Readd endianness check in x86 byteswap routine

caseif · Apr 18, 2024 · d221bc6 · d221bc6
1 parent 10f1ec9
commit d221bc6
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Showing 2 changed files with 22 additions and 15 deletions.
diff --git a/src/unpack/load.c b/src/unpack/load.c
@@ -72,7 +72,7 @@ static int _parse_package_header(arp_package_meta_t *meta, const unsigned char h
     }
 
     uint16_t major_version;
-    _copy_str_to_field(&major_version, header_data, PACKAGE_VERSION_LEN, PACKAGE_VERSION_OFF);
+    _copy_int_to_field(&major_version, header_data, PACKAGE_VERSION_LEN, PACKAGE_VERSION_OFF);
 
     if (major_version != 1) {
         arp_set_error("Package version is not supported");

diff --git a/src/util/common.c b/src/util/common.c
@@ -33,6 +33,12 @@
 void copy_int_as_le(void *dst, void *src, size_t len) {
     memcpy(dst, src, len);
 
+    int x = 1;
+    if (((unsigned char*) &x)[0] == 1) {
+        // system is little-endian, so no need to do any conversion
+        return;
+    }
+
     #ifdef _WIN32
     if (len == 2) {
         *((uint16_t*) dst) = _byteswap_ushort(*((uint16_t*) dst));
@@ -44,7 +50,6 @@ void copy_int_as_le(void *dst, void *src, size_t len) {
     #else
     if (len == 2) {
         *((uint16_t*) dst) = __builtin_bswap16(*((uint16_t*) dst));
-        ((uint8_t*) dst)[0] ^= ((uint8_t*) dst)[1];
     } else if (len == 3 || len == 4) {
         *((uint32_t*) dst) = __builtin_bswap32(*((uint32_t*) dst));
     } else if (len == 8) {
@@ -64,19 +69,21 @@ void copy_int_as_le(void *dst, void *src, size_t len) {
     memcpy(dst, src, len);
 
     int x = 1;
-    if (((unsigned char*) &x)[0] == 0) {
-        // system is big-endian, so we need to convert to little
-        if (len == 2) {
-            _swap_bytes(&dst, 0, 1);
-        } else if (len == 3 || len == 4) {
-            _swap_bytes(&dst, 0, 3);
-            _swap_bytes(&dst, 1, 2);
-        } else if (len == 8) {
-            _swap_bytes(&dst, 0, 7);
-            _swap_bytes(&dst, 1, 6);
-            _swap_bytes(&dst, 2, 5);
-            _swap_bytes(&dst, 3, 4);
-        }
+    if (((unsigned char*) &x)[0] == 1) {
+        // system is little-endian, so no need to do any conversion
+        return;
+    }
+
+    if (len == 2) {
+        _swap_bytes(&dst, 0, 1);
+    } else if (len == 3 || len == 4) {
+        _swap_bytes(&dst, 0, 3);
+        _swap_bytes(&dst, 1, 2);
+    } else if (len == 8) {
+        _swap_bytes(&dst, 0, 7);
+        _swap_bytes(&dst, 1, 6);
+        _swap_bytes(&dst, 2, 5);
+        _swap_bytes(&dst, 3, 4);
     }
 }
 #endif