Fix endianess issues on s390x architecture.

Endianess code should use memcpy instead of unions. This apparently
is more correct on old, optimizing compilers. Technically, this is
compilers being really stupid but we work with what we got.

That said, this endianess code is more complicated than needed.

src/core/buffer.c

@@ -371,17 +371,15 @@ JANET_CORE_FN(cfun_buffer_push_uint16,
     janet_fixarity(argc, 3);
     JanetBuffer *buffer = janet_getbuffer(argv, 0);
     int reverse = should_reverse_bytes(argv, 1);
-    union {
-        uint16_t data;
-        uint8_t bytes[2];
-    } u;
-    u.data = janet_getuinteger16(argv, 2);
+    uint16_t data = janet_getuinteger16(argv, 2);
+    uint8_t bytes[sizeof(data)];
+    memcpy(bytes, &data, sizeof(bytes));
     if (reverse) {
-        uint8_t temp = u.bytes[1];
-        u.bytes[1] = u.bytes[0];
-        u.bytes[0] = temp;
+        uint8_t temp = bytes[1];
+        bytes[1] = bytes[0];
+        bytes[0] = temp;
     }
-    janet_buffer_push_u16(buffer, *(uint16_t *) u.bytes);
+    janet_buffer_push_bytes(buffer, bytes, sizeof(bytes));
     return argv[0];
 }
 
@@ -392,14 +390,12 @@ JANET_CORE_FN(cfun_buffer_push_uint32,
     janet_fixarity(argc, 3);
     JanetBuffer *buffer = janet_getbuffer(argv, 0);
     int reverse = should_reverse_bytes(argv, 1);
-    union {
-        uint32_t data;
-        uint8_t bytes[4];
-    } u;
-    u.data = janet_getuinteger(argv, 2);
+    uint32_t data = janet_getuinteger(argv, 2);
+    uint8_t bytes[sizeof(data)];
+    memcpy(bytes, &data, sizeof(bytes));
     if (reverse)
-        reverse_u32(u.bytes);
-    janet_buffer_push_u32(buffer, *(uint32_t *) u.bytes);
+        reverse_u32(bytes);
+    janet_buffer_push_bytes(buffer, bytes, sizeof(bytes));
     return argv[0];
 }
 
@@ -410,14 +406,12 @@ JANET_CORE_FN(cfun_buffer_push_uint64,
     janet_fixarity(argc, 3);
     JanetBuffer *buffer = janet_getbuffer(argv, 0);
     int reverse = should_reverse_bytes(argv, 1);
-    union {
-        uint64_t data;
-        uint8_t bytes[8];
-    } u;
-    u.data = janet_getuinteger64(argv, 2);
+    uint64_t data = janet_getuinteger64(argv, 2);
+    uint8_t bytes[sizeof(data)];
+    memcpy(bytes, &data, sizeof(bytes));
     if (reverse)
-        reverse_u64(u.bytes);
-    janet_buffer_push_u64(buffer, *(uint64_t *) u.bytes);
+        reverse_u64(bytes);
+    janet_buffer_push_bytes(buffer, bytes, sizeof(bytes));
     return argv[0];
 }
 
@@ -428,14 +422,12 @@ JANET_CORE_FN(cfun_buffer_push_float32,
     janet_fixarity(argc, 3);
     JanetBuffer *buffer = janet_getbuffer(argv, 0);
     int reverse = should_reverse_bytes(argv, 1);
-    union {
-        float data;
-        uint8_t bytes[4];
-    } u;
-    u.data = (float) janet_getnumber(argv, 2);
+    float data = (float) janet_getnumber(argv, 2);
+    uint8_t bytes[sizeof(data)];
+    memcpy(bytes, &data, sizeof(bytes));
     if (reverse)
-        reverse_u32(u.bytes);
-    janet_buffer_push_u32(buffer, *(uint32_t *) u.bytes);
+        reverse_u32(bytes);
+    janet_buffer_push_bytes(buffer, bytes, sizeof(bytes));
     return argv[0];
 }
 
@@ -446,14 +438,12 @@ JANET_CORE_FN(cfun_buffer_push_float64,
     janet_fixarity(argc, 3);
     JanetBuffer *buffer = janet_getbuffer(argv, 0);
     int reverse = should_reverse_bytes(argv, 1);
-    union {
-        double data;
-        uint8_t bytes[8];
-    } u;
-    u.data = janet_getnumber(argv, 2);
+    double data = janet_getnumber(argv, 2);
+    uint8_t bytes[sizeof(data)];
+    memcpy(bytes, &data, sizeof(bytes));
     if (reverse)
-        reverse_u64(u.bytes);
-    janet_buffer_push_u64(buffer, *(uint64_t *) u.bytes);
+        reverse_u64(bytes);
+    janet_buffer_push_bytes(buffer, bytes, sizeof(bytes));
     return argv[0];
 }
 

src/core/os.c

@@ -174,6 +174,8 @@ JANET_CORE_FN(os_arch,
               "* :riscv64\n\n"
               "* :sparc\n\n"
               "* :wasm\n\n"
+              "* :s390\n\n"
+              "* :s390x\n\n"
               "* :unknown\n") {
     janet_fixarity(argc, 0);
     (void) argv;
@@ -200,6 +202,10 @@ JANET_CORE_FN(os_arch,
     return janet_ckeywordv("ppc");
 #elif (defined(__ppc64__) || defined(_ARCH_PPC64) || defined(_M_PPC))
     return janet_ckeywordv("ppc64");
+#elif (defined(__s390x__))
+    return janet_ckeywordv("s390x");
+#elif (defined(__s390__))
+    return janet_ckeywordv("s390");
 #else
     return janet_ckeywordv("unknown");
 #endif