From 26f718b04bc0fba3831124d9dec705c2febd426e Mon Sep 17 00:00:00 2001
From: Dan Engelbrecht <dan.engelbrecht@epicgames.com>
Date: Wed, 12 Mar 2025 11:19:06 +0100
Subject: fix mac/linux builds command (#303)

* fix linux/mac version of GetModificationTickFromPath and CopyFile
---
 src/zencore/filesystem.cpp | 35 ++++++++++++++++++++---------------
 1 file changed, 20 insertions(+), 15 deletions(-)

(limited to 'src/zencore/filesystem.cpp')

diff --git a/src/zencore/filesystem.cpp b/src/zencore/filesystem.cpp
index 85feab2f7..9f3f4f7fc 100644
--- a/src/zencore/filesystem.cpp
+++ b/src/zencore/filesystem.cpp
@@ -590,7 +590,7 @@ CopyFile(const std::filesystem::path& FromPath, const std::filesystem::path& ToP
 	ScopedFd $From = {FromFd};
 
 	// To file
-	int ToFd = open(ToPath.c_str(), O_WRONLY | O_CREAT | O_EXCL | O_CLOEXEC, 0666);
+	int ToFd = open(ToPath.c_str(), O_WRONLY | O_CREAT | O_CLOEXEC, 0666);
 	if (ToFd < 0)
 	{
 		ThrowLastError(fmt::format("failed to create file {}", ToPath));
@@ -598,9 +598,14 @@ CopyFile(const std::filesystem::path& FromPath, const std::filesystem::path& ToP
 	fchmod(ToFd, 0666);
 	ScopedFd $To = {ToFd};
 
+	struct stat Stat;
+	fstat(FromFd, &Stat);
+
+	size_t FileSizeBytes = Stat.st_size;
+
 	// Copy impl
-	static const size_t BufferSize = 64 << 10;
-	void*				Buffer	   = malloc(BufferSize);
+	const size_t BufferSize = Min(FileSizeBytes, 64u << 10);
+	void*		 Buffer		= malloc(BufferSize);
 	while (true)
 	{
 		int BytesRead = read(FromFd, Buffer, BufferSize);
@@ -610,7 +615,7 @@ CopyFile(const std::filesystem::path& FromPath, const std::filesystem::path& ToP
 			break;
 		}
 
-		if (write(ToFd, Buffer, BytesRead) != BufferSize)
+		if (write(ToFd, Buffer, BytesRead) != BytesRead)
 		{
 			Success = false;
 			break;
@@ -621,7 +626,7 @@ CopyFile(const std::filesystem::path& FromPath, const std::filesystem::path& ToP
 
 	if (!Success)
 	{
-		ThrowLastError("file copy failed"sv);
+		ThrowLastError(fmt::format("file copy from {} to {} failed", FromPath, ToPath));
 	}
 
 	return true;
@@ -1483,16 +1488,7 @@ GetModificationTickFromPath(const std::filesystem::path& Filename)
 	{
 		ThrowLastError(fmt::format("Failed to open file {} to check modification tick.", Filename));
 	}
-	auto _ = MakeGuard([Handle]() { CloseHandle(Handle); });
-#else
-	int Fd = open(Filename.c_str(), O_RDONLY | O_CLOEXEC);
-	if (Fd <= 9)
-	{
-		ThrowLastError(fmt::format("Failed to open file {} to check modification tick.", Filename));
-	}
-	Handle	  = (void*)uintptr_t(Fd);
-	auto	_ = MakeGuard([Handle]() { close(int(uintptr_t(Handle))); });
-#endif
+	auto			_ = MakeGuard([Handle]() { CloseHandle(Handle); });
 	std::error_code Ec;
 	uint64_t		ModificatonTick = GetModificationTickFromHandle(Handle, Ec);
 	if (Ec)
@@ -1500,6 +1496,15 @@ GetModificationTickFromPath(const std::filesystem::path& Filename)
 		ThrowSystemError(Ec.value(), Ec.message());
 	}
 	return ModificatonTick;
+#else
+	struct stat Stat;
+	int			err = stat(Filename.native().c_str(), &Stat);
+	if (err)
+	{
+		ThrowLastError(fmt::format("Failed to get mode of file {}", Filename));
+	}
+	return gsl::narrow<uint64_t>(Stat.st_mtime);
+#endif
 }
 
 std::filesystem::path
-- 
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