[Android] sqlcipher_mlock: mlock() error logs

[almozavr]

Issue

We see numerous logcat messages:
sqlcipher D sqlcipher_mlock: mlock() returned -1 errno=12

DB itself looks like it works normally.

Env

• module: "net.zetetic:sqlcipher-android"
• version: 4.6.0, 4.6.1
• room: 2.6.1
• android 14

[developernotes]

Hi @almozavr,

The output you are now seeing is due to changes in SQLCipher, and likely Android. Logging in SQLCipher was previously disabled, however, starting in SQLCipher 4.6.0 ¹, both ERROR and WARN log messages will be emitted. With the release of SQLCipher 4.6.1 ², we added the ability to filter log sources via PRAGMA cipher_log_source ³.

With the release of Android 14, the mlock() implementation drastically reduced the maximum allocation size per process from 64 MB down to 64 KB ⁴. This is likely the culprit that is triggering the errors you are seeing now.

Given this information, if you are using PRAGMA cipher_memory_security = ON;, you may wish to disable that as it will cause all allocations within SQLCipher to attempt memory locking which would further increase the level of error logging you may see. The default for PRAGMA cipher_memory_security is off.

In the future, we plan to investigate whether an alternative memory allocation strategy can minimize memory locking errors.

Footnotes

1. https://www.zetetic.net/blog/2024/05/21/sqlcipher-4.6.0-release/ ↩

2. https://www.zetetic.net/blog/2024/08/20/sqlcipher-4.6.1-release/ ↩

3. https://www.zetetic.net/sqlcipher/sqlcipher-api/#cipher_log_source ↩

4. https://developer.android.com/about/versions/14/behavior-changes-all#mlock ↩