termux-elf-cleaner

Utility for Android ELF files to remove unused parts that the linker warns about.

Description

When loading ELF files, the Android linker warns about unsupported dynamic section entries with warnings such as:

WARNING: linker: /data/data/org.kost.nmap.android.networkmapper/bin/nmap: unused DT entry: type 0x6ffffffe arg 0x8a7d4
WARNING: linker: /data/data/org.kost.nmap.android.networkmapper/bin/nmap: unused DT entry: type 0x6fffffff arg 0x3

This utility strips away the following dynamic section entries:

• DT_RPATH - not supported in any Android version.
• DT_VERDEF - supported from Android 6.0.
• DT_VERDEFNUM - supported from Android 6.0.
• DT_VERNEEDED - supported from Android 6.0.
• DT_VERNEEDNUM - supported from Android 6.0.
• DT_VERSYM - supported from Android 6.0.

It also removes the three ELF sections of type:

• SHT_GNU_verdef
• SHT_GNU_verneed
• SHT_GNU_versym

It no longer strips:

• DT_RUNPATH - supported from Android 7.0.

as Termux uses RUNPATH to hardcode /usr/lib into ELF files. Termux was previously setting LD_LIBRARY_PATH=/usr/lib, which had the ugly consequence that libraries such as /usr/lib/liblzma.so (Termux) clashed with /system/lib64/liblzma.so (Android), resulting in native Android programs (am, pm) being unable to link properly when LD_LIBRARY_PATH contained the Termux /usr/lib. With this fix, setting LD_LIBRARY_PATH is no longer needed.

Usage

usage: termux-elf-cleaner <filenames>

Processes ELF files to remove unsupported section types and
dynamic section entries which the Android linker warns about.

Author

Fredrik Fornwall (@fornwall).