From 8bc5cff9bef9710ae863b19f9026c5313373a872 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Tobias=20Nie=C3=9Fen?= Date: Thu, 25 Aug 2022 12:26:26 +0000 Subject: [PATCH] src: simplify and optimize GetOpenSSLVersion() The previous implementation was typically compiled to a fair amount of code even though all inputs are available at compile time. The fact that GetOpenSSLVersion() returns a std::string and used an uninitialized buffer with snprintf made it impossible to make GetOpenSSLVersion() a constexpr, and compilers would typically emit code to dynamically construct the resulting string. The simplified implementation usually boils down to a few mov instructions. (Ideally, this function could be a constexpr returning a std::string_view, but that does not have any advantage in the current design of node::Metadata::Versions which stores versions as std::string instances.) Also make the function static since it is not in an anonymous namespace and change the argument types and the return type of search() to types that are more appropriate, semantically. (The use of snprintf previously made this difficult.) Lastly, make the n argument of search() optional because the simplified implementation always sets it to 0 except during recursive calls within search() itself. --- src/node_metadata.cc | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) diff --git a/src/node_metadata.cc b/src/node_metadata.cc index d64236d9d834f5..a221dcde050ad7 100644 --- a/src/node_metadata.cc +++ b/src/node_metadata.cc @@ -35,21 +35,16 @@ Metadata metadata; } #if HAVE_OPENSSL -constexpr int search(const char* s, int n, int c) { - return *s == c ? n : search(s + 1, n + 1, c); +static constexpr size_t search(const char* s, char c, size_t n = 0) { + return *s == c ? n : search(s + 1, c, n + 1); } -std::string GetOpenSSLVersion() { +static inline std::string GetOpenSSLVersion() { // sample openssl version string format // for reference: "OpenSSL 1.1.0i 14 Aug 2018" - char buf[128]; - const char* etext = OPENSSL_VERSION_TEXT; - const int start = search(etext, 0, ' ') + 1; - etext += start; - const int end = search(etext, start, ' '); - const int len = end - start; - snprintf(buf, sizeof(buf), "%.*s", len, &OPENSSL_VERSION_TEXT[start]); - return std::string(buf); + constexpr size_t start = search(OPENSSL_VERSION_TEXT, ' ') + 1; + constexpr size_t len = search(&OPENSSL_VERSION_TEXT[start], ' '); + return std::string(OPENSSL_VERSION_TEXT, start, len); } #endif // HAVE_OPENSSL