[pacman-dev] [RFC] Find real library names with libdepends/libprovides

[Mohammad_Alsaleh]

I'm going to reply here before going into details about the individual
patches if that's okay.

On Wed, May 08, 2013 at 07:59:53PM -0400, Dave Reisner wrote:
> On Thu, May 09, 2013 at 12:15:27AM +0300, Mohammad Alsaleh wrote:
> > 
> >   makepkg only handles libprovides/libdepends correctly if the naming
> >   scheme is:
> > 
> >     lib${name}.so --> lib$name.so.$ver
> > 
> >   But it is not uncommon for libname.so to link to a '.so' file that
> >   does not follow this naming scheme. For example, these 2 schemes are
> >   sometimes used:
> >     lib$name.so --> libname$major.$major.$minor
> >     lib$name.so --> libname-$major.$major.$minor
> > 
> >   There exists other schemes.
> 
> Can you point out where these exist in the wild? They're hugely
> non-conformant, and glibc's ldconfig won't even read these files without
> specific nudging. I'm not sure how other implementations behave.
> 

Attaching a small script that should list all cases in '/usr/lib'.
There are 72 library names detected by this script in my system.

Actually, I came across this when I wanted to suggest adding libprovides
to popular libraries after libpng's upgrade. And when I tested adding
'libpng.so' to provides. I discovered that current code in makepkg
wouldn't work.

Investigating this further, I discovered that libpng is not a corner
case as shown by the output of the small script attached.

> > 
> >   With those cases, and before these patches, makepkg would add
> >   lib$name.so to provides unversioned and display a warning.
> > 
> >   And if another package adds lib$name.so as a dependency, the build
> >   will succeed and only a warning will be displayed.
> > 
> >   Not only makepkg fails to find version/arch for libraries in those
> >   scenarios. But the success of builds in both provide/depend sides
> >   might give the illusion that versioned sodepends are actually honored.
> > 
> >   If the idea behind these 2 patches is rejected. I would like to
> >   propose promoting the warning in find_libprovides() to an error.
> > 
> > [PATCH 1/2] makepkg: Search/Add real library names libprovide link to
> > [PATCH 2/2] makepkg: Search/Add real library names libdepend link to
> > 
> 
-------------- next part --------------
#!/bin/bash

cd /usr/lib

for library in *.so; do
	if [[ -h $library ]]; then
		full="$(basename $(realpath $library))"
		real=${full%.so*}.so
		if [[ "$real" != "$library"  ]]; then
			printf "$library --> $full"
			# Assuming all links/files reside in /usr/lib
			if [[ -e "$real"  ]]; then
				printf "  ($real exists)\n"
			else
				printf "  ($real does not exist)\n"
			fi
		fi
	fi
done