issue with .source() at 0.12.0

[T8RIN]

Trying to read from that source causes OperationNotPermitted error

Originally posted by @T8RIN in #180

[vinceglb]

Hi @T8RIN! Can you share a sample project that reproduces the problem? Thanks a lot for your help!

[T8RIN]

@Composable
fun rememberDocumentPicker(
    maxItems: Int? = null,
    extensions: Set<String>? = null,
    onSuccess: (List<String>) -> Unit
): ResultLauncher {
    val picker = rememberFilePickerLauncher(
        type = FileKitType.File(extensions),
        mode = FileKitMode.Multiple(maxItems),
        onResult = { files ->
            if (!files.isNullOrEmpty()) {
                onSuccess(files.map { it.path })
            }
        }
    )

    return remember(picker) { ResultLauncher(picker::launch) }
}

after calling PlatformFile(path).source().buffered() and attempting to read i get the issue

suspend inline fun String.chunkedFileRead(
    chunkSize: Int = CHUNK_SIZE,
    onChunk: suspend (ByteArray) -> Unit
): Boolean {
    val openedSource = PlatformFile(this).source().buffered()

    openedSource.use { source ->
        var endReached = false
        while (currentCoroutineContext().isActive && !endReached) {
            val chunk = try {
                source.readByteArray(chunkSize)
            } catch (_: EOFException) {
                endReached = true
                source.readByteArray().also {
                    if (it.isEmpty()) break
                }
            }

            println("chunk size = ${chunk.size}")
            onChunk(chunk)
        }
    }

    return true
}

[T8RIN]

@vinceglb

Weird thing that this only happens when PlatformFile is recreated like

val file: PlatformFile = .. //from documentPicker

file.source() // ok
PlatformFile(file.path).source() // not ok

[vinceglb]

Hi @T8RIN! Thanks again for the report.

I tried to reproduce the crash on my side, but without success.

I tested with the following code in a tiny project:

@Composable
fun App() {
    MaterialTheme {
        val scope = rememberCoroutineScope()
        val launcher = rememberFilePickerLauncher { file ->
            file?.let {
                scope.launch {
                    val path = file.path
                    println("path = $path")

                    val newFile = PlatformFile(path)

                    newFile.path.chunkedFileRead { chunk ->
                        println("read chunk of size ${chunk.size}")
                    }
                }
            }
        }

        Column(
            modifier = Modifier
                .background(MaterialTheme.colorScheme.primaryContainer)
                .safeContentPadding()
                .fillMaxSize(),
            horizontalAlignment = Alignment.CenterHorizontally,
        ) {
            Button(onClick = { launcher.launch() }) {
                Text("Open file picker")
            }
        }
    }
}

suspend inline fun String.chunkedFileRead(
    chunkSize: Int = CHUNK_SIZE,
    onChunk: suspend (ByteArray) -> Unit
): Boolean {
    val openedSource = PlatformFile(this).source().buffered()

    openedSource.use { source ->
        var endReached = false
        while (currentCoroutineContext().isActive && !endReached) {
            val chunk = try {
                source.readByteArray(chunkSize)
            } catch (_: EOFException) {
                endReached = true
                source.readByteArray().also {
                    if (it.isEmpty()) break
                }
            }

            println("chunk size = ${chunk.size}")
            onChunk(chunk)
        }
    }

    return true
}

const val CHUNK_SIZE = 1024

I tested on:

• a real iPhone
• local files
• iCloud files
• different combinations using PlatformFile(file.path) (including recreating the file from path before reading)
  I still could not reproduce the crash.

Could you share a tiny end-to-end reproducible project (minimal sample + exact steps to reproduce)? That would help me a lot to debug this properly 🙏

Note: if you save only the file path on iOS and try to restore access after app restart, iOS can throw an exception. To persist access across app restarts, you need to use bookmarkData() / bookmark restore APIs: Bookmark Data docs

[T8RIN]

I used it like file.path.chunkedFileRead, without creating platformFile twice

[T8RIN]

That's used to pass path to ui without relying on PlatformFile higher, but my problem solved by switching to use original platformFile references

[vinceglb]

I just tested with file.path.chunkedFileRead without any problem.

[T8RIN]

Weird enough, maybe you should try saving path to variable, and try to acess later not in onResult block?

[vinceglb]

I tested this version, still on a real iPhone, and same result:

@Composable
@Preview
fun App() {
    MaterialTheme {
        val scope = rememberCoroutineScope()

        var filePath by remember { mutableStateOf("") }

        fun test() {
            scope.launch {
                filePath.chunkedFileRead { chunk ->
                    println("chunk size = ${chunk.size}")
                }
            }
        }

        val launcher = rememberFilePickerLauncher { file ->
            file?.let { filePath = file.path }
        }

        Column(
            modifier = Modifier
                .background(MaterialTheme.colorScheme.primaryContainer)
                .safeContentPadding()
                .fillMaxSize(),
            horizontalAlignment = Alignment.CenterHorizontally,
        ) {
            Button(onClick = { launcher.launch() }) {
                Text("Open file picker")
            }

            Button(onClick = ::test) {
                Text("Read file")
            }
        }
    }
}

[T8RIN]

Which file are you selecting btw? Could you try picking an image

[T8RIN]

Also i'm experienced this on ios 26

[vinceglb]

I tried tiny and large files, .txt, .pdf, jpg, .mp4. I'm on iOS 26.2.1.

I also tried to pick using the file picker and the gallery picker: same result.

[T8RIN]

Maybe problem was in my wrapper function? Which i attached too?

[vinceglb]

I copy/pasted chunkedFileRead from your issue, and it works fine. I can see the logs "chunk size = 1024" and the last chunk that is lower like "chunk size = 161", that is correct.

[T8RIN]

I mean rememberDocumentPicker