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>

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>
Tetsuo Handa · Linus Torvalds
1 parent 57f4257eae
Showing 2 changed files with 30 additions and 0 deletions Side-by-side Diff
fs/seq_file.c
include/linux/seq_file.h
@@ -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;
@@ -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;
@@ -78,6 +79,20 @@
 		m->count += 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 *);
...	...	@@ -766,6 +766,21 @@
766	766	}
767	767	EXPORT_SYMBOL(seq_write);
768	768
	769	+/**
	770	+ * seq_pad - write padding spaces to buffer
	771	+ * @m: seq_file identifying the buffer to which data should be written
	772	+ * @c: the byte to append after padding if non-zero
	773	+ */
	774	+void seq_pad(struct seq_file *m, char c)
	775	+{
	776	+ int size = m->pad_until - m->count;
	777	+ if (size > 0)
	778	+ seq_printf(m, "%*s", size, "");
	779	+ if (c)
	780	+ seq_putc(m, c);
	781	+}
	782	+EXPORT_SYMBOL(seq_pad);
	783	+
769	784	struct list_head seq_list_start(struct list_head head, loff_t pos)
770	785	{
771	786	struct list_head *lh;
...	...	@@ -20,6 +20,7 @@
20	20	size_t size;
21	21	size_t from;
22	22	size_t count;
	23	+ size_t pad_until;
23	24	loff_t index;
24	25	loff_t read_pos;
25	26	u64 version;
...	...	@@ -78,6 +79,20 @@
78	79	m->count += num;
79	80	}
80	81	}
	82	+
	83	+/**
	84	+ * seq_setwidth - set padding width
	85	+ * @m: the seq_file handle
	86	+ * @size: the max number of bytes to pad.
	87	+ *
	88	+ * Call seq_setwidth() for setting max width, then call seq_printf() etc. and
	89	+ * finally call seq_pad() to pad the remaining bytes.
	90	+ */
	91	+static inline void seq_setwidth(struct seq_file *m, size_t size)
	92	+{
	93	+ m->pad_until = m->count + size;
	94	+}
	95	+void seq_pad(struct seq_file *m, char c);
81	96
82	97	char mangle_path(char s, const char p, const char esc);
83	98	int seq_open(struct file , const struct seq_operations );