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bug: dead keys with nil values can stay in weak tables

This commit is contained in:
Roberto Ierusalimschy 2017-08-31 13:14:41 -03:00
parent ac65bab25f
commit 029d269f4d
2 changed files with 47 additions and 12 deletions
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38
bugs
View File

@ -3680,9 +3680,9 @@ It needs an "interceptor" 'memcmp' function that continues
reading memory after a difference is found.]],
patch = [[
2c2
< ** $Id: bugs,v 1.155 2017/07/27 13:55:38 roberto Exp roberto $
< ** $Id: bugs,v 1.156 2017/08/12 13:12:42 roberto Exp roberto $
---
> ** $Id: bugs,v 1.155 2017/07/27 13:55:38 roberto Exp roberto $
> ** $Id: bugs,v 1.156 2017/08/12 13:12:42 roberto Exp roberto $
263c263,264
< for (option = LUA_STRFTIMEOPTIONS; *option != '\0'; option += oplen) {
---
@ -3837,6 +3837,40 @@ patch = [[
}
Bug{
what = [[dead keys with nil values can stay in weak tables]],
report = [[云风 Cloud Wu, 2017/08/15]],
since = [[5.2]],
fix = nil,
example = [[
-- The following chunk, under a memory checker like valgrind,
-- produces a memory access violation.
local a = setmetatable({}, {__mode = 'kv'})
a['ABCDEFGHIJKLMNOPQRSTUVWXYZ' .. 'abcdefghijklmnopqrstuvwxyz'] = {}
a[next(a)] = nil
collectgarbage()
print(a['BCDEFGHIJKLMNOPQRSTUVWXYZ' .. 'abcdefghijklmnopqrstuvwxyz'])
]],
patch = [[
--- lgc.c 2016/12/22 13:08:50 2.215
+++ lgc.c 2017/08/31 16:08:23
@@ -643,8 +643,9 @@
for (n = gnode(h, 0); n < limit; n++) {
if (!ttisnil(gval(n)) && (iscleared(g, gkey(n)))) {
setnilvalue(gval(n)); /* remove value ... */
- removeentry(n); /* and remove entry from table */
}
+ if (ttisnil(gval(n))) /* is entry empty? */
+ removeentry(n); /* remove entry from table */
}
}
}
]]
}
--[=[

21
lgc.c
View File

@ -1,5 +1,5 @@
/*
** $Id: lgc.c,v 2.232 2017/06/12 14:21:44 roberto Exp roberto $
** $Id: lgc.c,v 2.233 2017/06/29 15:06:44 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@ -117,7 +117,8 @@ static lu_mem atomic (lua_State *L);
/*
** If key is not marked, mark its entry as dead. This allows the
** Clear keys for empty entries in tables. If entry is empty
** and its key is not marked, mark its entry as dead. This allows the
** collection of the key, but keeps its entry in the table (its removal
** could break a chain). Other places never manipulate dead keys,
** because its associated nil value is enough to signal that the entry
@ -688,10 +689,10 @@ static void clearkeys (global_State *g, GCObject *l) {
Table *h = gco2t(l);
Node *n, *limit = gnodelast(h);
for (n = gnode(h, 0); n < limit; n++) {
if (!ttisnil(gval(n)) && (iscleared(g, gckeyN(n)))) {
setnilvalue(gval(n)); /* remove value ... */
removeentry(n); /* and remove entry from table */
}
if (!ttisnil(gval(n)) && (iscleared(g, gckeyN(n)))) /* unmarked key? */
setnilvalue(gval(n)); /* clear value */
if (ttisnil(gval(n))) /* is entry empty? */
removeentry(n); /* remove it from table */
}
}
}
@ -712,10 +713,10 @@ static void clearvalues (global_State *g, GCObject *l, GCObject *f) {
setnilvalue(o); /* remove value */
}
for (n = gnode(h, 0); n < limit; n++) {
if (iscleared(g, gcvalueN(gval(n)))) {
setnilvalue(gval(n)); /* remove value ... */
removeentry(n); /* and remove entry from table */
}
if (iscleared(g, gcvalueN(gval(n)))) /* unmarked value? */
setnilvalue(gval(n)); /* clear value */
if (ttisnil(gval(n))) /* is entry empty? */
removeentry(n); /* remove it from table */
}
}
}