usr/src/lib/libast/common/sfio/sfsetfd.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                   Phong Vo <kpv@research.att.com>                    *
  20 *                                                                      *
  21 ***********************************************************************/
  22 #include        "sfhdr.h"
  23
  24 /*      Change the file descriptor
  25 **
  26 **      Written by Kiem-Phong Vo.
  27 */
  28
  29 #if __STD_C
  30 static int _sfdup(int fd, int newfd)
  31 #else
  32 static int _sfdup(fd,newfd)
  33 int     fd;
  34 int     newfd;
  35 #endif
  36 {
  37         reg int dupfd;
  38
  39 #ifdef F_DUPFD  /* the simple case */
  40         while((dupfd = sysfcntlf(fd,F_DUPFD,newfd)) < 0 && errno == EINTR)
  41                 errno = 0;
  42         return dupfd;
  43
  44 #else   /* do it the hard way */
  45         if((dupfd = sysdupf(fd)) < 0 || dupfd >= newfd)
  46                 return dupfd;
  47
  48         /* dup() succeeded but didn't get the right number, recurse */
  49         newfd = _sfdup(fd,newfd);
  50
  51         /* close the one that didn't match */
  52         CLOSE(dupfd);
  53
  54         return newfd;
  55 #endif
  56 }
  57
  58 #if __STD_C
  59 int sfsetfd(Sfio_t* f, int newfd)
  60 #else
  61 int sfsetfd(f,newfd)
  62 Sfio_t  *f;
  63 int     newfd;
  64 #endif
  65 {
  66         reg int         oldfd;
  67         SFMTXDECL(f);
  68
  69         SFMTXENTER(f, -1);
  70
  71         if(f->flags&SF_STRING)
  72                 SFMTXRETURN(f, -1);
  73
  74         if((f->mode&SF_INIT) && f->file < 0)
  75         {       /* restoring file descriptor after a previous freeze */
  76                 if(newfd < 0)
  77                         SFMTXRETURN(f, -1);
  78         }
  79         else
  80         {       /* change file descriptor */
  81                 if((f->mode&SF_RDWR) != f->mode && _sfmode(f,0,0) < 0)
  82                         SFMTXRETURN(f, -1);
  83                 SFLOCK(f,0);
  84
  85                 oldfd = f->file;
  86                 if(oldfd >= 0)
  87                 {       if(newfd >= 0)
  88                         {       if((newfd = _sfdup(oldfd,newfd)) < 0)
  89                                 {       SFOPEN(f,0);
  90                                         SFMTXRETURN(f, -1);
  91                                 }
  92                                 CLOSE(oldfd);
  93                         }
  94                         else
  95                         {       /* sync stream if necessary */
  96                                 if(((f->mode&SF_WRITE) && f->next > f->data) ||
  97                                    (f->mode&SF_READ) || f->disc == _Sfudisc)
  98                                 {       if(SFSYNC(f) < 0)
  99                                         {       SFOPEN(f,0);
 100                                                 SFMTXRETURN(f, -1);
 101                                         }
 102                                 }
 103
 104                                 if(((f->mode&SF_WRITE) && f->next > f->data) ||
 105                                    ((f->mode&SF_READ) && f->extent < 0 &&
 106                                     f->next < f->endb) )
 107                                 {       SFOPEN(f,0);
 108                                         SFMTXRETURN(f, -1);
 109                                 }
 110
 111 #ifdef MAP_TYPE
 112                                 if((f->bits&SF_MMAP) && f->data)
 113                                 {       SFMUNMAP(f,f->data,f->endb-f->data);
 114                                         f->data = NIL(uchar*);
 115                                 }
 116 #endif
 117
 118                                 /* make stream appears uninitialized */
 119                                 f->endb = f->endr = f->endw = f->data;
 120                                 f->extent = f->here = 0;
 121                                 f->mode = (f->mode&SF_RDWR)|SF_INIT;
 122                                 f->bits &= ~SF_NULL;    /* off /dev/null handling */
 123                         }
 124                 }
 125
 126                 SFOPEN(f,0);
 127         }
 128
 129         /* notify changes */
 130         if(_Sfnotify)
 131                 (*_Sfnotify)(f, SF_SETFD, (void*)((long)newfd));
 132
 133         f->file = newfd;
 134
 135         SFMTXRETURN(f,newfd);
 136 }