1 ## fdsan  section
5 fdsan is a file descriptor sanitizer added to Android in API level 29.
6 In API level 29, fdsan warns when it finds a bug.
7 In API level 30, fdsan aborts when it finds a bug.
10 *What problem is fdsan trying to solve? Why should I care?*  argument
12 fdsan (file descriptor sanitizer) detects mishandling of file descriptor ownership, which tend to m…
45 *What does fdsan do?*  argument
47 fdsan attempts to detect and/or prevent file descriptor mismanagement by enforcing file descriptor …
49 …dan_owner_type` in [`<android/fdsan.h>`](https://android.googlesource.com/platform/bionic/+/main/l…
53 ### Enabling fdsan (as a user)  argument
54 *How do I use fdsan?*
56 fdsan has four severity levels:
59 …r, emit a warning to logcat, generate a tombstone, and then continue execution with fdsan disabled.
65 …fdsan has a global default of warn-once. fdsan can be made more or less strict at runtime via the …
67 The likelihood of fdsan catching a file descriptor error is proportional to the percentage of file …
69 ### Using fdsan to fix a bug  argument
70 *No, really, how do I use fdsan?*
140 …t for us. Let's use `android::base::unique_fd` in `victim` to guard the file descriptor with fdsan:
162 Now that we've guarded the file descriptor with fdsan, we should be able to find where the double c…
190 …(hopefully!) not a bug in fdsan, and will commonly be seen when tracking down double-closes in pro…
231 …s our toy example, which is a good reason to try to maximize the usage of fdsan-enabled types like…
233 ### Enabling fdsan (as a C++ library implementer)  argument
235 fdsan operates via two main primitives. `android_fdsan_exchange_owner_tag` modifies a file descript…
268 #include <android/fdsan.h>
369    * Solution: ¯\\\_(ツ)\_/¯. Use fdsan?  argument