Unix to Windows Porting Dictionary for HPC

header file: unistd.h

int access(const char *path, int mode);

header file: float.h

int _access(const char *path, int mode);

Checks access permissions of a file or pathname.

The Windows version does not use the same macros as the Unix version for file existence, read permission or write permission. Further the Windows version does not determine execute/search permission. Both the Unix and Windows version return -1 on failure and 0 (zero) on success for matching the mode.

Unix macro values can be mapped to Windows values as follows:

R_OK 04
W_OK 02
F_OK 00
X_OK (none)

where values may be logically OR'd together.

The function _waccess() is the wide-character version of _access(). There are versions of these functions with security enhancements: _access_s() _waccess_s() though these apply to the CRT only.

#include <io.h>

int ret;

ret = _access("/temp/myfile.txt", 04);
if (ret == -1) {
        /* file not readable */
}
else {
        /* file is readable */
}