Made openssl an optional requirement

PacktPublishing · Jul 1, 2024 · a798819 · a798819
1 parent d4aea19
commit a798819
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Showing 4 changed files with 13 additions and 52 deletions.
diff --git a/chapter04/ex07_pack_nsis_standalone/CMakeLists.txt b/chapter04/ex07_pack_nsis_standalone/CMakeLists.txt
@@ -15,10 +15,6 @@ if(NOT PROJECT_IS_TOP_LEVEL)
   message(FATAL_ERROR "The chapter-4, ex07_pack project is intended to be a standalone, top-level project. Do not include this directory.")
 endif()
 
-# Search the package OpenSSL and its component SSL, configuration fails if not found
-# this is used by the executable target
-find_package(OpenSSL COMPONENTS SSL)
-
 add_subdirectory(executable)
 add_subdirectory(library)
 

diff --git a/chapter04/ex07_pack_nsis_standalone/executable/CMakeLists.txt b/chapter04/ex07_pack_nsis_standalone/executable/CMakeLists.txt
@@ -18,7 +18,7 @@ add_executable(ch4_ex07_executable src/main.cpp)
 target_compile_features(ch4_ex07_executable PRIVATE cxx_std_11)
 
 # Link executable target to library target
-target_link_libraries(ch4_ex07_executable PRIVATE ch4_ex07_library OpenSSL::SSL)
+target_link_libraries(ch4_ex07_executable PRIVATE ch4_ex07_library)
 
 
 install(TARGETS ch4_ex07_executable)
diff --git a/chapter04/ex07_pack_nsis_standalone/executable/src/main.cpp b/chapter04/ex07_pack_nsis_standalone/executable/src/main.cpp
@@ -10,55 +10,12 @@
 
 #include <iomanip>
 #include <iostream>
-#include <openssl/evp.h>
-#include <openssl/sha.h>
 #include <sstream>
 #include <string>
 
-std::string sha256(const std::string &str) {
-  unsigned char hash[SHA256_DIGEST_LENGTH];
-  EVP_MD_CTX *mdctx;
 
-  if (!(mdctx = EVP_MD_CTX_new())) {
-    // Handle error
-    return "";
-  }
-
-  if (1 != EVP_DigestInit_ex(mdctx, EVP_sha256(), NULL)) {
-    // Handle error
-    EVP_MD_CTX_free(mdctx);
-    return "";
-  }
-
-  if (1 != EVP_DigestUpdate(mdctx, str.c_str(), str.size())) {
-    // Handle error
-    EVP_MD_CTX_free(mdctx);
-    return "";
-  }
-
-  unsigned int hash_len;
-  if (1 != EVP_DigestFinal_ex(mdctx, hash, &hash_len)) {
-    // Handle error
-    EVP_MD_CTX_free(mdctx);
-    return "";
-  }
-
-  EVP_MD_CTX_free(mdctx);
-
-  std::stringstream ss;
-  for (int i = 0; i < SHA256_DIGEST_LENGTH; i++) {
-    ss << std::hex << std::setw(2) << std::setfill('0') << (int)hash[i];
-  }
-
-  return ss.str();
-}
 
 int main(int, char **) {
   chapter4::ex07::greeter g;
   g.greet();
-
-  const std::string message{"CMake is awesome!"};
-
-  std::cout << "The sha256 hash of the message '" << message << "' is:\n";
-  std::cout << "\t" << sha256(message) << "\n";
 }
diff --git a/chapter05/find_package_example/CMakeLists.txt b/chapter05/find_package_example/CMakeLists.txt
@@ -15,11 +15,19 @@ project(
 # enable debuging for finding the package (For illustrative purposes)
 # set(CMAKE_FIND_DEBUG_MODE TRUE )
 
-# Search the package OpenSSL and its component SSL, configuration fails if not found
-# because of the keyword REQUIRED
-find_package(OpenSSL REQUIRED COMPONENTS SSL)
 
-# disable debugging again set(CMAKE_FIND_DEBUG_MODE FALSE )
+# Search the package OpenSSL and its component SSL. 
+# To have the configuration fail if not found, add the REQUIRED keyword like this:
+# find_package(OpenSSL COMPONENTS SSL REQUIRED)
+find_package(OpenSSL COMPONENTS SSL)
+
+# disable debugging again 
+# set(CMAKE_FIND_DEBUG_MODE FALSE )
+
+if(OpenSSL-NOTFOUND)
+    message(STATUS "OpenSSL package not found; Not building find-package example.")
+    return()
+endif()
 
 # Create a target to build an executable
 add_executable(ch5_find_package_example)