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seq_file: introduce seq_setwidth() and seq_pad()

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There are several users who want to know bytes written by seq_*() for
alignment purpose.  Currently they are using %n format for knowing it
because seq_*() returns 0 on success.

This patch introduces seq_setwidth() and seq_pad() for allowing them to
align without using %n format.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Joe Perches <joe@perches.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Tetsuo Handa 2013-11-14 14:31:56 -08:00 committed by Linus Torvalds
parent 57f4257eae
commit 839cc2a94c
2 changed files with 30 additions and 0 deletions
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15
fs/seq_file.c
View File

@ -766,6 +766,21 @@ int seq_write(struct seq_file *seq, const void *data, size_t len)
}
EXPORT_SYMBOL(seq_write);
/**
* seq_pad - write padding spaces to buffer
* @m: seq_file identifying the buffer to which data should be written
* @c: the byte to append after padding if non-zero
*/
void seq_pad(struct seq_file *m, char c)
{
int size = m->pad_until - m->count;
if (size > 0)
seq_printf(m, "%*s", size, "");
if (c)
seq_putc(m, c);
}
EXPORT_SYMBOL(seq_pad);
struct list_head *seq_list_start(struct list_head *head, loff_t pos)
{
struct list_head *lh;

15
include/linux/seq_file.h
View File

@ -20,6 +20,7 @@ struct seq_file {
size_t size;
size_t from;
size_t count;
size_t pad_until;
loff_t index;
loff_t read_pos;
u64 version;
@ -79,6 +80,20 @@ static inline void seq_commit(struct seq_file *m, int num)
}
}
/**
* seq_setwidth - set padding width
* @m: the seq_file handle
* @size: the max number of bytes to pad.
*
* Call seq_setwidth() for setting max width, then call seq_printf() etc. and
* finally call seq_pad() to pad the remaining bytes.
*/
static inline void seq_setwidth(struct seq_file *m, size_t size)
{
m->pad_until = m->count + size;
}
void seq_pad(struct seq_file *m, char c);
char *mangle_path(char *s, const char *p, const char *esc);
int seq_open(struct file *, const struct seq_operations *);
ssize_t seq_read(struct file *, char __user *, size_t, loff_t *);