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Safer temp video handling

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Cleanup deletes the actual shared file (and on error) instead of the old temp path in
Guard against empty response.body
Gate media-type detection so image sharing only checks image headers
Added unit test for rename-failure fallback
This commit is contained in:
davotoula
2026-01-18 22:17:44 +01:00
parent f2e484b18e
commit 1a04f16d1a
3 changed files with 125 additions and 38 deletions
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amethyst/src/main/java/com/vitorpamplona/amethyst/ui/components/ShareHelper.kt
+62 -35
View File
@@ -37,6 +37,12 @@ object ShareHelper {
private const val DEFAULT_VIDEO_EXTENSION = "mp4"
private const val SHARED_FILE_PREFIX = "shared_media"
data class SharableFile(
val uri: Uri,
val extension: String,
val file: File,
)
// Image type magic numbers
private val JPEG_MAGIC = byteArrayOf(0xFF.toByte(), 0xD8.toByte())
private val PNG_MAGIC = byteArrayOf(0x89.toByte(), 0x50.toByte(), 0x4E.toByte(), 0x47.toByte())
@@ -81,7 +87,7 @@ object ShareHelper {
private fun getImageExtension(file: File): String = getMediaExtension(file, isVideo = false)
fun getVideoExtension(file: File): String = getMediaExtension(file, isVideo = true)
private fun getVideoExtension(file: File): String = getMediaExtension(file, isVideo = true)
private fun getMediaExtension(
file: File,
@@ -97,43 +103,49 @@ object ShareHelper {
return defaultExtension
}
when {
// Image formats
// JPEG: Check first 2 bytes
matchesMagicNumbers(header, 0, JPEG_MAGIC) -> "jpg"
if (isVideo) {
when {
// Video formats
// WebM/MKV: Check first 4 bytes (EBML header)
// Both use Matroska container; default to webm as it's more common on web
matchesMagicNumbers(header, 0, WEBM_MAGIC) -> "webm"
// PNG: Check first 4 bytes
matchesMagicNumbers(header, 0, PNG_MAGIC) -> "png"
// AVI: Check "RIFF" (bytes 0-3) and "AVI " (bytes 8-11)
matchesMagicNumbers(header, 0, AVI_HEADER_START) &&
bytesRead >= 12 &&
matchesMagicNumbers(header, 8, AVI_HEADER_END) -> "avi"
// GIF: Check first 4 bytes for "GIF8"
matchesMagicNumbers(header, 0, GIF_MAGIC) -> "gif"
// MP4/MOV: Check for ftyp box (bytes 4-7 should be "ftyp")
bytesRead >= 12 && matchesMagicNumbers(header, 4, MOV_FTYP) -> detectMp4OrMov(header)
// WEBP: Check "RIFF" (bytes 0-3) and "WEBP" (bytes 8-11)
matchesMagicNumbers(header, 0, WEBP_HEADER_START) &&
bytesRead >= 12 &&
matchesMagicNumbers(header, 8, WEBP_HEADER_END) -> "webp"
// MP4/MOV alternative: moov, mdat, or free at offset 4
bytesRead >= 8 && (
matchesMagicNumbers(header, 4, MOV_MOOV) ||
matchesMagicNumbers(header, 4, MOV_MDAT) ||
matchesMagicNumbers(header, 4, MOV_FREE)
) -> "mp4"
// Video formats
// WebM/MKV: Check first 4 bytes (EBML header)
// Both use Matroska container; default to webm as it's more common on web
matchesMagicNumbers(header, 0, WEBM_MAGIC) -> "webm"
else -> defaultExtension
}
} else {
when {
// Image formats
// JPEG: Check first 2 bytes
matchesMagicNumbers(header, 0, JPEG_MAGIC) -> "jpg"
// AVI: Check "RIFF" (bytes 0-3) and "AVI " (bytes 8-11)
matchesMagicNumbers(header, 0, AVI_HEADER_START) &&
bytesRead >= 12 &&
matchesMagicNumbers(header, 8, AVI_HEADER_END) -> "avi"
// PNG: Check first 4 bytes
matchesMagicNumbers(header, 0, PNG_MAGIC) -> "png"
// MP4/MOV: Check for ftyp box (bytes 4-7 should be "ftyp")
bytesRead >= 12 && matchesMagicNumbers(header, 4, MOV_FTYP) -> detectMp4OrMov(header)
// GIF: Check first 4 bytes for "GIF8"
matchesMagicNumbers(header, 0, GIF_MAGIC) -> "gif"
// MP4/MOV alternative: moov, mdat, or free at offset 4
bytesRead >= 8 && (
matchesMagicNumbers(header, 4, MOV_MOOV) ||
matchesMagicNumbers(header, 4, MOV_MDAT) ||
matchesMagicNumbers(header, 4, MOV_FREE)
) -> "mp4"
// WEBP: Check "RIFF" (bytes 0-3) and "WEBP" (bytes 8-11)
matchesMagicNumbers(header, 0, WEBP_HEADER_START) &&
bytesRead >= 12 &&
matchesMagicNumbers(header, 8, WEBP_HEADER_END) -> "webp"
else -> defaultExtension
else -> defaultExtension
}
}
}
} catch (e: IOException) {
@@ -209,21 +221,36 @@ object ShareHelper {
fun prepareTempVideoForSharing(
context: Context,
tempFile: File,
): Pair<Uri, String> {
): SharableFile {
val extension = getVideoExtension(tempFile)
val timestamp = System.currentTimeMillis()
val sharableFile = File(context.cacheDir, "${SHARED_FILE_PREFIX}_$timestamp.$extension")
try {
tempFile.renameTo(sharableFile)
moveTempFileForSharing(tempFile, sharableFile)
} catch (e: Exception) {
Log.e(TAG, "Failed to rename temp video file for sharing", e)
throw e
}
return Pair(
FileProvider.getUriForFile(context, "${context.packageName}.provider", sharableFile),
extension,
return SharableFile(
uri = FileProvider.getUriForFile(context, "${context.packageName}.provider", sharableFile),
extension = extension,
file = sharableFile,
)
}
internal fun moveTempFileForSharing(
tempFile: File,
sharableFile: File,
rename: (File, File) -> Boolean = { source, dest -> source.renameTo(dest) },
) {
val renamed = rename(tempFile, sharableFile)
if (!renamed) {
tempFile.copyTo(sharableFile, overwrite = true)
if (!tempFile.delete()) {
Log.w(TAG, "Failed to delete temp file ${tempFile.path} after copy")
}
}
}
}
amethyst/src/main/java/com/vitorpamplona/amethyst/ui/components/ZoomableContentView.kt
+11 -3
View File
@@ -121,6 +121,7 @@ import okhttp3.Request
import okhttp3.coroutines.executeAsync
import okio.sink
import java.io.File
import java.io.IOException
import kotlin.time.Duration.Companion.seconds
@Composable
@@ -884,6 +885,7 @@ private suspend fun shareVideoFile(
onError: () -> Unit,
) {
val tempFile = ShareHelper.createTempVideoFile(context)
var sharedFile: File? = null
try {
withContext(Dispatchers.IO) {
// Download video using streaming
@@ -897,15 +899,20 @@ private suspend fun shareVideoFile(
client.newCall(request).executeAsync().use { response ->
check(response.isSuccessful) { "Download failed: ${response.code}" }
val responseBody = response.body
// Stream the response to the temp file
tempFile.outputStream().use { outputStream ->
response.body.source().readAll(outputStream.sink())
val bytesCopied = responseBody.source().readAll(outputStream.sink())
if (bytesCopied == 0L) {
throw IOException("Download failed: empty response body")
}
}
}
// Prepare the temp file for sharing (determines extension and creates sharable URI)
val (uri, extension) = ShareHelper.prepareTempVideoForSharing(context, tempFile)
val (uri, extension, sharableFile) = ShareHelper.prepareTempVideoForSharing(context, tempFile)
sharedFile = sharableFile
// Determine mime type
val determinedMimeType = mimeType ?: "video/$extension"
@@ -924,7 +931,7 @@ private suspend fun shareVideoFile(
// Schedule cleanup after 60 seconds to allow the receiving app time to copy the file
Handler(Looper.getMainLooper()).postDelayed({
tempFile.delete()
sharableFile.delete()
}, 60_000)
}
@@ -937,6 +944,7 @@ private suspend fun shareVideoFile(
// Clean up temp file on error
tempFile.delete()
sharedFile?.delete()
withContext(Dispatchers.Main) {
Toast
amethyst/src/test/java/com/vitorpamplona/amethyst/ui/components/ShareHelperTest.kt
+52
View File
@@ -0,0 +1,52 @@
/**
* Copyright (c) 2025 Vitor Pamplona
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
* Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package com.vitorpamplona.amethyst.ui.components
import org.junit.Assert.assertEquals
import org.junit.Assert.assertFalse
import org.junit.Assert.assertTrue
import org.junit.Test
import java.io.File
import java.nio.file.Files
class ShareHelperTest {
@Test
fun moveTempFileForSharing_renameFails_copiesAndDeletesSource() {
val tempDir = Files.createTempDirectory("sharehelpertest").toFile()
val tempFile = File(tempDir, "video.tmp")
val content = "test-content"
tempFile.writeText(content)
val targetFile = File(tempDir, "shared.mp4")
ShareHelper.moveTempFileForSharing(
tempFile,
targetFile,
rename = { _, _ -> false },
)
assertTrue(targetFile.exists())
assertEquals(content, targetFile.readText())
assertFalse(tempFile.exists())
targetFile.delete()
tempDir.delete()
}
}