Truxton file seek - Revision history

Sam at 21:34, 10 February 2021

2021-02-10T21:34:40Z

Sam: /* Sample */

2020-11-03T15:18:36Z

Sample

Sam: /* Sample */

2020-11-03T15:18:22Z

Sample

Sam: /* whence */

2020-11-03T15:18:09Z

whence

Sam at 10:57, 10 June 2020

2020-06-10T10:57:25Z

Sam at 13:06, 6 June 2020

2020-06-06T13:06:06Z

Sam: Created page with "This allows you to alter the offset into the opened file where the next read will take place. =Syntax= int64_t truxton_file_seek( uint64_t file_han..."

2020-06-02T21:31:46Z

Created page with "This allows you to alter the offset into the opened file where the next read will take place. =Syntax= <syntaxhighlight lang="C"> int64_t truxton_file_seek( uint64_t file_han..."

New page

This allows you to alter the offset into the opened file where the next read will take place.

=Syntax=
<syntaxhighlight lang="C">
int64_t truxton_file_seek( uint64_t file_handle, int64_t distance, int whence )
</syntaxhighlight>

=Parameters=
==<code>file_handle</code>==

The handle created by the [[truxton_file_open_id]] of [[truxton_file_open_md5]] call.

==<code>distance</code>==
The number of bytes to move from <code>whence</code>

==<code>whence</code>==
Where to seek from.
# - the beginning of the file
# - the current read offset
# - the end of the file

These values mimic standard C library's [https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_72/apis/lseek.htm lseek()] whence values.

=Return value=
The offset into the file where the next byte will be read from.

=Sample=

<syntaxhighlight lang="C" highlight="10">
int does_file_have_deep_philosophical_meaning(uint64_t truxton)
{
uint64_t file = truxton_file_open_id(truxton, "5ed3aeb7-3da4-5f5c-8c8f-af5200000000");

if ( file != 0 )
{
return(0);
}

truxton_file_seek(file, 42, 0 );

int64_t read_position = truxton_file_tell(file);

truxton_file_close(file);
truxton_file_free(file);

if ( read_position == 42 )
{
return(1);
}

return(0)
}
</syntaxhighlight>

@@ Line 35: / Line 35: @@
+    }
-    truxton_file_seek(file, 42, SEEK_SET );
+    truxton_file_seek(file, 42, SEEK_SET);
     int64_t read_position = truxton_file_tell(file);

@@ Line 2: / Line 2: @@
 =Syntax=
-<syntaxhighlight lang="C">
+<source lang="C">
 int64_t truxton_file_seek( uint64_t file_handle, int64_t distance, int whence );
-</syntaxhighlight>
+</source>
 =Parameters=
@@ Line 25: / Line 25: @@
 =Sample=
-<syntaxhighlight lang="C" highlight="10">
+<source lang="C" highlight="10">
-int does_file_have_deep_philosophical_meaning(uint64_t truxton)
+int does_file_have_deep_philosophical_meaning( uint64_t truxton )
+{
-    uint64_t file = truxton_file_open_id(truxton, "5ed3aeb7-3da4-5f5c-8c8f-af5200000000");
+    uint64_t file = truxton_file_open_id( truxton, "5ed3aeb7-3da4-5f5c-8c8f-af5200000000" );
     if ( file != 0 )
+    {
-       return(0);
+       return( 0 );
+    }
-    truxton_file_seek(file, 42, SEEK_SET);
+    truxton_file_seek( file, 42, SEEK_SET );
-    int64_t read_position = truxton_file_tell(file);
+    int64_t read_position = truxton_file_tell( file );
-    truxton_file_close(file);
+    truxton_file_close( file );
-    truxton_file_free(file);
+    truxton_file_free( file );
     if ( read_position == 42 )
+    {
-       return(1);
+       return( 1 );
+    }
-    return(0)
+    return( 0 )
+}
-</syntaxhighlight>
+</source>

@@ Line 15: / Line 15: @@
 ==<code>whence</code>==
 Where to seek from.
-# - the beginning of the file
+* <code>SEEK_SET</code> - 0 - the beginning of the file
-# - the current read offset
+* <code>SEEK_CUR</code> - 1 - the current read offset
-# - the end of the file
+* <code>SEEK_END</code> - 2 - the end of the file
 These values mimic standard C library's [https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_72/apis/lseek.htm lseek()] whence values.

@@ Line 9: / Line 9: @@
 ==<code>file_handle</code>==
-The handle created by the [[truxton_file_open_id]] of [[truxton_file_open_md5]] call.
+The handle created by the [[truxton_file_open_id]] or [[truxton_file_open_md5]] call.
 ==<code>distance</code>==