feat: Add Hex patch (#3034)

api/revanced-patches.api

@@ -28,6 +28,10 @@ public final class app/revanced/patches/all/misc/debugging/EnableAndroidDebuggin
 	public fun execute (Lapp/revanced/patcher/data/ResourceContext;)V
 }
 
+public final class app/revanced/patches/all/misc/hex/HexPatch : app/revanced/patches/shared/misc/hex/BaseHexPatch {
+	public fun <init> ()V
+}
+
 public final class app/revanced/patches/all/misc/network/OverrideCertificatePinningPatch : app/revanced/patcher/patch/ResourcePatch {
 	public static final field INSTANCE Lapp/revanced/patches/all/misc/network/OverrideCertificatePinningPatch;
 	public synthetic fun execute (Lapp/revanced/patcher/data/Context;)V
@@ -669,6 +673,21 @@ public abstract class app/revanced/patches/shared/misc/gms/BaseGmsCoreSupportRes
 	protected final fun getGmsCoreVendorGroupId ()Ljava/lang/String;
 }
 
+public abstract class app/revanced/patches/shared/misc/hex/BaseHexPatch : app/revanced/patcher/patch/RawResourcePatch {
+	public fun <init> ()V
+	public synthetic fun execute (Lapp/revanced/patcher/data/Context;)V
+	public fun execute (Lapp/revanced/patcher/data/ResourceContext;)V
+}
+
+public final class app/revanced/patches/shared/misc/hex/BaseHexPatch$Replacement {
+	public static final field Companion Lapp/revanced/patches/shared/misc/hex/BaseHexPatch$Replacement$Companion;
+	public fun <init> (Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)V
+	public final fun replacePattern ([B)V
+}
+
+public final class app/revanced/patches/shared/misc/hex/BaseHexPatch$Replacement$Companion {
+}
+
 public abstract class app/revanced/patches/shared/misc/integrations/BaseIntegrationsPatch : app/revanced/patcher/patch/BytecodePatch {
 	public fun <init> (Ljava/lang/String;Ljava/util/Set;)V
 	public fun <init> (Ljava/util/Set;)V

src/main/kotlin/app/revanced/patches/all/misc/hex/HexPatch.kt

@@ -0,0 +1,55 @@
+package app.revanced.patches.all.misc.hex
+
+import app.revanced.patcher.patch.PatchException
+import app.revanced.patcher.patch.annotation.Patch
+import app.revanced.patcher.patch.options.PatchOption.PatchExtensions.registerNewPatchOption
+import app.revanced.patches.shared.misc.hex.BaseHexPatch
+import app.revanced.util.Utils.trimIndentMultiline
+import app.revanced.patcher.patch.Patch as PatchClass
+
+@Patch(
+    name = "Hex",
+    description = "Replaces a hexadecimal patterns of bytes of files in an APK.",
+    use = false,
+)
+@Suppress("unused")
+class HexPatch : BaseHexPatch() {
+    // TODO: Instead of stringArrayOption, use a custom option type to work around
+    //  https://github.com/ReVanced/revanced-library/issues/48.
+    //  Replace the custom option type with a stringArrayOption once the issue is resolved.
+    private val replacementsOption by registerNewPatchOption<PatchClass<*>, List<String>>(
+        key = "replacements",
+        title = "replacements",
+        description = """
+            Hexadecimal patterns to search for and replace with another in a target file.
+            
+            A pattern is a sequence of case insensitive strings, each representing hexadecimal bytes, separated by spaces.
+            An example pattern is 'aa 01 02 FF'.
+
+            Every pattern must be followed by a pipe ('|'), the replacement pattern,
+            another pipe ('|'), and the path to the file to make the changes in relative to the APK root. 
+            The replacement pattern must have the same length as the original pattern.
+
+            Full example of a valid input:
+            'aa 01 02 FF|00 00 00 00|path/to/file'
+        """.trimIndentMultiline(),
+        required = true,
+        valueType = "StringArray",
+    )
+
+    override val replacements
+        get() = replacementsOption!!.map { from ->
+            val (pattern, replacementPattern, targetFilePath) = try {
+                from.split("|", limit = 3)
+            } catch (e: Exception) {
+                throw PatchException(
+                    "Invalid input: $from.\n" +
+                        "Every pattern must be followed by a pipe ('|'), " +
+                        "the replacement pattern, another pipe ('|'), " +
+                        "and the path to the file to make the changes in relative to the APK root. ",
+                )
+            }
+
+            Replacement(pattern, replacementPattern, targetFilePath)
+        }
+}

src/main/kotlin/app/revanced/patches/shared/misc/hex/BaseHexPatch.kt

@@ -0,0 +1,120 @@
+package app.revanced.patches.shared.misc.hex
+
+import app.revanced.patcher.data.ResourceContext
+import app.revanced.patcher.patch.PatchException
+import app.revanced.patcher.patch.RawResourcePatch
+import kotlin.math.max
+
+abstract class BaseHexPatch : RawResourcePatch() {
+    internal abstract val replacements: List<Replacement>
+
+    override fun execute(context: ResourceContext) {
+        replacements.groupBy { it.targetFilePath }.forEach { (targetFilePath, replacements) ->
+            val targetFile = try {
+                context[targetFilePath, true]
+            } catch (e: Exception) {
+                throw PatchException("Could not find target file: $targetFilePath")
+            }
+
+            // TODO: Use a file channel to read and write the file instead of reading the whole file into memory,
+            //  in order to reduce memory usage.
+            val targetFileBytes = targetFile.readBytes()
+
+            replacements.forEach { replacement ->
+                replacement.replacePattern(targetFileBytes)
+            }
+
+            targetFile.writeBytes(targetFileBytes)
+        }
+    }
+
+    /**
+     * Represents a pattern to search for and its replacement pattern.
+     *
+     * @property pattern The pattern to search for.
+     * @property replacementPattern The pattern to replace the [pattern] with.
+     * @property targetFilePath The path to the file to make the changes in relative to the APK root.
+     */
+    class Replacement(
+        private val pattern: String,
+        replacementPattern: String,
+        internal val targetFilePath: String,
+    ) {
+        private val patternBytes = pattern.toByteArrayPattern()
+        private val replacementPattern = replacementPattern.toByteArrayPattern()
+
+        init {
+            if (this.patternBytes.size != this.replacementPattern.size) {
+                throw PatchException("Pattern and replacement pattern must have the same length: $pattern")
+            }
+        }
+
+        /**
+         * Replaces the [patternBytes] with the [replacementPattern] in the [targetFileBytes].
+         *
+         * @param targetFileBytes The bytes of the file to make the changes in.
+         */
+        fun replacePattern(targetFileBytes: ByteArray) {
+            val startIndex = indexOfPatternIn(targetFileBytes)
+
+            if (startIndex == -1) {
+                throw PatchException("Pattern not found in target file: $pattern")
+            }
+
+            replacementPattern.copyInto(targetFileBytes, startIndex)
+        }
+
+        // TODO: Allow searching in a file channel instead of a byte array to reduce memory usage.
+        /**
+         * Returns the index of the first occurrence of [patternBytes] in the haystack
+         * using the Boyer-Moore algorithm.
+         *
+         * @param haystack The array to search in.
+         *
+         * @return The index of the first occurrence of the [patternBytes] in the haystack or -1
+         * if the [patternBytes] is not found.
+         */
+        private fun indexOfPatternIn(haystack: ByteArray): Int {
+            val needle = patternBytes
+
+            val haystackLength = haystack.size - 1
+            val needleLength = needle.size - 1
+            val right = IntArray(256) { -1 }
+
+            for (i in 0 until needleLength) right[needle[i].toInt().and(0xFF)] = i
+
+            var skip: Int
+            for (i in 0..haystackLength - needleLength) {
+                skip = 0
+
+                for (j in needleLength - 1 downTo 0)
+                    if (needle[j] != haystack[i + j]) {
+                        skip = max(1, j - right[haystack[i + j].toInt().and(0xFF)])
+
+                        break
+                    }
+
+                if (skip == 0) return i
+            }
+            return -1
+        }
+
+        companion object {
+            /**
+             * Convert a string representing a pattern of hexadecimal bytes to a byte array.
+             *
+             * @return The byte array representing the pattern.
+             * @throws PatchException If the pattern is invalid.
+             */
+            private fun String.toByteArrayPattern() = try {
+                split(" ").map { it.toInt(16).toByte() }.toByteArray()
+            } catch (e: NumberFormatException) {
+                throw PatchException(
+                    "Could not parse pattern: $this.  A pattern is a sequence of case insensitive strings " +
+                        "representing hexadecimal bytes separated by spaces",
+                    e,
+                )
+            }
+        }
+    }
+}