pathconf()
Return the value of a configurable limit
Synopsis:
#include <unistd.h> long pathconf( const char* path, int name );
Arguments:
- path
- The name of the file whose limit you want to get.
- name
- The name of the configurable limit; see below.
Library:
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
Description:
The pathconf() function returns a value of a configurable limit indicated by name, which is associated with the filename given in path.
Configurable limits are defined in <confname.h>, and include at least the following values:
- _PC_ASYNC_IO
- Defined if asynchronous I/O is supported for the file.
- _PC_CHOWN_RESTRICTED
- If defined (not -1), indicates that the use of the chown() function is restricted to a process with root privileges, and to changing the group ID of a file to the effective group ID of the process or to one of its supplementary group IDs.
- _PC_LINK_DIR
- Defined (not -1) if the filesystem permits the unlinking of a directory.
- _PC_LINK_MAX
- Maximum value of a file's link count.
- _PC_MAX_CANON
- Maximum number of bytes in a terminal's canonical input buffer (edit buffer).
- _PC_MAX_INPUT
- Maximum number of bytes in a terminal's raw input buffer.
- _PC_NAME_MAX
- Maximum number of bytes in a file name (not including the terminating null).
- _PC_NO_TRUNC
- If defined (not -1), indicates that the use of pathname components longer than the value given by _PC_NAME_MAX will generate an error.
- _PC_PATH_MAX
- Maximum number of bytes in a pathname (not including the terminating null).
- _PC_PIPE_BUF
- Maximum number of bytes that can be written atomically when writing to a pipe.
- _PC_PRIO_IO
- Defined (not -1) if prioritized I/O is supported for the file.
- _PC_SYNC_IO
- Defined (not -1) if synchronous I/O is supported for the file.
- _PC_VDISABLE
- If defined (not -1), this is the character value which can be used to individually disable special control characters in the termios control structure.
Returns:
The requested configurable limit, or -1 if an error occurs (errno is set).
Errors:
- EACCES
- Search permission is denied for a component of path.
- EINVAL
- The name argument is invalid, or the indicated limit isn't supported.
- ELOOP
- Too many levels of symbolic links or prefixes.
- ENAMETOOLONG
- The path argument, or a component of path, is too long.
- ENOENT
- The file doesn't exist.
- ENOSYS
- The pathconf() function isn't implemented for the filesystem specified in path.
- ENOTDIR
- A component of the path prefix isn't a directory.
Examples:
#include <stdio.h> #include <stdlib.h> #include <unistd.h> int main( void ) { long value; value = pathconf( "/dev/con1", _PC_MAX_INPUT ); printf( "Input buffer size is %ld bytes\n", value ); return EXIT_SUCCESS; }
Classification:
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | No |
Signal handler | Yes |
Thread | Yes |