MuntashirAkon/AppManager · error · IOException

+ path + cannot be opened for both reading.

Error message

+ path + cannot be opened for both reading.

What it means

VirtualFileSystem.openChannel(path, mode) throws this IOException when mode requires read and checkAccess(path, OsConstants.R_OK) fails — the path is not readable. Note the message string itself has a copy-paste bug ("cannot be opened for both reading."), but the condition is the read-only branch of the access pre-flight.

Source

Thrown at app/src/main/java/io/github/muntashirakon/io/fs/VirtualFileSystem.java:1009

    @NonNull
    public FileChannel openChannel(String path, int mode) throws IOException {
        boolean read = false;
        boolean write = false;
        if ((mode & MODE_READ_WRITE) != 0) {
            read = true;
            write = true;
        } else if ((mode & MODE_READ_ONLY) != 0) {
            read = true;
        } else if ((mode & MODE_WRITE_ONLY) != 0) {
            write = true;
        } else {
            throw new IllegalArgumentException("Bad mode: " + mode);
        }

        if (read && write && !checkAccess(path, OsConstants.R_OK | OsConstants.W_OK)) {
            throw new IOException(path + " cannot be opened for both reading and writing.");
        } else if (read && !checkAccess(path, OsConstants.R_OK)) {
            throw new IOException(path + " cannot be opened for both reading.");
        } else if (write && !checkAccess(path, OsConstants.W_OK)) {
            throw new IOException(path + " cannot be opened for both writing.");
        }
        Node<?> targetNode = getNode(path);
        if (targetNode == null) {
            throw new FileNotFoundException(path + " does not exist.");
        }
        if (!targetNode.isFile()) {
            throw new IOException(path + " is not a file.");
        }
        return FileSystemManager.getLocal().openChannel(getCachedFile(targetNode, write), mode);
    }

    @NonNull
    public ParcelFileDescriptor openFileDescriptor(String path, int mode) throws IOException {
        boolean read = false;
        boolean write = false;
        if ((mode & MODE_READ_WRITE) != 0) {

View on GitHub (pinned to 0152f468fc)

Solutions

1. Confirm the path is readable via checkAccess(path, R_OK) before opening
2. Request the needed host-OS permissions or use a provider/mount with read access
3. If root/privileged access is expected, verify the privileged mount is actually active
4. If the file should be writable, note you still need read permission for read-write mode

Example fix

// before
FileChannel ch = vfs.openChannel("/data/data/other.app/db", MODE_READ_ONLY); // no read access
// after
if (!vfs.checkAccess(path, OsConstants.R_OK)) {
    requestAccessOrEscalate(path); // e.g. root/SAF flow
}
FileChannel ch = vfs.openChannel(path, MODE_READ_ONLY);

boolean readable = vfs.checkAccess(path, OsConstants.R_OK);

try {
    FileChannel ch = vfs.openChannel(path, MODE_READ_ONLY);
} catch (IOException e) {
    // trigger permission/privilege acquisition flow
}

When it happens

Trigger: Calling openChannel with MODE_READ_ONLY (or MODE_READ_WRITE where the read check fails first... it does not — this branch is read-only) on a file the caller cannot read: restricted directory, permission bits, or a provider denying reads.

Common situations: Reading another app's private files without root; file with 0600 owned by a different UID; SELinux/AppArmor restriction on the backing path; broken provider authorization.

Understand the failure class

Background: Permission denied / not authorized / 403 Forbidden: access-control rejections when the caller lacks the required role, grant, or ownership — this error's family across 18 libraries.

Related errors

• + path + does not exist.
• + path + is not a file.
• Bad mode: + mode
• + path + cannot be opened for both reading and writing.
• + path + cannot be opened for both writing.

AI-assisted analysis of MuntashirAkon/AppManager@0152f468fc (2026-09-12). Data as JSON: /api/errors/9a032359ad3882ac. Report an issue: GitHub.