outs for programs using alternae memory allocators:

[unix-history] / usr / src / lib / libc / stdio / findfp.c

/*
* Copyright (c) 1983, 1985 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/

#ifndef lint
static char sccsid[] = "@(#)findfp.c    5.3 (Berkeley) %G%";
#endif not lint

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

extern int errno;

#define active(iop)     ((iop)->_flag & (_IOREAD|_IOWRT|_IORW))

#define NSTATIC 20      /* stdin + stdout + stderr + the usual */

FILE _iob[NSTATIC] = {
       { 0, NULL, NULL, 0, _IOREAD,            0 },    /* stdin  */
       { 0, NULL, NULL, 0, _IOWRT,             1 },    /* stdout */
       { 0, NULL, NULL, 0, _IOWRT|_IONBF,      2 },    /* stderr */
};

extern  char    *calloc();

static  FILE    **iobglue;
static  FILE    **endglue;
static  int     nfiles;

FILE *
_findiop()
{
       register FILE **iov;
       register FILE *fp;

       if (iobglue == 0 && _stdio_init() == 0) {
               errno = ENOMEM;
               return (NULL);
       }

       iov = iobglue;
       while (*iov != NULL && active(*iov))
               if (++iov >= endglue) {
                       errno = EMFILE;
                       return (NULL);
               }

       if (*iov == NULL)
               *iov = (FILE *)calloc(1, sizeof **iov);

       return (*iov);
}

_stdio_init()
{
       register FILE **iov;
       register FILE *fp;

       nfiles = getdtablesize();

       iobglue = (FILE **)calloc(nfiles, sizeof *iobglue);
       if (iobglue == NULL)
               return (0);

       endglue = iobglue + nfiles;

       for (fp = _iob, iov = iobglue; fp < &_iob[NSTATIC]; /* void */)
               *iov++ = fp++;
       return (1);
}

f_prealloc()
{
       register FILE **iov;
       register FILE *fp;

       if (iobglue == NULL && _stdio_init() == 0)
               return;

       for (iov = iobglue; iov < endglue; iov++)
               if (*iov == NULL)
                       *iov = (FILE *)calloc(1, sizeof **iov);
}

_fwalk(function)
       register int (*function)();
{
       register FILE **iov;
       register FILE *fp;

       if (iobglue == NULL) {
               for (fp = _iob; fp < &_iob[NSTATIC]; fp++)
                       if (active(fp))
                               (*function)(fp);
       } else {
               for (iov = iobglue; iov < endglue; iov++)
                       if (*iov && active(*iov))
                               (*function)(*iov);
       }
}

_cleanup()
{
       extern int fclose();

       _fwalk(fclose);
}