTACK 68000

6
lua.h
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@@ -37,10 +37,10 @@
/*
** Pseudo-indices
** (-LUAI_MAXSTACK is the minimum valid index; we keep some free empty
** space after that to help overflow detection)
** (The stack size is limited to INT_MAX/2; we keep some free empty
** space after that to help overflow detection.)
*/
#define LUA_REGISTRYINDEX (-LUAI_MAXSTACK - 1000)
#define LUA_REGISTRYINDEX (-(INT_MAX/2 + 1000))
#define lua_upvalueindex(i) (LUA_REGISTRYINDEX - (i))

14
luaconf.h
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@@ -763,20 +763,6 @@
** =====================================================================
*/
/*
@@ LUAI_MAXSTACK limits the size of the Lua stack.
** CHANGE it if you need a different limit. This limit is arbitrary;
** its only purpose is to stop Lua from consuming unlimited stack
** space and to reserve some numbers for pseudo-indices.
** (It must fit into max(int)/2.)
*/
#if 1000000 < (INT_MAX / 2)
#define LUAI_MAXSTACK 1000000
#else
#define LUAI_MAXSTACK (INT_MAX / 2u)
#endif
/*
@@ LUA_EXTRASPACE defines the size of a raw memory area associated with
** a Lua state with very fast access.