Add error handling, refactor macro name generation, and improve C string escaping in xmake.lua

[Copilot]

The before_build hook in xmake.lua lacked error handling for file I/O failures and used complex inline logic for macro name generation and C string escaping that didn't handle all control characters.

Changes

• io.open error handling: capture the second return value and assert immediately, surfacing a clear message instead of a cryptic nil-index error downstream
• io.readfile error handling: explicit raise on nil return before any string operations
• generate_macro_name() helper: extracted the previously inline path→macro-name logic into a local function, eliminating the duplication and making the loop body easier to read
• Improved C string escaping: replaced the single newline gsub with a two-pass approach:
  • Pass 1 maps every control character (null, \a–\r, and any other byte < 32) to its C escape or \xNN fallback
  • Pass 2 splits any remaining literal newlines across adjacent C string literals for readability

-- Before
local header_file = io.open(header_path, "w")   -- no error check
local content = io.readfile(file)                -- no error check
content = content:gsub("\n", '\\n" \\\n"')       -- only handles newlines

-- After
local header_file, err = io.open(header_path, "w")
assert(header_file, "failed to open header file '" .. header_path .. "': " .. tostring(err))
local content = io.readfile(file)
if not content then raise("failed to read file: %s", file) end
content = content:gsub("[%z\1-\31]", function(c) --[[ per-byte escape ]] end)
content = content:gsub("\n", '\\n"\n"')

Original prompt

Please apply the following diffs and create a pull request.
Once the PR is ready, give it a title based on the messages of the fixes being applied.

[{"message":"Missing error handling for file opening operation. If io.open fails, it returns nil and subsequent write operations will cause a runtime error. Add a check to ensure header_file is not nil before proceeding.","fixFiles":[{"filePath":"xmake.lua","diff":"diff --git a/xmake.lua b/xmake.lua\n--- a/xmake.lua\n+++ b/xmake.lua\n@@ -28,7 +28,8 @@\n \tlocal header_path = path.join(os.projectdir(), build_dir, \".gens\", target:name(), \"embedded_libs_data.h\")\n \n \tos.mkdir(path.directory(header_path))\n-\tlocal header_file = io.open(header_path, \"w\")\n+\tlocal header_file, err = io.open(header_path, \"w\")\n+\tassert(header_file, \"failed to open header file '\" .. header_path .. \"': \" .. tostring(err))\n \theader_file:write(\"// Auto-generated embedded libs\\n\\n\")\n \n \tlocal embed_dirs = {\n"}]},{"message":"The macro name generation logic is complex and duplicated. Consider extracting this into a separate function like generate_macro_name(rel_path) to improve readability and maintainability.","fixFiles":[{"filePath":"xmake.lua","diff":"diff --git a/xmake.lua b/xmake.lua\n--- a/xmake.lua\n+++ b/xmake.lua\n@@ -24,6 +24,30 @@\n add_includedirs(\"build/.gens/adan\", { public = true })\n \n before_build(function(target)\n+\tlocal function generate_macro_name(rel_path)\n+\t\tlocal parts = rel_path:split(\"[/\\\\]\")\n+\t\tlocal macro_name = \"\"\n+\t\tif #parts > 1 then\n+\t\t\tlocal dir_name = parts[1]\n+\t\t\tlocal file_parts = {}\n+\t\t\tfor i = 2, #parts do\n+\t\t\t\ttable.insert(file_parts, parts[i])\n+\t\t\tend\n+\t\t\tlocal file_part = table.concat(file_parts, \"_\")\n+\t\t\tlocal file_id = file_part:gsub(\"%.\", \"_\")\n+\t\t\tlocal dir_up = dir_name:upper()\n+\t\t\tlocal file_up = file_id:upper()\n+\t\t\tif file_up:find(\"^\" .. dir_up .. \"_\") then\n+\t\t\t\tmacro_name = file_up\n+\t\t\telse\n+\t\t\t\tmacro_name = dir_up .. \"_\" .. file_up\n+\t\t\tend\n+\t\telse\n+\t\t\tmacro_name = rel_path:gsub(\"%.\", \"_\"):upper()\n+\t\tend\n+\t\treturn macro_name\n+\tend\n+\n \tlocal build_dir = \"build\"\n \tlocal header_path = path.join(os.projectdir(), build_dir, \".gens\", target:name(), \"embedded_libs_data.h\")\n \n@@ -45,26 +69,7 @@\n \n \t\t\tfor _, file in ipairs(files) do\n \t\t\t\tlocal rel_path = path.relative(file, dir)\n-\t\t\t\tlocal parts = rel_path:split(\"[/\\\\]\")\n-\t\t\t\tlocal macro_name = \"\"\n-\t\t\t\tif #parts > 1 then\n-\t\t\t\t\tlocal dir_name = parts[1]\n-\t\t\t\t\tlocal file_parts = {}\n-\t\t\t\t\tfor i = 2, #parts do\n-\t\t\t\t\t\ttable.insert(file_parts, parts[i])\n-\t\t\t\t\tend\n-\t\t\t\t\tlocal file_part = table.concat(file_parts, \"_\")\n-\t\t\t\t\tlocal file_id = file_part:gsub(\"%.\", \"_\")\n-\t\t\t\t\tlocal dir_up = dir_name:upper()\n-\t\t\t\t\tlocal file_up = file_id:upper()\n-\t\t\t\t\tif file_up:find(\"^\" .. dir_up .. \"_\") then\n-\t\t\t\t\t\tmacro_name = file_up\n-\t\t\t\t\telse\n-\t\t\t\t\t\tmacro_name = dir_up .. \"_\" .. file_up\n-\t\t\t\t\tend\n-\t\t\t\telse\n-\t\t\t\t\tmacro_name = rel_path:gsub(\"%.\", \"_\"):upper()\n-\t\t\t\tend\n+\t\t\t\tlocal macro_name = generate_macro_name(rel_path)\n \n \t\t\t\tlocal content = io.readfile(file)\n \t\t\t\t-- Escape content for inclusion as a C string literal in a header:\n"}]},{"message":"Missing error handling for file read operation. If io.readfile fails, it may return nil and subsequent string operations will cause a runtime error. Add a check to ensure content is not nil before proceeding with string transformations.","fixFiles":[{"filePath":"xmake.lua","diff":"diff --git a/xmake.lua b/xmake.lua\n--- a/xmake.lua\n+++ b/xmake.lua\n@@ -67,6 +67,9 @@\n \t\t\t\tend\n \n \t\t\t\tlocal content = io.readfile(file)\n+\t\t\t\tif not content then\n+\t\t\t\t\traise(\"failed to read file: %s\", file)\n+\t\t\t\tend\n \t\t\t\t-- Escape content for inclusion as a C string literal in a header:\n \t\t\t\t-- 1) escape backslashes, 2) escape double quotes, 3) convert newlines\n \t\t\t\t--    to '\\n' and split the C string across multiple lines.\n"}]},{"message":"The content escaping logic may not handle all edge cases for C string literals. Consider additional escaping for characters like carriage returns (\\r), tabs (\\t), and null bytes that could cause issues in generated C code.","fixFiles":[{"filePath":"xmake.lua","diff":"diff --git a/xmake.lua b/xmake.lua\n--- a/xmake.lua\n+++ b/xmake.lua\n@@ -68,11 +68,40 @@\n \n \t\t\t\tlocal content = io.readfile(file)\n \t\t\t\t-- Escape content for inclusion as a C string literal in a header:\n-\t\t\t\t-- 1) escape backslashes, 2) escape double quotes, 3) convert newlines\n-\t\t\t\t--    to '\\n' and split the C string across multiple lines.\n+\t\t\t\t-- 1) escape backslashes and double quotes\n+\t\t\t\t-- 2) escape control characters (including null bytes) using C-style escapes\n+\t\t\t\t-- 3) convert remaining n...

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