path: root/include/linux/string.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_STRING_H_
#define _LINUX_STRING_H_

#include <linux/args.h>
#include <linux/array_size.h>
#include <linux/compiler.h>	/* for inline */
#include <linux/types.h>	/* for size_t */
#include <linux/stddef.h>	/* for NULL */
#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) __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
 */
#include <asm/string.h>

#ifndef __HAVE_ARCH_STRCPY
extern char * strcpy(char *,const char *);
#endif
#ifndef __HAVE_ARCH_STRNCPY
extern char * strncpy(char *,const char *, __kernel_size_t);
#endif
ssize_t sized_strscpy(char *, const char *, size_t);

/*
 * 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 *);
#endif
#ifndef __HAVE_ARCH_STRNCAT
extern char * strncat(char *, const char *, __kernel_size_t);
#endif
#ifndef __HAVE_ARCH_STRLCAT
extern size_t strlcat(char *, const char *, __kernel_size_t);
#endif
#ifndef __HAVE_ARCH_STRCMP
extern int strcmp(const char *,const char *);
#endif
#ifndef __HAVE_ARCH_STRNCMP
extern int strncmp(const char *,const char *,__kernel_size_t);
#endif
#ifndef __HAVE_ARCH_STRCASECMP
extern int strcasecmp(const char *s1, const char *s2);
#endif
#ifndef __HAVE_ARCH_STRNCASECMP
extern int strncasecmp(const char *s1, const char *s2, size_t n);
#endif
#ifndef __HAVE_ARCH_STRCHR
extern char * strchr(const char *,int);
#endif
#ifndef __HAVE_ARCH_STRCHRNUL
extern char * strchrnul(const char *,int);
#endif
extern char * strnchrnul(const char *, size_t, int);
#ifndef __HAVE_ARCH_STRNCHR
extern char * strnchr(const char *, size_t, int);
#endif
#ifndef __HAVE_ARCH_STRRCHR
extern char * strrchr(const char *,int);
#endif
extern char * __must_check skip_spaces(const char *);

extern char *strim(char *);

static inline __must_check char *strstrip(char *str)
{
	return strim(str);
}

#ifndef __HAVE_ARCH_STRSTR
extern char * strstr(const char *, const char *);
#endif
#ifndef __HAVE_ARCH_STRNSTR
extern char * strnstr(const char *, const char *, size_t);
#endif
#ifndef __HAVE_ARCH_STRLEN
extern __kernel_size_t strlen(const char *);
#endif
#ifndef __HAVE_ARCH_STRNLEN
extern __kernel_size_t strnlen(const char *,__kernel_size_t);
#endif
#ifndef __HAVE_ARCH_STRPBRK
extern char * strpbrk(const char *,const char *);
#endif
#ifndef __HAVE_ARCH_STRSEP
extern char * strsep(char **,const char *);
#endif
#ifndef __HAVE_ARCH_STRSPN
extern __kernel_size_t strspn(const char *,const char *);
#endif
#ifndef __HAVE_ARCH_STRCSPN
extern __kernel_size_t strcspn(const char *,const char *);
#endif

#ifndef __HAVE_ARCH_MEMSET
extern void * memset(void *,int,__kernel_size_t);
#endif

#ifndef __HAVE_ARCH_MEMSET16
extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
#endif

#ifndef __HAVE_ARCH_MEMSET32
extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
#endif

#ifndef __HAVE_ARCH_MEMSET64
extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
#endif

static inline void *memset_l(unsigned long *p, unsigned long v,
		__kernel_size_t n)
{
	if (BITS_PER_LONG == 32)
		return memset32((uint32_t *)p, v, n);
	else
		return memset64((uint64_t *)p, v, n);
}

static inline void *memset_p(void **p, void *v, __kernel_size_t n)
{
	if (BITS_PER_LONG == 32)
		return memset32((uint32_t *)p, (uintptr_t)v, n);
	else
		return memset64((uint64_t *)p, (uintptr_t)v, n);
}

extern void **__memcat_p(void **a, void **b);
#define memcat_p(a, b) ({					\
	BUILD_BUG_ON_MSG(!__same_type(*(a), *(b)),		\
			 "type mismatch in memcat_p()");	\
	(typeof(*a) *)__memcat_p((void **)(a), (void **)(b));	\
})

#ifndef __HAVE_ARCH_MEMCPY
extern void * memcpy(void *,const void *,__kernel_size_t);
#endif
#ifndef __HAVE_ARCH_MEMMOVE
extern void * memmove(void *,const void *,__kernel_size_t);
#endif
#ifndef __HAVE_ARCH_MEMSCAN
extern void * memscan(void *,int,__kernel_size_t);
#endif
#ifndef __HAVE_ARCH_MEMCMP
extern int memcmp(const void *,const void *,__kernel_size_t);
#endif
#ifndef __HAVE_ARCH_BCMP
extern int bcmp(const void *,const void *,__kernel_size_t);
#endif
#ifndef __HAVE_ARCH_MEMCHR
extern void * memchr(const void *,int,__kernel_size_t);
#endif
#ifndef __HAVE_ARCH_MEMCPY_FLUSHCACHE
static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
{
	memcpy(dst, src, cnt);
}
#endif

void *memchr_inv(const void *s, int c, size_t n);
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_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);

/* 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);

/**
 * sysfs_match_string - matches given string in an array
 * @_a: array of strings
 * @_s: string to match with
 *
 * Helper for __sysfs_match_string(). Calculates the size of @a automatically.
 */
#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);
#endif

extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
				       const void *from, size_t available);

int ptr_to_hashval(const void *ptr, unsigned long *hashval_out);

/**
 * strstarts - does @str start with @prefix?
 * @str: string to examine
 * @prefix: prefix to look for.
 */
static inline bool strstarts(const char *str, const char *prefix)
{
	return strncmp(str, prefix, strlen(prefix)) == 0;
}

size_t memweight(const void *ptr, size_t bytes);

/**
 * memzero_explicit - Fill a region of memory (e.g. sensitive
 *		      keying data) with 0s.
 * @s: Pointer to the start of the area.
 * @count: The size of the area.
 *
 * Note: usually using memset() is just fine (!), but in cases
 * where clearing out _local_ data at the end of a scope is
 * necessary, memzero_explicit() should be used instead in
 * order to prevent the compiler from optimising away zeroing.
 *
 * memzero_explicit() doesn't need an arch-specific version as
 * it just invokes the one of memset() implicitly.
 */
static inline void memzero_explicit(void *s, size_t count)
{
	memset(s, 0, count);
	barrier_data(s);
}

/**
 * kbasename - return the last part of a pathname.
 *
 * @path: path to extract the filename from.
 */
static inline const char *kbasename(const char *path)
{
	const char *tail = strrchr(path, '/');
	return tail ? tail + 1 : path;
}

#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

void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count,
		    int pad);

/**
 * 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 = __builtin_object_size(dest, 1);	\
	const size_t _src_len = __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)

/**
 * 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 = __builtin_object_size(dest, 1);	\
	const size_t _src_len = __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)

/**
 * 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 = __builtin_object_size(dest, 1);	\
	const size_t _src_len = __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)

/**
 * 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 = __builtin_object_size(dest, 1);	\
	const size_t _src_len = __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)

/**
 * 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));	\
})

/**
 * 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.
 */
#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
 * @str: The string to test
 * @prefix: The string to see if @str starts with
 *
 * A common way to test a prefix of a string is to do:
 *  strncmp(str, prefix, sizeof(prefix) - 1)
 *
 * But this can lead to bugs due to typos, or if prefix is a pointer
 * and not a constant. Instead use str_has_prefix().
 *
 * Returns:
 * * strlen(@prefix) if @str starts with @prefix
 * * 0 if @str does not start with @prefix
 */
static __always_inline size_t str_has_prefix(const char *str, const char *prefix)
{
	size_t len = strlen(prefix);
	return strncmp(str, prefix, len) == 0 ? len : 0;
}

#endif /* _LINUX_STRING_H_ */