Types and Constants

Core types and constants exported by the Windows module.

Module: Windows

INVALID_HANDLE_VALUE

Microsoft documentation: CreateFileA

const INVALID_HANDLE_VALUE = -1;

The failure sentinel returned by CreateFileA and FindFirstFileA. Cast it to the handle pointer type when comparing it with a returned *opaque.

StdHandle

Microsoft documentation: GetStdHandle

Member	Value	Description
Error	0xFFFFFFF4	Standard error device.
Output	0xFFFFFFF5	Standard output device.
Input	0xFFFFFFF6	Standard input device.

File Enums

FileAccess

Microsoft documentation: FileAccess enum

Member	Value	Description
Read	0x80000000	Generic read.
Write	0x40000000	Generic write.
ReadWrite	0xC0000000	Read and write.

FileShare

Microsoft documentation: FileShare enum

Member	Value	Description
None	0	Prevent subsequent sharing.
Read	1	Permit subsequent read access.
Write	2	Permit subsequent write access.
Delete	4	Permit subsequent delete access.

Combine share modes with bitwise OR when multiple modes are needed.

CreationDisposition

Microsoft documentation: CreateFileA creation disposition

Member	Value	Behavior
CreateNew	1	Create only when the target does not exist.
CreateAlways	2	Create or overwrite.
OpenExisting	3	Open only when the target exists.
OpenAlways	4	Open or create.
TruncateExisting	5	Open and truncate an existing file.

FileAttributes

Microsoft documentation: FileAttributes enum

Member	Value	Description
ReadOnly	0x1	Read-only file or directory.
Hidden	0x2	Hidden from ordinary listings.
System	0x4	Used by the operating system.
Directory	0x10	Directory entry.
Archive	0x20	Marked for archival.
Normal	0x80	No other attributes set.
Temporary	0x100	Used for temporary storage.

Normal must be used alone. Other compatible attributes can be combined with bitwise OR, although APIs typed as FileAttributes may accept one enum value.

SeekOrigin

Microsoft documentation: SeekOrigin enum

Member	Value	Base position
Begin	0	Beginning of the file.
Current	1	Current file pointer.
End	2	End of the file.

FileTime

Microsoft documentation: FILETIME structure

struct FileTime {
    lowDateTime:  uint32;
    highDateTime: uint32;
}

The two fields form an unsigned 64-bit count of 100-nanosecond intervals since January 1, 1601 UTC. lowDateTime contains the low-order bits.

SystemTime

Microsoft documentation: SYSTEMTIME structure

struct SystemTime {
    year:         uint16;
    month:        uint16;
    dayOfWeek:    uint16;
    day:          uint16;
    hour:         uint16;
    minute:       uint16;
    second:       uint16;
    milliseconds: uint16;
}

Field	Typical range	Description
year	Full year	Year.
month	1–12	January is 1.
dayOfWeek	0–6	Sunday is 0.
day	1–31	Day of month.
hour	0–23	Hour.
minute	0–59	Minute.
second	0–59	Second.
milliseconds	0–999	Millisecond within the second.

Win32FindDataA

Microsoft documentation: WIN32_FIND_DATAA structure

struct Win32FindDataA {
    fileAttributes:   uint32;
    creationTime:     FileTime;
    lastAccessTime:   FileTime;
    lastWriteTime:    FileTime;
    fileSizeHigh:     uint32;
    fileSizeLow:      uint32;
    reserved0:        uint32;
    reserved1:        uint32;
    fileName:         char8[260];
    alternateFileName: char8[14];
}

fileSizeHigh and fileSizeLow form the high and low halves of the unsigned 64-bit file size. The filename arrays contain null-terminated ANSI strings. Applications must not depend on the reserved fields.

See also

• CodePage — text encoding identifiers
• File I/O — use the file enums
• File enumeration — populate Win32FindDataA