vfs - start making the VFS

kernel/src/lib/string.c

@@ -1,4 +1,5 @@
 #include <lib/string.h>
+#include <mm/liballoc/liballoc.h>
 #include <stddef.h>
 
 int strlen(const char *str) {
@@ -16,14 +17,14 @@ int strcmp(const char *s1, const char *s2) {
   return *s1 - *s2;
 }
 
-char *strcpy(char *dest, const char *src)
-{
-    if (dest == NULL || src == NULL)
-        return NULL;
-    
-    char *temp = dest;
-    while((*dest++ = *src++) != '\0'); 
-    return temp;
+char *strcpy(char *dest, const char *src) {
+  if (dest == NULL || src == NULL)
+    return NULL;
+
+  char *temp = dest;
+  while ((*dest++ = *src++) != '\0')
+    ;
+  return temp;
 }
 
 char *strchr(const char *s, int c) {
@@ -35,23 +36,36 @@ char *strchr(const char *s, int c) {
 }
 
 char *strrchr(const char *s, int c) {
-    const char *p = NULL;
+  const char *p = NULL;
 
-    for (;;) {
-        if (*s == (char)c)
-            p = s;
-        if (*s++ == '\0')
-            return (char *)p;
-    }
+  for (;;) {
+    if (*s == (char)c)
+      p = s;
+    if (*s++ == '\0')
+      return (char *)p;
+  }
 }
 
 int oct2bin(unsigned char *str, int size) {
-    int n = 0;
-    unsigned char *c = str;
-    while (size-- > 0) {
-        n *= 8;
-        n += *c - '0';
-        c++;
-    }
-    return n;
+  int n = 0;
+  unsigned char *c = str;
+  while (size-- > 0) {
+    n *= 8;
+    n += *c - '0';
+    c++;
+  }
+  return n;
+}
+
+char *strdup(const char *str) {
+  if (str == NULL)
+    return NULL;
+
+  int len = strlen(str);
+  char *dup = (char *)malloc(len + 1);
+  if (dup == NULL)
+    return NULL;
+
+  strcpy(dup, str);
+  return dup;
 }

kernel/src/lib/string.h

@@ -5,4 +5,5 @@ int strcmp(const char *s1, const char *s2);
 char *strchr(const char *s, int c);
 char *strcpy(char *dest, const char *src);
 char *strrchr(const char *s, int c);
-int oct2bin(unsigned char *str, int size);
+int oct2bin(unsigned char *str, int size);
+char *strdup(const char *str);