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Commit 2043f495 authored by Al Viro's avatar Al Viro
Browse files

new helper: single_open_size() 



Same as single_open(), but preallocates the buffer of given size.
Doesn't make any sense for sizes up to PAGE_SIZE and doesn't make
sense if output of show() exceeds PAGE_SIZE only rarely - seq_read()
will take care of growing the buffer and redoing show().  If you
_know_ that it will be large, it might make more sense to look into
saner iterator, rather than go with single-shot one.  If that's
impossible, single_open_size() might be for you.

Again, don't use that without a good reason; occasionally that's really
the best way to go, but very often there are better solutions.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 70ef457d

fs/seq_file.c

+18 −0
Original line number Original line Diff line number Diff line
@@ -599,6 +599,24 @@ int single_open(struct file *file, int (*show)(struct seq_file *, void *), 
}

}

EXPORT_SYMBOL(single_open);

EXPORT_SYMBOL(single_open);





int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),

		void *data, size_t size)

{

	char *buf = kmalloc(size, GFP_KERNEL);

	int ret;

	if (!buf)

		return -ENOMEM;

	ret = single_open(file, show, data);

	if (ret) {

		kfree(buf);

		return ret;

	}

	((struct seq_file *)file->private_data)->buf = buf;

	((struct seq_file *)file->private_data)->size = size;

	return 0;

}

EXPORT_SYMBOL(single_open_size);



int single_release(struct inode *inode, struct file *file)

int single_release(struct inode *inode, struct file *file)

{

{

	const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;

	const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;

include/linux/seq_file.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -123,6 +123,7 @@ static inline int seq_nodemask_list(struct seq_file *m, nodemask_t *mask) 
}

}





int single_open(struct file *, int (*)(struct seq_file *, void *), void *);

int single_open(struct file *, int (*)(struct seq_file *, void *), void *);

int single_open_size(struct file *, int (*)(struct seq_file *, void *), void *, size_t);

int single_release(struct inode *, struct file *);

int single_release(struct inode *, struct file *);

void *__seq_open_private(struct file *, const struct seq_operations *, int);

void *__seq_open_private(struct file *, const struct seq_operations *, int);

int seq_open_private(struct file *, const struct seq_operations *, int);

int seq_open_private(struct file *, const struct seq_operations *, int);