cmake: make libssh2-config work with all TLS-backends

CMake:

- Find*: set `<modulename>_FOUND` for compatibility when found via
  `pkg-config`. E.g. `MbedTLS_FOUND`.
  `find_package_handle_standard_args()` sets both `<MODULENAME>_FOUND`
  and `<Modulename>_FOUND` when detecting the dependency. Some CMake
  code relies on this and 3rd-party code may rely on it too. Make sure
  to set the latter variant when detecting the dependency via
  `pkg-config`, where we don't call
  `find_package_handle_standard_args()`.

  CMake sets these variable to `TRUE` (not `ON` or `1`). Replicate this
  for compatibility.

- libssh2-config.cmake: inherit default `LIBSSH2_USE_PKGCONFIG`.
  Follow-up to a3aa6b4ca8 #1525

- document variables consumed by `libssh2-config.cmake.in`.

- `libssh2-config.cmake`: fix to link to non-OpenSSL crypto backends.
  This is most likely not how this is supposed to be done, but better
  than failing.
  What's the canonical way to do this, and how OpenSSL and zlib does it
  is yet to be figured out.

- use `ZLIB::ZLIB` to reference zlib.
- use `IN ITEMS` where missed.
- harmonize variable dump output formats.

CMake `find_package` integration tests:

- extend to all crypto backends (was: OpenSSL).
- show libssh2 variables set by `find_package()`.
- stop building examples and tests for the consumed package.
  For performance.
- enable zlib, for coverage.
- be verbose when building the test targets.

ci/GHA:

- add packaged mbedTLS (2.x) build to Linux matrix.
- alphasort some tests.

Follow-up to d9c2e550ca #1460
Follow-up to 82b09f9b3a #1322

Closes #1534

.github/workflows/ci.yml

@@ -58,7 +58,7 @@ jobs:
       MAKEFLAGS: -j5
     steps:
       - name: 'install prereqs'
-        run: sudo apt-get -o Dpkg::Use-Pty=0 install libssl-dev
+        run: sudo apt-get -o Dpkg::Use-Pty=0 install libgcrypt-dev libssl-dev libmbedtls-dev libwolfssl-dev
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
@@ -66,8 +66,14 @@ jobs:
         run: ./tests/cmake/test.sh FetchContent
       - name: 'via add_subdirectory'
         run: ./tests/cmake/test.sh add_subdirectory
-      - name: 'via find_package'
+      - name: 'via find_package OpenSSL'
-        run: ./tests/cmake/test.sh find_package
+        run: ./tests/cmake/test.sh find_package OpenSSL
+      - name: 'via find_package Libgcrypt'
+        run: ./tests/cmake/test.sh find_package Libgcrypt
+      - name: 'via find_package mbedTLS'
+        run: ./tests/cmake/test.sh find_package mbedTLS
+      - name: 'via find_package wolfSSL'
+        run: ./tests/cmake/test.sh find_package wolfSSL
 
   build_linux:
     name: 'linux'
@@ -78,7 +84,7 @@ jobs:
       matrix:
         compiler: [gcc, clang]
         arch: [amd64]
-        crypto: [OpenSSL, wolfSSL, Libgcrypt, mbedTLS]
+        crypto: [OpenSSL, Libgcrypt, mbedTLS, wolfSSL]
         build: [cmake]
         zlib: ['OFF', 'ON']
         include:
@@ -136,7 +142,7 @@ jobs:
             zlib: 'ON'
           - compiler: gcc
             arch: i386
-            crypto: mbedTLS
+            crypto: mbedTLS-from-source
             build: cmake
             zlib: 'ON'
           - compiler: clang
@@ -177,14 +183,15 @@ jobs:
       - name: 'install packages'
         run: |
           [ '${{ matrix.crypto }}' = 'OpenSSL' ] && pkg='libssl-dev'
-          [ '${{ matrix.crypto }}' = 'wolfSSL' ] && pkg='libwolfssl-dev'
           [ '${{ matrix.crypto }}' = 'Libgcrypt' ] && pkg='libgcrypt-dev'
+          [ '${{ matrix.crypto }}' = 'mbedTLS' ] && pkg='libmbedtls-dev'
+          [ '${{ matrix.crypto }}' = 'wolfSSL' ] && pkg='libwolfssl-dev'
           if [ -n "${pkg}" ]; then
             sudo apt-get -o Dpkg::Use-Pty=0 install "${pkg}:${{ matrix.arch }}"
           fi
 
       - name: 'cache mbedTLS'
-        if: ${{ matrix.crypto == 'mbedTLS' }}
+        if: ${{ matrix.crypto == 'mbedTLS-from-source' }}
         uses: actions/cache@1bd1e32a3bdc45362d1e726936510720a7c30a57 # v4
         id: cache-mbedtls
         with:
@@ -192,7 +199,7 @@ jobs:
           key: ${{ runner.os }}-mbedtls-${{ env.mbedtls-version }}-${{ matrix.arch }}
 
       - name: 'install mbedTLS from source'
-        if: ${{ matrix.crypto == 'mbedTLS' }}
+        if: ${{ matrix.crypto == 'mbedTLS-from-source' }}
         run: |
           if [ '${{ steps.cache-mbedtls.outputs.cache-hit }}' != 'true' ]; then
             curl -fsS -L https://github.com/Mbed-TLS/mbedtls/releases/download/mbedtls-${{ env.mbedtls-version }}/mbedtls-${{ env.mbedtls-version }}.tar.bz2 | tar -xjf -
@@ -444,6 +451,8 @@ jobs:
              [ '${{ matrix.crypto }}' = 'LibreSSL' ] || \
              [[ '${{ matrix.crypto }}' = 'OpenSSL-'* ]]; then
             crypto='OpenSSL'
+          elif [[ '${{ matrix.crypto }}' = 'mbedTLS-'* ]]; then
+            crypto='mbedTLS'
           elif [[ '${{ matrix.crypto }}' = 'wolfSSL-'* ]]; then
             crypto='wolfSSL'
           else
@@ -753,10 +762,6 @@ jobs:
             install: libressl
             configure: --with-crypto=openssl --with-libssl-prefix="$(brew --prefix)/opt/libressl"
             cmake: -DCRYPTO_BACKEND=OpenSSL -DOPENSSL_ROOT_DIR="$(brew --prefix)/opt/libressl"
-          - name: 'wolfSSL'
-            install: wolfssl
-            configure: --with-crypto=wolfssl --with-libwolfssl-prefix="$(brew --prefix)"
-            cmake: -DCRYPTO_BACKEND=wolfSSL
           - name: 'Libgcrypt'
             install: libgcrypt
             configure: --with-crypto=libgcrypt --with-libgcrypt-prefix="$(brew --prefix)"
@@ -765,6 +770,10 @@ jobs:
             install: mbedtls
             configure: --with-crypto=mbedtls --with-libmbedcrypto-prefix="$(brew --prefix)"
             cmake: -DCRYPTO_BACKEND=mbedTLS
+          - name: 'wolfSSL'
+            install: wolfssl
+            configure: --with-crypto=wolfssl --with-libwolfssl-prefix="$(brew --prefix)"
+            cmake: -DCRYPTO_BACKEND=wolfSSL
     steps:
       - name: 'install packages'
         run: brew install ${{ matrix.build == 'autotools' && 'automake libtool' || 'ninja' }} ${{ matrix.crypto.install }}

CMakeLists.txt

@@ -55,8 +55,8 @@ project(libssh2 C)
 function(libssh2_dumpvars)  # Dump all defined variables with their values
   message("::group::CMake Variable Dump")
   get_cmake_property(_vars VARIABLES)
-  foreach(_var ${_vars})
+  foreach(_var IN ITEMS ${_vars})
-    message("${_var} = ${${_var}}")
+    message("${_var} = '${${_var}}'")
   endforeach()
   message("::endgroup::")
 endfunction()
@@ -405,9 +405,8 @@ if(CRYPTO_BACKEND STREQUAL "OpenSSL" OR NOT CRYPTO_BACKEND)
     endif()
 
     find_package(ZLIB)
-
     if(ZLIB_FOUND)
-      list(APPEND LIBSSH2_LIBS ${ZLIB_LIBRARIES})
+      list(APPEND LIBSSH2_LIBS ZLIB::ZLIB)
     endif()
   endif()
 endif()
@@ -433,10 +432,8 @@ if(CRYPTO_BACKEND STREQUAL "wolfSSL" OR NOT CRYPTO_BACKEND)
     endif()
 
     find_package(ZLIB)
-
     if(ZLIB_FOUND)
-      list(APPEND CRYPTO_BACKEND_INCLUDE_DIR ${ZLIB_INCLUDE_DIR})  # Public wolfSSL headers require zlib headers
+      list(APPEND LIBSSH2_LIBS ZLIB::ZLIB)  # Public wolfSSL headers require zlib headers
-      list(APPEND LIBSSH2_LIBS ${ZLIB_LIBRARIES})
     endif()
   endif()
 endif()

cmake/FindLibgcrypt.cmake

@@ -29,6 +29,7 @@ if(LIBSSH2_USE_PKGCONFIG AND
 endif()
 
 if(LIBGCRYPT_FOUND)
+  set(Libgcrypt_FOUND TRUE)
   string(REPLACE ";" " " LIBGCRYPT_CFLAGS "${LIBGCRYPT_CFLAGS}")
   message(STATUS "Found Libgcrypt (via pkg-config): ${LIBGCRYPT_INCLUDE_DIRS} (found version \"${LIBGCRYPT_VERSION}\")")
 else()

cmake/FindMbedTLS.cmake

@@ -29,6 +29,7 @@ if(LIBSSH2_USE_PKGCONFIG AND
 endif()
 
 if(MBEDTLS_FOUND)
+  set(MbedTLS_FOUND TRUE)
   string(REPLACE ";" " " MBEDTLS_CFLAGS "${MBEDTLS_CFLAGS}")
   message(STATUS "Found MbedTLS (via pkg-config): ${MBEDTLS_INCLUDE_DIRS} (found version \"${MBEDTLS_VERSION}\")")
 else()

cmake/FindWolfSSL.cmake

@@ -29,6 +29,7 @@ if(LIBSSH2_USE_PKGCONFIG AND
 endif()
 
 if(WOLFSSL_FOUND)
+  set(WolfSSL_FOUND TRUE)
   string(REPLACE ";" " " WOLFSSL_CFLAGS "${WOLFSSL_CFLAGS}")
   message(STATUS "Found WolfSSL (via pkg-config): ${WOLFSSL_INCLUDE_DIRS} (found version \"${WOLFSSL_VERSION}\")")
 else()

cmake/libssh2-config.cmake.in

@@ -1,17 +1,34 @@
 # Copyright (C) The libssh2 project and its contributors.
 # SPDX-License-Identifier: BSD-3-Clause
 
+option(LIBSSH2_USE_PKGCONFIG "Enable pkg-config to detect @PROJECT_NAME@ dependencies. Default: @LIBSSH2_USE_PKGCONFIG@" "@LIBSSH2_USE_PKGCONFIG@")
+
 include(CMakeFindDependencyMacro)
 list(PREPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR})
 
+set(_libdirs "")
+set(_libs "")
+
 if("@CRYPTO_BACKEND@" STREQUAL "OpenSSL")
   find_dependency(OpenSSL)
 elseif("@CRYPTO_BACKEND@" STREQUAL "wolfSSL")
   find_dependency(WolfSSL)
+  if(WOLFSSL_FOUND)
+    list(APPEND _libdirs ${WOLFSSL_LIBRARY_DIRS})
+    list(APPEND _libs ${WOLFSSL_LIBRARIES})
+  endif()
 elseif("@CRYPTO_BACKEND@" STREQUAL "Libgcrypt")
   find_dependency(Libgcrypt)
+  if(LIBGCRYPT_FOUND)
+    list(APPEND _libdirs ${LIBGCRYPT_LIBRARY_DIRS})
+    list(APPEND _libs ${LIBGCRYPT_LIBRARIES})
+  endif()
 elseif("@CRYPTO_BACKEND@" STREQUAL "mbedTLS")
   find_dependency(MbedTLS)
+  if(MBEDTLS_FOUND)
+    list(APPEND _libdirs ${MBEDTLS_LIBRARY_DIRS})
+    list(APPEND _libs ${MBEDTLS_LIBRARIES})
+  endif()
 endif()
 
 if(@ZLIB_FOUND@)
@@ -29,3 +46,18 @@ endif()
 if(NOT TARGET Libssh2::@LIB_NAME@)
   add_library(Libssh2::@LIB_NAME@ ALIAS @PROJECT_NAME@::@LIB_SELECTED@)
 endif()
+
+foreach(_target IN ITEMS @PROJECT_NAME@::@LIB_SHARED@ @PROJECT_NAME@::@LIB_STATIC@)
+  if(TARGET "${_target}")
+    if(_libdirs)
+      if(CMAKE_VERSION VERSION_LESS 3.13)
+        set_target_properties("${_target}" PROPERTIES INTERFACE_LINK_DIRECTORIES "${_libdirs}")
+      else()
+        target_link_directories("${_target}" INTERFACE ${_libdirs})
+      endif()
+    endif()
+    if(_libs)
+      target_link_libraries("${_target}" INTERFACE ${_libs})
+    endif()
+  endif()
+endforeach()

src/CMakeLists.txt

@@ -326,8 +326,14 @@ install(
   FILES "${CMAKE_CURRENT_BINARY_DIR}/libssh2.pc"
   DESTINATION "${CMAKE_INSTALL_LIBDIR}/pkgconfig")
 
-#
+# Consumed variables:
-
+#   CRYPTO_BACKEND
+#   LIB_NAME
+#   LIB_SELECTED
+#   LIB_SHARED
+#   LIB_STATIC
+#   LIBSSH2_USE_PKGCONFIG
+#   ZLIB_FOUND
 include(CMakePackageConfigHelpers)
 write_basic_package_version_file(
   "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}-config-version.cmake"

tests/cmake/CMakeLists.txt

@@ -21,10 +21,20 @@ if(TEST_INTEGRATION_MODE STREQUAL "find_package")
       libssh2_FOUND
       libssh2_VERSION
     )
-    if(${result_var})
+    if(NOT ${result_var})
-      message(STATUS "${result_var}: |${${result_var}}|")
+      message(FATAL_ERROR "'${result_var}' variable expected, but not set by the libssh2 package.")
-    else()
+    endif()
-      message(FATAL_ERROR "'${result_var}' variable not set by the libssh2 package.")
+  endforeach()
+  # Show variables set by find_package()
+  get_cmake_property(_vars VARIABLES)
+  foreach(_var IN ITEMS ${_vars})
+    string(TOUPPER "${_var}" _var_upper)
+    if(_var_upper MATCHES "LIBSSH2")
+      get_property(_var_type CACHE ${_var} PROPERTY TYPE)
+      if(_var_type)
+        set(_var_type ":${_var_type}")
+      endif()
+      message("find_package() sets: ${_var}${_var_type} = '${${_var}}'")
     endif()
   endforeach()
 elseif(TEST_INTEGRATION_MODE STREQUAL "add_subdirectory")

tests/cmake/test.sh

@@ -27,13 +27,15 @@ if [ "${mode}" = 'all' ] || [ "${mode}" = 'add_subdirectory' ]; then
 fi
 
 if [ "${mode}" = 'all' ] || [ "${mode}" = 'find_package' ]; then
-  rm -rf bld-libssh2
+  crypto="${2:-OpenSSL}"
-  cmake ../.. -B bld-libssh2
+  bld="bld-libssh2-${crypto}"
-  cmake --build bld-libssh2
+  rm -rf "${bld}"
-  cmake --install bld-libssh2 --prefix bld-libssh2/_pkg
+  cmake ../.. -B "${bld}" -DBUILD_EXAMPLES=OFF -DBUILD_TESTING=OFF -DENABLE_ZLIB_COMPRESSION=ON -DCRYPTO_BACKEND="${crypto}"
+  cmake --build "${bld}"
+  cmake --install "${bld}" --prefix "${bld}/_pkg"
   rm -rf bld-find_package
   cmake -B bld-find_package \
     -DTEST_INTEGRATION_MODE=find_package \
-    -DCMAKE_PREFIX_PATH="${PWD}/bld-libssh2/_pkg/lib/cmake/libssh2"
+    -DCMAKE_PREFIX_PATH="${PWD}/${bld}/_pkg/lib/cmake/libssh2"
-  cmake --build bld-find_package
+  cmake --build bld-find_package --verbose
 fi