These examples can help you program your optical file system using the integrated file system.
This topic demonstrates the use of the integrated file system UNIX-type APIs that pertain to the QOPT physical file system and are used with the ILE C for i5/OS™ programming language.
For more information about UNIX-Type APIs, see the UNIX-Type APIs topic in the iSeries™ Information Center.
/**********************************************************************/
/* */
/* This program demonstrates the use of various integrated file */
/* system functions applied to the QOPT physical file system */
/* including: */
/* chdir() - change current directory */
/* close() - close file */
/* closedir() - close directory */
/* creat() - create file */
/* lseek() - seek file (change file offset) */
/* open() - open file */
/* opendir() - open directory */
/* read() - read file */
/* readdir() - read directory entry */
/* rewinddir() - rewind directory entries */
/* stat() - directory statistics */
/* write() - write file */
/* */
/**********************************************************************/
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <dirent.h>
#include <sys/stat.h>
#include <fcntl.h>
void main (void)
{
/*****************************************************************/
/* local variables, contents and defines */
/*****************************************************************/
char path[294]; /* optical path */
DIR *dirP; /* pointer to the directory */
int filedes; /* open file descriptor */
struct dirent *direntP; /* directory entry structure */
struct stat info; /* dir/file information */
int volume_number; /* what it says... */
int rc = 0; /* function return codes */
int kk = 0; /* local counter */
char data[] = "The quick red fox jumped over the fence";
/*****************************************************************/
/* Retrieve the list of volumes from the QOPT physical file */
/* system by opening the QOPT pfs root directory and reading the */
/* directory entries. */
/*****************************************************************/
memset(path, /* clear path name */
0x00,
sizeof(path));
strcpy(path, /* set physical file system */
"/QOPT");
rc = stat("/QOPT", &info);; /* determine number of files */
if (rc != 0)
perror("stat() failed:");
dirP = opendir(path); /* open the directory */
if (dirP == NULL)
perror("opendir() failed:");
for (kk = 1; kk <= info.st_nlink; kk++)
{
direntP = readdir(dirP);
if (direntP == NULL)
perror("readdir() failed:");
printf("%d) %s\n", kk, direntP->d_name);
}
/*****************************************************************/
/* Prompt user for the volume they want to work with and make it */
/* the current directory. */
/*****************************************************************/
printf("\nEnter the number the volume you want to work with:\n");
scanf("%d", &volume_number);;
rewinddir(dirP); /* beginning of directory */
for (kk = 1; kk <= volume_number; kk++)
direntP = readdir(dirP); /* get requested dir. entry */
strcat(path, "/");
strcat(path, direntP->d_name);
rc = chdir(path); /* set current working dir. */
if (rc != 0)
perror("chdir() failed:");
if (getcwd(path, sizeof(path)) == NULL)
perror("getcwd() failed:");
printf("\nThe current working directory is: %s\n", path);
rc = closedir(dirP); /* close the directory */
if (rc != 0)
perror("closedir() failed:");
/*****************************************************************/
/* Create and open a file write only. If the file exists it */
/* will be truncated. The owner will have read, write, and */
/* execute authority to the file. */
/*****************************************************************/
strcat(path, "/");
printf("\nEnter a file name:\n");
scanf("%s", &path[strlen(path)]);
filedes = creat(path, S_IRWXU);
if (filedes == -1)
{
perror("creat() failed");
return;
}
rc = write(filedes, data, sizeof(data));
if (rc == -1)
perror("write() failed:");
close(filedes);
/*****************************************************************/
/* Read back the file and print it. */
/*****************************************************************/
memset(data, 0x00, sizeof(data));
filedes = open(path, O_RDWR);
if (filedes == -1)
{
perror("open() failed");
return;
}
read(filedes, data, sizeof(data));
if (filedes == -1)
{
perror("read() failed");
return;
}
printf("\nThe data written to file is: %s\n", data);
/*****************************************************************/
/* Change the offset into the file and change part of it. Read */
/* the entire file, print it out and close the file. */
/*****************************************************************/
lseek(filedes, 4, SEEK_SET);
rc = write(filedes, "slow old ", 9);
if (rc == -1)
{
perror("write() failed");
return;
}
lseek(filedes, 18, SEEK_SET);
rc = write(filedes, "went under ", 11);
if (rc == -1)
{
perror("write() failed");
return;
}
lseek(filedes, 0, SEEK_SET);
read(filedes, data, sizeof(data));
if (filedes == -1)
{
perror("read() failed");
return;
}
printf("\nThe data now is: %s\n", data);
close(filedes);
printf("Done...\n");
return;
}