libcsupport/src/open.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /**
0004  *  @file
0005  *
0006  *  @brief Open a File
0007  *  @ingroup libcsupport
0008  */
0009
0010 /*
0011  *  COPYRIGHT (c) 1989-2010.
0012  *  On-Line Applications Research Corporation (OAR).
0013  *
0014  *  Modifications to support reference counting in the file system are
0015  *  Copyright (c) 2012 embedded brains GmbH & Co. KG
0016  *
0017  * Redistribution and use in source and binary forms, with or without
0018  * modification, are permitted provided that the following conditions
0019  * are met:
0020  * 1. Redistributions of source code must retain the above copyright
0021  *    notice, this list of conditions and the following disclaimer.
0022  * 2. Redistributions in binary form must reproduce the above copyright
0023  *    notice, this list of conditions and the following disclaimer in the
0024  *    documentation and/or other materials provided with the distribution.
0025  *
0026  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0027  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0028  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0029  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0030  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0031  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0032  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0033  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0034  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0035  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0036  * POSSIBILITY OF SUCH DAMAGE.
0037  */
0038
0039 #ifdef HAVE_CONFIG_H
0040 #include "config.h"
0041 #endif
0042
0043 #include <sys/stat.h>
0044 #include <fcntl.h>
0045 #include <stdarg.h>
0046 #include <unistd.h>
0047
0048 #include <rtems/libio_.h>
0049
0050 static void create_regular_file(
0051   rtems_filesystem_eval_path_context_t *ctx,
0052   mode_t mode
0053 )
0054 {
0055   int rv = 0;
0056   const rtems_filesystem_location_info_t *currentloc =
0057     rtems_filesystem_eval_path_get_currentloc( ctx );
0058   const char *token = rtems_filesystem_eval_path_get_token( ctx );
0059   size_t tokenlen = rtems_filesystem_eval_path_get_tokenlen( ctx );
0060
0061   rv = rtems_filesystem_mknod(
0062     currentloc,
0063     token,
0064     tokenlen,
0065     S_IFREG | mode,
0066     0
0067   );
0068
0069   if ( rv == 0 ) {
0070     /* The mode only applies to future accesses of the newly created file */
0071     rtems_filesystem_eval_path_set_flags( ctx, 0 );
0072
0073     rtems_filesystem_eval_path_set_path( ctx, token, tokenlen );
0074     rtems_filesystem_eval_path_continue( ctx );
0075   } else {
0076     rtems_filesystem_eval_path_error( ctx, 0 );
0077   }
0078 }
0079
0080 static int do_open(
0081   rtems_libio_t *iop,
0082   const char *path,
0083   int oflag,
0084   mode_t mode
0085 )
0086 {
0087   int rv = 0;
0088   int fd = rtems_libio_iop_to_descriptor( iop );
0089   int rwflag = oflag + 1;
0090   bool read_access = (rwflag & _FREAD) == _FREAD;
0091   bool write_access = (rwflag & _FWRITE) == _FWRITE;
0092   bool make = (oflag & O_CREAT) == O_CREAT;
0093   bool exclusive = (oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL);
0094   bool truncate = (oflag & O_TRUNC) == O_TRUNC;
0095   bool open_dir;
0096 #ifdef O_NOFOLLOW
0097   int follow = (oflag & O_NOFOLLOW) == O_NOFOLLOW ? 0 : RTEMS_FS_FOLLOW_LINK;
0098 #else
0099   int follow = RTEMS_FS_FOLLOW_LINK;
0100 #endif
0101   int eval_flags = follow
0102     | (read_access ? RTEMS_FS_PERMS_READ : 0)
0103     | (write_access ? RTEMS_FS_PERMS_WRITE : 0)
0104     | (make ? RTEMS_FS_MAKE : 0)
0105     | (exclusive ?  RTEMS_FS_EXCLUSIVE : 0);
0106   rtems_filesystem_eval_path_context_t ctx;
0107   const rtems_filesystem_location_info_t *currentloc;
0108   bool create_reg_file;
0109
0110   rtems_filesystem_eval_path_start( &ctx, path, eval_flags );
0111
0112   currentloc = rtems_filesystem_eval_path_get_currentloc( &ctx );
0113   create_reg_file = !currentloc->mt_entry->no_regular_file_mknod;
0114
0115   if ( create_reg_file && rtems_filesystem_eval_path_has_token( &ctx ) ) {
0116     create_regular_file( &ctx, mode );
0117   }
0118
0119 #ifdef O_DIRECTORY
0120   open_dir = ( oflag & O_DIRECTORY ) == O_DIRECTORY;
0121 #else
0122   open_dir = false;
0123 #endif
0124
0125   if ( write_access || open_dir ) {
0126     mode_t type = rtems_filesystem_location_type( currentloc );
0127
0128     if ( create_reg_file && write_access && S_ISDIR( type ) ) {
0129       rtems_filesystem_eval_path_error( &ctx, EISDIR );
0130     }
0131
0132     if ( open_dir && !S_ISDIR( type ) ) {
0133       rtems_filesystem_eval_path_error( &ctx, ENOTDIR );
0134     }
0135   }
0136
0137   rtems_filesystem_eval_path_extract_currentloc( &ctx, &iop->pathinfo );
0138   rtems_filesystem_eval_path_cleanup( &ctx );
0139
0140   rtems_libio_iop_flags_set( iop, rtems_libio_fcntl_flags( oflag ) );
0141
0142   rv = (*iop->pathinfo.handlers->open_h)( iop, path, oflag, mode );
0143
0144   if ( rv == 0 ) {
0145     /*
0146      * Postpone the setting of LIBIO_FLAGS_OPEN after the truncation of the
0147      * file, this ensures that the file descriptor cannot be used or closed
0148      * during or just before the truncation by some other thread.
0149      */
0150     if ( truncate ) {
0151       if ( write_access ) {
0152         rv = (*iop->pathinfo.handlers->ftruncate_h)( iop, 0 );
0153       } else {
0154         rv = -1;
0155         errno = EINVAL;
0156       }
0157
0158       if ( rv != 0 ) {
0159         (*iop->pathinfo.handlers->close_h)( iop );
0160       }
0161     }
0162
0163     if ( rv == 0 ) {
0164       rtems_libio_iop_flags_set( iop, LIBIO_FLAGS_OPEN );
0165       rv = fd;
0166     } else {
0167       rv = -1;
0168     }
0169   }
0170
0171   if ( rv < 0 ) {
0172     rtems_libio_free( iop );
0173   }
0174
0175   return rv;
0176 }
0177
0178 /**
0179 *  POSIX 1003.1 5.3.1 - Open a File
0180 */
0181 int open( const char *path, int oflag, ... )
0182 {
0183   int rv = 0;
0184   va_list ap;
0185   mode_t mode = 0;
0186   rtems_libio_t *iop = NULL;
0187
0188   va_start( ap, oflag );
0189
0190   mode = va_arg( ap, mode_t );
0191
0192   iop = rtems_libio_allocate();
0193   if ( iop != NULL ) {
0194     rv = do_open( iop, path, oflag, mode );
0195   } else {
0196     errno = ENFILE;
0197     rv = -1;
0198   }
0199
0200   va_end( ap );
0201
0202   return rv;
0203 }
0204
0205
0206
0207 #if defined(RTEMS_NEWLIB) && !defined(HAVE__OPEN_R)
0208
0209 #include <reent.h>
0210
0211 /**
0212  *  This is the Newlib dependent reentrant version of open().
0213  */
0214 int _open_r(
0215   struct _reent *ptr RTEMS_UNUSED,
0216   const char    *buf,
0217   int            oflag,
0218   int            mode
0219 )
0220 {
0221   return open( buf, oflag, mode );
0222 }
0223 #endif