From cfbe378f906061ee56f91acfbdf569d0d3fb9556 Mon Sep 17 00:00:00 2001 From: Roberto Ierusalimschy Date: Fri, 23 Sep 2022 10:57:35 -0300 Subject: Small simplification in overflow check in 'getfield' Subtracting a small non-negative int from a non-negative int cannot overflow, and adding a non-negative int to INT_MIN cannot overflow. --- loslib.c | 4 +--- testes/files.lua | 9 +++++++++ 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/loslib.c b/loslib.c index 3e20d622..854dcf69 100644 --- a/loslib.c +++ b/loslib.c @@ -260,9 +260,7 @@ static int getfield (lua_State *L, const char *key, int d, int delta) { res = d; } else { - /* unsigned avoids overflow when lua_Integer has 32 bits */ - if (!(res >= 0 ? (lua_Unsigned)res <= (lua_Unsigned)INT_MAX + delta - : (lua_Integer)INT_MIN + delta <= res)) + if (!(res >= 0 ? res - delta <= INT_MAX : INT_MIN + delta <= res)) return luaL_error(L, "field '%s' is out-of-bound", key); res -= delta; } diff --git a/testes/files.lua b/testes/files.lua index 16cf9b6a..78f962e5 100644 --- a/testes/files.lua +++ b/testes/files.lua @@ -825,8 +825,17 @@ checkerr("missing", os.time, {hour = 12}) -- missing date if string.packsize("i") == 4 then -- 4-byte ints checkerr("field 'year' is out-of-bound", os.time, {year = -(1 << 31) + 1899, month = 1, day = 1}) + + checkerr("field 'year' is out-of-bound", os.time, + {year = -(1 << 31), month = 1, day = 1}) + + if math.maxinteger > 2^31 then -- larger lua_integer? + checkerr("field 'year' is out-of-bound", os.time, + {year = (1 << 31) + 1900, month = 1, day = 1}) + end end + if not _port then -- test Posix-specific modifiers assert(type(os.date("%Ex")) == 'string') -- cgit v1.2.1