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Top Forums Programming What is use of "char __user *buf"? Post 302837267 by shamrock on Thursday 25th of July 2013 12:29:37 PM
Old 07-25-2013
The use of char __user *buf is typically found in the linux kernel...denoting that this address is in the user space. For example when writing to disk the kernel copies the contents of *buf into a kernel space buffer before writing it out to disk. Similarly when a process requests a read operation...the device driver at the behest of the kernel reads the desired disk blocks into a kernel space buffer...and then copies them into the user space buffer pointed to by *buf.
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NE_BUFFER_DESTROY(3)						neon API reference					      NE_BUFFER_DESTROY(3)

NAME
ne_buffer_destroy, ne_buffer_finish - destroy a buffer object SYNOPSIS
#include <ne_string.h> void ne_buffer_destroy (ne_buffer *buf); char *ne_buffer_finish (ne_buffer *buf); DESCRIPTION
ne_buffer_destroy frees all memory associated with the buffer. ne_buffer_finish frees the buffer structure, but not the actual string stored in the buffer, which is returned and must be free()d by the caller. Any use of the buffer object after calling either of these functions gives undefined behaviour. RETURN VALUE
ne_buffer_finish returns the malloc-allocated string stored in the buffer. EXAMPLES
An example use of ne_buffer_finish; the duplicate function returns a string made up of n copies of str: static char *duplicate(int n, const char *str) { ne_buffer *buf = ne_buffer_create(); while (n--) { ne_buffer_zappend(buf, str); } return ne_buffer_finish(buf); } SEE ALSO
ne_buffer(3), ne_buffer_create(3), ne_buffer_zappend(3) AUTHOR
Joe Orton <neon@webdav.org>. neon 0.23.5 8 October 2002 NE_BUFFER_DESTROY(3)
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