compiler/posixc/open.c

   1 /*
   2     Copyright © 1995-2012, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     POSIX.1-2008 function open().
   6 */
   7
   8 #include <stdarg.h>
   9 #include "__fdesc.h"
  10
  11 /*****************************************************************************
  12
  13     NAME */
  14 #include <fcntl.h>
  15
  16         int open (
  17
  18 /*  SYNOPSIS */
  19         const char * pathname,
  20         int              flags,
  21         ...)
  22
  23 /*  FUNCTION
  24         Opens a file with the specified flags and name.
  25
  26     INPUTS
  27         pathname - Path and filename of the file you want to open.
  28         flags - Most be exactly one of: O_RDONLY, O_WRONLY or O_RDWR
  29                 to open a file for reading, writing or for reading and
  30                 writing.
  31
  32                 The mode can be modified by or'ing the following bits in:
  33
  34                 O_CREAT: Create the file if it doesn't exist (only for
  35                         O_WRONLY or O_RDWR). If this flag is set, then
  36                         open() will look for a third parameter mode. mode
  37                         must contain the access modes for the file
  38                         (mostly 0644).
  39                 O_EXCL: Only with O_CREAT. If the file does already exist,
  40                         then open() fails. See BUGS.
  41                 O_NOCTTY:
  42                 O_TRUNC: If the file exists, then it gets overwritten. This
  43                         is the default and the opposite to O_APPEND.
  44                 O_APPEND: If the file exists, then the startung position for
  45                         writes is the end of the file.
  46                 O_NONBLOCK or O_NDELAY: Opens the file in non-blocking mode.
  47                         If there is no data in the file, then read() on a
  48                         terminal will return immediately instead of waiting
  49                         until data arrives. Has no effect on write().
  50                 O_SYNC: The process will be stopped for each write() and the
  51                         data will be flushed before the write() returns.
  52                         This ensures that the data is physically written
  53                         when write() returns. If this flag is not specified,
  54                         the data is written into a buffer and flushed only
  55                         once in a while.
  56
  57     RESULT
  58         -1 for error or a file descriptor for use with read(), write(), etc.
  59
  60     NOTES
  61         If the filesystem doesn't allow to specify different access modes
  62         for users, groups and others, then the user modes are used.
  63
  64         This function must not be used in a shared library or
  65         in a threaded application.
  66
  67
  68     EXAMPLE
  69
  70     BUGS
  71         The flag O_EXCL is not very reliable if the file resides on a NFS
  72         filesystem.
  73
  74         Most flags are not supported right now.
  75
  76     SEE ALSO
  77         close(), read(), write(), fopen()
  78
  79     INTERNALS
  80
  81 ******************************************************************************/
  82 {
  83     mode_t mode = 0644;
  84
  85     if (flags & O_CREAT)
  86     {
  87         va_list ap;
  88
  89         va_start(ap, flags);
  90         mode = va_arg(ap, int);
  91         va_end(ap);
  92     }
  93
  94     return __open(__getfirstfd(0), pathname, flags, mode);
  95 } /* open */
  96