linux-kernel - [PATCH -next 1/3] seq: Add a seq

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Date:	Tue, 10 Dec 2013 21:12:42 -0800
From:	Joe Perches <joe@...ches.com>
To:	Alexander Viro <viro@...iv.linux.org.uk>
Cc:	Kees Cook <keescook@...omium.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH -next 1/3] seq: Add a seq_overflow test.

seq_printf and seq_puts returns are often misused.

Instead of checking the seq_printf or seq_puts return,
add a new seq_overflow function to test if a seq_file has
overflowed the available buffer space.

This will eventually allow seq_printf and seq_puts to be
converted to have a void return instead of the int return
that is often assumed to have a size_t value instead of an
error/no-error value.

Signed-off-by: Joe Perches <joe@...ches.com>
---
 fs/seq_file.c            | 15 ++++++++-------
 include/linux/seq_file.h |  2 ++
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 1d641bb..aab0736 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -14,16 +14,17 @@
 #include <asm/uaccess.h>
 #include <asm/page.h>
 
-
-/*
- * seq_files have a buffer which can may overflow. When this happens a larger
- * buffer is reallocated and all the data will be printed again.
- * The overflow state is true when m->count == m->size.
+/**
+ * seq_overflow - test if a seq_file has overflowed the space available
+ * @m: the seq_file handle
+ *
+ * Returns -1 when an overflow has occurred, 0 otherwise.
  */
-static bool seq_overflow(struct seq_file *m)
+int seq_overflow(struct seq_file *m)
 {
-	return m->count == m->size;
+	return m->count == m->size ? -1 : 0;
 }
+EXPORT_SYMBOL(seq_overflow);
 
 static void seq_set_overflow(struct seq_file *m)
 {
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 52e0097..f8f9dc0 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -107,6 +107,8 @@ int seq_write(struct seq_file *seq, const void *data, size_t len);
 __printf(2, 3) int seq_printf(struct seq_file *, const char *, ...);
 __printf(2, 0) int seq_vprintf(struct seq_file *, const char *, va_list args);
 
+int seq_overflow(struct seq_file *m);
+
 int seq_path(struct seq_file *, const struct path *, const char *);
 int seq_dentry(struct seq_file *, struct dentry *, const char *);
 int seq_path_root(struct seq_file *m, const struct path *path,
-- 
1.8.1.2.459.gbcd45b4.dirty

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