Android/bionic support

[tathastu871]

if possible patch use of backtrace and prevent using execinfo.h needed
Trying to compile and include shournal in termux official repo

[tycho-kirchner]

Hi. This should be possible, but would you mind telling me what exactly your platform is? (;
execinfo.h seems to be part of (g)libc on Linux, so I guess it should be available.

[tathastu871]

Hi. This should be possible, but would you mind telling me what exactly your platform is? (; execinfo.h seems to be part of (g)libc on Linux, so I guess it should be available.

Termux
aarch64 on bionic(android)

Wrapping the execinfo.h in

#ifndef __ANDROID__ 
#include <execinfo.h>
#endif 

is current workaround being used for other packages that were built. But in shournal it was producing unidentified/undefined backtrace functions.

Hence developers of termux recommened to patch program to not use execinfo.h and backtrace related functions.

[tathastu871]

Since smartphones are faster than laptops nowadays with octa core most people use termux as desktop linux replacement.

Linux applications can either be used directly on termux by compiling them as aarch64 and linking with bionic. Or inside proot distros like ubuntu-termux, arch-termux as arm64 binaries.

Hence having shournal on termux is quite beneficial

[tathastu871]

See this patch https://wiki.termux.com/images/9/9d/OF_5.0_termux.patch all execinfo and backtrace and related functions are enclosed within #ifndef __ANDROID__ .. #endif

[tycho-kirchner]

Wow. Haven't considered porting shournal to Android yet. Just checked: at least fanotify seems to be available in bionic: ./libc/kernel/uapi/linux/fanotify.h.
I suspect this is only the tip of the iceberg of compilation problems (did you check?), so if the port is within scope I'd perform that as a common patch series. Would you like to support?

[tathastu871]

on termux gcc toolchain has many problems. although gcc 9,10,11 are available.
Hence all packages are built using clang as CC
Missing execinfo.h workaround:
src/common/util/util.cpp
Around line 211 is function that uses backtrace and execinfo.h enclose it entirely with if endif as shown above.
this seems to supress error.

Next error missing stdio_filebuf.h

[tycho-kirchner]

stdio_filebuf.h and referencing functions parseGenericKeyValFile, parseRealUidOf can be removed, they are not used.

[tathastu871]

/data/data/com.termux/files/home/home/shournal/shournal/src/common/stdiocpp.cpp:20:73: error: member access into incomplete type 'const FILE' (aka 'const __sFILE')
/data/data/com.termux/files/home/home/shournal/shournal/src/common/stdiocpp.cpp:81:12: error: no member named 'fgetc_unlocked' in the global namespace; did you mean simply 'fgetc_unlocked'?
/data/data/com.termux/files/home/home/shournal/shournal/src/common/stdiocpp.cpp:87:28: error: no member named 'fwrite_unlocked' in the global namespace; did you mean simply 'fwrite_unlocked'?
/data/data/com.termux/files/home/home/shournal/shournal/src/common/stdiocpp.cpp:107:12: error: no member named 'fread_unlocked' in the global namespace; did you mean simply 'fread_unlocked'?
4 errors generated.

[tycho-kirchner]

Those are simple. Use the locked ones instead (without _unlocked-suffix) (#ifndef __ANDROID__). I'm setting up an Android VM, so later I'll be able to test myself as well.

[tycho-kirchner]

Before digging further into this, could you please check the following points:

• is your kernel compiled with fanotify support?
• initializing fanotify requires CAP_SYS_ADMIN, which is normally implemented using a setuid-binary. Will Android
  sandboxing mechanisms allow for that?
• Otherwise/additionally shournal's kernel module may be ported as well, which again requires a rooted device (access to /sys). I'm not sure whether this is going to get too exhaustive here...

[tathastu871]

Another tool named fsmon with fanotify and inotify backends is properly working on termux.

[tycho-kirchner]

Another tool named fsmon with fanotify and inotify backends is properly working on termux.

Did you check? Reading this

* inotify (linux / android)
* fanotify (linux > 2.6.36 / android with custom kernel)

implies that while inotify works out of the box, fanotify requires a custom kernel (whatever that means).

See also this SO post.

[tathastu871]

Another tool named fsmon with fanotify and inotify backends is properly working on termux.

Did you check? Reading this

* inotify (linux / android)
* fanotify (linux > 2.6.36 / android with custom kernel)

implies that while inotify works out of the box, fanotify requires a custom kernel (whatever that means).

Root is required

[tycho-kirchner]

@tathastu871 I just check in my Android x86 virtual machine:

$ zgrep -i fanotify /proc/config.gz
# CONFIG_FANOTIFY is not set

Does your kernel include fanotify support? Otherwise I guess instead of compiling a custom kernel it
may be more feasible to rather use shournal's kernel module if and only if the kernel was compiled
with CONFIG_TRACEPOINTS=y and CONFIG_FTRACE=y. Is that the case on your machine?

[tathastu871]

Well my phone is not easily rootable so i cant test it. maybe termux developers can