Unix to Windows Porting Dictionary for HPC

header files: unistd.h, sys/types.h

uid_t getuid();

uid_t geteuid();

Obtains the user identity that the process is running as.

Unix systems maintain a user identity (UID) as a numeric value that is guaranteed unique only for the system the process is running on. In contrast, on Windows, a security identifier (SID) that is unique across all Windows systems is used to identify a user. A SID necessarily consumes more storage space than a UID.

The information about the SID for a running process is stored in the security token for a process. The SID is obtained indirectly by performing an information query on the security token of a process.

A Unix process maintains a distinction between the UID of the user that started the process (the real UID) and the UID of the user that the process is running as (the effective UID). Windows does not maintain this distinction. The value of a SID will be the equivalent of the Unix effective UID. Since the equivalent of the Unix real UID cannot be obtained using the SID is recommended for Windows when the real or effective UID is needed.

#include <Winbase.h>

HANDLE Thandle;
DWORD DAmask, size;
SID SidInfo;

DAmask = TOKEN_READ;

if (OpenProcessToken(GetCurrentProcess(), DAmask, &Thandle)) {
        printf("error: could not open token\n");
        return(1);
}

if (GetTokenInformation(Thandle, TokenLogonSid, &SidInfo, sizeof(SidInfo), &size) == 0) {
        printf("error: get token information failed\n");
}
else {
        printf("success: the SID was obtained from the token\n");
}