source: rtems/c/src/lib/libc/open.c @ df49c60

4.104.114.84.95
Last change on this file since df49c60 was 08311cc3, checked in by Joel Sherrill <joel.sherrill@…>, on 11/17/99 at 17:51:34

Updated copyright notice.

  • Property mode set to 100644
File size: 5.5 KB
Line 
1/*
2 *  open() - POSIX 1003.1 5.3.1 - Open a File
3 *
4 *  COPYRIGHT (c) 1989-1999.
5 *  On-Line Applications Research Corporation (OAR).
6 *
7 *  The license and distribution terms for this file may be
8 *  found in the file LICENSE in this distribution or at
9 *  http://www.OARcorp.com/rtems/license.html.
10 *
11 *  $Id$
12 */
13
14#include "libio_.h"
15
16#include <unistd.h>
17
18/*
19 *  Returns file descriptor on success or -1 and errno set to one of the
20 *  following:
21 *
22 *    EACCESS  - Seach permission is denied on a component of the path prefix,
23 *               or the file exists and the permissions specified by the
24 *               flags are denied, or the file does not exist and write
25 *               permission is denied for the parent directory of the file
26 *               to be created, or O_TRUNC is specified and write permission
27 *               is denied.
28 *    EEXIST   - O_CREAT and O_EXCL are set and the named file exists.
29 *    EINTR    - The open( operation was interrupted by a signal.
30 *    EINVAL   - This implementation does not support synchronized IO for this
31 *               file.
32 *    EISDIR   - The named file is a directory and the flags argument
33 *               specified write or read/write access.
34 *    EMFILE   - Too many file descriptors are in used by this process.
35 *    ENAMETOOLONG -
36 *               The length of the path exceeds PATH_MAX or a pathname
37 *               component is longer than NAME_MAX while POSIX_NO_TRUNC
38 *               is in effect.
39 *    ENFILE   - Too many files are open in the system.
40 *    ENOENT   - O_CREAT is not set and and the anmed file does not exist,
41 *               or O_CREAT is set and eitehr the path prefix does not exist
42 *               or the path argument points to an empty string.
43 *    ENOSPC   - The directory or file system that would contain the new file
44 *               cannot be extended.
45 *    ENOTDIR  - A component of the path prefix is not a directory.
46 *    ENXIO    - O_NONBLOCK is set, the named file is a FIFO, O_WRONLY is
47 *               set, and no process has the file open for reading.
48 *    EROFS    - The named file resides on a read-only file system and either
49 *               O_WRONLY, O_RDWR, O_CREAT (if the file does not exist), or
50 *               O_TRUNC is set in the flags argument.
51 */
52
53int open(
54  const char   *pathname,
55  int           flags,
56  ...
57)
58{
59  va_list                             ap;
60  int                                 mode;
61  int                                 rc;
62  rtems_libio_t                      *iop = 0;
63  int                                 status;
64  rtems_filesystem_location_info_t    loc;
65  int                                 eval_flags;
66
67
68  /*
69   * Set the Evaluation flags
70   */
71
72  eval_flags = 0;
73  status = flags + 1;
74  if ( ( status & _FREAD ) == _FREAD )
75    eval_flags |= RTEMS_LIBIO_PERMS_READ;
76  if ( ( status & _FWRITE ) == _FWRITE )
77    eval_flags |= RTEMS_LIBIO_PERMS_WRITE;
78
79 
80  va_start(ap, flags);
81
82  mode = va_arg( ap, int );
83
84  /*
85   * NOTE: This comment is OBSOLETE.  The proper way to do this now
86   *       would be to support a magic mounted file system.
87   *
88   *             Additional external I/O handlers would be supported by adding
89   *             code to pick apart the pathname appropriately. The networking
90   *             code does not require changes here since network file
91   *             descriptors are obtained using socket(), not open().
92   */
93
94  /* allocate a file control block */
95  iop = rtems_libio_allocate();
96  if ( iop == 0 ) {
97    rc = ENFILE;
98    goto done;
99  }
100
101  /*
102   *  See if the file exists.
103   */
104
105  status = rtems_filesystem_evaluate_path(
106     pathname, eval_flags, &loc, TRUE );
107
108  if ( status == -1 ) {
109    if ( errno != ENOENT ) {
110      rc = errno;
111      goto done;
112    }
113
114    /* If the file does not exist and we are not trying to create it--> error */
115    if ( !(flags & O_CREAT) ) {
116      rc = ENOENT;
117      goto done;
118    }
119
120    /* Create the node for the new regular file */
121    rc = mknod( pathname, S_IFREG | mode, 0LL );
122    if ( rc ) {
123      rc = errno;
124      goto done;
125    }
126
127    /* Sanity check to see if the file name exists after the mknod() */
128    status = rtems_filesystem_evaluate_path( pathname, 0x0, &loc, TRUE );
129    if ( status != 0 ) {   /* The file did not exist */
130      rc = EACCES;
131      goto done;
132    }
133
134  } else if ((flags & (O_EXCL|O_CREAT)) == (O_EXCL|O_CREAT)) {
135    /* We were trying to create a file that already exists */
136    rc = EEXIST;
137    goto done;
138  }
139
140  /*
141   *  Fill in the file control block based on the loc structure
142   *  returned by successful path evaluation.
143   */
144
145  iop->offset     = 0;
146  iop->handlers   = loc.handlers;
147  iop->file_info  = loc.node_access;
148  iop->flags     |= rtems_libio_fcntl_flags( flags );
149  iop->pathinfo   = loc;
150
151  if ( !iop->handlers->open ) {
152    rc = ENOTSUP;
153    goto done;
154  }
155
156  rc = (*iop->handlers->open)( iop, pathname, flags, mode );
157  if ( rc )
158    goto done;
159
160  /*
161   *  Optionally truncate the file.
162   */
163
164  if ( (flags & O_TRUNC) == O_TRUNC ) {
165    rc = ftruncate( iop - rtems_libio_iops, 0 );
166  }
167   
168  /*
169   *  Single exit and clean up path.
170   */
171
172done:
173  va_end(ap);
174
175  if ( rc ) {
176    if ( iop )
177      rtems_libio_free( iop );
178    set_errno_and_return_minus_one( rc );
179  }
180
181  rtems_filesystem_freenode( &loc );
182
183  return iop - rtems_libio_iops;
184}
185
186/*
187 *  _open_r
188 *
189 *  This is the Newlib dependent reentrant version of open().
190 */
191
192#if defined(RTEMS_NEWLIB)
193
194#include <reent.h>
195
196int _open_r(
197  struct _reent *ptr,
198  const char    *buf,
199  int            flags,
200  int            mode
201)
202{
203  return open( buf, flags, mode );
204}
205#endif
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