Open for shared access a file associated with a given descriptor
Synopsis:
#include <unistd.h>
int sopenfd( int fd,
int oflag,
int sflag );
Arguments:
- fd
- A file descriptor associated with the file that you want to open.
- oflag
- How you want to open the file; a combination of the following bits:
- O_RDONLY — permit the file to be only read.
- O_WRONLY — permit the file to be only written.
- O_RDWR — permit the file to be both read and written.
- O_APPEND — cause each record that's written to
be written at the end of the file.
- O_CLOEXEC — close the file descriptor if the program calls
one of the exec*(), posix_spawn*(), or spawn*() functions.
- O_LARGEFILE — allow the file offset to be 64 bits long.
- O_TRUNC — truncate the file to contain no data.
- sflag
- How you want the file to be shared; a combination of the following bits:
- SH_COMPAT — this flag is ignored in the QNX implementation.
- SH_DENYRW — prevent read or write access to the file.
- SH_DENYWR — prevent write access to the file.
- SH_DENYRD — prevent read access to the file.
- SH_DENYNO — permit both read and write access to the file.
Library:
libc
Use the -l c option to
qcc
to link against this library.
This library is usually included automatically.
Description:
The sopenfd() function opens for shared access
the file associated with the file descriptor, fd.
The access mode, oflag, must be equal to or more restrictive than the access mode
of the source fd.
Note that:
openfd( fd, oflag );
is the same as:
sopenfd( fd, oflag, SH_DENYNO );
Returns:
The file descriptor, or -1 if an error occurs
(errno is set).
Errors:
- EBADF
- Invalid file descriptor fd.
- EACCES
- The access mode specified by oflag isn't equal to or more restrictive
than the access mode of the source fd.
- EBUSY
- Sharing mode (sflag) was denied due to a conflicting open.
Classification:
Unix
| Safety: |
|
|---|
| Cancellation point |
Yes |
| Interrupt handler |
No |
| Signal handler |
Yes |
| Thread |
Yes |