properly format the debug-id as an OLE GUID

Author: supervacuus

sentry-android-core/src/main/java/io/sentry/android/core/internal/tombstone/OleGuidFormatter.java

@@ -0,0 +1,85 @@
+package io.sentry.android.core.internal.tombstone;
+
+import androidx.annotation.Nullable;
+
+/**
+ * Used to convert a build/code-id hex string into a little-endian GUID string (from OLE) which is
+ * the expected format for the debug-id.
+ *
+ * <p>Each component used in a GUID uses little-endian representation. But the last two components
+ * (`clock_seq` and `node`) were represented in memory as eight individual bytes (which makes them
+ * look like big endian when formatted as a string).
+ *
+ * <p>Conversion example from the sentry development docs:
+ *
+ * <pre>
+ * f1c3bcc0 2798 65fe 3058 404b2831d9e6 4135386c
+ *  32-bit   16   16   2x8     6x8       Ignored
+ *   LE      LE   LE   LE      LE
+ *   =       =    =    =       =
+ * c0bcc3f1-9827-fe65-3058-404b2831d9e6
+ * </pre>
+ *
+ * Note: Java bytes are signed. When promoted (e.g. during formatting or bit shifts), they
+ * sign-extend to int, unlike uint8_t in C. We therefore mask with & 0xff to preserve the intended
+ * unsigned byte values.
+ */
+public class OleGuidFormatter {
+  public static String convert(final @Nullable String hex) {
+    if (hex == null) {
+      throw new NullPointerException("GUID conversion input hex string");
+    }
+    if ((hex.length() % 2) != 0) {
+      throw new IllegalArgumentException("The GUID conversion input hex string has odd length");
+    }
+    if (hex.length() < 32) {
+      throw new IllegalArgumentException(
+          "Need at least 16 bytes (32 hex chars) to convert to GUID");
+    }
+
+    final byte[] b = hexToBytes(hex);
+
+    final long timeLow = u32le(b, 0);
+    final int timeMid = u16le(b, 4);
+    final int timeHiAndVersion = u16le(b, 6);
+
+    return String.format(
+        "%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+        timeLow,
+        timeMid,
+        timeHiAndVersion,
+        // clock_seq_hi_and_reserved
+        b[8] & 0xff,
+        // clock_seq_low
+        b[9] & 0xff,
+        // node (6 MAC components)
+        b[10] & 0xff,
+        b[11] & 0xff,
+        b[12] & 0xff,
+        b[13] & 0xff,
+        b[14] & 0xff,
+        b[15] & 0xff);
+  }
+
+  private static int u16le(byte[] b, int offset) {
+    return (b[offset] & 0xff) | ((b[offset + 1] & 0xff) << 8);
+  }
+
+  private static long u32le(byte[] b, int offset) {
+    return (long) (b[offset] & 0xff)
+        | ((long) (b[offset + 1] & 0xff) << 8)
+        | ((long) (b[offset + 2] & 0xff) << 16)
+        | ((long) (b[offset + 3] & 0xff) << 24);
+  }
+
+  private static byte[] hexToBytes(String hex) {
+    int numBytes = 16;
+    byte[] result = new byte[numBytes];
+    for (int byteIdx = 0; byteIdx < numBytes; byteIdx++) {
+      int hi = Character.digit(hex.charAt(byteIdx * 2), numBytes);
+      int lo = Character.digit(hex.charAt(byteIdx * 2 + 1), numBytes);
+      result[byteIdx] = (byte) ((hi << 4) | lo);
+    }
+    return result;
+  }
+}

sentry-android-core/src/main/java/io/sentry/android/core/internal/tombstone/TombstoneParser.java

@@ -198,7 +198,7 @@ private DebugMeta createDebugMeta(@NonNull final TombstoneProtos.Tombstone tombs
       final DebugImage image = new DebugImage();
       image.setCodeId(module.getBuildId());
       image.setCodeFile(module.getMappingName());
-      image.setDebugId(module.getBuildId());
+      image.setDebugId(OleGuidFormatter.convert(module.getBuildId()));
       image.setImageAddr(formatHex(module.getBeginAddress()));
       image.setImageSize(module.getEndAddress() - module.getBeginAddress());
       image.setType("elf");

sentry-android-core/src/test/java/io/sentry/android/core/internal/tombstone/OleGuidFormatterTest.kt

@@ -0,0 +1,33 @@
+package io.sentry.android.core.internal.tombstone
+
+import java.lang.NullPointerException
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
+
+class OleGuidFormatterTest {
+
+  @Test
+  fun `a null input string throws`() {
+    assertFailsWith<NullPointerException> { OleGuidFormatter.convert(null) }
+  }
+
+  @Test
+  fun `an input string with fewer than 32 characters throws`() {
+    assertFailsWith<IllegalArgumentException> { OleGuidFormatter.convert("abcd") }
+  }
+
+  @Test
+  fun `an input string with odd number of characters throws`() {
+    assertFailsWith<IllegalArgumentException> {
+      OleGuidFormatter.convert("0123456789abcdef0123456789abcdef0")
+    }
+  }
+
+  @Test
+  fun `an input example from the develop docs leads to the expected result`() {
+    val input = "f1c3bcc0279865fe3058404b2831d9e64135386c"
+    val output = OleGuidFormatter.convert(input)
+    assertEquals("c0bcc3f1-9827-fe65-3058-404b2831d9e6", output)
+  }
+}