Veritas File System 5.1 SP1 Administrator"s Guide (5900-1499, April 2011)

Providing API access for the FCL feature allows backward

compatibility for applications. The API allows applications to

parse the FCL file independent of the FCL layout changes. Even if

the hidden disk layout of the FCL changes, the API automatically

translates the returned data to match the expected output record.

As a result, the user does not need to modify or recompile the

application due to changes in the on-disk FCL layout.

Backward

compatibility

The following sample code fragment reads the FCL superblock, checks that the

state of the FCL is VX_FCLS_ON, issues a call to vxfs_fcl_sync to obtain a finishing

offset to read to, determines the first valid offset in the FCL file, then reads the

entries in 8K chunks from this offset. The section process fcl entries is what an

application developer must supply to process the entries in the FCL file.

#include <stdint.h>

#include <stdio.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/fcntl.h>

#include <errno.h>

#include <fcl.h>

#include <vxfsutil.h>

#define FCL_READSZ 8192

char* fclname = "/mnt/lost+found/changelog";

int read_fcl(fclname) char* fclname;

{

struct fcl_sb fclsb;

uint64_t off, lastoff;

size_t size;

char buf[FCL_READSZ], *bufp = buf;

int fd;

int err = 0;

if ((fd = open(fclname, O_RDONLY)) < 0) {

return ENOENT;

}

if ((off = lseek(fd, 0, SEEK_SET)) != 0) {

close(fd);

return EIO;

}

size = read(fd, &fclsb, sizeof (struct fcl_sb));

if (size < 0) {

close(fd);

return EIO;

File Change Log

File Change Log programmatic interface