Update zend_string.h

Author: LamentXU123

Zend/zend_string.h

@@ -318,39 +318,29 @@ static zend_always_inline zend_string *zend_string_safe_realloc(zend_string *s,
 }
 
 static zend_always_inline char *zend_cstr_append_char(const char *str, size_t len, char c) {
-    char *res = (char *)safe_emalloc(len, 1, 2);
-    if (len > 0) {
-        zend_mempcpy(res, str, len);
-    }
-    res[len] = c;
-    res[len + 1] = '\0';
+    char *res = (char *)safe_emalloc(len + 2, 1, 0);
+    char *p = zend_mempcpy(res, str, len);
+    *p++ = c;
+    *p = '\0';
     return res;
 }
 
 static zend_always_inline char *zend_cstr_concat(const char *s1, size_t len1, const char *s2, size_t len2) {
-    char *res = (char *)safe_emalloc(len1, 1, len2 + 1);
-    if (len1 > 0) {
-        zend_mempcpy(res, s1, len1);
-    }
-    if (len2 > 0) {
-        zend_mempcpy(res + len1, s2, len2);
-    }
-    res[len1 + len2] = '\0';
+    char *res = (char *)safe_emalloc(len1 + len2 + 1, 1, 0);
+    char *p = res;
+    p = zend_mempcpy(p, s1, len1);
+    p = zend_mempcpy(p, s2, len2);
+    *p = '\0';
     return res;
 }
 
 static zend_always_inline char *zend_cstr_concat3(const char *s1, size_t len1, const char *s2, size_t len2, const char *s3, size_t len3) {
-    char *res = (char *)safe_emalloc(len1, 1, len2 + len3 + 1);
-    if (len1 > 0) {
-        zend_mempcpy(res, s1, len1);
-    }
-    if (len2 > 0) {
-        zend_mempcpy(res + len1, s2, len2);
-    }
-    if (len3 > 0) {
-        zend_mempcpy(res + len1 + len2, s3, len3);
-    }
-    res[len1 + len2 + len3] = '\0';
+    char *res = (char *)safe_emalloc(len1 + len2 + len3 + 1, 1, 0);
+    char *p = res;
+    p = zend_mempcpy(p, s1, len1);
+    p = zend_mempcpy(p, s2, len2);
+    p = zend_mempcpy(p, s3, len3);
+    *p = '\0';
     return res;
 }