new: string.h

kernel/common/string.c

@@ -0,0 +1,109 @@
+#include "string.h"
+#include "glib.h"
+
+/**
+ * @brief 拷贝整个字符串
+ *
+ * @param dst 目标地址
+ * @param src 源地址
+ * @return char* 目标字符串
+ */
+char *strcpy(char *dst, const char *src)
+{
+    while (*src)
+    {
+        *(dst++) = *(src++);
+    }
+    *dst = 0;
+
+    return dst;
+}
+
+long strnlen(const char *src, unsigned long maxlen)
+{
+
+    if (src == NULL)
+        return 0;
+    register int __res = 0;
+    while (src[__res] != '\0' && __res < maxlen)
+    {
+        ++__res;
+    }
+    return __res;
+}
+
+/*
+        比较字符串 FirstPart and SecondPart
+        FirstPart = SecondPart =>  0
+        FirstPart > SecondPart =>  1
+        FirstPart < SecondPart => -1
+*/
+
+int strcmp(char *FirstPart, char *SecondPart)
+{
+    register int __res;
+    __asm__ __volatile__("cld	\n\t"
+                         "1:	\n\t"
+                         "lodsb	\n\t"
+                         "scasb	\n\t"
+                         "jne	2f	\n\t"
+                         "testb	%%al,	%%al	\n\t"
+                         "jne	1b	\n\t"
+                         "xorl	%%eax,	%%eax	\n\t"
+                         "jmp	3f	\n\t"
+                         "2:	\n\t"
+                         "movl	$1,	%%eax	\n\t"
+                         "jl	3f	\n\t"
+                         "negl	%%eax	\n\t"
+                         "3:	\n\t"
+                         : "=a"(__res)
+                         : "D"(FirstPart), "S"(SecondPart)
+                         :);
+    return __res;
+}
+
+char *strncpy(char *dst, const char *src, long count)
+{
+    __asm__ __volatile__("cld	\n\t"
+                         "1:	\n\t"
+                         "decq	%2	\n\t"
+                         "js	2f	\n\t"
+                         "lodsb	\n\t"
+                         "stosb	\n\t"
+                         "testb	%%al,	%%al	\n\t"
+                         "jne	1b	\n\t"
+                         "rep	\n\t"
+                         "stosb	\n\t"
+                         "2:	\n\t"
+                         :
+                         : "S"(src), "D"(dst), "c"(count)
+                         : "ax", "memory");
+    return dst;
+}
+
+long strncpy_from_user(char *dst, const char *src, unsigned long size)
+{
+    if (!verify_area((uint64_t)src, size))
+        return 0;
+
+    strncpy(dst, src, size);
+    return size;
+}
+
+/**
+ * @brief 测量来自用户空间的字符串的长度，会检验地址空间是否属于用户空间
+ * @param src
+ * @param maxlen
+ * @return long
+ */
+long strnlen_user(const char *src, unsigned long maxlen)
+{
+
+    unsigned long size = strlen(src);
+    // 地址不合法
+    if (!verify_area((uint64_t)src, size))
+        return 0;
+
+    return size <= maxlen ? size : maxlen;
+}
+