fix: shrink native jars and harden platform detection

Strip the symbol/debug tables from the ELF shared library at link time
(-s): an unstripped libzstd.so carried full debug_info and was ~6x larger
than needed (4.0M -> ~650K). Delete the .pdb (multi-MB debug database) and
.lib import library that lld emits next to a Windows .dll; neither is needed
at runtime and both were being bundled into the native JAR. Net effect: the
linux-x86_64 native jar drops 1.2M -> 285K and windows-x86_64 1.2M -> 372K.

Harden NativeLibrary.classifier(): an unrecognized CPU arch silently mapped
to x86_64, deferring failure to a cryptic dlopen error. Now throw a clear
UnsatisfiedLinkError naming the unsupported arch, with an explicit amd64
branch so Linux JVMs (which report os.arch=amd64) still resolve x86_64.

Normalize blank-line separators between independent handle blocks in
Bindings (the frame/skippable cluster was packed unlike the rest of the file).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: dfa1

scripts/build-zstd.sh

@@ -75,8 +75,14 @@ trap 'rm -rf "$WORK"' EXIT
 # symbol into the PE export table (the classic, reliable MinGW DLL path).
 VIS_FLAG="-fvisibility=hidden"
 LINK_EXTRA=""
+# Strip the symbol/debug tables at link time. An unstripped ELF .so carries full
+# debug_info and is ~6x larger than needed (4.0M -> ~250K); -s drops it. PE/COFF
+# keeps its exports in the export table (separate from the symbol table), but
+# lld still emits a multi-megabyte .pdb and an import .lib next to the .dll —
+# those are deleted after the link below rather than suppressed via strip.
+STRIP_FLAG="-s"
 case "$CLASSIFIER" in
-    windows-*) VIS_FLAG=""; LINK_EXTRA="-Wl,--export-all-symbols" ;;
+    windows-*) VIS_FLAG=""; LINK_EXTRA="-Wl,--export-all-symbols"; STRIP_FLAG="" ;;
 esac
 CFLAGS="-O3 -DNDEBUG -DZSTD_DISABLE_ASM=1 -DXXH_NAMESPACE=ZSTD_ $VIS_FLAG \
         -I$ZSTD_LIB -I$ZSTD_LIB/common -fPIC"
@@ -95,6 +101,11 @@ wait
 SONAME_FLAG=""
 [ "$LIB_NAME" = "libzstd.so" ] && SONAME_FLAG="-Wl,-soname,libzstd.so.1"
 
-zig cc -target "$ZIG_TARGET" -shared $SONAME_FLAG $LINK_EXTRA -o "$DEST_DIR/$LIB_NAME" "$WORK"/*.o
+zig cc -target "$ZIG_TARGET" -shared $STRIP_FLAG $SONAME_FLAG $LINK_EXTRA -o "$DEST_DIR/$LIB_NAME" "$WORK"/*.o
+
+# lld emits a .pdb (debug database, multiple MB) and a .lib (import library) next
+# to a Windows .dll; neither is needed at runtime and both would be bundled into
+# the native JAR. Keep only the shared library itself in the resources directory.
+find "$DEST_DIR" -type f ! -name "$LIB_NAME" -delete
 
 echo "[build-zstd] Installed: $DEST_DIR/$LIB_NAME"

zstd/src/main/java/io/github/dfa1/zstd/Bindings.java

@@ -43,30 +43,37 @@ final class Bindings {
     // unsigned ZSTD_isFrame(const void* buffer, size_t size)
     static final MethodHandle IS_FRAME =
             NativeLibrary.lookup("ZSTD_isFrame", FunctionDescriptor.of(JAVA_INT, ADDRESS, JAVA_LONG));
+
     // size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize)
     static final MethodHandle FIND_FRAME_COMPRESSED_SIZE =
             NativeLibrary.lookup("ZSTD_findFrameCompressedSize",
                     FunctionDescriptor.of(JAVA_LONG, ADDRESS, JAVA_LONG));
+
     // unsigned long long ZSTD_decompressBound(const void* src, size_t srcSize)
     static final MethodHandle DECOMPRESS_BOUND =
             NativeLibrary.lookup("ZSTD_decompressBound",
                     FunctionDescriptor.of(JAVA_LONG, ADDRESS, JAVA_LONG));
+
     // unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize)
     static final MethodHandle GET_DICT_ID_FROM_FRAME =
             NativeLibrary.lookup("ZSTD_getDictID_fromFrame",
                     FunctionDescriptor.of(JAVA_INT, ADDRESS, JAVA_LONG));
+
     // size_t ZSTD_getFrameHeader(ZSTD_FrameHeader* zfh, const void* src, size_t srcSize)
     static final MethodHandle GET_FRAME_HEADER =
             NativeLibrary.lookup("ZSTD_getFrameHeader",
                     FunctionDescriptor.of(JAVA_LONG, ADDRESS, ADDRESS, JAVA_LONG));
+
     // unsigned ZSTD_isSkippableFrame(const void* buffer, size_t size)
     static final MethodHandle IS_SKIPPABLE_FRAME =
             NativeLibrary.lookup("ZSTD_isSkippableFrame",
                     FunctionDescriptor.of(JAVA_INT, ADDRESS, JAVA_LONG));
+
     // size_t ZSTD_writeSkippableFrame(void* dst, size_t dstCap, const void* src, size_t srcSize, unsigned magicVariant)
     static final MethodHandle WRITE_SKIPPABLE_FRAME =
             NativeLibrary.lookup("ZSTD_writeSkippableFrame",
                     FunctionDescriptor.of(JAVA_LONG, ADDRESS, JAVA_LONG, ADDRESS, JAVA_LONG, JAVA_INT));
+
     // size_t ZSTD_readSkippableFrame(void* dst, size_t dstCap, unsigned* magicVariant, const void* src, size_t srcSize)
     static final MethodHandle READ_SKIPPABLE_FRAME =
             NativeLibrary.lookup("ZSTD_readSkippableFrame",
@@ -83,6 +90,7 @@ final class Bindings {
     // ZSTD_ErrorCode ZSTD_getErrorCode(size_t functionResult)
     static final MethodHandle GET_ERROR_CODE =
             NativeLibrary.lookup("ZSTD_getErrorCode", FunctionDescriptor.of(JAVA_INT, JAVA_LONG));
+
     // const char* ZSTD_getErrorString(ZSTD_ErrorCode code)
     static final MethodHandle GET_ERROR_STRING =
             NativeLibrary.lookup("ZSTD_getErrorString", FunctionDescriptor.of(ADDRESS, JAVA_INT));

zstd/src/main/java/io/github/dfa1/zstd/NativeLibrary.java

@@ -95,7 +95,16 @@ private static String classifier() {
         } else {
             osName = "linux";
         }
-        String archName = (arch.equals("aarch64") || arch.equals("arm64")) ? "aarch64" : "x86_64";
+        String archName;
+        if (arch.equals("aarch64") || arch.equals("arm64")) {
+            archName = "aarch64";
+        } else if (arch.equals("x86_64") || arch.equals("amd64")) {
+            archName = "x86_64";
+        } else {
+            throw new UnsatisfiedLinkError(
+                    "Unsupported CPU architecture '" + arch + "'; zstd-java ships native libraries "
+                            + "only for x86_64 and aarch64");
+        }
         return osName + "-" + archName;
     }