[bench] Avoid function call arguments which are pointers to uninitialized values #9949

pull practicalswift wants to merge 1 commits into bitcoin:master from practicalswift:avoid-pointers-to-unitialized-values-in-function-calls changing 1 files +2 −2

practicalswift commented at 11:28 AM on March 8, 2017: contributor

Prior to this commit:

bench/checkblock.cpp:41:5: warning: Function call argument is a pointer to uninitialized value [clang-analyzer-core.CallAndMessage]
    stream.write(&a, 1); // Prevent compaction

in src/bench/base58.cpp:None in 4c5671f708 outdated

  12 | @@ -13,10 +13,10 @@
  13 |  
  14 |  static void Base58Encode(benchmark::State& state)
  15 |  {
  16 | -    unsigned char buff[32] = {
  17 | +    unsigned char buff[33] = {

laanwj commented at 2:27 PM on March 8, 2017:

A NUL terminator is unnecessary here, as the array is not interpreted as a string.

[bench] Avoid function call arguments which are pointers to uninitialized values 218d915445

in src/bench/checkblock.cpp:None in 4c5671f708 outdated

  21 | @@ -22,7 +22,7 @@ static void DeserializeBlockTest(benchmark::State& state)
  22 |      CDataStream stream((const char*)block_bench::block413567,
  23 |              (const char*)&block_bench::block413567[sizeof(block_bench::block413567)],
  24 |              SER_NETWORK, PROTOCOL_VERSION);
  25 | -    char a;
  26 | +    char a = '\0';

laanwj commented at 2:28 PM on March 8, 2017:

ACK on this change

practicalswift force-pushed on Mar 8, 2017
practicalswift commented at 3:41 PM on March 8, 2017: contributor

@laanwj Thanks for the quick review! This PR is now limited to fixing the two uninitialized values in src/bench/checkblock.cpp.
paveljanik commented at 3:48 PM on March 8, 2017: contributor

ACK https://github.com/bitcoin/bitcoin/pull/9949/commits/218d915445b5936c2de1ffe1e2c97b3f3d20becc
MarcoFalke commented at 4:02 PM on March 8, 2017: member

Uninitialized values are fine if they are not read?
TheBlueMatt commented at 9:16 PM on March 8, 2017: member

@MarcoFalke it looks like these are read, however (well, copied and never acted on, but still technically undefined behavior).

utACK 218d915445b5936c2de1ffe1e2c97b3f3d20becc
fanquake added the label Tests on Mar 9, 2017
practicalswift commented at 12:18 PM on April 10, 2017: contributor

Adding link to "Always initialize an object" (ES.20) in the C++ Core Guidelines.
laanwj merged this on Apr 10, 2017
laanwj closed this on Apr 10, 2017
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