dpkg-shlibdeps: Add new -I option to ignore package build directories

This option can be used to completely ignore local package build trees,
for example in cases where've got multiple compatible builds of the same
shared library, which provide use the same SONAME, and we want all our
local objects to use the same single library instead of whatever came
first. Using -x in the above case does not work, because that just
removes the dependency after processing, so we end up with missing
dependencies.

Closes: #821025

debian/changelog

@@ -77,6 +77,8 @@ dpkg (1.18.5) UNRELEASED; urgency=medium
   * Add support for a new --build option to define build type by a
     comma-separated list of components (“source”, “any”, “all”, “binary” or
     “full”) in dpkg-genchanges and dpkg-buildpackage.
+  * Add new -I option to dpkg-shlibdeps to ignore package build directories.
+    Closes: #821025
   * Portability:
     - Move DPKG_ADMINDIR environment variable name out from update-alternatives
       code, to make life easier for non-dpkg-based systems.

man/dpkg-shlibdeps.1

@@ -232,6 +232,11 @@ and you want to ensure that you get the dependency from a given binary
 package. You can use this option multiple times: directories will be
 tried in the same order before directories of other binary packages.
 .TP
+.BI \-I package-build-dir
+Ignore \fIpackage-build-dir\fP when looking for shlibs, symbols, and shared
+library files (since dpkg 1.18.5).
+You can use this option multiple times.
+.TP
 .BI \-\-ignore\-missing\-info
 Do not fail if dependency information can't be found for a shared library
 (since dpkg 1.14.8).

scripts/dpkg-shlibdeps.pl

@@ -71,15 +71,10 @@ my $warnings = WARN_SYM_NOT_FOUND | WARN_DEP_AVOIDABLE;
 my $debug = 0;
 my @exclude = ();
 my @pkg_dir_to_search = ();
+my @pkg_dir_to_ignore = ();
 my $host_arch = get_host_arch();
 
 my (@pkg_shlibs, @pkg_symbols, @pkg_root_dirs);
-if (-d 'debian') {
-    push @pkg_symbols, glob 'debian/*/DEBIAN/symbols';
-    push @pkg_shlibs, glob 'debian/*/DEBIAN/shlibs';
-    my %uniq = map { guess_pkg_root_dir($_) => 1 } (@pkg_symbols, @pkg_shlibs);
-    push @pkg_root_dirs, keys %uniq;
-}
 
 my ($stdout, %exec);
 foreach (@ARGV) {
@@ -93,6 +88,8 @@ foreach (@ARGV) {
 	Dpkg::Shlibs::add_library_dir($1);
     } elsif (m/^-S(.*)$/) {
 	push @pkg_dir_to_search, $1;
+    } elsif (m/^-I(.*)$/) {
+	push @pkg_dir_to_ignore, $1;
     } elsif (m/^-O$/) {
 	$stdout = 1;
     } elsif (m/^-O(.+)$/) {
@@ -146,6 +143,18 @@ foreach (@ARGV) {
 }
 usageerr(g_('need at least one executable')) unless scalar keys %exec;
 
+sub ignore_pkgdir {
+    my $path = shift;
+    return any { $path =~ /^\Q$_\E/ } @pkg_dir_to_ignore;
+}
+
+if (-d 'debian') {
+    push @pkg_symbols, grep { !ignore_pkgdir($_) } glob 'debian/*/DEBIAN/symbols';
+    push @pkg_shlibs, grep { !ignore_pkgdir($_) } glob 'debian/*/DEBIAN/shlibs';
+    my %uniq = map { guess_pkg_root_dir($_) => 1 } (@pkg_symbols, @pkg_shlibs);
+    push @pkg_root_dirs, keys %uniq;
+}
+
 my $control = Dpkg::Control::Info->new();
 my $fields = $control->get_source();
 my $bd_value = deps_concat($fields->{'Build-Depends'}, $fields->{'Build-Depends-Arch'});
@@ -563,7 +572,9 @@ sub usage {
   -t<type>                 set package type (default is deb).
   -x<package>              exclude package from the generated dependencies.
   -S<package-build-dir>    search needed libraries in the given
-                           package build directory first.
+                             package build directory first.
+  -I<package-build-dir>    ignore needed libraries, shlibs and symbols files
+                             in the given build directory.
   -v                       enable verbose mode (can be used multiple times).
   --ignore-missing-info    don't fail if dependency information can't be found.
   --warnings=<value>       define set of active warnings (see manual page).
@@ -806,7 +817,10 @@ sub my_find_library {
     # - package build tree of the binary which is analyzed
     # - package build tree given on the command line (option -S)
     # - other package build trees that contain either a shlibs or a
-    # symbols file
+    #   symbols file
+    # But ignore:
+    # - package build tree given on the command line (option -I)
+
     my @builddirs;
     my $pkg_root = guess_pkg_root_dir($execfile);
     push @builddirs, $pkg_root if defined $pkg_root;
@@ -815,6 +829,7 @@ sub my_find_library {
     my %dir_checked;
     foreach my $builddir (@builddirs) {
 	next if defined($dir_checked{$builddir});
+	next if ignore_pkgdir($builddir);
 	$file = find_library($lib, \@RPATH, $format, $builddir);
 	return $file if defined($file);
 	$dir_checked{$builddir} = 1;