usr/src/lib/libc/port/stdio/fopen.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 (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1988 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 /*
  31  * University Copyright- Copyright (c) 1982, 1986, 1988
  32  * The Regents of the University of California
  33  * All Rights Reserved
  34  *
  35  * University Acknowledgment- Portions of this document are derived from
  36  * software developed by the University of California, Berkeley, and its
  37  * contributors.
  38  */
  39
  40 #pragma ident   "%Z%%M% %I%     %E% SMI"
  41
  42 #include "lint.h"
  43 #include "file64.h"
  44 #include <sys/types.h>
  45 #include <stdio.h>
  46 #include <mtlib.h>
  47 #include <fcntl.h>
  48 #include <unistd.h>
  49 #include <limits.h>
  50 #include <thread.h>
  51 #include <synch.h>
  52 #include <stdlib.h>
  53 #include <errno.h>
  54 #include "stdiom.h"
  55 #include "xpg6.h"
  56
  57 /* Final argument to _endopen depends on build environment */
  58 #define LARGE_OPEN              (_FILE_OFFSET_BITS == 64)
  59
  60 FILE *
  61 fopen(const char *name, const char *type) /* open name, return new stream */
  62 {
  63         FILE *iop;
  64         FILE  *rc;
  65
  66         iop = _findiop();
  67         /*
  68          * Note that iop is not locked here, since no other thread could
  69          * possibly call _endopen with the same iop at this point.
  70          */
  71         rc = _endopen(name, type, iop, LARGE_OPEN);
  72
  73         if (rc == NULL && iop != NULL)
  74                 iop->_flag = 0; /* release iop */
  75
  76         return (rc);
  77 }
  78
  79 static FILE *
  80 _freopen_null(const char *type, FILE *iop)
  81 {
  82         char    plus, mode;
  83         int     oflag, nflag, fd, accmode;
  84         mbstate_t       *mb;
  85
  86         if (iop == NULL || iop->_flag == 0) {
  87                 errno = EBADF;
  88                 return (NULL);
  89         }
  90
  91         if (!(iop->_flag & _IONBF) && (iop->_flag & (_IOWRT | _IOREAD | _IORW)))
  92                 (void) _fflush_u(iop);
  93
  94         if (iop->_flag & _IOMYBUF) {
  95                 free((char *)iop->_base - PUSHBACK);
  96         }
  97         iop->_base = NULL;
  98         iop->_ptr = NULL;
  99         /*
 100          * Clear stream orientation, clear stream encoding rule, and set
 101          * stream's mbstate_t object to describe an initial conversion state.
 102          */
 103         mb = _getmbstate(iop);
 104         if (mb != NULL)
 105                 (void) memset(mb, 0, sizeof (mbstate_t));
 106         iop->_cnt = 0;
 107         _setorientation(iop, _NO_MODE);
 108
 109         fd = FILENO(iop);
 110         mode = type[0];
 111         if (mode != 'r' && mode != 'w' && mode != 'a') {
 112                 errno = EINVAL;
 113                 goto errret;
 114         }
 115
 116         if ((oflag = fcntl(fd, F_GETFL)) == -1)
 117                 goto errret;
 118
 119         if ((plus = type[1]) == 'b')
 120                 plus = type[2];
 121
 122         /*
 123          * Because the filename has not been specified, the underlying file
 124          * will not be closed and reopened.  The access modes of an open
 125          * file descriptor can't be changed via fcntl().  When '+' is
 126          * specified, the old access mode needs to be O_RDWR.  When 'r' is
 127          * specified, the old access mode needs to be O_RDONLY or O_RDWR.
 128          * When 'a' or 'w' is specified, the old access mode needs to be
 129          * O_WRONLY or O_RDWR.  Otherwise, fail with EBADF, indicating that
 130          * the underlying file descriptor was not opened with a mode that
 131          * would allow the stream to do successful I/O with the requested mode.
 132          */
 133
 134         accmode = oflag & O_ACCMODE;
 135         if ((accmode == O_RDONLY && (mode != 'r' || plus == '+')) ||
 136             (accmode == O_WRONLY && (mode == 'r' || plus == '+'))) {
 137                 (void) close(fd);
 138                 errno = EBADF;
 139                 goto errret_noclose;
 140         }
 141
 142 #ifdef  _LP64
 143         iop->_flag &= ~0377;    /* clear lower 8-bits */
 144         if (mode == 'r') {
 145                 iop->_flag |= _IOREAD;
 146                 nflag = oflag & ~O_APPEND;
 147         } else if (mode == 'w') {
 148                 iop->_flag |= _IOWRT;
 149                 nflag = oflag & ~O_APPEND;
 150         } else {
 151                 iop->_flag |= _IOWRT;
 152                 nflag = oflag | O_APPEND;
 153         }
 154         if (plus == '+') {
 155                 iop->_flag = (iop->_flag & ~(_IOREAD | _IOWRT)) | _IORW;
 156         }
 157 #else
 158         if (mode == 'r') {
 159                 iop->_flag = _IOREAD;
 160                 nflag = oflag & ~O_APPEND;
 161         } else if (mode == 'w') {
 162                 iop->_flag = _IOWRT;
 163                 nflag = oflag & ~O_APPEND;
 164         } else {
 165                 iop->_flag = _IOWRT;
 166                 nflag = oflag | O_APPEND;
 167         }
 168         if (plus == '+') {
 169                 iop->_flag = _IORW;
 170         }
 171 #endif
 172         /*
 173          * Change mode of underlying fd as much as possible without closing
 174          * and reopening it.  Ignore truncate failures, eg. with stdout.
 175          */
 176         if (mode == 'w')
 177                 (void) ftruncate64(fd, (off64_t)0);
 178
 179         if (fcntl(fd, F_SETFL, nflag) == -1)
 180                 goto errret;
 181
 182         /* ignore seek failures, eg. with pipes */
 183         (void) lseek64(fd, (off64_t)0, SEEK_SET);
 184
 185         return (iop);
 186
 187 errret:
 188         if (errno != EBADF)
 189                 (void) close(fd);
 190
 191 errret_noclose:
 192         iop->_flag = 0;         /* release iop */
 193         return (NULL);
 194 }
 195
 196 FILE *
 197 freopen(const char *name, const char *type, FILE *iop)
 198 {
 199         FILE *rc;
 200         rmutex_t *lk;
 201
 202         if (name == NULL && __xpg6 & _C99SUSv3_freopen_NULL_filename) {
 203                 /*
 204                  * XPG6:  If name is a null pointer, freopen will attempt to
 205                  * change the mode of the stream to that specified by type.
 206                  */
 207                 FLOCKFILE(lk, iop);
 208                 rc = _freopen_null(type, iop);
 209                 FUNLOCKFILE(lk);
 210                 return (rc);
 211         }
 212         /*
 213          * there may be concurrent calls to reopen the same stream - need
 214          * to make freopen() atomic
 215          */
 216         FLOCKFILE(lk, iop);
 217         /*
 218          * new function to do everything that fclose() does, except
 219          * to release the iop - this cannot yet be released since
 220          * _endopen() is yet to be called on this iop
 221          */
 222
 223         (void) close_fd(iop);
 224
 225         rc = _endopen(name, type, iop, LARGE_OPEN);
 226
 227         if (rc == NULL)
 228                 iop->_flag = 0; /* release iop */
 229
 230         FUNLOCKFILE(lk);
 231         return (rc);
 232 }