Commit e075f591 authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
Browse files

seq_file: add seq_set_overflow(), seq_overflow() 



It is undocumented but a seq_file's overflow state is indicated by
m->count == m->size.  Add seq_set_overflow() and seq_overflow() to
set/check overflow status explicitly.

Based on an idea from Eric Dumazet.

[akpm@linux-foundation.org: tweak code comment]
Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1b26c9b3

fs/seq_file.c

+26 −10
Original line number Diff line number Diff line
@@ -13,6 +13,22 @@ 
#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.

 */

static bool seq_overflow(struct seq_file *m)

{

	return m->count == m->size;

}



static void seq_set_overflow(struct seq_file *m)

{

	m->count = m->size;

}



/**

 *	seq_open -	initialize sequential file

 *	@file: file we initialize
@@ -92,7 +108,7 @@ static int traverse(struct seq_file *m, loff_t offset) 
			error = 0;

			m->count = 0;

		}

		if (m->count == m->size)

		if (seq_overflow(m))

			goto Eoverflow;

		if (pos + m->count > offset) {

			m->from = offset - pos;
@@ -234,7 +250,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) 
			break;

		}

		err = m->op->show(m, p);

		if (m->count == m->size || err) {

		if (seq_overflow(m) || err) {

			m->count = offs;

			if (likely(err <= 0))

				break;
@@ -361,7 +377,7 @@ int seq_escape(struct seq_file *m, const char *s, const char *esc) 
			*p++ = '0' + (c & 07);

			continue;

		}

		m->count = m->size;

		seq_set_overflow(m);

		return -1;

        }

	m->count = p - m->buf;
@@ -383,7 +399,7 @@ int seq_printf(struct seq_file *m, const char *f, ...) 
			return 0;

		}

	}

	m->count = m->size;

	seq_set_overflow(m);

	return -1;

}

EXPORT_SYMBOL(seq_printf);
@@ -512,7 +528,7 @@ int seq_bitmap(struct seq_file *m, const unsigned long *bits, 
			return 0;

		}

	}

	m->count = m->size;

	seq_set_overflow(m);

	return -1;

}

EXPORT_SYMBOL(seq_bitmap);
@@ -528,7 +544,7 @@ int seq_bitmap_list(struct seq_file *m, const unsigned long *bits, 
			return 0;

		}

	}

	m->count = m->size;

	seq_set_overflow(m);

	return -1;

}

EXPORT_SYMBOL(seq_bitmap_list);
@@ -639,7 +655,7 @@ int seq_puts(struct seq_file *m, const char *s) 
		m->count += len;

		return 0;

	}

	m->count = m->size;

	seq_set_overflow(m);

	return -1;

}

EXPORT_SYMBOL(seq_puts);
@@ -673,7 +689,7 @@ int seq_put_decimal_ull(struct seq_file *m, char delimiter, 
	m->count += len;

	return 0;

overflow:

	m->count = m->size;

	seq_set_overflow(m);

	return -1;

}

EXPORT_SYMBOL(seq_put_decimal_ull);
@@ -683,7 +699,7 @@ int seq_put_decimal_ll(struct seq_file *m, char delimiter, 
{

	if (num < 0) {

		if (m->count + 3 >= m->size) {

			m->count = m->size;

			seq_set_overflow(m);

			return -1;

		}

		if (delimiter)
@@ -711,7 +727,7 @@ int seq_write(struct seq_file *seq, const void *data, size_t len) 
		seq->count += len;

		return 0;

	}

	seq->count = seq->size;

	seq_set_overflow(seq);

	return -1;

}

EXPORT_SYMBOL(seq_write);