Manas103 opened a new issue, #48793:
URL: https://github.com/apache/arrow/issues/48793
### Describe the bug, including details regarding any error messages,
version, and platform.
## Describe the bug, including details regarding any error messages,
version, and platform.
## Problem
The `__map_mman_error()` function in `cpp/src/arrow/io/mman.h` does not
properly map Windows error codes to POSIX errno values. The function currently
has a TODO comment and returns raw Windows error codes (DWORD values like 2, 5,
6, etc.) instead of POSIX errno values (like ENOENT, EACCES, EBADF, etc.).
## Repro
The function is called internally by Windows memory mapping operations
(`mmap`, `munmap`, `mprotect`, `msync`, `mlock`, `munlock`) when Windows API
calls fail. The current implementation:
```
// In cpp/src/arrow/io/mman.h, line 42-46 (before fix)
static inline int __map_mman_error(const DWORD err, const int deferr) {
if (err == 0) return 0;
// TODO: implement
return err; // Returns raw Windows error code (e.g., 2, 5, 6, 112)
}
```
When memory mapping operations fail on Windows, `GetLastError()` returns
Windows error codes (e.g., `ERROR_FILE_NOT_FOUND = 2`, `ERROR_ACCESS_DENIED =
5`, `ERROR_NOT_ENOUGH_MEMORY = 8`). These values are then assigned to errno,
which should contain POSIX errno values.
## Output
This breaks errno-based error handling because:
- Windows error codes (typically small integers like 2-112) are not valid
POSIX errno values
- Code that checks errno == ENOENT will fail even when ERROR_FILE_NOT_FOUND
(2) occurs
- Error messages and error handling logic expecting POSIX errno values
receive raw Windows error codes instead
For example, when `CreateFileMapping` fails with `ERROR_FILE_NOT_FOUND` (2),
`errno` is set to 2 instead of `ENOENT` (which is typically 2 on many systems,
but this is coincidental and not guaranteed).
## Expected Behavior
The function should map Windows error codes to POSIX errno values, matching
Arrow's existing WinErrorToErrno() conventions. Common mappings should include:
- `ERROR_FILE_NOT_FOUND` (2) → `ENOENT`
- `ERROR_ACCESS_DENIED` (5) → `EACCES`
- `ERROR_INVALID_HANDLE` (6) → `EBADF`
- `ERROR_NOT_ENOUGH_MEMORY` (8) → `ENOMEM`
- `ERROR_DISK_FULL` (112) → `ENOSPC`
- etc
## Component(s)
C++
### Component(s)
C++
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