d_open.gml

来自「开放源码的编译器open watcom 1.6.0版的源代码」· GML 代码 · 共 103 行

.func _dos_open
#include <&doshdr>
#include <fcntl.h>
#include <share.h>
unsigned _dos_open( const char *path,
                    unsigned mode,
                    int *&fd );
.ixfunc2 '&DosFunc' &func
.ixfunc2 '&OsIo' &func
.funcend
.desc begin
The &func function uses system call 0x3D to open the file specified by
.arg path,
which must be an existing file.
The
.arg mode
argument specifies the file's access, sharing and inheritance permissions.
The access mode must be one of:
.begterm 12 $compact
.termhd1 Mode
.termhd2 Meaning
.term O_RDONLY
Read only
.term O_WRONLY
Write only
.term O_RDWR
Both read and write
.endterm
.np
The sharing permissions, if specified, must be one of:
.begterm 12 $compact
.termhd1 Permission
.termhd2 Meaning
.term SH_COMPAT
Set compatibility mode.
.term SH_DENYRW
Prevent read or write access to the file.
.term SH_DENYWR
Prevent write access of the file.
.term SH_DENYRD
Prevent read access to the file.
.term SH_DENYNO
Permit both read and write access to the file.
.endterm
.np
The inheritance permission, if specified, is:
.begterm 12
.termhd1 Permission
.termhd2 Meaning
.term O_NOINHERIT
File is not inherited by a child process
.endterm
.desc end
.return begin
The &func function returns zero if successful.
Otherwise, it returns an
MS-DOS error code and sets
.kw errno
to one of the following values:
.begterm 12
.termhd1 Constant
.termhd2 Meaning
.term EACCES
Access denied because
.arg path
specifies a directory or a volume ID, or opening a read-only file
for write access
.term EINVAL
A sharing mode was specified when file sharing is not installed,
or access-mode value is invalid
.term EMFILE
No more &handle.s available, (too many open files)
.term ENOENT
Path or file not found
.endterm
.return end
.see begin
.seelist &function. _dos_close _dos_creat _dos_creatnew _dos_open
.seelist &function. _dos_read _dos_write fdopen fopen
.seelist &function. freopen _fsopen _grow_handles _hdopen open
.seelist &function. _open_osfhandle _popen sopen
.see end
.exmp begin
#include <stdio.h>
#include <&doshdr>
#include <fcntl.h>
#include <share.h>
.exmp break
void main()
  {
    int &fd;
.exmp break
    if( _dos_open( "file", O_RDONLY, &amp.&fd ) != 0 ) {
        printf( "Unable to open file\n" );
    } else {
        printf( "Open succeeded\n" );
        _dos_close( &fd );
    }
  }
.exmp end
.class DOS
.system