errno.c

#include <stdio.h>
#include <windows.h>
#include <errno.h>
#include <stdlib.h>

/* This is the error table that defines the mapping between OS error
   codes and errno values */

struct errentry {
	unsigned long int oserrcode;		/* OS return value */
	int errnocode;				/* System V error code */
};

static struct errentry errtable[] = {
	{  ERROR_SUCCESS,                 0        },  /* 0 */
	{  ERROR_INVALID_FUNCTION,       EINVAL    },  /* 1 */
	{  ERROR_FILE_NOT_FOUND,         ENOENT    },  /* 2 */
	{  ERROR_PATH_NOT_FOUND,         ENOENT    },  /* 3 */
	{  ERROR_TOO_MANY_OPEN_FILES,    EMFILE    },  /* 4 */
        {  ERROR_ACCESS_DENIED,          EACCES    },  /* 5 */
	{  ERROR_INVALID_HANDLE,         EBADF     },  /* 6 */
	{  ERROR_ARENA_TRASHED,          ENOMEM    },  /* 7 */
	{  ERROR_NOT_ENOUGH_MEMORY,      ENOMEM    },  /* 8 */
        {  ERROR_INVALID_BLOCK,          ENOMEM    },  /* 9 */
	{  ERROR_BAD_ENVIRONMENT,        E2BIG     },  /* 10 */
	{  ERROR_BAD_FORMAT,             ENOEXEC   },  /* 11 */
	{  ERROR_INVALID_ACCESS,         EINVAL    },  /* 12 */
	{  ERROR_INVALID_DATA,           EINVAL    },  /* 13 */
	{  ERROR_INVALID_DRIVE,          ENOENT    },  /* 15 */
	{  ERROR_CURRENT_DIRECTORY,      EACCES    },  /* 16 */
	{  ERROR_NOT_SAME_DEVICE,        EXDEV     },  /* 17 */
	{  ERROR_NO_MORE_FILES,          ENOENT    },  /* 18 */
	{  ERROR_LOCK_VIOLATION,         EACCES    },  /* 33 */
	{  ERROR_BAD_NETPATH,            ENOENT    },  /* 53 */
	{  ERROR_NETWORK_ACCESS_DENIED,  EACCES    },  /* 65 */
	{  ERROR_BAD_NET_NAME,           ENOENT    },  /* 67 */
	{  ERROR_FILE_EXISTS,            EEXIST    },  /* 80 */
	{  ERROR_CANNOT_MAKE,            EACCES    },  /* 82 */
	{  ERROR_FAIL_I24,               EACCES    },  /* 83 */
	{  ERROR_INVALID_PARAMETER,      EINVAL    },  /* 87 */
	{  ERROR_NO_PROC_SLOTS,          EAGAIN    },  /* 89 */
	{  ERROR_DRIVE_LOCKED,           EACCES    },  /* 108 */
	{  ERROR_BROKEN_PIPE,            EPIPE     },  /* 109 */
	{  ERROR_DISK_FULL,              ENOSPC    },  /* 112 */
	{  ERROR_INVALID_TARGET_HANDLE,  EBADF     },  /* 114 */
	{  ERROR_INVALID_HANDLE,         EINVAL    },  /* 124 */
	{  ERROR_WAIT_NO_CHILDREN,       ECHILD    },  /* 128 */
	{  ERROR_CHILD_NOT_COMPLETE,     ECHILD    },  /* 129 */
	{  ERROR_DIRECT_ACCESS_HANDLE,   EBADF     },  /* 130 */
	{  ERROR_NEGATIVE_SEEK,          EINVAL    },  /* 131 */
	{  ERROR_SEEK_ON_DEVICE,         EACCES    },  /* 132 */
	{  ERROR_DIR_NOT_EMPTY,          ENOTEMPTY },  /* 145 */
	{  ERROR_NOT_LOCKED,             EACCES    },  /* 158 */
	{  ERROR_BAD_PATHNAME,           ENOENT    },  /* 161 */
	{  ERROR_MAX_THRDS_REACHED,      EAGAIN    },  /* 164 */
        {  ERROR_LOCK_FAILED,            EACCES    },  /* 167 */
	{  ERROR_ALREADY_EXISTS,         EEXIST    },  /* 183 */
	{  ERROR_FILENAME_EXCED_RANGE,   ENOENT    },  /* 206 */
	{  ERROR_NESTING_NOT_ALLOWED,    EAGAIN    },  /* 215 */
	{  ERROR_OPERATION_ABORTED,	 EINTR	   },  /* 995 */	
	{  ERROR_NOT_ENOUGH_QUOTA,       ENOMEM    }    /* 1816 */
};

/* size of the table */
#define ERRTABLESIZE (sizeof(errtable)/sizeof(*errtable))

/* The following two constants must be the minimum and maximum
   values in the (contiguous) range of Exec Failure errors. */
#define MIN_EXEC_ERROR ERROR_INVALID_STARTING_CODESEG
#define MAX_EXEC_ERROR ERROR_INFLOOP_IN_RELOC_CHAIN

/* These are the low and high value in the range of errors that are
   access violations */
#define MIN_EACCES_RANGE ERROR_WRITE_PROTECT
#define MAX_EACCES_RANGE ERROR_SHARING_BUFFER_EXCEEDED

static int __cdecl _get_errno_from_oserr(unsigned long int oserrno) {
	int i;

	/* check the table for the OS error code */
	for(i = 0; i < ERRTABLESIZE; i++) {
		if(oserrno == errtable[i].oserrcode) {
			return errtable[i].errnocode;
		}
	}

	/* The error code wasn't in the table.  We check for a range of */
	/* EACCES errors or exec failure errors (ENOEXEC).  Otherwise   */
	/* EINVAL is returned.                                          */

	if(oserrno >= MIN_EACCES_RANGE && oserrno <= MAX_EACCES_RANGE) return EACCES;
	else if(oserrno >= MIN_EXEC_ERROR && oserrno <= MAX_EXEC_ERROR) return ENOEXEC;
	else return EINVAL;
}

static int new_errno = 0;

/*
int oserror_to_errno(unsigned long int errorcode) {
	new_errno = _get_errno_from_oserr(errorcode);
	return new_errno;
}*/

int *__cdecl _errno() {
	if(GetLastError() != 0xFFFFFFFF) {
		new_errno = _get_errno_from_oserr(GetLastError());
		SetLastError(0xFFFFFFFF);
	}
	return &new_errno;
}