Meta: Error out on find_program errors with CMake less than 3.18

We have seen some cases where the build fails for folks, and they are
missing unzip/tar/gzip etc. We can catch some of these in CMake itself,
so lets make sure to handle that uniformly across the build system.

The REQUIRED flag to `find_program` was only added on in CMake 3.18 and
above, so we can't rely on that to actually halt the program execution.

CMakeLists.txt

@@ -49,10 +49,7 @@ endif()
 
 if (NOT HACKSTUDIO_BUILD)
 
-    # FIXME: With cmake 3.18, we can change unzip/untar steps to use
+    include(check_for_dependencies)
-    #        file(  ARCHIVE_EXTRACT) instead
-    find_program(UNZIP unzip REQUIRED)
-    find_program(TAR tar REQUIRED)
 
     # Host tools, required to generate files for the build
     find_package(Lagom CONFIG REQUIRED)
@@ -309,7 +306,7 @@ endif()
 if(EXISTS ${PCI_IDS_GZ_PATH} AND NOT EXISTS ${PCI_IDS_INSTALL_PATH})
     message(STATUS "Extracting PCI ID database from ${PCI_IDS_GZ_PATH}...")
     file(MAKE_DIRECTORY ${CMAKE_INSTALL_DATAROOTDIR})
-    execute_process(COMMAND gzip -d -c "${PCI_IDS_GZ_PATH}" OUTPUT_FILE "${PCI_IDS_INSTALL_PATH}")
+    execute_process(COMMAND "${GZIP_TOOL}" -d -c "${PCI_IDS_GZ_PATH}" OUTPUT_FILE "${PCI_IDS_INSTALL_PATH}")
 endif()
 
 set(USB_IDS_FILE usb.ids)
@@ -325,5 +322,5 @@ endif()
 if(EXISTS ${USB_IDS_GZ_PATH} AND NOT EXISTS ${USB_IDS_INSTALL_PATH})
     message(STATUS "Extracting USB ID database from ${USB_IDS_GZ_PATH}...")
     file(MAKE_DIRECTORY ${CMAKE_INSTALL_DATAROOTDIR})
-    execute_process(COMMAND gzip -d -c "${USB_IDS_GZ_PATH}" OUTPUT_FILE "${USB_IDS_INSTALL_PATH}")
+    execute_process(COMMAND "${GZIP_TOOL}" -d -c "${USB_IDS_GZ_PATH}" OUTPUT_FILE "${USB_IDS_INSTALL_PATH}")
 endif()

Meta/CMake/check_for_dependencies.cmake

@@ -0,0 +1,23 @@
+#
+# Check for the dependencies that the Serenity (target) and Lagom (host) builds require.
+#
+
+# FIXME: With cmake 3.18, we can change unzip/untar/gzip steps to use
+#        file(  ARCHIVE_EXTRACT) instead
+#
+#        Additionally we have to emit an error message for each tool,
+#        as REQUIRED only works with cmake 3.18 and above.
+find_program(UNZIP_TOOL unzip REQUIRED)
+if (NOT UNZIP_TOOL)
+    message(FATAL_ERROR "Failed to locate unzip on your machine, please install it and re-read the SerenityOS build documentation.")
+endif()
+
+find_program(TAR_TOOL tar REQUIRED)
+if (NOT TAR_TOOL)
+    message(FATAL_ERROR "Failed to locate tar on your machine, please install it and re-read the SerenityOS build documentation.")
+endif()
+
+find_program(GZIP_TOOL gzip REQUIRED)
+if (NOT GZIP_TOOL)
+    message(FATAL_ERROR "Failed to locate gzip on your machine, please install it and re-read the SerenityOS build documentation.")
+endif()

Meta/CMake/time_zone_data.cmake

@@ -41,7 +41,7 @@ set(TZDB_ZONE_1970_PATH "${TZDB_PATH}/${TZDB_ZONE_1970_SOURCE}")
 function(extract_tzdb_file source path)
     if(EXISTS "${TZDB_ZIP_PATH}" AND NOT EXISTS "${path}")
         message(STATUS "Extracting TZDB ${source} from ${TZDB_ZIP_PATH}...")
-        execute_process(COMMAND tar -C "${TZDB_PATH}" -xf "${TZDB_ZIP_PATH}" "${source}" RESULT_VARIABLE tar_result)
+        execute_process(COMMAND "${TAR_TOOL}" -C "${TZDB_PATH}" -xf "${TZDB_ZIP_PATH}" "${source}" RESULT_VARIABLE tar_result)
         if (NOT tar_result EQUAL 0)
             message(FATAL_ERROR "Failed to unzip ${source} from ${TZDB_ZIP_PATH} with status ${tar_result}")
         endif()

Meta/CMake/unicode_data.cmake

@@ -91,7 +91,7 @@ set(CLDR_UNITS_PATH "${CLDR_PATH}/${CLDR_UNITS_SOURCE}")
 function(extract_cldr_file source path)
     if(EXISTS "${CLDR_ZIP_PATH}" AND NOT EXISTS "${path}")
         message(STATUS "Extracting CLDR ${source} from ${CLDR_ZIP_PATH}...")
-        execute_process(COMMAND unzip -q "${CLDR_ZIP_PATH}" "${source}/**" -d "${CLDR_PATH}" RESULT_VARIABLE unzip_result)
+        execute_process(COMMAND "${UNZIP_TOOL}" -q "${CLDR_ZIP_PATH}" "${source}/**" -d "${CLDR_PATH}" RESULT_VARIABLE unzip_result)
         if (NOT unzip_result EQUAL 0)
             message(FATAL_ERROR "Failed to unzip ${source} from ${CLDR_ZIP_PATH} with status ${unzip_result}")
         endif()

Meta/CMake/wasm_spec_tests.cmake

@@ -22,8 +22,8 @@ if(INCLUDE_WASM_SPEC_TESTS)
     if(EXISTS ${WASM_SPEC_TEST_GZ_PATH} AND NOT EXISTS ${WASM_SPEC_TEST_PATH})
         message(STATUS "Extracting the WebAssembly testsuite from ${WASM_SPEC_TEST_GZ_PATH}...")
         file(MAKE_DIRECTORY ${WASM_SPEC_TEST_PATH})
-        execute_process(COMMAND gzip -k -d ${WASM_SPEC_TEST_GZ_PATH})
+        execute_process(COMMAND "${GZIP_TOOL}" -k -d ${WASM_SPEC_TEST_GZ_PATH})
-        execute_process(COMMAND tar -xf ${WASM_SPEC_TEST_TAR_PATH})
+        execute_process(COMMAND "${TAR_TOOL}" -xf ${WASM_SPEC_TEST_TAR_PATH})
         execute_process(COMMAND rm ${WASM_SPEC_TEST_TAR_PATH})
         file(GLOB WASM_TESTS "${CMAKE_BINARY_DIR}/testsuite-main/*.wast")
         foreach(PATH ${WASM_TESTS})

Meta/Lagom/CMakeLists.txt

@@ -32,6 +32,7 @@ if(NOT COMMAND serenity_option)
     endmacro()
 endif()
 
+include(check_for_dependencies)
 include(lagom_options)
 
 if(ENABLE_ALL_THE_DEBUG_MACROS)