保存時にURLからファイル名を決める際のサニタイズの改善

app/src/androidTest/java/jp/juggler/subwaytooter/testutil/TestUtils.kt

@@ -55,8 +55,8 @@ suspend fun <T : Throwable?> assertThrowsSuspend(
                 expected += "@" + Integer.toHexString(System.identityHashCode(expectedThrowable))
                 actual += "@" + Integer.toHexString(System.identityHashCode(actualThrowable))
             }
-            val mismatchMessage = (buildPrefix(message)
-                    + format("unexpected exception type thrown;", expected, actual))
+            val mismatchMessage = (buildPrefix(message) +
+                    format("unexpected exception type thrown;", expected, actual))
 
             // The AssertionError(String, Throwable) ctor is only available on JDK7.
             val assertionError = AssertionError(mismatchMessage)

app/src/main/java/jp/juggler/subwaytooter/ActMediaViewer.kt

@@ -49,6 +49,7 @@ import kotlinx.coroutines.yield
 import okhttp3.Request
 import java.io.ByteArrayInputStream
 import java.io.IOException
+import java.nio.charset.StandardCharsets
 import java.util.*
 import javax.net.ssl.HttpsURLConnection
 import kotlin.math.max
@@ -675,13 +676,49 @@ class ActMediaViewer : AppCompatActivity(), View.OnClickListener {
             download_history_list.addLast(DownloadHistory(now, url))
         }
 
-        val fileName = (
-                url.mayUri()?.pathSegments?.findLast { !it.isNullOrBlank() }
-                    ?: url
-                        .replaceFirst("https?://".asciiRegex(), "")
-                        .replaceAll("[^.\\w\\d]+".asciiPattern(), "-")
-                )
-            .take(20)
+        /**
+         * Linuxはフォルダ中のファイルの名前の上限が255バイトと決まっている。
+         * その上限に収まるように文字を切りたいが、それはUTF-8の区切りを考慮する必要がある。
+         */
+        fun shortenName(src: String, limitBytes: Int): String {
+            val bytes = src.encodeUTF8()
+            if (bytes.size <= limitBytes) return src
+            // 制限バイト数の終端の一つ先
+            var pos = limitBytes
+            while (pos >= 0) {
+                if (bytes[pos].toInt().and(0x80) == 0) {
+                    // 現在位置がUTF-8の後続ではないなら、その手前までを返す
+                    return String(bytes, 0, pos, StandardCharsets.UTF_8)
+                }
+                // 現在位置はUTF-8の文字の2バイト目以降なので、この手前で切ると文字が壊れる
+                --pos
+            }
+            // UTF-8表現がおかしい
+            return "media"
+        }
+
+        var fileName = url.mayUri()?.pathSegments?.findLast { !it.isNullOrBlank() }
+            ?: url.replaceFirst("https?://".asciiRegex(), "")
+
+        // Windowsでファイル名に使えない文字を避ける
+        fileName = """[\\/|"<>?*:-]+""".toRegex().replace(fileName, "-")
+
+        // 末尾から20文字以内にある最初のドット
+        val extDotPos = fileName.indexOf('.', startIndex = max(0, fileName.length - 20))
+        val fileNameMaxBytes = 255
+        fileName = if (extDotPos == -1) {
+            // 拡張子なし
+            shortenName(fileName, fileNameMaxBytes)
+        } else {
+            // 拡張子の手前だけを短縮する
+            val extPart = fileName.substring(extDotPos)
+            val extPartBytes = extPart.encodeUTF8().size
+            val namePart = shortenName(
+                fileName.substring(0, extDotPos),
+                fileNameMaxBytes - extPartBytes
+            )
+            "$namePart$extPart"
+        }
 
         val request = DownloadManager.Request(url.toUri())
         request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, fileName)

app/src/main/java/jp/juggler/subwaytooter/api/TootApiClientExt.kt

@@ -163,7 +163,8 @@ class ResponseBeforeRead(
                     throw SendException(
                         response = response,
                         request = request,
-                        message = parseErrorResponse(ex.withCaption("readString failed."))
+                        message = parseErrorResponse(ex.withCaption("readString failed.")),
+                        cause = ex,
                     )
                 }
             }
@@ -219,7 +220,8 @@ class ResponseBeforeRead(
                     throw SendException(
                         response = response,
                         request = request,
-                        message = parseErrorResponse(ex.withCaption("readString failed."))
+                        message = parseErrorResponse(ex.withCaption("readString failed.")),
+                        cause = ex,
                     )
                 }
             }
@@ -304,7 +306,7 @@ suspend fun ResponseWith<String?>.stringToJsonObject(): JsonObject =
                 else -> throw SendException(
                     response = response,
                     request = response.request,
-                    message = parseErrorResponse("not a JSON object.")
+                    message = parseErrorResponse("not a JSON object."),
                 )
             }
         }
@@ -317,6 +319,7 @@ suspend fun ResponseWith<String?>.stringToJsonObject(): JsonObject =
                     response = response,
                     request = response.request,
                     message = ex.withCaption("readJsonObject failed. ($errorSuffix)"),
+                    cause = ex,
                 )
             }
         }