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 <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>
diff --git a/fs/seq_file.c b/fs/seq_file.c
index a290157..1cd2388 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -766,6 +766,21 @@
}
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 4e32edc..52e0097 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -20,6 +20,7 @@
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 @@
}
}
+/**
+ * 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 *);
