Improve Windows mode bits

We were too zealous about security before by only setting the owner bits
and that would cause issues for projects like redbean that check "other"
bits to determine if it's safe to serve a file. Since that doesn't exist
on Windows, it's better to have things work than not work. So what we'll
do instead is return modes like 0664 for files and 0775 for directories.

Author: jart

libc/calls/fstat-nt.c

@@ -122,34 +122,29 @@ textwindows int sys_fstat_nt_handle(int64_t handle, const char16_t *path,
   st.st_blksize = 4096;
   st.st_gid = st.st_uid = sys_getuid_nt();
 
-  // We'll use the "umask" to fake out the mode bits.
-  uint32_t umask = atomic_load_explicit(&__umask, memory_order_acquire);
-
   switch (GetFileType(handle)) {
     case kNtFileTypeUnknown:
       break;
     case kNtFileTypeChar:
-      st.st_mode = S_IFCHR | (0666 & ~umask);
+      st.st_mode = S_IFCHR | 0664;
       st.st_dev = 0x66666666;
       st.st_ino = handle;
       break;
     case kNtFileTypePipe:
-      st.st_mode = S_IFIFO | (0666 & ~umask);
+      st.st_mode = S_IFIFO | 0664;
       st.st_dev = 0x55555555;
       st.st_ino = handle;
       break;
     case kNtFileTypeDisk: {
       struct NtByHandleFileInformation wst;
       if (GetFileInformationByHandle(handle, &wst)) {
-        st.st_mode = 0444 & ~umask;
+        st.st_mode = 0444;
         if ((wst.dwFileAttributes & kNtFileAttributeDirectory) ||
-            IsWindowsExecutable(handle, path)) {
-          st.st_mode |= 0111 & ~umask;
-        }
+            IsWindowsExecutable(handle, path))
+          st.st_mode |= 0111;
         st.st_flags = wst.dwFileAttributes;
-        if (!(wst.dwFileAttributes & kNtFileAttributeReadonly)) {
-          st.st_mode |= 0222 & ~umask;
-        }
+        if (!(wst.dwFileAttributes & kNtFileAttributeReadonly))
+          st.st_mode |= 0220;
         if (wst.dwFileAttributes & kNtFileAttributeReparsePoint) {
           st.st_mode |= S_IFLNK;
         } else if (wst.dwFileAttributes & kNtFileAttributeDirectory) {
@@ -195,7 +190,7 @@ textwindows int sys_fstat_nt_handle(int64_t handle, const char16_t *path,
       } else if (GetVolumeInformationByHandle(
                      handle, 0, 0, &wst.dwVolumeSerialNumber, 0, 0, 0, 0)) {
         st.st_dev = wst.dwVolumeSerialNumber;
-        st.st_mode = S_IFDIR | (0444 & ~umask);
+        st.st_mode = S_IFDIR | 0555;
       } else {
         // both GetFileInformationByHandle and
         // GetVolumeInformationByHandle failed

libc/intrin/umask.c

@@ -19,4 +19,4 @@
 #include "libc/atomic.h"
 #include "libc/calls/internal.h"
 
-atomic_int __umask;
+atomic_int __umask = 0777;

libc/runtime/winmain.greg.c

@@ -316,7 +316,6 @@ abi int64_t WinMain(int64_t hInstance, int64_t hPrevInstance,
   __imp_GetSystemInfo(&si);
   __pagesize = si.dwPageSize;
   __gransize = si.dwAllocationGranularity;
-  __umask = 077;
   __pid = __imp_GetCurrentProcessId();
   if (!(__sig.process = __sig_map_process(__pid, kNtOpenAlways)))
     __sig.process = &fake_process_signals;