Commit 839cc2a9 authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Linus Torvalds

seq_file: introduce seq_setwidth() and seq_pad()

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: default avatarTetsuo Handa <>
Signed-off-by: default avatarKees Cook <>
Cc: Joe Perches <>
Cc: David Miller <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 57f4257e
......@@ -766,6 +766,21 @@ int seq_write(struct seq_file *seq, const void *data, size_t len)
* 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);
struct list_head *seq_list_start(struct list_head *head, loff_t pos)
struct list_head *lh;
......@@ -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 *);
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