From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/lib/string.c | 140 +++++++++++++++++++++++++++-------------------
1 files changed, 82 insertions(+), 58 deletions(-)
diff --git a/kernel/lib/string.c b/kernel/lib/string.c
index f7f7770..4288e01 100644
--- a/kernel/lib/string.c
+++ b/kernel/lib/string.c
@@ -27,6 +27,7 @@
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/errno.h>
+#include <linux/slab.h>
#include <asm/byteorder.h>
#include <asm/word-at-a-time.h>
@@ -172,8 +173,9 @@
* doesn't unnecessarily force the tail of the destination buffer to be
* zeroed. If zeroing is desired please use strscpy_pad().
*
- * Return: The number of characters copied (not including the trailing
- * %NUL) or -E2BIG if the destination buffer wasn't big enough.
+ * Returns:
+ * * The number of characters copied (not including the trailing %NUL)
+ * * -E2BIG if count is 0 or @src was truncated.
*/
ssize_t strscpy(char *dest, const char *src, size_t count)
{
@@ -181,7 +183,7 @@
size_t max = count;
long res = 0;
- if (count == 0)
+ if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
return -E2BIG;
#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
@@ -237,6 +239,40 @@
#endif
/**
+ * strscpy_pad() - Copy a C-string into a sized buffer
+ * @dest: Where to copy the string to
+ * @src: Where to copy the string from
+ * @count: 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, zeros
+ * the tail of the destination buffer.
+ *
+ * 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 %NUL)
+ * * -E2BIG if count is 0 or @src was truncated.
+ */
+ssize_t strscpy_pad(char *dest, const char *src, size_t count)
+{
+ ssize_t written;
+
+ written = strscpy(dest, src, count);
+ if (written < 0 || written == count - 1)
+ return written;
+
+ memset(dest + written + 1, 0, count - written - 1);
+
+ return written;
+}
+EXPORT_SYMBOL(strscpy_pad);
+
+/**
* stpcpy - copy a string from src to dest returning a pointer to the new end
* of dest, including src's %NUL-terminator. May overrun dest.
* @dest: pointer to end of string being copied into. Must be large enough
@@ -259,39 +295,6 @@
return --dest;
}
EXPORT_SYMBOL(stpcpy);
-
-/**
- * strscpy_pad() - Copy a C-string into a sized buffer
- * @dest: Where to copy the string to
- * @src: Where to copy the string from
- * @count: 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, zeros
- * the tail of the destination buffer.
- *
- * For full explanation of why you may want to consider using the
- * 'strscpy' functions please see the function docstring for strscpy().
- *
- * Return: The number of characters copied (not including the trailing
- * %NUL) or -E2BIG if the destination buffer wasn't big enough.
- */
-ssize_t strscpy_pad(char *dest, const char *src, size_t count)
-{
- ssize_t written;
-
- written = strscpy(dest, src, count);
- if (written < 0 || written == count - 1)
- return written;
-
- memset(dest + written + 1, 0, count - written - 1);
-
- return written;
-}
-EXPORT_SYMBOL(strscpy_pad);
#ifndef __HAVE_ARCH_STRCAT
/**
@@ -423,6 +426,9 @@
* strchr - Find the first occurrence of a character in a string
* @s: The string to be searched
* @c: The character to search for
+ *
+ * Note that the %NUL-terminator is considered part of the string, and can
+ * be searched for.
*/
char *strchr(const char *s, int c)
{
@@ -452,6 +458,23 @@
EXPORT_SYMBOL(strchrnul);
#endif
+/**
+ * strnchrnul - Find and return a character in a length limited string,
+ * or end of string
+ * @s: The string to be searched
+ * @count: The number of characters to be searched
+ * @c: The character to search for
+ *
+ * Returns pointer to the first occurrence of 'c' in s. If c is not found,
+ * then return a pointer to the last character of the string.
+ */
+char *strnchrnul(const char *s, size_t count, int c)
+{
+ while (count-- && *s && *s != (char)c)
+ s++;
+ return (char *)s;
+}
+
#ifndef __HAVE_ARCH_STRRCHR
/**
* strrchr - Find the last occurrence of a character in a string
@@ -476,12 +499,18 @@
* @s: The string to be searched
* @count: The number of characters to be searched
* @c: The character to search for
+ *
+ * Note that the %NUL-terminator is considered part of the string, and can
+ * be searched for.
*/
char *strnchr(const char *s, size_t count, int c)
{
- for (; count-- && *s != '\0'; ++s)
+ while (count--) {
if (*s == (char)c)
return (char *)s;
+ if (*s++ == '\0')
+ break;
+ }
return NULL;
}
EXPORT_SYMBOL(strnchr);
@@ -694,6 +723,14 @@
* @n: number of strings in the array or -1 for NULL terminated arrays
* @string: string to match with
*
+ * This routine will look for a string in an array of strings up to the
+ * n-th element in the array or until the first NULL element.
+ *
+ * Historically the value of -1 for @n, was used to search in arrays that
+ * are NULL terminated. However, the function does not make a distinction
+ * when finishing the search: either @n elements have been compared OR
+ * the first NULL element was found.
+ *
* Return:
* index of a @string in the @array if matches, or %-EINVAL otherwise.
*/
@@ -722,6 +759,14 @@
*
* Returns index of @str in the @array or -EINVAL, just like match_string().
* Uses sysfs_streq instead of strcmp for matching.
+ *
+ * This routine will look for a string in an array of strings up to the
+ * n-th element in the array or until the first NULL element.
+ *
+ * Historically the value of -1 for @n, was used to search in arrays that
+ * are NULL terminated. However, the function does not make a distinction
+ * when finishing the search: either @n elements have been compared OR
+ * the first NULL element was found.
*/
int __sysfs_match_string(const char * const *array, size_t n, const char *str)
{
@@ -759,27 +804,6 @@
}
EXPORT_SYMBOL(memset);
#endif
-
-/**
- * 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.
- */
-void memzero_explicit(void *s, size_t count)
-{
- memset(s, 0, count);
- barrier_data(s);
-}
-EXPORT_SYMBOL(memzero_explicit);
#ifndef __HAVE_ARCH_MEMSET16
/**
--
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