Re: [Wireshark-dev] lua_bitop.c: MSVC2013 Code Analysis Warning
This appears to be a false positive.
According to:
https://msdn.microsoft.com/en-us/library/9t02bbsx.aspx
...the warning is generated because If the shift overflowed the 32-bit value,
bits are lost. But that's what is actually intended in bitop (it's a 32-bit
bit operations library).
I believe the error gets flagged by MSVC because of this line in lua_bitop.c,
line #96:
#define BRET(b) lua_pushnumber(L, (lua_Number)(SBits)(b)); return 1;
...since 'b' resolves to (b n), and lua_Number is a double, then line #116
ends up being this:
static int bit_lshift(lua_State *L) {
uint32_t b = barg(L, 1);
uint32_t n = barg(L, 2) 31;
lua_pushnumber(L, (double)(int32_t)(b n));
return 1;
}
So MSVC doesn't like that lua_pushnumber() line, apparently. But that's the
intended behavior, because Lua numbers are doubles.
-hadriel
On Feb 7, 2015, at 4:54 PM, Bill Meier wme...@newsguy.com wrote:
Hadriel:
MSVC2013 Code Analysis is giving the following warning:
...\ws-git\epan\wslua\lua_bitop.c(116) : warning C6297: Arithmetic overflow:
32-bit value is shifted, then cast to 64-bit value. Results might not be an
expected value.
After quick look at the code, my reaction:
Uh Oh... Twisty maze of passages
So I'm going to punt.
Can you take a look (or redirect upstream) or whatever ?
Thanks
Bill
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Re: [Wireshark-dev] lua_bitop.c: MSVC2013 Code Analysis Warning
I'll take a look. -hadriel On Feb 7, 2015, at 4:54 PM, Bill Meier wme...@newsguy.com wrote: Hadriel: MSVC2013 Code Analysis is giving the following warning: ...\ws-git\epan\wslua\lua_bitop.c(116) : warning C6297: Arithmetic overflow: 32-bit value is shifted, then cast to 64-bit value. Results might not be an expected value. After quick look at the code, my reaction: Uh Oh... Twisty maze of passages So I'm going to punt. Can you take a look (or redirect upstream) or whatever ? Thanks Bill ___ Sent via:Wireshark-dev mailing list wireshark-dev@wireshark.org Archives:http://www.wireshark.org/lists/wireshark-dev Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev mailto:wireshark-dev-requ...@wireshark.org?subject=unsubscribe
[Wireshark-dev] lua_bitop.c: MSVC2013 Code Analysis Warning
Hadriel: MSVC2013 Code Analysis is giving the following warning: ...\ws-git\epan\wslua\lua_bitop.c(116) : warning C6297: Arithmetic overflow: 32-bit value is shifted, then cast to 64-bit value. Results might not be an expected value. After quick look at the code, my reaction: Uh Oh... Twisty maze of passages So I'm going to punt. Can you take a look (or redirect upstream) or whatever ? Thanks Bill ___ Sent via:Wireshark-dev mailing list wireshark-dev@wireshark.org Archives:http://www.wireshark.org/lists/wireshark-dev Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev mailto:wireshark-dev-requ...@wireshark.org?subject=unsubscribe
