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authorMiklos Szeredi <mszeredi@suse.cz>2009-09-21 14:48:36 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2009-09-24 07:47:35 -0400
commitf84398068d9c2babe41500504ef247ae07081857 (patch)
tree7306df97a7ee62f314f4db152fb2afceff156988
parentf9098980ffea9c749622ff8ddf3b6d5831902a46 (diff)
vfs: seq_file: add helpers for data filling
Add two helpers that allow access to the seq_file's own buffer, but hide 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. Make these inline functions in seq_file.h, as suggested by Al. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/seq_file.c75
-rw-r--r--include/linux/seq_file.h38
2 files changed, 77 insertions, 36 deletions
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 66efd0aa8fb3..eae7d9dbf3ff 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -429,20 +429,21 @@ 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);
@@ -454,27 +455,28 @@ 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;
- }
- err = -ENAMETOOLONG;
+ 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;
}
/*
@@ -482,20 +484,21 @@ int seq_path_root(struct seq_file *m, struct path *path, struct path *root,
*/
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,
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 0c6a86b79596..8366d8f12e53 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -35,6 +35,44 @@ struct seq_operations {
#define SEQ_SKIP 1
+/**
+ * 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.
+ */
+static inline 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.
+ */
+static inline 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;
+ }
+}
+
char *mangle_path(char *s, char *p, char *esc);
int seq_open(struct file *, const struct seq_operations *);
ssize_t seq_read(struct file *, char __user *, size_t, loff_t *);