LSPosed/LSPosed · error · IllegalArgumentException

Length ${length} is out of range for ${filename}

Error message

Length ${length} is out of range for ${filename}

What it means

The same ranged readFile method in DirectAccessService throws IllegalArgumentException when offset + length exceeds the file size (line 99). The implementation allocates byte[length] and does a single fis.read(content), so a length running past EOF would silently return a short read; the API rejects it up front instead.

Source

Thrown at core/src/main/java/de/robv/android/xposed/services/DirectAccessService.java:100

        if (length > 0 && (offset + length) > size) {
            throw new IllegalArgumentException("Length " + length + " is out of range for " + filename);
        } else if (length <= 0) {
            length = (int) (size - offset);
        }

View on GitHub (pinned to df74d83eb0)

Solutions

1. Query statFile first and clamp length to (int)(size - offset)
2. Pass length <= 0 to mean 'rest of the file' — the implementation then computes length = size - offset itself
3. If chunking large files, compute each chunk from the fresh size, not a cached one

Example fix

// before
FileResult r = service.readFile(path, offset, 4096, prevSize, prevTime);

// after
FileResult st = service.statFile(path);
int len = (int) Math.min(4096, st.size - offset);
FileResult r = service.readFile(path, offset, len, st.size, st.mtime);

FileResult st = service.statFile(filename);
if (length > st.size - offset) {
    length = (int) (st.size - offset); // clamp to EOF
}

try {
    return service.readFile(filename, offset, length, prevSize, prevTime);
} catch (IllegalArgumentException e) {
    if (e.getMessage() != null && e.getMessage().startsWith("Length")) {
        return service.readFile(filename, offset, 0, prevSize, prevTime); // length<=0 = rest of file
    }
    throw e;
}

When it happens

Trigger: Calling readFile(path, offset, length, prevSize, prevTime) with length > size - offset, e.g. offset=10, length=100 on a 50-byte file, or when the file shrank between stat and read.

Common situations: Hardcoded chunk sizes for reading structured files whose actual size is smaller than expected; reading with stale cached length after the file was truncated.

Related errors

• Offset ${offset} is out of range for ${filename}
• Error ${errno}${defaultText}${filename}
• hooker should not be null!
• Hooker should be annotated with @XposedHooker
• BeforeInvocation method format is invalid

AI-assisted analysis of LSPosed/LSPosed@df74d83eb0 (2026-08-14). Data as JSON: /api/errors/5c44490ecb905989. Report an issue: GitHub.