Fix multiple runtime APIs that were incorrectly using std::string::reserve

lute/io/src/io.cpp

@@ -2,7 +2,7 @@
 #include "Luau/Variant.h"
 #include "lute/runtime.h"
 
-#include <uv.h>
+#include "uv.h"
 #include <memory>
 
 #include "lua.h"

lute/process/src/process.cpp

@@ -1,12 +1,13 @@
 #include "lute/process.h"
 #include "lute/runtime.h"
+#include "lute/uvutils.h"
 
 #include "Luau/Common.h"
 
 #include "lua.h"
 #include "lualib.h"
 
-#include <uv.h>
+#include "uv.h"
 
 #include <functional>
 #include <map>
@@ -432,28 +433,12 @@ int run(lua_State* L)
 
 int homedir(lua_State* L)
 {
-    std::string buffer;
-
-    size_t homedir_size = 255;
-    buffer.reserve(homedir_size);
-
-    int status = uv_os_homedir(buffer.data(), &homedir_size);
-    if (status == UV_ENOBUFS)
-    {
-        // libuv gives us the new size if it's under sized
-        buffer.reserve(homedir_size);
-
-        status = uv_os_homedir(buffer.data(), &homedir_size);
-    }
-
-    if (status != 0)
-    {
-        luaL_error(L, "failed to get home directory");
-        return 1;
-    }
-
-    lua_pushlstring(L, buffer.c_str(), buffer.size());
+    auto result = uvutils::getStringFromUv(uv_os_homedir);
+    if (uvutils::UvError* error = result.get_if<uvutils::UvError>())
+        luaL_error(L, "failed to get home directory: %s", error->toString().c_str());
 
+    std::string* homeDir = result.get_if<std::string>();
+    lua_pushlstring(L, homeDir->c_str(), homeDir->size());
     return 1;
 }
 
@@ -470,28 +455,12 @@ int exitFunc(lua_State* L)
 
 int cwd(lua_State* L)
 {
-    std::string buffer;
-
-    size_t cwd_size = 255;
-    buffer.reserve(cwd_size);
-
-    int status = uv_cwd(buffer.data(), &cwd_size);
-    if (status == UV_ENOBUFS)
-    {
-        // libuv gives us the new size if it's under sized
-        buffer.reserve(cwd_size);
-
-        status = uv_cwd(buffer.data(), &cwd_size);
-    }
-
-    if (status != 0)
-    {
-        luaL_error(L, "failed to get current working directory");
-        return 1;
-    }
-
-    lua_pushlstring(L, buffer.c_str(), buffer.size());
+    auto result = uvutils::getStringFromUv(uv_cwd);
+    if (uvutils::UvError* error = result.get_if<uvutils::UvError>())
+        luaL_error(L, "failed to get current working directory: %s", error->toString().c_str());
 
+    std::string* cwd = result.get_if<std::string>();
+    lua_pushlstring(L, cwd->c_str(), cwd->size());
     return 1;
 };
 

lute/runtime/CMakeLists.txt

@@ -4,9 +4,11 @@ target_sources(Lute.Runtime PRIVATE
     include/lute/ref.h
     include/lute/runtime.h
     include/lute/userdatas.h
+    include/lute/uvutils.h
 
     src/ref.cpp
     src/runtime.cpp
+    src/uvutils.cpp
 )
 
 target_compile_features(Lute.Runtime PUBLIC cxx_std_17)

lute/runtime/include/lute/uvutils.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "Luau/Variant.h"
+
+#include <cstddef>
+#include <string>
+
+namespace uvutils
+{
+
+struct UvError
+{
+    UvError(int code);
+    std::string toString() const;
+
+    int code;
+};
+
+typedef int (*BufferWriter)(char* buffer, size_t* size);
+
+// Abstracts away buffer management when getting strings from libuv functions.
+Luau::Variant<std::string, UvError> getStringFromUv(BufferWriter bufferWriter, size_t initialBufferSize = 256);
+
+} // namespace uvutils

lute/runtime/src/uvutils.cpp

@@ -0,0 +1,39 @@
+#include "lute/uvutils.h"
+
+#include "uv.h"
+
+namespace uvutils
+{
+
+UvError::UvError(int code)
+    : code(code)
+{
+}
+
+std::string UvError::toString() const
+{
+    return uv_strerror(code);
+}
+
+Luau::Variant<std::string, UvError> getStringFromUv(BufferWriter bufferWriter, size_t initialBufferSize)
+{
+    std::string buffer;
+    size_t size = initialBufferSize;
+    buffer.resize(size);
+
+    int writeStatus = bufferWriter(buffer.data(), &size);
+    if (writeStatus == UV_ENOBUFS)
+    {
+        // `size` now contains the required size
+        buffer.resize(size);
+        writeStatus = bufferWriter(buffer.data(), &size);
+    }
+
+    if (writeStatus < 0)
+        return UvError{writeStatus};
+
+    buffer.resize(size);
+    return buffer;
+}
+
+} // namespace uvutils

lute/system/src/system.cpp

@@ -1,13 +1,16 @@
 #include "lute/system.h"
+#include "lute/uvutils.h"
+
 #include "lua.h"
 #include "lualib.h"
+
 #include "uv.h"
+
 #include <cstddef>
 #include <cstdio>
 #include <cstdlib>
 #include <iterator>
 #include <string>
-#include <vector>
 
 namespace libsystem
 {
@@ -88,24 +91,12 @@ int lua_totalmemory(lua_State* L)
 
 int lua_hostname(lua_State* L)
 {
-    size_t sz = 255;
-    std::string hostname;
-    hostname.reserve(sz);
-
-    int res = uv_os_gethostname(hostname.data(), &sz);
-    if (res == UV_ENOBUFS)
-    {
-        hostname.reserve(sz); // libuv updates the size to what's required
-        res = uv_os_gethostname(hostname.data(), &sz);
-    }
-
-    if (res != 0)
-    {
-        luaL_error(L, "libuv error: %s", uv_strerror(res));
-    }
-
-    lua_pushlstring(L, hostname.c_str(), hostname.size());
+    auto result = uvutils::getStringFromUv(uv_os_gethostname);
+    if (uvutils::UvError* error = result.get_if<uvutils::UvError>())
+        luaL_error(L, "failed to get hostname: %s", error->toString().c_str());
 
+    std::string* hostname = result.get_if<std::string>();
+    lua_pushlstring(L, hostname->c_str(), hostname->size());
     return 1;
 }
 
@@ -126,26 +117,13 @@ int lua_uptime(lua_State* L)
 
 int lua_tmpdir(lua_State* L)
 {
-    size_t size = 255;
-    std::string tmpdir;
-    tmpdir.reserve(size);
-
-    int res = uv_os_tmpdir(tmpdir.data(), &size);
-    if (res == UV_ENOBUFS)
-    {
-        tmpdir.reserve(size); // libuv updates the size to what's required
-        res = uv_os_tmpdir(tmpdir.data(), &size);
-    }
-
-    if (res != 0)
-    {
-        luaL_error(L, "libuv error: %s", uv_strerror(res));
-    }
-
-    lua_pushlstring(L, tmpdir.c_str(), tmpdir.size());
+    auto result = uvutils::getStringFromUv(uv_os_tmpdir);
+    if (uvutils::UvError* error = result.get_if<uvutils::UvError>())
+        luaL_error(L, "failed to get temporary directory: %s", error->toString().c_str());
 
+    std::string* tmpDir = result.get_if<std::string>();
+    lua_pushlstring(L, tmpDir->c_str(), tmpDir->size());
     return 1;
-
 }
 } // namespace libsystem
 

tests/path.posix.test.luau

@@ -483,7 +483,7 @@ test.suite("PathPosixResolveSuite", function(suite)
 		-- This test assumes we're in some working directory
 		local result = path.posix.resolve("documents/file.txt")
 		-- Absolute Windows paths will be parsed as relative posix paths because they don't start with /
-		assert.eq(result.absolute, system.win32)
+		assert.neq(result.absolute, system.win32)
 		-- The exact parts will depend on the current working directory
 		-- But we can check that it ends with our relative path
 		local endIndex = #result.parts
@@ -513,7 +513,7 @@ test.suite("PathPosixResolveSuite", function(suite)
 		-- Should return normalized current working directory
 		local result = path.posix.resolve()
 		-- Absolute Windows paths will be parsed as relative posix paths because they don't start with /
-		assert.eq(result.absolute, system.win32)
+		assert.neq(result.absolute, system.win32)
 		-- Can't test exact parts since cwd varies
 	end)