ftruncate(2POSIX)

NAME | SYNOPSIS | API RESTRICTIONS | FEATURES | DESCRIPTION | RESTRICTION | RETURN VALUES | ERRORS | ATTRIBUTES | SEE ALSO | BUGS

NAME

truncate, ftruncate- truncate a file to a specified length

SYNOPSIS

#include <unistd.h>

int truncate(const char * path, off_t length);
int ftruncate(int fd, off_t length);

API RESTRICTIONS

The function or functions documented here may not be used safely in all application contexts with all APIs provided in the ChorusOS 5.0 product.

See API(5FEA) for details.

FEATURES

MSDOSFS, NFS_CLIENT, UFS

DESCRIPTION

The truncate call causes the file named by path or referenced by fd to be truncated to a maximum of length bytes in size. If the file had previously been larger than the size specified, the extra data is lost. It must be possible to write to the file in order to use ftruncate .

RESTRICTION

An ftruncate operation performed after the first mmap(2POSIX) on the object will fail.

RETURN VALUES

If successful, truncate returns a value of 0; otherwise a value of -1 is returned, and errno is set to indicate one of the following error conditions.

ERRORS

The error messages for truncate are the following:

[ENOTDIR]

A component of the path prefix is not a directory.

[ENAMETOOLONG]

A component of a pathname exceeded NAME_MAX characters, or an entire pathname exceeded PATH_MAX characters.

[ENOENT]

The file named does not exist.

[EACCES]

Search permission is denied for a component of the path prefix.

[EACCES]

The file named is not writable by the user.

[ELOOP]

Too many symbolic links were encountered in translating the pathname.

[EISDIR]

The file named is a directory.

[EROFS]

The file named resides on a read-only file system.

[ETXTBSY]

The file is a pure procedure (shared text) file that is being executed.

[EIO]

An I/O error occurred updating the inode.

[EFAULT]

In user mode, path points outside the process's allocated address space. In supervisor mode, this is not detected, and the target's state is unknown.

The error messages for ftruncate are the following:

[EBADF]

The fd is not a valid descriptor.

[EINVAL]

The fd references a socket, not a file.

[EINVAL]

The fd is not open for writing.

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface Stability	Evolving

SEE ALSO

mmap(2POSIX) , open(2POSIX)

BUGS

These calls should be kept general to allow ranges of bytes in a file to be discarded.

ChorusOS 5.0  Last Revised December 2001

NAME | SYNOPSIS | API RESTRICTIONS | FEATURES | DESCRIPTION | RESTRICTION | RETURN VALUES | ERRORS | ATTRIBUTES | SEE ALSO | BUGS