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<h1 class="topictitle1">Examples: Integrated file system</h1>
<div><p>These examples can help you program your optical file system using
the integrated file system.</p>
<div class="section"><p>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.</p>
<div class="p">The
programming examples demonstrate the following functions: <ul><li>Retrieving optical directory entries</li>
<li>Creating an optical file</li>
<li>Writing a file</li>
<li>Closing a file</li>
<li>Opening a file</li>
<li>Reading a file</li>
<li>Changing the offset into a file</li>
</ul>
</div>
<p>For more information about UNIX-Type APIs, see the <a href="../apis/unix.htm">UNIX-Type APIs</a> topic in the iSeries™ Information
Center.</p>
</div>
<div class="example"><h4 class="sectiontitle">Sample code</h4>This sample program demonstrates the use
of various integrated file system APIs. <div class="note"><span class="notetitle">Note:</span> By using the following code
examples, you agree to the terms of the <a href="codedisclaimer.htm">Code license and disclaimer information</a>.</div>
<pre>/**********************************************************************/
/* */
/* 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 &lt;stdio.h&gt;
#include &lt;unistd.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;dirent.h&gt;
#include &lt;sys/stat.h&gt;
#include &lt;fcntl.h&gt;
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", &amp;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 &lt;= info.st_nlink; kk++)
{
direntP = readdir(dirP);
if (direntP == NULL)
perror("readdir() failed:");
printf("%d) %s\n", kk, direntP-&gt;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", &amp;volume_number);;
rewinddir(dirP); /* beginning of directory */
for (kk = 1; kk &lt;= volume_number; kk++)
direntP = readdir(dirP); /* get requested dir. entry */
strcat(path, "/");
strcat(path, direntP-&gt;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", &amp;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;
}</pre>
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<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="ifs.htm" title="Read this topic collection to learn how to use UNIX-type APIs to program your optical file system.">Integrated file system programming</a></div>
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