build: prepare builds for clang-cl, add cmake ossfuzz support

- cmake: add support to build ossfuzz. Enable with `-DBUILD_OSSFUZZ=ON`. Also supports `-DLIB_FUZZING_ENGINE=` like autotools does. - check for `__clang__` when suppressing warnings in source. Necessary for clang-cl, which set `__clang__`, but doesn't set `__GNU__`. - cmake: optimize out 4 picky warning option detections with gcc. - cmake: bring `-pedantic-error`, `-Wall` use closer to curl's. - cmake: set `-Wno-language-extension-token` for clang-cl. - cmake: escape only the necessary `-W` options for clang-cl. - cmake: apply picky warnings to C++. - cmake: replace `unset(VAR)` with `set(VAR "")` for init. - cmake: prefer dash-style MSVC options. - cmake: simplify `MATCHES` expression. - cmake: formatting/whitespace. - ci/GHA: bump `actions/upload-artifact` to v4 Closes #1524
2025-07-23 16:21:00 +03:00 · 2024-10-30 00:59:03 +01:00
parent af5c9fb88f
commit 854cfa8292
22 changed files with 158 additions and 131 deletions
--- a/.github/workflows/cifuzz.yml
+++ b/.github/workflows/cifuzz.yml
@ -31,7 +31,7 @@ jobs:
        dry-run: false
        language: c
    - name: Upload Crash
-      uses: actions/upload-artifact@v3
+      uses: actions/upload-artifact@v4
      if: ${{ failure() && steps.build.outcome == 'success' }}
      with:
        name: artifacts
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -122,8 +122,9 @@ endif()

 option(BUILD_EXAMPLES "Build libssh2 examples" ON)
 option(BUILD_TESTING "Build libssh2 test suite" ON)
+option(BUILD_OSSFUZZ "Build libssh2 OSS-Fuzz" OFF)

-if(NOT BUILD_STATIC_LIBS AND NOT BUILD_SHARED_LIBS)
+if((NOT BUILD_STATIC_LIBS AND NOT BUILD_SHARED_LIBS) OR BUILD_OSSFUZZ)
  set(BUILD_STATIC_LIBS ON)
 endif()

@ -228,7 +229,7 @@ endif()
 # duration of these tests.
 if(MSVC AND ENABLE_WERROR)
  cmake_push_check_state()
-  set(CMAKE_REQUIRED_FLAGS "/WX-")
+  set(CMAKE_REQUIRED_FLAGS "-WX-")
 endif()

 if(HAVE_SYS_TIME_H)
--- a/cmake/PickyWarnings.cmake
+++ b/cmake/PickyWarnings.cmake
@ -3,47 +3,48 @@

 include(CheckCCompilerFlag)

+set(_picky "")
+
 option(ENABLE_WERROR "Turn compiler warnings into errors" OFF)
 option(PICKY_COMPILER "Enable picky compiler options" ON)

 if(ENABLE_WERROR)
  if(MSVC)
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /WX")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /WX")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -WX")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -WX")
  else()  # llvm/clang and gcc style options
    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror")
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror")
  endif()
+
+  if(((CMAKE_COMPILER_IS_GNUCC AND
+       NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 5.0 AND
+       NOT CMAKE_VERSION VERSION_LESS 3.23.0) OR  # to avoid check_symbol_exists() conflicting with GCC -pedantic-errors
+     CMAKE_C_COMPILER_ID MATCHES "Clang"))
+    list(APPEND _picky "-pedantic-errors")
+  endif()
 endif()

 if(MSVC)
  # Use the highest warning level for Visual Studio.
-  if(PICKY_COMPILER)
-    if(CMAKE_CXX_FLAGS MATCHES "[/-]W[0-4]")
-      string(REGEX REPLACE "[/-]W[0-4]" "/W4" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-    else()
-      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W4")
-    endif()
  if(CMAKE_C_FLAGS MATCHES "[/-]W[0-4]")
-      string(REGEX REPLACE "[/-]W[0-4]" "/W4" CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
+    string(REGEX REPLACE "[/-]W[0-4]" "-W4" CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
  else()
-      set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W4")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -W4")
+  endif()
+  if(CMAKE_CXX_FLAGS MATCHES "[/-]W[0-4]")
+    string(REGEX REPLACE "[/-]W[0-4]" "-W4" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+  else()
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -W4")
  endif()
 endif()
-elseif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_C_COMPILER_ID MATCHES "Clang")
+
+if(PICKY_COMPILER)
+  if(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_C_COMPILER_ID MATCHES "Clang")

    # https://clang.llvm.org/docs/DiagnosticsReference.html
    # https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html

-  if(NOT CMAKE_CXX_FLAGS MATCHES "-Wall")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
-  endif()
-  if(NOT CMAKE_C_FLAGS MATCHES "-Wall")
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
-  endif()
-
-  if(PICKY_COMPILER)
-
    # _picky_enable = Options we want to enable as-is.
    # _picky_detect = Options we want to test first and enable if available.

@ -55,15 +56,9 @@ elseif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_C_COMPILER_I
    endif()

    list(APPEND _picky_enable
-      -pedantic
+      -Wall -pedantic
    )

-    if(ENABLE_WERROR)
-      list(APPEND _picky_enable
-        -pedantic-errors
-      )
-    endif()
-
    # ----------------------------------
    # Add new options here, if in doubt:
    # ----------------------------------
@ -119,29 +114,29 @@ elseif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_C_COMPILER_I
      -Wvla                                # clang  2.8  gcc  4.3
    )

-    set(_picky_common
-      -Wdouble-promotion                   # clang  3.6  gcc  4.6  appleclang  6.3
-      -Wenum-conversion                    # clang  3.2  gcc 10.0  appleclang  4.6  g++ 11.0
-      -Wpragmas                            # clang  3.5  gcc  4.1  appleclang  6.0
-      -Wunused-const-variable              # clang  3.4  gcc  6.0  appleclang  5.1
-    )
-
    if(CMAKE_C_COMPILER_ID MATCHES "Clang")
      list(APPEND _picky_enable
        ${_picky_common_old}
        -Wshift-sign-overflow              # clang  2.9
        -Wshorten-64-to-32                 # clang  1.0
-        -Wlanguage-extension-token         # clang  3.0
        -Wformat=2                         # clang  3.0  gcc  4.8
      )
+      if(NOT MSVC)
+        list(APPEND _picky_enable
+          -Wlanguage-extension-token       # clang  3.0
+        )
+      endif()
      # Enable based on compiler version
      if((CMAKE_C_COMPILER_ID STREQUAL "Clang"      AND NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.6) OR
         (CMAKE_C_COMPILER_ID STREQUAL "AppleClang" AND NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 6.3))
        list(APPEND _picky_enable
-          ${_picky_common}
-        # -Wunreachable-code-break         # clang  3.5            appleclang  6.0  # Not used: Silent in "unity" builds
+          -Wdouble-promotion               # clang  3.6  gcc  4.6  appleclang  6.3
+          -Wenum-conversion                # clang  3.2  gcc 10.0  appleclang  4.6  g++ 11.0
          -Wheader-guard                   # clang  3.4            appleclang  5.1
+          -Wpragmas                        # clang  3.5  gcc  4.1  appleclang  6.0
          -Wsometimes-uninitialized        # clang  3.2            appleclang  4.6
+        # -Wunreachable-code-break         # clang  3.5            appleclang  6.0  # Not used: Silent in "unity" builds
+          -Wunused-const-variable          # clang  3.4  gcc  6.0  appleclang  5.1
        )
      endif()
      if((CMAKE_C_COMPILER_ID STREQUAL "Clang"      AND NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.9) OR
@ -165,9 +160,6 @@ elseif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_C_COMPILER_I
        )
      endif()
    else()  # gcc
-      list(APPEND _picky_detect
-        ${_picky_common}
-      )
      # Enable based on compiler version
      if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.3)
        list(APPEND _picky_enable
@ -175,8 +167,8 @@ elseif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_C_COMPILER_I
          -Wclobbered                      #             gcc  4.3
          -Wmissing-parameter-type         #             gcc  4.3
          -Wold-style-declaration          #             gcc  4.3
+          -Wpragmas                        # clang  3.5  gcc  4.1  appleclang  6.0
          -Wstrict-aliasing=3              #             gcc  4.0
-          -Wtrampolines                    #             gcc  4.3
        )
      endif()
      if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.5 AND MINGW)
@ -186,7 +178,9 @@ elseif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_C_COMPILER_I
      endif()
      if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.8)
        list(APPEND _picky_enable
+          -Wdouble-promotion               # clang  3.6  gcc  4.6  appleclang  6.3
          -Wformat=2                       # clang  3.0  gcc  4.8
+          -Wtrampolines                    #             gcc  4.6
        )
      endif()
      if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 5.0)
@ -201,6 +195,7 @@ elseif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_C_COMPILER_I
            -fdelete-null-pointer-checks
          -Wshift-negative-value           # clang  3.7  gcc  6.0 (clang default)
          -Wshift-overflow=2               # clang  3.0  gcc  6.0 (clang default: -Wshift-overflow)
+          -Wunused-const-variable          # clang  3.4  gcc  6.0  appleclang  5.1
        )
      endif()
      if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 7.0)
@ -216,14 +211,13 @@ elseif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_C_COMPILER_I
      if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 10.0)
        list(APPEND _picky_enable
          -Warith-conversion               #             gcc 10.0
+          -Wenum-conversion                # clang  3.2  gcc 10.0  appleclang  4.6  g++ 11.0
        )
      endif()
    endif()

    #

-    unset(_picky)
-
    foreach(_ccopt IN LISTS _picky_enable)
      list(APPEND _picky "${_ccopt}")
    endforeach()
@ -239,24 +233,28 @@ elseif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_C_COMPILER_I
        list(APPEND _picky "${_ccopt}")
      endif()
    endforeach()
+  endif()
+endif()

 # clang-cl
 if(CMAKE_C_COMPILER_ID STREQUAL "Clang" AND MSVC)
-      if(CMAKE_VERSION VERSION_LESS 3.12)
+  list(APPEND _picky "-Wno-language-extension-token")  # Allow __int64
+
  set(_picky_tmp "")
  foreach(_ccopt IN LISTS _picky)
-          list(APPEND _picky_tmp "/clang:${_ccopt}")
+    # Prefix -Wall, otherwise clang-cl interprets it as an MSVC option and translates it to -Weverything
+    if(_ccopt MATCHES "^-W" AND NOT _ccopt STREQUAL "-Wall")
+      list(APPEND _picky_tmp ${_ccopt})
+    else()
+      list(APPEND _picky_tmp "-clang:${_ccopt}")
+    endif()
  endforeach()
  set(_picky ${_picky_tmp})
-      else()
-        list(TRANSFORM _picky PREPEND "/clang:")
-      endif()
 endif()

 if(_picky)
  string(REPLACE ";" " " _picky "${_picky}")
  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${_picky}")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${_picky}")
  message(STATUS "Picky compiler options: ${_picky}")
 endif()
-  endif()
-endif()
--- a/example/direct_tcpip.c
+++ b/example/direct_tcpip.c
@ -248,12 +248,12 @@ int main(int argc, char *argv[])
    for(;;) {
        fd_set fds;
        FD_ZERO(&fds);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
        FD_SET(forwardsock, &fds);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
        tv.tv_sec = 0;
@ -263,12 +263,12 @@ int main(int argc, char *argv[])
            fprintf(stderr, "failed to select().\n");
            goto shutdown;
        }
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
        if(rc && FD_ISSET(forwardsock, &fds)) {
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
            len = recv(forwardsock, buf, sizeof(buf), 0);
--- a/example/scp_nonblock.c
+++ b/example/scp_nonblock.c
@ -64,12 +64,12 @@ static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)

    FD_ZERO(&fd);

-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
    FD_SET(socket_fd, &fd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

--- a/example/scp_write_nonblock.c
+++ b/example/scp_write_nonblock.c
@ -48,12 +48,12 @@ static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)

    FD_ZERO(&fd);

-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
    FD_SET(socket_fd, &fd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

--- a/example/sftp_RW_nonblock.c
+++ b/example/sftp_RW_nonblock.c
@ -56,12 +56,12 @@ static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)

    FD_ZERO(&fd);

-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
    FD_SET(socket_fd, &fd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

@ -258,13 +258,13 @@ int main(int argc, char *argv[])

        FD_ZERO(&fd);
        FD_ZERO(&fd2);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
        FD_SET(sock, &fd);
        FD_SET(sock, &fd2);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

@ -329,13 +329,13 @@ int main(int argc, char *argv[])

            FD_ZERO(&fd);
            FD_ZERO(&fd2);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
            FD_SET(sock, &fd);
            FD_SET(sock, &fd2);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

--- a/example/sftp_nonblock.c
+++ b/example/sftp_nonblock.c
@ -65,12 +65,12 @@ static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)

    FD_ZERO(&fd);

-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
    FD_SET(socket_fd, &fd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

--- a/example/sftp_write_nonblock.c
+++ b/example/sftp_write_nonblock.c
@ -54,12 +54,12 @@ static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)

    FD_ZERO(&fd);

-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
    FD_SET(socket_fd, &fd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

--- a/example/sftp_write_sliding.c
+++ b/example/sftp_write_sliding.c
@ -55,12 +55,12 @@ static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)

    FD_ZERO(&fd);

-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
    FD_SET(socket_fd, &fd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

--- a/example/ssh2_agent_forwarding.c
+++ b/example/ssh2_agent_forwarding.c
@ -50,12 +50,12 @@ static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)

    FD_ZERO(&fd);

-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
    FD_SET(socket_fd, &fd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

--- a/example/ssh2_echo.c
+++ b/example/ssh2_echo.c
@ -47,12 +47,12 @@ static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)

    FD_ZERO(&fd);

-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
    FD_SET(socket_fd, &fd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

--- a/example/ssh2_exec.c
+++ b/example/ssh2_exec.c
@ -51,12 +51,12 @@ static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)

    FD_ZERO(&fd);

-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
    FD_SET(socket_fd, &fd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

--- a/example/tcpip-forward.c
+++ b/example/tcpip-forward.c
@ -246,12 +246,12 @@ int main(int argc, char *argv[])
    for(;;) {
        fd_set fds;
        FD_ZERO(&fds);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
        FD_SET(forwardsock, &fds);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
        tv.tv_sec = 0;
@ -261,12 +261,12 @@ int main(int argc, char *argv[])
            fprintf(stderr, "failed to select().\n");
            goto shutdown;
        }
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
        if(rc && FD_ISSET(forwardsock, &fds)) {
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
            ssize_t nwritten;
--- a/example/x11.c
+++ b/example/x11.c
@ -210,12 +210,12 @@ static int x11_send_receive(LIBSSH2_CHANNEL *channel, libssh2_socket_t sock)
    timeval_out.tv_usec = 0;

    FD_ZERO(&set);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
    FD_SET(sock, &set);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

@ -415,12 +415,12 @@ int main(int argc, char *argv[])
    for(;;) {

        FD_ZERO(&set);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
        FD_SET(fileno(stdin), &set);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@ -49,7 +49,7 @@ endif()

 ## Options

-unset(_libssh2_definitions)
+set(_libssh2_definitions "")

 option(CLEAR_MEMORY "Enable clearing of memory before being freed" ON)
 if(NOT CLEAR_MEMORY)
@ -76,8 +76,8 @@ list(APPEND LIBSSH2_LIBS ${LIBSSH2_LIBS_SOCKET})
 list(APPEND libssh2_INCLUDE_DIRS ${CMAKE_CURRENT_BINARY_DIR})

 if(MSVC)
-  set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} /Zi /Od")
-  set(CMAKE_SHARED_LINKER_FLAGS_DEBUG "${CMAKE_SHARED_LINKER_FLAGS_DEBUG} /DEBUG")
+  set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -Zi -Od")
+  set(CMAKE_SHARED_LINKER_FLAGS_DEBUG "${CMAKE_SHARED_LINKER_FLAGS_DEBUG} -DEBUG")
 endif()

 ## Sources
@ -100,7 +100,7 @@ if(WIN32 AND (BUILD_STATIC_LIBS OR BUILD_STATIC_FOR_TESTS) AND BUILD_SHARED_LIBS
  set(STATIC_LIB_SUFFIX "_static")
 endif()

-unset(_libssh2_export)
+set(_libssh2_export "")

 # we want it to be called libssh2 on all platforms
 if(BUILD_STATIC_LIBS OR BUILD_STATIC_FOR_TESTS)
@ -212,7 +212,7 @@ endif()
 set(_ldflags "")

 # Avoid getting unnecessary -L options for known system directories.
-unset(_sys_libdirs)
+set(_sys_libdirs "")
 foreach(_libdir IN LISTS CMAKE_SYSTEM_PREFIX_PATH)
  if(_libdir MATCHES "/$")
    set(_libdir "${_libdir}lib")
@ -237,7 +237,7 @@ foreach(_libdir IN LISTS LIBSSH2_LIBDIRS)
  endif()
 endforeach()

-unset(_implicit_libs)
+set(_implicit_libs "")
 if(NOT MINGW AND NOT UNIX)
  set(_implicit_libs ${CMAKE_C_IMPLICIT_LINK_LIBRARIES})
 endif()
@ -259,7 +259,7 @@ foreach(_lib IN LISTS _implicit_libs LIBSSH2_LIBS)
  endif()
  if(_lib MATCHES "^-")
    list(APPEND _ldflags "${_lib}")
-  elseif(_lib MATCHES ".*/.*")
+  elseif(_lib MATCHES "/")
    # This gets a bit more complex, because we want to specify the
    # directory separately, and only once per directory
    get_filename_component(_libdir ${_lib} DIRECTORY)
--- a/src/libssh2_priv.h
+++ b/src/libssh2_priv.h
@ -45,7 +45,7 @@

 /* FIXME: Disable warnings for 'src' */
 #if !defined(LIBSSH2_TESTS) && !defined(LIBSSH2_WARN_SIGN_CONVERSION)
-#ifdef __GNUC__
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
 #endif
--- a/src/mbedtls.h
+++ b/src/mbedtls.h
@ -41,7 +41,7 @@

 #define LIBSSH2_CRYPTO_ENGINE libssh2_mbedtls

-#ifdef __GNUC__
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 /* mbedTLS (as of v3.5.1) has a `[-Werror=arith-conversion]`
   warning in its public headers. */
@ -73,7 +73,7 @@
 #include <mbedtls/pk.h>
 #include <mbedtls/error.h>

-#ifdef __GNUC__
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif

--- a/src/session.c
+++ b/src/session.c
@ -675,12 +675,12 @@ int _libssh2_wait_socket(LIBSSH2_SESSION *session, time_t start_time)

        if(dir & LIBSSH2_SESSION_BLOCK_INBOUND) {
            FD_ZERO(&rfd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
            FD_SET(session->socket_fd, &rfd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
            readfd = &rfd;
@ -688,12 +688,12 @@ int _libssh2_wait_socket(LIBSSH2_SESSION *session, time_t start_time)

        if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND) {
            FD_ZERO(&wfd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
            FD_SET(session->socket_fd, &wfd);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
            writefd = &wfd;
@ -1655,24 +1655,24 @@ libssh2_poll(LIBSSH2_POLLFD * fds, unsigned int nfds, long timeout)
        switch(fds[i].type) {
        case LIBSSH2_POLLFD_SOCKET:
            if(fds[i].events & LIBSSH2_POLLFD_POLLIN) {
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
                FD_SET(fds[i].fd.socket, &rfds);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
                if(fds[i].fd.socket > maxfd)
                    maxfd = fds[i].fd.socket;
            }
            if(fds[i].events & LIBSSH2_POLLFD_POLLOUT) {
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
                FD_SET(fds[i].fd.socket, &wfds);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
                if(fds[i].fd.socket > maxfd)
@ -1681,12 +1681,12 @@ libssh2_poll(LIBSSH2_POLLFD * fds, unsigned int nfds, long timeout)
            break;

        case LIBSSH2_POLLFD_CHANNEL:
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
            FD_SET(fds[i].fd.channel->session->socket_fd, &rfds);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
            if(fds[i].fd.channel->session->socket_fd > maxfd)
@ -1696,12 +1696,12 @@ libssh2_poll(LIBSSH2_POLLFD * fds, unsigned int nfds, long timeout)
            break;

        case LIBSSH2_POLLFD_LISTENER:
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
            FD_SET(fds[i].fd.listener->session->socket_fd, &rfds);
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
            if(fds[i].fd.listener->session->socket_fd > maxfd)
@ -1880,7 +1880,7 @@ libssh2_poll(LIBSSH2_POLLFD * fds, unsigned int nfds, long timeout)
            for(i = 0; i < nfds; i++) {
                switch(fds[i].type) {
                case LIBSSH2_POLLFD_SOCKET:
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
@ -1893,7 +1893,7 @@ libssh2_poll(LIBSSH2_POLLFD * fds, unsigned int nfds, long timeout)
                    if(fds[i].revents) {
                        active_fds++;
                    }
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
                    break;
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@ -85,7 +85,7 @@ foreach(_test IN LISTS DOCKER_TESTS STANDALONE_TESTS SSHD_TESTS)
  elseif(TARGET ${LIB_STATIC})
    set(_lib_for_tests ${LIB_STATIC})
  else()
-    unset(_lib_for_tests)
+    set(_lib_for_tests "")
    message(STATUS "Skip test requiring static libssh2 lib: ${_test}")
  endif()

@ -132,7 +132,7 @@ foreach(_test IN LISTS STANDALONE_TESTS)
 endforeach()

 if(RUN_SSHD_TESTS AND SSHD_EXECUTABLE)
-  unset(_sshd_test_targets)
+  set(_sshd_test_targets "")
  foreach(_test IN LISTS SSHD_TESTS)
    if(TARGET ${_test})
      set(_sshd_test_targets "${_sshd_test_targets} $<TARGET_FILE:${_test}>")
@ -176,3 +176,7 @@ add_target_to_copy_dependencies(
  TARGET copy_test_dependencies
  DEPENDENCIES ${RUNTIME_DEPENDENCIES}
  BEFORE_TARGETS ${TEST_TARGETS})
+
+if(BUILD_OSSFUZZ)
+  add_subdirectory(ossfuzz)
+endif()
--- a/tests/ossfuzz/CMakeLists.txt
+++ b/tests/ossfuzz/CMakeLists.txt
@ -0,0 +1,24 @@
+# Copyright (C) Viktor Szakats
+# SPDX-License-Identifier: BSD-3-Clause
+
+enable_language(CXX)
+
+add_library(standaloneengine STATIC "standaloneengine.cc")
+target_include_directories(standaloneengine PRIVATE
+  "${PROJECT_SOURCE_DIR}/include")
+set_target_properties(standaloneengine PROPERTIES UNITY_BUILD OFF)
+
+add_executable(ssh2_client_fuzzer "ssh2_client_fuzzer.cc" "testinput.h")
+target_include_directories(ssh2_client_fuzzer PRIVATE
+  "${PROJECT_SOURCE_DIR}/include")
+if(LIB_FUZZING_ENGINE)
+  if(LIB_FUZZING_ENGINE STREQUAL "-fsanitize=fuzzer")  # FIXME: compiler-specific
+    set_target_properties(ssh2_client_fuzzer PROPERTIES LINK_FLAGS "${LIB_FUZZING_ENGINE}")
+  else()
+    target_link_libraries(ssh2_client_fuzzer ${LIB_FUZZING_ENGINE})
+  endif()
+else()
+  target_link_libraries(ssh2_client_fuzzer standaloneengine)
+endif()
+target_link_libraries(ssh2_client_fuzzer ${LIB_STATIC} ${LIBSSH2_LIBS_SOCKET})
+set_target_properties(ssh2_client_fuzzer PROPERTIES UNITY_BUILD OFF)
--- a/tests/ossfuzz/Makefile.am
+++ b/tests/ossfuzz/Makefile.am
@ -31,4 +31,4 @@ ssh2_client_fuzzer_LDFLAGS = $(AM_LDFLAGS) -static
 libstandaloneengine_a_SOURCES = standaloneengine.cc
 libstandaloneengine_a_CXXFLAGS = $(AM_CXXFLAGS)

-EXTRA_DIST = ossfuzz.sh
+EXTRA_DIST = CMakeLists.txt ossfuzz.sh