W dniu 05.01.2019 o 15:32, Liu Hao pisze:
> 在 2019/1/5 21:14, Johannes Pfau 写道:
>> Liu Hao:
>>> There are a few resolution to this at different levels. The most ideal
>>> solution would be providing an `access()` function that behaves
>>> expectedly in gnulib or libiberty, so this recipe can be ported
>>> elsewhere. Modifying GCC source should be considered the least preferred
>>> and last option.
>>
>> OK, that's what I thought. I've attached a new patch for libiberty,
>> could you please have a quick look at it before I submit it to GCC?
>>
>> It currently only handles F_OK which is the only case which really
>> seems to matter for GCC. I do not know how to check if a file is effectively
>> readable/writeable/executable in the windows api. And it seems
>> reimplementing R_OK and all the other flags would mean effectively
>> rewriting the complete access function. What do you think?
>>
>
> A complete version looks basically like this:
>
> ```c
> DWORD attr = GetFileAttributesA(pathname);
> if (attr == INVALID_FILE_ATTRIBUTES)
> {
> // Set `errno` accordingly.
> switch (GetLastError())
> {
> case ERROR_FILE_NOT_FOUND:
> case ERROR_PATH_NOT_FOUND:
> errno = ENOENT;
> break;
> case ERROR_ACCESS_DENIED:
> errno = EACCES;
> break;
> default:
> errno = EINVAL;
> }
> return -1;
> }
> switch (mode)
> {
> case F_OK:
> case R_OK:
> // It is always existent and readable.
> return 0;
> case W_OK:
> // Directories are always writeable.
> if (attr & FILE_ATTRIBUTE_DIRECTORY)
> return 0;
> // Read-only files are not writeable.
> if (attr & FILE_ATTRIBUTE_READONLY)
> {
> errno = EACCES;
> return -1;
> }
> return 0;
> case X_OK:
> // On Windows all files are presumed to be executable.
> // They can be opened in a command prompt without any arguments.
> return 0;
> default:
> errno = EINVAL;
> return -1;
> }
> ```
ucrtbase.dll is affected too (msvcr100 works OK), so maybe it is better to add
your access() function to msvcr110/120 and ucrtbase (as a replacement) instead
of patching GCC.
Regards,
Mateusz
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