usr/src/lib/libbc/libc/stdio/common/findiop.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 1987 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1984 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 /*LINTLIBRARY*/
  33 #include <stdio.h>
  34 #include <errno.h>
  35 #include <malloc.h>
  36 #include "iob.h"
  37
  38 #define active(iop)     ((iop)->_flag & (_IOREAD|_IOWRT|_IORW))
  39
  40 static unsigned char sbuf[NSTATIC][_SBFSIZ];
  41 unsigned char (*_smbuf)[_SBFSIZ] = sbuf;
  42 static  FILE    **iobglue;
  43 static  FILE    **endglue;
  44
  45 /*
  46  * Find a free FILE for fopen et al.
  47  * We have a fixed static array of entries, and in addition
  48  * may allocate additional entries dynamically, up to the kernel
  49  * limit on the number of open files.
  50  * At first just check for a free slot in the fixed static array.
  51  * If none are available, then we allocate a structure to glue together
  52  * the old and new FILE entries, which are then no longer contiguous.
  53  */
  54 FILE *
  55 _findiop(void)
  56 {
  57         FILE **iov, *iop;
  58         FILE *fp;
  59
  60         if(iobglue == NULL) {
  61                 for(iop = _iob; iop < _iob + NSTATIC; iop++)
  62                         if(!active(iop))
  63                                 return(iop);
  64
  65                 if(_f_morefiles() == 0) {
  66                         errno = ENOMEM;
  67                         return(NULL);
  68                 }
  69         }
  70
  71         iov = iobglue;
  72         while(*iov != NULL && active(*iov))
  73                 if (++iov >= endglue) {
  74                         errno = EMFILE;
  75                         return(NULL);
  76                 }
  77
  78         if(*iov == NULL)
  79                 *iov = (FILE *)calloc(1, sizeof **iov);
  80
  81         return(*iov);
  82 }
  83
  84 int
  85 _f_morefiles(void)
  86 {
  87         FILE **iov;
  88         FILE *fp;
  89         unsigned char *cp;
  90         int nfiles;
  91
  92         nfiles = getdtablesize();
  93
  94         iobglue = (FILE **)calloc(nfiles, sizeof *iobglue);
  95         if(iobglue == NULL)
  96                 return(0);
  97
  98         if((_smbuf = (unsigned char (*)[_SBFSIZ])malloc(nfiles * sizeof *_smbuf)) == NULL) {
  99                 free((char *)iobglue);
 100                 iobglue = NULL;
 101                 return(0);
 102         }
 103
 104         endglue = iobglue + nfiles;
 105
 106         for(fp = _iob, iov = iobglue; fp < &_iob[NSTATIC]; /* void */)
 107                 *iov++ = fp++;
 108
 109         return(1);
 110 }
 111
 112 void
 113 f_prealloc(void)
 114 {
 115         FILE **iov;
 116         FILE *fp;
 117
 118         if(iobglue == NULL && _f_morefiles() == 0)
 119                 return;
 120
 121         for(iov = iobglue; iov < endglue; iov++)
 122                 if(*iov == NULL)
 123                         *iov = (FILE *)calloc(1, sizeof **iov);
 124 }
 125
 126 void
 127 _fwalk(int (*function)(FILE *))
 128 {
 129         FILE **iov;
 130         FILE *fp;
 131
 132         if(function == NULL)
 133                 return;
 134
 135         if(iobglue == NULL) {
 136                 for(fp = _iob; fp < &_iob[NSTATIC]; fp++)
 137                         if(active(fp))
 138                                 (*function)(fp);
 139         } else {
 140                 for(iov = iobglue; iov < endglue; iov++)
 141                         if(*iov && active(*iov))
 142                                 (*function)(*iov);
 143         }
 144 }