Merge #17280: refactor: Change occurences of c_str() used with size() to data()

f3b51eb9352d7a7c5dfa15615efc8bc0a52ffecf Fix occurences of c_str() used with size() to data() (Wladimir J. van der Laan)

Pull request description:

  Using `data()` better communicates the intent here.

  ~~Also, depending on how `c_str()` is implemented, this fixes undefined behavior: The part of the string after the first NULL character might have undefined contents (or even be inaccessible, worst case).~~ Apparently [this is no longer an issue with C++11](https://github.com/bitcoin/bitcoin/pull/17281#discussion_r339742128).

ACKs for top commit:
  fjahr:
    Code review ACK f3b51eb
  practicalswift:
    ACK f3b51eb9352d7a7c5dfa15615efc8bc0a52ffecf -- diff looks correct, `data()` more idiomatic
  ryanofsky:
    Code review ACK f3b51eb9352d7a7c5dfa15615efc8bc0a52ffecf. Most of these calls (including one in crypter.cpp) are passing text strings, not binary strings likely to contain `\0` and were probably safe before, but much better to avoid the possibility of bugs like this.

Tree-SHA512: 842e1bdd37efc4ece2ecb87ca34962aafef0a192180051def630607e349dc9c8b4e562481fff3de474515f493b4ee3ea53b00269a801a66e625326a38dfce5b8

1 files changed, 1 insertions, 1 deletions

diff --git a/src/wallet/crypter.cpp b/src/wallet/crypter.cpp
index f6179aa298..b50f00e7d1 100644
--- a/src/wallet/crypter.cpp
+++ b/src/wallet/crypter.cpp
@@ -23,7 +23,7 @@ int CCrypter::BytesToKeySHA512AES(const std::vector<unsigned char>& chSalt, cons
     unsigned char buf[CSHA512::OUTPUT_SIZE];
     CSHA512 di;
 
-    di.Write((const unsigned char*)strKeyData.c_str(), strKeyData.size());
+    di.Write((const unsigned char*)strKeyData.data(), strKeyData.size());
     di.Write(chSalt.data(), chSalt.size());
     di.Finalize(buf);