[pacman-dev] [PATCH] makepkg: libprovides: don't provide both versioned and unversioned sonames

[Allan McRae]

On 15/5/20 3:05 am, Eli Schwartz wrote:
> If multiple files match the pattern libfoo.so*, we want to check each of
> them and see if they are shared libraries, and if so, if they have
> versions attached.
> 
> But some packages can have both shared libraries and random files which
> match the filename pattern. This is true at least for files in
> /usr/share/gdb/auto-load/, which must match the filename they are paired
> with, followed by "-gdb.py" (or some other gdb scripting ext), but
> definitely don't contain a shared library. In this case, we don't want
> to double-report the library in the generated provides.
> 
> It's also possible (probably) for a package to provide a versioned as
> well as an unversioned shared library, but in such cases a single
> provides entry is sufficient to cover both cases (and the libdepends
> for the depending package would contain an unversioned dependency).
> 
> Solve this by keeping track of whether we have added a versioned soname
> provides already, and then only adding a maximum of one unversioned
> provides *iff* there isn't a versioned one yet.
> 
> Signed-off-by: Eli Schwartz <eschwartz at archlinux.org>
> ---


This patch is fine, but I don't like "newp" as a variable name.  It will
not help me understand this in a years time.

How about versioned_provides=() instead?

> 
> Notes:
>     Currently we only have gdb/auto-load/ scripts for shared libraries in:
>     - gcc
>     - glib2
>     - gstreamer
>     - efl
>     
>     In the first 3 cases, libprovides is entirely useless anyway.
>     
>     libstdc++ is perpetually stable (backwards-compatible ABI) just like glibc.

Except when it did get an soname bump...  Those were the days!

>     glib2 actually does use libprovides, despite that it makes no sense for glib2
>     to libprovide anything, as the glib2 developers have this thing where they
>     always use a soname of "0" and bump ABI versions by changing libglib-2.0.so to
>     libglib-3.0.so -- as a result if you want to track dependencies you need to
>     change to a different soname manually, and might as well just depend on the
>     package itself (which already has a version in the pkgname).
>     
>     (gstreamer is in the same boat as glib2 because it is part of the same ecosystem.)
>     
>     efl doesn't currently libprovide "libeo.so", but if it did, then the issue
>     would exist and be fixed by this patch. And more generally, any project wishing
>     to implement gdb/auto-load/ scripts could have this issue, so it makes sense to
>     make it work nicely.
> 
>  scripts/makepkg.sh.in | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/scripts/makepkg.sh.in b/scripts/makepkg.sh.in
> index d1416d15..3f746b77 100644
> --- a/scripts/makepkg.sh.in
> +++ b/scripts/makepkg.sh.in
> @@ -516,9 +516,10 @@ find_libdepends() {
>  
>  
>  find_libprovides() {
> -	local p libprovides missing
> +	local p newp libprovides missing
>  	for p in "${provides[@]}"; do
>  		missing=0
> +		newp=()
>  		case "$p" in
>  			*.so)
>  				mapfile -t filename < <(find "$pkgdir" -type f -name $p\*)
> @@ -531,7 +532,6 @@ find_libprovides() {
>  							local sofile=$(LC_ALL=C readelf -d "$fn" 2>/dev/null | sed -n 's/.*Library soname: \[\(.*\)\].*/\1/p')
>  							if [[ -z "$sofile" ]]; then
>  								warning "$(gettext "Library listed in %s is not versioned: %s")" "'provides'" "$p"
> -								libprovides+=("$p")
>  								continue
>  							fi
>  
> @@ -541,25 +541,25 @@ find_libprovides() {
>  							# extract the library major version
>  							local soversion="${sofile##*\.so\.}"
>  
> -							libprovides+=("${p}=${soversion}-${soarch}")
> +							newp+=("${p}=${soversion}-${soarch}")
>  						else
>  							warning "$(gettext "Library listed in %s is not a shared object: %s")" "'provides'" "$p"
> -							libprovides+=("$p")
>  						fi
>  					done
>  				else
> -					libprovides+=("$p")
>  					missing=1
>  				fi
>  				;;
> -			*)
> -				libprovides+=("$p")
> -				;;
>  		esac
>  
>  		if (( missing )); then
>  			warning "$(gettext "Cannot find library listed in %s: %s")" "'provides'" "$p"
>  		fi
> +		if (( ${#newp[@]} > 0 )); then
> +			libprovides+=("${newp[@]}")
> +		else
> +			libprovides+=("$p")
> +		fi
>  	done
>  
>  	(( ${#libprovides[@]} )) && printf '%s\n' "${libprovides[@]}"
>