osfinfo.c

C标准库源代码

        if ( flags & _O_NOINHERIT )
            fileflags |= FNOINHERIT;

        /* find out what type of file (file/device/pipe) */

        isdev = GetFileType((HANDLE)osfhandle);
        if (isdev == FILE_TYPE_UNKNOWN) {
            /* OS error */
            _dosmaperr( GetLastError() );   /* map error */
            return -1;
        }

        /* is isdev value to set flags */
        if (isdev == FILE_TYPE_CHAR)
            fileflags |= FDEV;
        else if (isdev == FILE_TYPE_PIPE)
            fileflags |= FPIPE;


        /* attempt to allocate a C Runtime file handle */

        if ( (fh = _alloc_osfhnd()) == -1 ) {
            errno = EMFILE;         /* too many open files */
            _doserrno = 0L;         /* not an OS error */
            return -1;              /* return error to caller */
        }

        /*
         * the file is open. now, set the info in _osfhnd array
         */

        _set_osfhnd(fh, osfhandle);

        fileflags |= FOPEN;     /* mark as open */

        _osfile(fh) = fileflags;    /* set osfile entry */

        _unlock_fh(fh);         /* unlock handle */

        return fh;          /* return handle */
}


#ifdef _MT

/***
*void _lock_fhandle(int fh) - lock file handle
*
*Purpose:
*       Assert the lock associated with the passed file handle.
*
*Entry:
*       int fh  - CRT file handle
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/

void __cdecl _lock_fhandle (
        int fh
        )
{
        ioinfo *pio = _pioinfo(fh);

        /*
         * Make sure the lock has been initialized.
         */
        if ( pio->lockinitflag == 0 ) {

            _mlock( _LOCKTAB_LOCK );

            if ( pio->lockinitflag == 0 ) {
                InitializeCriticalSection( &(pio->lock) );
                pio->lockinitflag++;
            }

            _munlock( _LOCKTAB_LOCK);
        }

        EnterCriticalSection( &(_pioinfo(fh)->lock) );
}


/***
*void _unlock_fhandle(int fh) - unlock file handle
*
*Purpose:
*       Release the lock associated with passed file handle.
*
*Entry:
*       int fh  - CRT file handle
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/

void __cdecl _unlock_fhandle (
        int fh
        )
{
        LeaveCriticalSection( &(_pioinfo(fh)->lock) );
}

#endif  /* _MT */


#else  /* _MAC */


#include <cruntime.h>
#include <errno.h>
#include <internal.h>
#include <fcntl.h>
#include <msdos.h>
#include <stdlib.h>

/***
*int _alloc_osfhnd() - get free _osfhnd[] entry
*
*Purpose:
*       Finds the first free entry in _osfhnd[], mark it in use and return
*       the index of the entry to the caller.
*
*Entry:
*       none
*
*Exit:
*       returns index of entry in fh, if successful
*       return -1, if no free entry is found in _osfhnd[].
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _alloc_osfhnd(
        void
        )
{
        int fh;         /* _osfhnd[] index */

        /*
         * search _osfhnd[] for an entry that is not currently being used.
         * if one is found, mark it in use and set the _osfhandle field to
         * 0xffffffff.
         */
        for ( fh = 0 ; fh < _nfile ; fh++ ) {
            if ( (_osfile[fh] & FOPEN) == 0 ) {
                /*
                 * free entry found! initialize it and
                 * break out of the loop
                 */
                _osfhnd[fh] = (long)0xffffffff;
                break;
            }
        }

        /*
         * return the index of the previously free table entry, if one was
         * found. return -1 otherwise.
         */
        return( (fh >= _nfile) ? -1 : fh );
}


/***
*int _set_osfhnd(int fh) - set OS file handle table value
*
*Purpose:
*       If fh is in range and if _osfhnd[fh] is marked with 0xfffffff
*       then set _osfhnd[fh] to the passed value.
*
*Entry:
*       int fh -    index of _osfhnd[] entry
*       long fh     -   new value of this handle entry
*
*Exit:
*       Returns zero if successful.
*       Returns -1 and sets errno to EBADF otherwise.
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _set_osfhnd (
        int fh,     /* index into _osfhnd[] (user's file handle) */
        long value
        )
{
        if ( ((unsigned)fh < (unsigned)_nfile) &&
             _osfhnd[fh] == (long)0xffffffff
           ) {
            _osfhnd[fh] = value;
            return(0);
        } else {
            errno = EBADF;      /* bad handle */
            _macerrno = 0L;     /* not an OS error */
            return -1;
        }
}


/***
*int _free_osfhnd(int fh) - free OS file handle table entry
*
*Purpose:
*       If fh is in range and if _osfhnd[fh] is in use and NOT marked
*       with 0xfffffff
*
*Entry:
*       int fh -    index of _osfhnd[] entry
*
*Exit:
*       Returns zero if successful.
*       Returns -1 and sets errno to EBADF otherwise.
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _free_osfhnd (
        int fh      /* index into _osfhnd[] (user's file handle) */
        )
{
        if ( ((unsigned)fh < (unsigned)_nfile) &&
             (_osfile[fh] & FOPEN) &&
             _osfhnd[fh] != (long)0xffffffff
           ) {
            _osfhnd[fh] = (long)0xffffffff;
            return(0);
        } else {
            errno = EBADF;      /* bad handle */
            _macerrno = 0L;     /* not an OS error */
            return -1;
        }
}


/***
*long _get_osfhandle(int fh) - get OS file handle
*
*Purpose:
*       If fh is in range and if _osfhnd[fh] is marked free, return
*       _osfhnd[fh]
*
*Entry:
*       int fh -    index of _osfhnd[] entry
*
*Exit:
*       Returns the OS file handle if successful.
*       Returns -1 and sets errno to EBADF otherwise.
*
*Exceptions:
*
*******************************************************************************/

long __cdecl _get_osfhandle (
        int fh      /* index into _osfhnd[] (user's file handle) */
        )
{
        if ( ((unsigned)fh < (unsigned)_nfile) && (_osfile[fh] & FOPEN))
            return(_osfhnd[fh]);
        else {
            errno = EBADF;      /* bad handle */
            _macerrno = 0L;     /* not an OS error */
            return -1;
        }
}

/***
*int _open_osfhandle(long osfhandle, int flags) - open C Runtime file handle
*
*Purpose:
*       This function allocates a free C Runtime file handle and sets it
*       to point to the Win32 file handle specified by the first parameter.
*
*Entry:
*       long osfhandle -Win32 file handle to associate with C Runtime file handle.
*       int flags -     flags to associate with C Runtime file handle.
*
*Exit:
*       returns index of entry in fh, if successful
*       return -1, if no free entry is found in _osfhnd[].
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _open_osfhandle(
        long osfhandle,
        int flags
        )
{
        int fh;
        char fileflags;         /* _osfile flags */

        /* copy relavent flags from second parameter */

        fileflags = 0;
        if ( flags & _O_RDONLY )
            fileflags |= FRDONLY;
        else if ( flags & _O_APPEND )
                fileflags |= FAPPEND;
        else if ( flags & _O_TEXT )
                fileflags |= FTEXT;

        /* attempt to allocate a C Runtime file handle */

        if ( (fh = _alloc_osfhnd()) == -1 ) {
            errno = EMFILE;     /* too many open files */
            _macerrno = 0L;         /* not an OS error */
            return -1;      /* return error to caller */
        }

        /*
         * the file is open. now, set the info in _osfhnd array
         */

        _set_osfhnd(fh, osfhandle);

        fileflags |= FOPEN;     /* mark as open */

        _osfile[fh] = fileflags;    /* set osfile entry */

        return fh;          /* return handle */
}


#endif  /* _MAC */