From 1e975f64f777ffd726d9d5c72952b66dcc4c0a5c Mon Sep 17 00:00:00 2001
From: Sebastian Messmer <mail@smessmer.de>
Date: Sun, 14 Feb 2016 15:55:54 +0100
Subject: [PATCH] Improve error messages when libraries aren't found

---
 src/cpp-utils/CMakeLists.txt |  2 +-
 src/fspp/CMakeLists.txt      |  5 +++--
 utils.cmake                  | 30 ++++++++++++++++++++++++++++--
 3 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/src/cpp-utils/CMakeLists.txt b/src/cpp-utils/CMakeLists.txt
index f4abfd41..9519158c 100644
--- a/src/cpp-utils/CMakeLists.txt
+++ b/src/cpp-utils/CMakeLists.txt
@@ -43,7 +43,7 @@ endif(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
 target_link_libraries(${PROJECT_NAME} PRIVATE pthread curl)
 
 # TODO From Crypto++ 5.7 on, it should support cmake with find_package() instead of find_library().
-find_library(CryptoPP cryptopp $ENV{CRYPTOPP_LIB_PATH})
+find_library_with_path(CryptoPP cryptopp CRYPTOPP_LIB_PATH)
 target_link_libraries(${PROJECT_NAME} PUBLIC ${CryptoPP} scrypt spdlog)
 
 target_add_boost(${PROJECT_NAME} filesystem system thread)
diff --git a/src/fspp/CMakeLists.txt b/src/fspp/CMakeLists.txt
index 5ea55702..5df5b4c2 100644
--- a/src/fspp/CMakeLists.txt
+++ b/src/fspp/CMakeLists.txt
@@ -22,9 +22,10 @@ target_activate_cpp14(${PROJECT_NAME})
 
 if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
   set(CMAKE_FIND_FRAMEWORK LAST)
-  find_library(FUSE osxfuse $ENV{FUSE_LIB_PATH})
+  set(FUSE_LIB_NAME "osxfuse")
 else(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
-  find_library(FUSE fuse $ENV{FUSE_LIB_PATH})
+  set(FUSE_LIB_NAME "fuse")
 endif(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
 
+find_library_with_path(FUSE ${FUSE_LIB_NAME} FUSE_LIB_PATH)
 target_link_libraries(${PROJECT_NAME} PUBLIC ${FUSE})
diff --git a/utils.cmake b/utils.cmake
index cb7ae82c..4c2ead5b 100644
--- a/utils.cmake
+++ b/utils.cmake
@@ -63,7 +63,6 @@ function(require_gcc_version VERSION)
     endif (CMAKE_COMPILER_IS_GNUCXX)
 endfunction(require_gcc_version)
 
-
 ##################################################
 # Specify that a specific minimal version of clang is required
 #
@@ -76,4 +75,31 @@ function(require_clang_version VERSION)
             message(FATAL_ERROR "Needs at least clang version ${VERSION}, found clang ${CMAKE_CXX_COMPILER_VERSION}")
         endif (CMAKE_CXX_COMPILER_VERSION VERSION_LESS ${VERSION})
     endif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-endfunction(require_clang_version)
\ No newline at end of file
+endfunction(require_clang_version)
+
+##################################################
+# Find the location of a library and return its full path in OUTPUT_VARIABLE.
+# If PATH_VARIABLE points to a defined variable, then the library will only be searched in this path.
+# If PATH_VARIABLE points to a undefined variable, default system locations will be searched.
+#
+# Uses (the following will search for fuse in system locations by default, and if the user passes -DFUSE_LIB_PATH to cmake, it will only search in this path.
+#  find_library_with_path(MYLIBRARY fuse FUSE_LIB_PATH)
+#  target_link_library(target ${MYLIBRARY})
+##################################################
+function(find_library_with_path OUTPUT_VARIABLE LIBRARY_NAME PATH_VARIABLE)
+    if(${PATH_VARIABLE})
+        find_library(${OUTPUT_VARIABLE} ${LIBRARY_NAME} PATHS ${${PATH_VARIABLE}} NO_DEFAULT_PATH)
+        if (${OUTPUT_VARIABLE} MATCHES NOTFOUND)
+            message(FATAL_ERROR "Didn't find ${LIBRARY_NAME} in path specified by the ${PATH_VARIABLE} parameter (${${PATH_VARIABLE}}). Pass in the correct path or remove the parameter to try common system locations.")
+        else(${OUTPUT_VARIABLE} MATCHES NOTFOUND)
+            message(STATUS "Found ${LIBRARY_NAME} in user-defined path ${${PATH_VARIABLE}}")
+        endif(${OUTPUT_VARIABLE} MATCHES NOTFOUND)
+    else(${PATH_VARIABLE})
+        find_library(${OUTPUT_VARIABLE} ${LIBRARY_NAME})
+        if (${OUTPUT_VARIABLE} MATCHES NOTFOUND)
+            message(FATAL_ERROR "Didn't find ${LIBRARY_NAME} library. If ${LIBRARY_NAME} is installed, try passing in the library location with -D${PATH_VARIABLE}=/path/to/${LIBRARY_NAME}/lib.")
+        else(${OUTPUT_VARIABLE} MATCHES NOTFOUND)
+            message(STATUS "Found ${LIBRARY_NAME} in system location")
+        endif(${OUTPUT_VARIABLE} MATCHES NOTFOUND)
+    endif(${PATH_VARIABLE})
+endfunction(find_library_with_path)
\ No newline at end of file