[I9500][Discussion]Libraries, are we using all? - Galaxy S 4 Developer Discussion [Developers-Only]

I9500 firmwares come with around 380mb full of libraries. I know, we need most of them in order to make sensors and innovative applications work. But the question is, are they all needed? I believe we can slim out the firmware by removing possible unwanted libraries..

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Rahulrulez said:
I9500 firmwares come with around 380mb full of libraries. I know, we need most of them in order to make sensors and innovative applications work. But the question is, are they all needed? I believe we can slim out the firmware by removing possible unwanted libraries..
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I would like to know this as well. I've tried to remove some of them that I thought shouldn't be used, but it caused problems with some apps... FC's, bootloops in some cases...
Would love to have someone that knows enough about it explain how they go about removing libraries properly or even how to go about determining what apps rely on what libraries... if that's at all possible.

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Unknownforce said:
I would like to know this as well. I've tried to remove some of them that I thought shouldn't be used, but it caused problems with some apps... FC's, bootloops in some cases...
Would love to have someone that knows enough about it explain how they go about removing libraries properly or even how to go about determining what apps rely on what libraries... if that's at all possible.
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We can do this with a little bit of grep magic.
Any time a shared object is loaded it is loaded by calling the function:
Code:
Ljava/lang/System;->loadLibrary(Ljava/lang/String;)V
If we baksmali/decomple all of the apks in question into folders we can search for all of the loadlibrary calls.
We can look for this using this command:
Code:
grep -r 'loadLibrary' ./path/to/RomFolder
In following examples I will use './' as the path. Which, in this case, is whatever the current folder is.
This just gives us a list of the files that we need to look into to see which libraries are called.
Let's look for the line with the string constant that is passed into the function by using the -B argument (show lines before the matching line):
Code:
grep -r -B 2 'loadLibrary' ./
Note: The Library name CAN be stored in the string resources, or passed another way. If you see a result at this stage that is not a string literal, you may need to look there.
Okay, so now we have a list of function names, but our output is a bit messy. Let's pipe it to grep one more time so that we can filter out the stuff that is not useful.
Code:
grep -r -B 2 'loadLibrary' ./ | grep 'const-string .*["]'
Now that's better, but we still have a lot of duplicates. We can use the sort command's -u switch to only show unique entries. (Note: this will not display any result until the command has fully completed.)
Code:
grep -r -B 2 'loadLibrary' ./ | grep 'const-string .*["]' | sort -u
And of course, we can pipe that to a file so that we can save the results.
Code:
grep -r -B 2 'loadLibrary' ./ | grep 'const-string .*["]' | sort -u > functions.txt

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Awesome write up. Thanks bud! :good:
Sent from my SPH-L720 using xda app-developers app

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Amazing. Now all we need is to decompile all the apks and list out which libraries are being used..

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Rahulrulez said:
Amazing. Now all we need is to decompile all the apks and list out which libraries are being used..
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When I get some time, I'm gonna write a script to go through a folder of apk's decompile them all, one at a time, pull the list of necessary libraries, append that to a text file, then delete the output (so that it doesn't burn up my mini Virtual Box's hard drive ) Then maybe put it all together in a comprehensible list of all libraries and list out all the apk's that use it. Maybe something on a Google Doc in like a spreadsheet or something.

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Unknownforce said:
When I get some time, I'm gonna write a script to go through a folder of apk's decompile them all, one at a time, pull the list of necessary libraries, append that to a text file, then delete the output (so that it doesn't burn up my mini Virtual Box's hard drive ) Then maybe put it all together in a comprehensible list of all libraries and list out all the apk's that use it. Maybe something on a Google Doc in like a spreadsheet or something.
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Yes. I already have SGS4 app information database spreadsheet. People are really helping out. I can make the script too.. but only when I get some time from my job

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Rahulrulez said:
Yes. I already have SGS4 app information database spreadsheet. People are really helping out. I can make the script too.. but only when I get some time from my job
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This script could easily be enhanced to loop forever through multiple .apk files passed as an argument using the shift command.
Don't forget to chmod this file with +x
ListReqs.sh
Code:
#!/bin/sh
# This Script will use apktool to decompile a single .apk file passed as an argument, and grep for library files that are loaded.
# replace apktool with java -jar /path/to/apktool.jar if you don't have a launcher script set up for it in path.
# You could also just as easily replace apktool d with baksmali, so as not to waste time decompiling resources.
apktool d $1 $1.out
grep -r -B 2 'loadLibrary' $1.out | grep 'const-string .*["]' | sort -u > $1.txt
rm -R $1.out
Usage:
Code:
find -name '*.apk' ./ -exec /path/to/ListReqs.sh {} \;