_fsopen
Opens a stream with file sharing.
Defined in header <stdio.h>
Syntax
#include <stdio.h>
#include <share.h>
FILE *fsopenCconst char *filename, const char *mode, int shflg);Portability
| DOS | UNIX | Windows | ANSI C | C++ only |
|---|---|---|---|---|
| ■ | ■ |
Remarks
_fsopen opens the file named by filename and associates a stream with it. _fsopen returns a pointer to be used to identify the stream in subsequent operations.
The mode string used in calls to _fsopen is one of the following values:
Mode Description
Open for reading only. Create for writing. If a file by that name already exists, it will be overwritten. Append; open for writing at end of file, or create for writing if the file does not exist.
| r+ | Open an existing file for update (reading and writing). |
| 10+ | Create a new file for update (reading and writing). If a file by that name already exists, it will be overwritten. |
| a+ | Open for append; open for update at the end of the file, or create if the file does not exist. |
To specify that a given file is being opened or created in text mode, append a f to the mode string {rt, iv+t, and so on). Similarly, to specify binary mode, append abto the mode string (wb, a+b, and so on). _fsopen also allows the f or t" to be inserted between the letter and the + character in the mode string; for example, rt+ is equivalent to r+t.
If a f or b is not given in the mode string, the mode is governed by the
| global variable _fmode. If Jrnode is set to O_BINARY, | files are opened in |
binary mode. If _fmode is set to O_TEXT, they are opened in text mode. These O_... constants are defined in fcntl.h.
When a file is opened for update, both input and output can be done on the resulting stream. However, output cannot be followed directly by input without an intervening (seek or rewind, and input cannot be directly followed by output without an intervening fseek, rewind, or an input that encounters end-of-file.
shflag specifies the type of file-sharing allowed on the file filename. The
| file-sharing flags are ignored if the DOS SHARE command | has not been |
run. Symbolic constants for shflag are defined in share.h.
| Value of shflag | What it does |
| SH_COMPAT | Sets compatibility mode |
| SH_DENYRW | Denies read/write access |
| SH_DENYWR | Denies write access |
| SH_DENYRD | Denies read access |
| SH_DENYNONE | Permits read/write access |
| SH DENYNO | Permits read/write access |
Return value
On successful completion, _fsopen returns a pointer to the newly opened stream. In the event of error, it returns null.
See also
Example
#include <io.h>
#include <process.h>
#include <share.h>
#include <stdio.h>
int main (void)
{
FILE *f;
int status;
f = _fsopen("c:\\test.$$$", SH DENYNO)
if (f == NULL) {
printf( "_fsopen failed\n"i
exit(l);
status = access ("c:\\test.$$$", 6);
if (status == 0)
printf( "read/write access allowed\n");
else
printf( "read/write access not allowed\n");
fclose (f);
return 0;Differences from modern implementations
Nothing recorded yet.
Modern references
These are search links, not yet checked by hand.
Stable link: /3.1/stdio.h/_fsopen/
· short form /3.1/_fsopen/