From 839cc2a94cc3665bafe32203c2f095f4dd470a80 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Thu, 14 Nov 2013 14:31:56 -0800 Subject: [PATCH] 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: Tetsuo Handa Signed-off-by: Kees Cook Cc: Joe Perches Cc: David Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/seq_file.c | 15 +++++++++++++++ include/linux/seq_file.h | 15 +++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/fs/seq_file.c b/fs/seq_file.c index a290157265ef..1cd2388ca5bd 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -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; diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h index 4e32edc8f506..52e0097f61f0 100644 --- a/include/linux/seq_file.h +++ b/include/linux/seq_file.h @@ -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 *); -- 2.30.2