@@ -211,12 +211,10 @@ Other notes:
is 4096.
- show() methods should return the number of bytes printed into the
- buffer. This is the return value of scnprintf().
+ buffer.
-- show() must not use snprintf() when formatting the value to be
- returned to user space. If you can guarantee that an overflow
- will never happen you can use sprintf() otherwise you must use
- scnprintf().
+- show() should only use sysfs_emit() or sysfs_emit_at() when formatting
+ the value to be returned to user space.
- store() should return the number of bytes used from the buffer. If the
entire buffer has been used, just return the count argument.
@@ -17,6 +17,7 @@
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/seq_file.h>
+#include <linux/mm.h>
#include "sysfs.h"
#include "../kernfs/kernfs-internal.h"
@@ -549,3 +550,57 @@ void sysfs_remove_bin_file(struct kobjec
kernfs_remove_by_name(kobj->sd, attr->attr.name);
}
EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);
+
+/**
+ * sysfs_emit - scnprintf equivalent, aware of PAGE_SIZE buffer.
+ * @buf: start of PAGE_SIZE buffer.
+ * @fmt: format
+ * @...: optional arguments to @format
+ *
+ *
+ * Returns number of characters written to @buf.
+ */
+int sysfs_emit(char *buf, const char *fmt, ...)
+{
+ va_list args;
+ int len;
+
+ if (WARN(!buf || offset_in_page(buf),
+ "invalid sysfs_emit: buf:%p\n", buf))
+ return 0;
+
+ va_start(args, fmt);
+ len = vscnprintf(buf, PAGE_SIZE, fmt, args);
+ va_end(args);
+
+ return len;
+}
+EXPORT_SYMBOL_GPL(sysfs_emit);
+
+/**
+ * sysfs_emit_at - scnprintf equivalent, aware of PAGE_SIZE buffer.
+ * @buf: start of PAGE_SIZE buffer.
+ * @at: offset in @buf to start write in bytes
+ * @at must be >= 0 && < PAGE_SIZE
+ * @fmt: format
+ * @...: optional arguments to @fmt
+ *
+ *
+ * Returns number of characters written starting at &@buf[@at].
+ */
+int sysfs_emit_at(char *buf, int at, const char *fmt, ...)
+{
+ va_list args;
+ int len;
+
+ if (WARN(!buf || offset_in_page(buf) || at < 0 || at >= PAGE_SIZE,
+ "invalid sysfs_emit_at: buf:%p at:%d\n", buf, at))
+ return 0;
+
+ va_start(args, fmt);
+ len = vscnprintf(buf + at, PAGE_SIZE - at, fmt, args);
+ va_end(args);
+
+ return len;
+}
+EXPORT_SYMBOL_GPL(sysfs_emit_at);
@@ -301,6 +301,11 @@ static inline void sysfs_enable_ns(struc
return kernfs_enable_ns(kn);
}
+__printf(2, 3)
+int sysfs_emit(char *buf, const char *fmt, ...);
+__printf(3, 4)
+int sysfs_emit_at(char *buf, int at, const char *fmt, ...);
+
#else /* CONFIG_SYSFS */
static inline int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
@@ -507,6 +512,17 @@ static inline void sysfs_enable_ns(struc
{
}
+__printf(2, 3)
+static inline int sysfs_emit(char *buf, const char *fmt, ...)
+{
+ return 0;
+}
+
+__printf(3, 4)
+static inline int sysfs_emit_at(char *buf, int at, const char *fmt, ...)
+{
+ return 0;
+}
#endif /* CONFIG_SYSFS */
static inline int __must_check sysfs_create_file(struct kobject *kobj,