The return values of seq_printf/puts/putc are frequently misused.
Start down a path to remove all the return value uses of these
functions.
Make the static bool seq_overflow public along with a rename of
the function to seq_is_buf_full. Rename the still static
seq_set_overflow to seq_set_buf_full.
Update the documentation to not show return types for seq_printf
et al. Add a description of seq_is_buf_full.
Signed-off-by: Joe Perches <joe@xxxxxxxxxxx>
---
Documentation/filesystems/seq_file.txt | 28 ++++++++++++++++------------
fs/seq_file.c | 28 ++++++++++++++--------------
include/linux/seq_file.h | 8 ++++++++
3 files changed, 38 insertions(+), 26 deletions(-)
diff --git a/Documentation/filesystems/seq_file.txt b/Documentation/filesystems/seq_file.txt
index a1e2e0d..794dbde 100644
--- a/Documentation/filesystems/seq_file.txt
+++ b/Documentation/filesystems/seq_file.txt
@@ -171,27 +171,23 @@ output must be passed to the seq_file code. Some utility functions have
been defined which make this task easy.
Most code will simply use seq_printf(), which works pretty much like
-printk(), but which requires the seq_file pointer as an argument. It is
-common to ignore the return value from seq_printf(), but a function
-producing complicated output may want to check that value and quit if
-something non-zero is returned; an error return means that the seq_file
-buffer has been filled and further output will be discarded.
+printk(), but which requires the seq_file pointer as an argument.
For straight character output, the following functions may be used:
- int seq_putc(struct seq_file *m, char c);
- int seq_puts(struct seq_file *m, const char *s);
- int seq_escape(struct seq_file *m, const char *s, const char *esc);
+ seq_putc(struct seq_file *m, char c);
+ seq_puts(struct seq_file *m, const char *s);
+ seq_escape(struct seq_file *m, const char *s, const char *esc);
The first two output a single character and a string, just like one would
expect. seq_escape() is like seq_puts(), except that any character in s
which is in the string esc will be represented in octal form in the output.
-There is also a pair of functions for printing filenames:
+There are also a pair of functions for printing filenames:
- int seq_path(struct seq_file *m, struct path *path, char *esc);
- int seq_path_root(struct seq_file *m, struct path *path,
- struct path *root, char *esc)
+ seq_path(struct seq_file *m, struct path *path, char *esc);
+ seq_path_root(struct seq_file *m, struct path *path,
+ struct path *root, char *esc)
Here, path indicates the file of interest, and esc is a set of characters
which should be escaped in the output. A call to seq_path() will output
@@ -200,6 +196,14 @@ root is desired, it can be used with seq_path_root(). Note that, if it
turns out that path cannot be reached from root, the value of root will be
changed in seq_file_root() to a root which *does* work.
+A function producing complicated output may want to check
+ bool seq_is_buf_full(struct seq_file *m);
+and avoid further seq_<output> calls if true is returned.
+
+A true return from seq_is_buf_full means that the seq_file buffer is full
+and further output will be discarded. The seq_show function will attempt
+to allocate a larger buffer and retry printing.
+
Making it all work
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 1d641bb..2fda3a1 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -14,18 +14,18 @@
#include <asm/uaccess.h>
#include <asm/page.h>
-
/*
- * seq_files have a buffer which can may overflow. When this happens a larger
+ * seq_files have a buffer which 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)
+bool seq_is_buf_full(struct seq_file *m)
{
return m->count == m->size;
}
+EXPORT_SYMBOL(seq_is_buf_full);
-static void seq_set_overflow(struct seq_file *m)
+static void seq_set_buf_full(struct seq_file *m)
{
m->count = m->size;
}
@@ -112,7 +112,7 @@ static int traverse(struct seq_file *m, loff_t offset)
error = 0;
m->count = 0;
}
- if (seq_overflow(m))
+ if (seq_is_buf_full(m))
goto Eoverflow;
if (pos + m->count > offset) {
m->from = offset - pos;
@@ -255,7 +255,7 @@ Fill:
break;
}
err = m->op->show(m, p);
- if (seq_overflow(m) || err) {
+ if (seq_is_buf_full(m) || err) {
m->count = offs;
if (likely(err <= 0))
break;
@@ -384,7 +384,7 @@ int seq_escape(struct seq_file *m, const char *s, const char *esc)
*p++ = '0' + (c & 07);
continue;
}
- seq_set_overflow(m);
+ seq_set_buf_full(m);
return -1;
}
m->count = p - m->buf;
@@ -403,7 +403,7 @@ int seq_vprintf(struct seq_file *m, const char *f, va_list args)
return 0;
}
}
- seq_set_overflow(m);
+ seq_set_buf_full(m);
return -1;
}
EXPORT_SYMBOL(seq_vprintf);
@@ -545,7 +545,7 @@ int seq_bitmap(struct seq_file *m, const unsigned long *bits,
return 0;
}
}
- seq_set_overflow(m);
+ seq_set_buf_full(m);
return -1;
}
EXPORT_SYMBOL(seq_bitmap);
@@ -561,7 +561,7 @@ int seq_bitmap_list(struct seq_file *m, const unsigned long *bits,
return 0;
}
}
- seq_set_overflow(m);
+ seq_set_buf_full(m);
return -1;
}
EXPORT_SYMBOL(seq_bitmap_list);
@@ -690,7 +690,7 @@ int seq_puts(struct seq_file *m, const char *s)
m->count += len;
return 0;
}
- seq_set_overflow(m);
+ seq_set_buf_full(m);
return -1;
}
EXPORT_SYMBOL(seq_puts);
@@ -724,7 +724,7 @@ int seq_put_decimal_ull(struct seq_file *m, char delimiter,
m->count += len;
return 0;
overflow:
- seq_set_overflow(m);
+ seq_set_buf_full(m);
return -1;
}
EXPORT_SYMBOL(seq_put_decimal_ull);
@@ -734,7 +734,7 @@ int seq_put_decimal_ll(struct seq_file *m, char delimiter,
{
if (num < 0) {
if (m->count + 3 >= m->size) {
- seq_set_overflow(m);
+ seq_set_buf_full(m);
return -1;
}
if (delimiter)
@@ -762,7 +762,7 @@ int seq_write(struct seq_file *seq, const void *data, size_t len)
seq->count += len;
return 0;
}
- seq_set_overflow(seq);
+ seq_set_buf_full(seq);
return -1;
}
EXPORT_SYMBOL(seq_write);
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 52e0097..8a8f87f 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -43,6 +43,14 @@ struct seq_operations {
#define SEQ_SKIP 1
/**
+ * seq_is_buf_full - check if the buffer associated to seq_file is full
+ * @m: the seq_file handle
+ *
+ * Returns true if the buffer is full
+ */
+bool seq_is_buf_full(struct seq_file *m);
+
+/**
* seq_get_buf - get buffer to write arbitrary data to
* @m: the seq_file handle
* @bufp: the beginning of the buffer is stored here
--
1.8.1.2.459.gbcd45b4.dirty
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