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Message-Id: <E1MkZk0-00006N-So@pomaz-ex.szeredi.hu>
Date: Mon, 07 Sep 2009 10:38:24 +0200
From: Miklos Szeredi <miklos@...redi.hu>
To: akpm@...ux-foundation.org
CC: Valdis.Kletnieks@...edu, hugh.dickins@...cali.co.uk,
miklos@...redi.hu, akpm@...ux-foundation.org, matthew@....cx,
agruen@...e.de, viro@...iv.linux.org.uk, hch@....de,
linux-kernel@...r.kernel.org
Subject: [patch 1/2] vfs: seq_file: add helpers for data filling
From: Miklos Szeredi <mszeredi@...e.cz>
Add two helpers that allow access to the seq_file's own buffer, but
hides the internal details of seq_files.
This allows easier implementation of special purpose filling
functions. It also cleans up some existing functions which duplicated
the seq_file logic.
Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
---
fs/seq_file.c | 112 ++++++++++++++++++++++++++++++++---------------
include/linux/seq_file.h | 3 +
2 files changed, 80 insertions(+), 35 deletions(-)
Index: linux-2.6/fs/seq_file.c
===================================================================
--- linux-2.6.orig/fs/seq_file.c 2009-09-03 19:40:10.000000000 +0200
+++ linux-2.6/fs/seq_file.c 2009-09-04 14:58:04.000000000 +0200
@@ -419,6 +419,44 @@ char *mangle_path(char *s, char *p, char
EXPORT_SYMBOL(mangle_path);
/**
+ * seq_get_buf - get buffer to write arbitrary data to
+ * @m: the seq_file handle
+ * @bufp: the beginning of the buffer is stored here
+ *
+ * Return the number of bytes available in the buffer, or zero if
+ * there's no space.
+ */
+size_t seq_get_buf(struct seq_file *m, char **bufp)
+{
+ BUG_ON(m->count > m->size);
+ if (m->count < m->size)
+ *bufp = m->buf + m->count;
+ else
+ *bufp = NULL;
+
+ return m->size - m->count;
+}
+
+/**
+ * seq_commit - commit data to the buffer
+ * @m: the seq_file handle
+ * @num: the number of bytes to commit
+ *
+ * Commit @num bytes of data written to a buffer previously acquired
+ * by seq_buf_get. To signal an error condition, or that the data
+ * didn't fit in the available space, pass a negative @num value.
+ */
+void seq_commit(struct seq_file *m, int num)
+{
+ if (num < 0) {
+ m->count = m->size;
+ } else {
+ BUG_ON(m->count + num > m->size);
+ m->count += num;
+ }
+}
+
+/**
* seq_path - seq_file interface to print a pathname
* @m: the seq_file handle
* @path: the struct path to print
@@ -429,20 +467,21 @@ EXPORT_SYMBOL(mangle_path);
*/
int seq_path(struct seq_file *m, struct path *path, char *esc)
{
- if (m->count < m->size) {
- char *s = m->buf + m->count;
- char *p = d_path(path, s, m->size - m->count);
+ char *buf;
+ size_t size = seq_get_buf(m, &buf);
+ int res = -1;
+
+ if (size) {
+ char *p = d_path(path, buf, size);
if (!IS_ERR(p)) {
- s = mangle_path(s, p, esc);
- if (s) {
- p = m->buf + m->count;
- m->count = s - m->buf;
- return s - p;
- }
+ char *end = mangle_path(buf, p, esc);
+ if (end)
+ res = end - buf;
}
}
- m->count = m->size;
- return -1;
+ seq_commit(m, res);
+
+ return res;
}
EXPORT_SYMBOL(seq_path);
@@ -454,26 +493,28 @@ EXPORT_SYMBOL(seq_path);
int seq_path_root(struct seq_file *m, struct path *path, struct path *root,
char *esc)
{
- int err = -ENAMETOOLONG;
- if (m->count < m->size) {
- char *s = m->buf + m->count;
+ char *buf;
+ size_t size = seq_get_buf(m, &buf);
+ int res = -ENAMETOOLONG;
+
+ if (size) {
char *p;
spin_lock(&dcache_lock);
- p = __d_path(path, root, s, m->size - m->count);
+ p = __d_path(path, root, buf, size);
spin_unlock(&dcache_lock);
- err = PTR_ERR(p);
+ res = PTR_ERR(p);
if (!IS_ERR(p)) {
- s = mangle_path(s, p, esc);
- if (s) {
- p = m->buf + m->count;
- m->count = s - m->buf;
- return 0;
- }
+ char *end = mangle_path(buf, p, esc);
+ if (end)
+ res = end - buf;
+ else
+ res = -ENAMETOOLONG;
}
}
- m->count = m->size;
- return err;
+ seq_commit(m, res);
+
+ return res < 0 ? res : 0;
}
/*
@@ -481,20 +522,21 @@ int seq_path_root(struct seq_file *m, st
*/
int seq_dentry(struct seq_file *m, struct dentry *dentry, char *esc)
{
- if (m->count < m->size) {
- char *s = m->buf + m->count;
- char *p = dentry_path(dentry, s, m->size - m->count);
+ char *buf;
+ size_t size = seq_get_buf(m, &buf);
+ int res = -1;
+
+ if (size) {
+ char *p = dentry_path(dentry, buf, size);
if (!IS_ERR(p)) {
- s = mangle_path(s, p, esc);
- if (s) {
- p = m->buf + m->count;
- m->count = s - m->buf;
- return s - p;
- }
+ char *end = mangle_path(buf, p, esc);
+ if (end)
+ res = end - buf;
}
}
- m->count = m->size;
- return -1;
+ seq_commit(m, res);
+
+ return res;
}
int seq_bitmap(struct seq_file *m, const unsigned long *bits,
Index: linux-2.6/include/linux/seq_file.h
===================================================================
--- linux-2.6.orig/include/linux/seq_file.h 2009-09-04 13:17:03.000000000 +0200
+++ linux-2.6/include/linux/seq_file.h 2009-09-04 14:26:49.000000000 +0200
@@ -48,6 +48,9 @@ int seq_write(struct seq_file *seq, cons
int seq_printf(struct seq_file *, const char *, ...)
__attribute__ ((format (printf,2,3)));
+size_t seq_get_buf(struct seq_file *m, char **bufp);
+void seq_commit(struct seq_file *m, int num);
+
int seq_path(struct seq_file *, struct path *, char *);
int seq_dentry(struct seq_file *, struct dentry *, char *);
int seq_path_root(struct seq_file *m, struct path *path, struct path *root,
--
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