diff options
Diffstat (limited to 'include/linux/string.h')
| -rw-r--r-- | include/linux/string.h | 569 |
1 files changed, 298 insertions, 271 deletions
diff --git a/include/linux/string.h b/include/linux/string.h index b1f3894a0a3e..01621ad0f598 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -2,18 +2,63 @@ #ifndef _LINUX_STRING_H_ #define _LINUX_STRING_H_ - +#include <linux/args.h> +#include <linux/array_size.h> +#include <linux/cleanup.h> /* for DEFINE_FREE() */ #include <linux/compiler.h> /* for inline */ #include <linux/types.h> /* for size_t */ #include <linux/stddef.h> /* for NULL */ -#include <stdarg.h> +#include <linux/err.h> /* for ERR_PTR() */ +#include <linux/errno.h> /* for E2BIG */ +#include <linux/overflow.h> /* for check_mul_overflow() */ +#include <linux/stdarg.h> #include <uapi/linux/string.h> extern char *strndup_user(const char __user *, long); -extern void *memdup_user(const void __user *, size_t); -extern void *vmemdup_user(const void __user *, size_t); +extern void *memdup_user(const void __user *, size_t) __realloc_size(2); +extern void *vmemdup_user(const void __user *, size_t) __realloc_size(2); extern void *memdup_user_nul(const void __user *, size_t); +/** + * memdup_array_user - duplicate array from user space + * @src: source address in user space + * @n: number of array members to copy + * @size: size of one array member + * + * Return: an ERR_PTR() on failure. Result is physically + * contiguous, to be freed by kfree(). + */ +static inline __realloc_size(2, 3) +void *memdup_array_user(const void __user *src, size_t n, size_t size) +{ + size_t nbytes; + + if (check_mul_overflow(n, size, &nbytes)) + return ERR_PTR(-EOVERFLOW); + + return memdup_user(src, nbytes); +} + +/** + * vmemdup_array_user - duplicate array from user space + * @src: source address in user space + * @n: number of array members to copy + * @size: size of one array member + * + * Return: an ERR_PTR() on failure. Result may be not + * physically contiguous. Use kvfree() to free. + */ +static inline __realloc_size(2, 3) +void *vmemdup_array_user(const void __user *src, size_t n, size_t size) +{ + size_t nbytes; + + if (check_mul_overflow(n, size, &nbytes)) + return ERR_PTR(-EOVERFLOW); + + return vmemdup_user(src, nbytes); +} + /* * Include machine specific inline routines */ @@ -25,15 +70,83 @@ extern char * strcpy(char *,const char *); #ifndef __HAVE_ARCH_STRNCPY extern char * strncpy(char *,const char *, __kernel_size_t); #endif -#ifndef __HAVE_ARCH_STRLCPY -size_t strlcpy(char *, const char *, size_t); -#endif -#ifndef __HAVE_ARCH_STRSCPY -ssize_t strscpy(char *, const char *, size_t); -#endif +ssize_t sized_strscpy(char *, const char *, size_t); -/* Wraps calls to strscpy()/memset(), no arch specific code required */ -ssize_t strscpy_pad(char *dest, const char *src, size_t count); +/* + * The 2 argument style can only be used when dst is an array with a + * known size. + */ +#define __strscpy0(dst, src, ...) \ + sized_strscpy(dst, src, sizeof(dst) + __must_be_array(dst) + \ + __must_be_cstr(dst) + __must_be_cstr(src)) +#define __strscpy1(dst, src, size) \ + sized_strscpy(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src)) + +#define __strscpy_pad0(dst, src, ...) \ + sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) + \ + __must_be_cstr(dst) + __must_be_cstr(src)) +#define __strscpy_pad1(dst, src, size) \ + sized_strscpy_pad(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src)) + +/** + * strscpy - Copy a C-string into a sized buffer + * @dst: Where to copy the string to + * @src: Where to copy the string from + * @...: Size of destination buffer (optional) + * + * Copy the source string @src, or as much of it as fits, into the + * destination @dst buffer. The behavior is undefined if the string + * buffers overlap. The destination @dst buffer is always NUL terminated, + * unless it's zero-sized. + * + * The size argument @... is only required when @dst is not an array, or + * when the copy needs to be smaller than sizeof(@dst). + * + * Preferred to strncpy() since it always returns a valid string, and + * doesn't unnecessarily force the tail of the destination buffer to be + * zero padded. If padding is desired please use strscpy_pad(). + * + * Returns the number of characters copied in @dst (not including the + * trailing %NUL) or -E2BIG if @size is 0 or the copy from @src was + * truncated. + */ +#define strscpy(dst, src, ...) \ + CONCATENATE(__strscpy, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__) + +#define sized_strscpy_pad(dest, src, count) ({ \ + char *__dst = (dest); \ + const char *__src = (src); \ + const size_t __count = (count); \ + ssize_t __wrote; \ + \ + __wrote = sized_strscpy(__dst, __src, __count); \ + if (__wrote >= 0 && __wrote < __count) \ + memset(__dst + __wrote + 1, 0, __count - __wrote - 1); \ + __wrote; \ +}) + +/** + * strscpy_pad() - Copy a C-string into a sized buffer + * @dst: Where to copy the string to + * @src: Where to copy the string from + * @...: Size of destination buffer + * + * Copy the string, or as much of it as fits, into the dest buffer. The + * behavior is undefined if the string buffers overlap. The destination + * buffer is always %NUL terminated, unless it's zero-sized. + * + * If the source string is shorter than the destination buffer, the + * remaining bytes in the buffer will be filled with %NUL bytes. + * + * For full explanation of why you may want to consider using the + * 'strscpy' functions please see the function docstring for strscpy(). + * + * Returns: + * * The number of characters copied (not including the trailing %NULs) + * * -E2BIG if count is 0 or @src was truncated. + */ +#define strscpy_pad(dst, src, ...) \ + CONCATENATE(__strscpy_pad, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__) #ifndef __HAVE_ARCH_STRCAT extern char * strcat(char *, const char *); @@ -169,26 +282,47 @@ static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt) #endif void *memchr_inv(const void *s, int c, size_t n); -char *strreplace(char *s, char old, char new); +char *strreplace(char *str, char old, char new); + +/** + * mem_is_zero - Check if an area of memory is all 0's. + * @s: The memory area + * @n: The size of the area + * + * Return: True if the area of memory is all 0's. + */ +static inline bool mem_is_zero(const void *s, size_t n) +{ + return !memchr_inv(s, 0, n); +} extern void kfree_const(const void *x); extern char *kstrdup(const char *s, gfp_t gfp) __malloc; extern const char *kstrdup_const(const char *s, gfp_t gfp); extern char *kstrndup(const char *s, size_t len, gfp_t gfp); -extern void *kmemdup(const void *src, size_t len, gfp_t gfp); +extern void *kmemdup_noprof(const void *src, size_t len, gfp_t gfp) __realloc_size(2); +#define kmemdup(...) alloc_hooks(kmemdup_noprof(__VA_ARGS__)) + +extern void *kvmemdup(const void *src, size_t len, gfp_t gfp) __realloc_size(2); extern char *kmemdup_nul(const char *s, size_t len, gfp_t gfp); +extern void *kmemdup_array(const void *src, size_t count, size_t element_size, gfp_t gfp) + __realloc_size(2, 3); +/* lib/argv_split.c */ extern char **argv_split(gfp_t gfp, const char *str, int *argcp); extern void argv_free(char **argv); -extern bool sysfs_streq(const char *s1, const char *s2); -extern int kstrtobool(const char *s, bool *res); -static inline int strtobool(const char *s, bool *res) -{ - return kstrtobool(s, res); -} +DEFINE_FREE(argv_free, char **, if (!IS_ERR_OR_NULL(_T)) argv_free(_T)) + +/* lib/cmdline.c */ +extern int get_option(char **str, int *pint); +extern char *get_options(const char *str, int nints, int *ints); +extern unsigned long long memparse(const char *ptr, char **retptr); +extern bool parse_option_str(const char *str, const char *option); +extern char *next_arg(char *args, char **param, char **val); +extern bool sysfs_streq(const char *s1, const char *s2); int match_string(const char * const *array, size_t n, const char *string); int __sysfs_match_string(const char * const *array, size_t n, const char *s); @@ -202,9 +336,8 @@ int __sysfs_match_string(const char * const *array, size_t n, const char *s); #define sysfs_match_string(_a, _s) __sysfs_match_string(_a, ARRAY_SIZE(_a), _s) #ifdef CONFIG_BINARY_PRINTF -int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args); -int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf); -int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4); +__printf(3, 0) int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args); +__printf(3, 0) int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf); #endif extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, @@ -255,264 +388,158 @@ static inline const char *kbasename(const char *path) return tail ? tail + 1 : path; } -#define __FORTIFY_INLINE extern __always_inline __attribute__((gnu_inline)) -#define __RENAME(x) __asm__(#x) - -void fortify_panic(const char *name) __noreturn __cold; -void __read_overflow(void) __compiletime_error("detected read beyond size of object passed as 1st parameter"); -void __read_overflow2(void) __compiletime_error("detected read beyond size of object passed as 2nd parameter"); -void __read_overflow3(void) __compiletime_error("detected read beyond size of object passed as 3rd parameter"); -void __write_overflow(void) __compiletime_error("detected write beyond size of object passed as 1st parameter"); - #if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE) +#include <linux/fortify-string.h> +#endif +#ifndef unsafe_memcpy +#define unsafe_memcpy(dst, src, bytes, justification) \ + memcpy(dst, src, bytes) +#endif -#ifdef CONFIG_KASAN -extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr); -extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp); -extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy); -extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove); -extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset); -extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat); -extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy); -extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen); -extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat); -extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy); -#else -#define __underlying_memchr __builtin_memchr -#define __underlying_memcmp __builtin_memcmp -#define __underlying_memcpy __builtin_memcpy -#define __underlying_memmove __builtin_memmove -#define __underlying_memset __builtin_memset -#define __underlying_strcat __builtin_strcat -#define __underlying_strcpy __builtin_strcpy -#define __underlying_strlen __builtin_strlen -#define __underlying_strncat __builtin_strncat -#define __underlying_strncpy __builtin_strncpy -#endif - -__FORTIFY_INLINE char *strncpy(char *p, const char *q, __kernel_size_t size) -{ - size_t p_size = __builtin_object_size(p, 0); - if (__builtin_constant_p(size) && p_size < size) - __write_overflow(); - if (p_size < size) - fortify_panic(__func__); - return __underlying_strncpy(p, q, size); -} - -__FORTIFY_INLINE char *strcat(char *p, const char *q) -{ - size_t p_size = __builtin_object_size(p, 0); - if (p_size == (size_t)-1) - return __underlying_strcat(p, q); - if (strlcat(p, q, p_size) >= p_size) - fortify_panic(__func__); - return p; -} - -__FORTIFY_INLINE __kernel_size_t strlen(const char *p) -{ - __kernel_size_t ret; - size_t p_size = __builtin_object_size(p, 0); - - /* Work around gcc excess stack consumption issue */ - if (p_size == (size_t)-1 || - (__builtin_constant_p(p[p_size - 1]) && p[p_size - 1] == '\0')) - return __underlying_strlen(p); - ret = strnlen(p, p_size); - if (p_size <= ret) - fortify_panic(__func__); - return ret; -} - -extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen); -__FORTIFY_INLINE __kernel_size_t strnlen(const char *p, __kernel_size_t maxlen) -{ - size_t p_size = __builtin_object_size(p, 0); - __kernel_size_t ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size); - if (p_size <= ret && maxlen != ret) - fortify_panic(__func__); - return ret; -} - -/* defined after fortified strlen to reuse it */ -extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy); -__FORTIFY_INLINE size_t strlcpy(char *p, const char *q, size_t size) -{ - size_t ret; - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); - if (p_size == (size_t)-1 && q_size == (size_t)-1) - return __real_strlcpy(p, q, size); - ret = strlen(q); - if (size) { - size_t len = (ret >= size) ? size - 1 : ret; - if (__builtin_constant_p(len) && len >= p_size) - __write_overflow(); - if (len >= p_size) - fortify_panic(__func__); - __underlying_memcpy(p, q, len); - p[len] = '\0'; - } - return ret; -} - -/* defined after fortified strlen and strnlen to reuse them */ -__FORTIFY_INLINE char *strncat(char *p, const char *q, __kernel_size_t count) -{ - size_t p_len, copy_len; - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); - if (p_size == (size_t)-1 && q_size == (size_t)-1) - return __underlying_strncat(p, q, count); - p_len = strlen(p); - copy_len = strnlen(q, count); - if (p_size < p_len + copy_len + 1) - fortify_panic(__func__); - __underlying_memcpy(p + p_len, q, copy_len); - p[p_len + copy_len] = '\0'; - return p; -} - -__FORTIFY_INLINE void *memset(void *p, int c, __kernel_size_t size) -{ - size_t p_size = __builtin_object_size(p, 0); - if (__builtin_constant_p(size) && p_size < size) - __write_overflow(); - if (p_size < size) - fortify_panic(__func__); - return __underlying_memset(p, c, size); -} - -__FORTIFY_INLINE void *memcpy(void *p, const void *q, __kernel_size_t size) -{ - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); - if (__builtin_constant_p(size)) { - if (p_size < size) - __write_overflow(); - if (q_size < size) - __read_overflow2(); - } - if (p_size < size || q_size < size) - fortify_panic(__func__); - return __underlying_memcpy(p, q, size); -} - -__FORTIFY_INLINE void *memmove(void *p, const void *q, __kernel_size_t size) -{ - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); - if (__builtin_constant_p(size)) { - if (p_size < size) - __write_overflow(); - if (q_size < size) - __read_overflow2(); - } - if (p_size < size || q_size < size) - fortify_panic(__func__); - return __underlying_memmove(p, q, size); -} - -extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan); -__FORTIFY_INLINE void *memscan(void *p, int c, __kernel_size_t size) -{ - size_t p_size = __builtin_object_size(p, 0); - if (__builtin_constant_p(size) && p_size < size) - __read_overflow(); - if (p_size < size) - fortify_panic(__func__); - return __real_memscan(p, c, size); -} - -__FORTIFY_INLINE int memcmp(const void *p, const void *q, __kernel_size_t size) -{ - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); - if (__builtin_constant_p(size)) { - if (p_size < size) - __read_overflow(); - if (q_size < size) - __read_overflow2(); - } - if (p_size < size || q_size < size) - fortify_panic(__func__); - return __underlying_memcmp(p, q, size); -} +void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count, + int pad); -__FORTIFY_INLINE void *memchr(const void *p, int c, __kernel_size_t size) -{ - size_t p_size = __builtin_object_size(p, 0); - if (__builtin_constant_p(size) && p_size < size) - __read_overflow(); - if (p_size < size) - fortify_panic(__func__); - return __underlying_memchr(p, c, size); -} +/** + * strtomem_pad - Copy NUL-terminated string to non-NUL-terminated buffer + * + * @dest: Pointer of destination character array (marked as __nonstring) + * @src: Pointer to NUL-terminated string + * @pad: Padding character to fill any remaining bytes of @dest after copy + * + * This is a replacement for strncpy() uses where the destination is not + * a NUL-terminated string, but with bounds checking on the source size, and + * an explicit padding character. If padding is not required, use strtomem(). + * + * Note that the size of @dest is not an argument, as the length of @dest + * must be discoverable by the compiler. + */ +#define strtomem_pad(dest, src, pad) do { \ + const size_t _dest_len = __must_be_byte_array(dest) + \ + __must_be_noncstr(dest) + \ + ARRAY_SIZE(dest); \ + const size_t _src_len = __must_be_cstr(src) + \ + __builtin_object_size(src, 1); \ + \ + BUILD_BUG_ON(!__builtin_constant_p(_dest_len) || \ + _dest_len == (size_t)-1); \ + memcpy_and_pad(dest, _dest_len, src, \ + strnlen(src, min(_src_len, _dest_len)), pad); \ +} while (0) -void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv); -__FORTIFY_INLINE void *memchr_inv(const void *p, int c, size_t size) -{ - size_t p_size = __builtin_object_size(p, 0); - if (__builtin_constant_p(size) && p_size < size) - __read_overflow(); - if (p_size < size) - fortify_panic(__func__); - return __real_memchr_inv(p, c, size); -} +/** + * strtomem - Copy NUL-terminated string to non-NUL-terminated buffer + * + * @dest: Pointer of destination character array (marked as __nonstring) + * @src: Pointer to NUL-terminated string + * + * This is a replacement for strncpy() uses where the destination is not + * a NUL-terminated string, but with bounds checking on the source size, and + * without trailing padding. If padding is required, use strtomem_pad(). + * + * Note that the size of @dest is not an argument, as the length of @dest + * must be discoverable by the compiler. + */ +#define strtomem(dest, src) do { \ + const size_t _dest_len = __must_be_byte_array(dest) + \ + __must_be_noncstr(dest) + \ + ARRAY_SIZE(dest); \ + const size_t _src_len = __must_be_cstr(src) + \ + __builtin_object_size(src, 1); \ + \ + BUILD_BUG_ON(!__builtin_constant_p(_dest_len) || \ + _dest_len == (size_t)-1); \ + memcpy(dest, src, strnlen(src, min(_src_len, _dest_len))); \ +} while (0) -extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup); -__FORTIFY_INLINE void *kmemdup(const void *p, size_t size, gfp_t gfp) -{ - size_t p_size = __builtin_object_size(p, 0); - if (__builtin_constant_p(size) && p_size < size) - __read_overflow(); - if (p_size < size) - fortify_panic(__func__); - return __real_kmemdup(p, size, gfp); -} +/** + * memtostr - Copy a possibly non-NUL-term string to a NUL-term string + * @dest: Pointer to destination NUL-terminates string + * @src: Pointer to character array (likely marked as __nonstring) + * + * This is a replacement for strncpy() uses where the source is not + * a NUL-terminated string. + * + * Note that sizes of @dest and @src must be known at compile-time. + */ +#define memtostr(dest, src) do { \ + const size_t _dest_len = __must_be_byte_array(dest) + \ + __must_be_cstr(dest) + \ + ARRAY_SIZE(dest); \ + const size_t _src_len = __must_be_noncstr(src) + \ + __builtin_object_size(src, 1); \ + const size_t _src_chars = strnlen(src, _src_len); \ + const size_t _copy_len = min(_dest_len - 1, _src_chars); \ + \ + BUILD_BUG_ON(!__builtin_constant_p(_dest_len) || \ + !__builtin_constant_p(_src_len) || \ + _dest_len == 0 || _dest_len == (size_t)-1 || \ + _src_len == 0 || _src_len == (size_t)-1); \ + memcpy(dest, src, _copy_len); \ + dest[_copy_len] = '\0'; \ +} while (0) -/* defined after fortified strlen and memcpy to reuse them */ -__FORTIFY_INLINE char *strcpy(char *p, const char *q) -{ - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); - if (p_size == (size_t)-1 && q_size == (size_t)-1) - return __underlying_strcpy(p, q); - memcpy(p, q, strlen(q) + 1); - return p; -} +/** + * memtostr_pad - Copy a possibly non-NUL-term string to a NUL-term string + * with NUL padding in the destination + * @dest: Pointer to destination NUL-terminates string + * @src: Pointer to character array (likely marked as __nonstring) + * + * This is a replacement for strncpy() uses where the source is not + * a NUL-terminated string. + * + * Note that sizes of @dest and @src must be known at compile-time. + */ +#define memtostr_pad(dest, src) do { \ + const size_t _dest_len = __must_be_byte_array(dest) + \ + __must_be_cstr(dest) + \ + ARRAY_SIZE(dest); \ + const size_t _src_len = __must_be_noncstr(src) + \ + __builtin_object_size(src, 1); \ + const size_t _src_chars = strnlen(src, _src_len); \ + const size_t _copy_len = min(_dest_len - 1, _src_chars); \ + \ + BUILD_BUG_ON(!__builtin_constant_p(_dest_len) || \ + !__builtin_constant_p(_src_len) || \ + _dest_len == 0 || _dest_len == (size_t)-1 || \ + _src_len == 0 || _src_len == (size_t)-1); \ + memcpy(dest, src, _copy_len); \ + memset(&dest[_copy_len], 0, _dest_len - _copy_len); \ +} while (0) -/* Don't use these outside the FORITFY_SOURCE implementation */ -#undef __underlying_memchr -#undef __underlying_memcmp -#undef __underlying_memcpy -#undef __underlying_memmove -#undef __underlying_memset -#undef __underlying_strcat -#undef __underlying_strcpy -#undef __underlying_strlen -#undef __underlying_strncat -#undef __underlying_strncpy -#endif +/** + * memset_after - Set a value after a struct member to the end of a struct + * + * @obj: Address of target struct instance + * @v: Byte value to repeatedly write + * @member: after which struct member to start writing bytes + * + * This is good for clearing padding following the given member. + */ +#define memset_after(obj, v, member) \ +({ \ + u8 *__ptr = (u8 *)(obj); \ + typeof(v) __val = (v); \ + memset(__ptr + offsetofend(typeof(*(obj)), member), __val, \ + sizeof(*(obj)) - offsetofend(typeof(*(obj)), member)); \ +}) /** - * memcpy_and_pad - Copy one buffer to another with padding - * @dest: Where to copy to - * @dest_len: The destination buffer size - * @src: Where to copy from - * @count: The number of bytes to copy - * @pad: Character to use for padding if space is left in destination. + * memset_startat - Set a value starting at a member to the end of a struct + * + * @obj: Address of target struct instance + * @v: Byte value to repeatedly write + * @member: struct member to start writing at + * + * Note that if there is padding between the prior member and the target + * member, memset_after() should be used to clear the prior padding. */ -static inline void memcpy_and_pad(void *dest, size_t dest_len, - const void *src, size_t count, int pad) -{ - if (dest_len > count) { - memcpy(dest, src, count); - memset(dest + count, pad, dest_len - count); - } else - memcpy(dest, src, dest_len); -} +#define memset_startat(obj, v, member) \ +({ \ + u8 *__ptr = (u8 *)(obj); \ + typeof(v) __val = (v); \ + memset(__ptr + offsetof(typeof(*(obj)), member), __val, \ + sizeof(*(obj)) - offsetof(typeof(*(obj)), member)); \ +}) /** * str_has_prefix - Test if a string has a given prefix |