diff options
| -rw-r--r-- | Documentation/filesystems/sysfs.rst | 8 | ||||
| -rw-r--r-- | fs/sysfs/file.c | 55 | ||||
| -rw-r--r-- | include/linux/sysfs.h | 15 |
3 files changed, 73 insertions, 5 deletions
diff --git a/Documentation/filesystems/sysfs.rst b/Documentation/filesystems/sysfs.rst index ab0f7795792b..d44249050f4a 100644 --- a/Documentation/filesystems/sysfs.rst +++ b/Documentation/filesystems/sysfs.rst @@ -242,12 +242,10 @@ 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. diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index eb6897ab78e7..96d0da65e088 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -15,6 +15,7 @@ #include <linux/list.h> #include <linux/mutex.h> #include <linux/seq_file.h> +#include <linux/mm.h> #include "sysfs.h" @@ -707,3 +708,57 @@ int sysfs_change_owner(struct kobject *kobj, kuid_t kuid, kgid_t kgid) return 0; } EXPORT_SYMBOL_GPL(sysfs_change_owner); + +/** + * 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); diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index 34e84122f635..2caa34c1ca1a 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -329,6 +329,10 @@ int sysfs_groups_change_owner(struct kobject *kobj, int sysfs_group_change_owner(struct kobject *kobj, const struct attribute_group *groups, kuid_t kuid, kgid_t kgid); +__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 */ @@ -576,6 +580,17 @@ static inline int sysfs_group_change_owner(struct kobject *kobj, return 0; } +__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, |