Use GITHUB_TOKEN if set (#5070)

* Use GITHUB_TOKEN if set

We have been having an error from Github saying that API rate limit
exceeded for IP. It hits the limit more often if your public IP is
shared by many other collegues.

{"message":"API rate limit exceeded for 216.228.112.22. (But here's the good news: Authenticated requests get a higher rate limit. Check out the documentation for more details.)","documentation_url":"https://docs.github.com/rest/overview/resources-in-the-rest-api#rate-limiting"}

The suggested solution from GitHub is to use gh.exe tool with "auth
login" arguments. It will store a token and allow us to use API more
than the limit set for IP without token.

However, our cmake build doesn't use gh.exe and API is called via REST.
This commit adds an extra header to the HTTP request with the
infomration of the github token if the value is.

Usage: cmake.exe --preset vs2019 -DSLANG_GITHUB_TOKEN=your_token_here

* Adding a warning message to use LANG_GITHUB_TOKEN

---------

Co-authored-by: Yong He <yonghe@outlook.com>

2 files changed, 26 insertions, 6 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index e1225022e..6580e2680 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -101,6 +101,8 @@ option(SLANG_ENABLE_TESTS "Enable test targets, some tests may require SLANG_ENA
 option(SLANG_ENABLE_EXAMPLES "Enable example targets, requires SLANG_ENABLE_GFX" ON)
 option(SLANG_ENABLE_REPLAYER "Enable slang-replay tool" ON)
 
+option(SLANG_GITHUB_TOKEN "Use a given token value for accessing Github REST API" "")
+
 enum_option(
     SLANG_LIB_TYPE
     # Default
@@ -136,7 +138,7 @@ enum_option(
 if(SLANG_SLANG_LLVM_FLAVOR MATCHES FETCH_BINARY)
     # If the user didn't specify a URL, find the best one now
     if(NOT SLANG_SLANG_LLVM_BINARY_URL)
-        get_best_slang_binary_release_url(url)
+        get_best_slang_binary_release_url("${SLANG_GITHUB_TOKEN}" url)
         if(NOT DEFINED url)
             message(FATAL_ERROR "Unable to find binary release for slang-llvm, please set a different SLANG_SLANG_LLVM_FLAVOR or set SLANG_SLANG_LLVM_BINARY_URL manually")
         endif()
diff --git a/cmake/GitHubRelease.cmake b/cmake/GitHubRelease.cmake
index e63fb7885..dd9dd8fe1 100644
--- a/cmake/GitHubRelease.cmake
+++ b/cmake/GitHubRelease.cmake
@@ -1,4 +1,4 @@
-function(check_release_and_get_latest owner repo version os arch out_var)
+function(check_release_and_get_latest owner repo version os arch github_token out_var)
     # Construct the URL for the specified version's release API endpoint
     set(version_url "https://api.github.com/repos/${owner}/${repo}/releases/tags/v${version}")
 
@@ -17,8 +17,22 @@ function(check_release_and_get_latest owner repo version os arch out_var)
         set(${found_var} "${found}" PARENT_SCOPE)
     endfunction()
 
-    # Download the specified release info from GitHub
-    file(DOWNLOAD "${version_url}" "${json_output_file}" STATUS download_statuses)
+    # Prepare download arguments
+    set(download_args
+        "${version_url}"
+        "${json_output_file}"
+        STATUS download_statuses
+    )
+
+    if(github_token)
+        # Add authorization header if token is provided
+        list(APPEND download_args HTTPHEADER "Authorization: token ${github_token}")
+    endif()
+
+    # Perform the download
+    file(DOWNLOAD ${download_args})
+
+    # Check if the downloading was successful
     list(GET download_statuses 0 status_code)
     if(status_code EQUAL 0)
         file(READ "${json_output_file}" json_content)
@@ -34,6 +48,10 @@ function(check_release_and_get_latest owner repo version os arch out_var)
         message(WARNING "Failed to find ${desired_zip} in release assets for ${version} from ${version_url}\nFalling back to latest version if it differs")
     else()
         message(WARNING "Failed to download release info for version ${version} from ${version_url}\nFalling back to latest version if it differs")
+
+        if(status_code EQUAL 22)
+            message(WARNING "If API rate limit is exceeded, Github allows a higher limit when you use token. Try a cmake option -DSLANG_GITHUB_TOKEN=your_token_here")
+	endif()
     endif()
 
 
@@ -69,7 +87,7 @@ function(check_release_and_get_latest owner repo version os arch out_var)
     endif()
 endfunction()
 
-function(get_best_slang_binary_release_url out_var)
+function(get_best_slang_binary_release_url github_token out_var)
     if(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|amd64|AMD64")
         set(arch "x86_64")
     elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64|ARM64|arm64")
@@ -93,7 +111,7 @@ function(get_best_slang_binary_release_url out_var)
     set(owner "shader-slang")
     set(repo "slang")
 
-    check_release_and_get_latest(${owner} ${repo} ${SLANG_VERSION_NUMERIC} ${os} ${arch} release_version)
+    check_release_and_get_latest(${owner} ${repo} ${SLANG_VERSION_NUMERIC} ${os} ${arch} "${github_token}" release_version)
     if(DEFINED release_version)
       set(${out_var} "https://github.com/${owner}/${repo}/releases/download/v${release_version}/slang-${release_version}-${os}-${arch}.zip" PARENT_SCOPE)
     endif()