From d5ab121183ddcbd4482e690886000f0c1d14faaa Mon Sep 17 00:00:00 2001
From: Nikita Smith <git.nikita.smith@gmail.com>
Date: Mon, 10 Feb 2025 13:56:38 -0800
Subject: [PATCH] pre-allocate file size before write

---
 src/linker/lnk_io.c               |  4 ++++
 src/os/core/os_core.h             |  1 +
 src/os/core/win32/os_core_win32.c | 13 +++++++++++++
 3 files changed, 18 insertions(+)

diff --git a/src/linker/lnk_io.c b/src/linker/lnk_io.c
index e781b1e8..792c28e7 100644
--- a/src/linker/lnk_io.c
+++ b/src/linker/lnk_io.c
@@ -195,6 +195,10 @@ lnk_write_data_list_to_file_path(String8 path, String8 temp_path, String8List da
   }
 
   if (!os_handle_match(file_handle, os_handle_zero())) {
+    if (!os_file_reserve_size(file_handle, data.total_size)) {
+      lnk_log(LNK_Log_IO_Write, "Failed to pre-allocate file %S with size %M", path, data.total_size);
+    }
+
     // write data nodes
     {
       for (String8Node *data_n = data.first; data_n != 0; data_n = data_n->next) {
diff --git a/src/os/core/os_core.h b/src/os/core/os_core.h
index 3f4075b0..30b7c142 100644
--- a/src/os/core/os_core.h
+++ b/src/os/core/os_core.h
@@ -209,6 +209,7 @@ internal FileProperties os_properties_from_file(OS_Handle file);
 internal OS_FileID      os_id_from_file(OS_Handle file);
 internal B32            os_rename_file_by_handle(OS_Handle file, String8 new_name);
 internal B32            os_rename_file(String8 orig_name, String8 new_name);
+internal B32            os_file_reserve_size(OS_Handle file, U64 size);
 internal B32            os_delete_file_at_path(String8 path);
 internal B32            os_copy_file_path(String8 dst, String8 src);
 internal String8        os_full_path_from_path(Arena *arena, String8 path);
diff --git a/src/os/core/win32/os_core_win32.c b/src/os/core/win32/os_core_win32.c
index d2b01c69..fc615797 100644
--- a/src/os/core/win32/os_core_win32.c
+++ b/src/os/core/win32/os_core_win32.c
@@ -494,6 +494,19 @@ os_rename_file_by_handle(OS_Handle file, String8 new_name)
   return is_renamed;
 }
 
+internal B32
+os_file_reserve_size(OS_Handle file, U64 size)
+{
+  HANDLE handle = (HANDLE)file.u64[0];
+
+  FILE_ALLOCATION_INFO alloc_info    = {0};
+  alloc_info.AllocationSize.LowPart  = size & max_U32;
+  alloc_info.AllocationSize.HighPart = (size >> 32) & max_U32;
+
+  BOOL is_reserved = SetFileInformationByHandle(handle, FileAllocationInfo, &alloc_info, sizeof(alloc_info));
+  return is_reserved;
+}
+
 internal B32
 os_delete_file_at_path(String8 path)
 {