Bug#461350: [shared-libs] Check for a missing libc dependency indicating ${shlibs:Depends} problems

[Niko Tyni <ntyni@debian.org>]

Package: lintian
Version: 1.23.42
Severity: wishlist
Tags: patch

As discussed in the debian-devel thread starting at

 http://lists.debian.org/debian-devel/2008/01/msg00612.html

it would be nice if lintian could check for binary packages containing
ELF files dynamically linked against libc.so.* without depending on the
corresponding libc* package.

The attached patch tries to be smart with the relation between the libc
package name and the library file. I'm not sure if this is too fragile:
if the assumption that libcXXX contains libc.so.XXX breaks, the check
will output an error for every package.

The alternative I see is to hardcode the libc names for each architecture,
which would be a (smallish) maintenance burden.

Note that there's an issue with -dbg packages and dh_shlibdeps (#461339)
that should possibly be taken into account here. I'm not sure how yet;
let's see what happens with the bug first.

Cheers,
-- 
Niko Tyni   ntyni@debian.org

diff --git a/checks/shared-libs b/checks/shared-libs
index ed1cf77..c77098b 100644
--- a/checks/shared-libs
+++ b/checks/shared-libs
@@ -74,6 +74,7 @@ my %SONAME;
 my %INTERP;
 my %STACK;
 my %TEXTREL;
+my %NEEDED;
 my %objsomething;
 my %sharedobject;
 my %index_info;
@@ -106,6 +107,8 @@ while (<IN>) {
 	$INTERP{$file} = 1;
     } elsif (m/^\s*STACK\s/) {
 	$STACK{$file} = 0;
+    } elsif (m/^\s*NEEDED\s+(\S+)/o) {
+        $NEEDED{$1} = $file;
     } else {
         if (defined $STACK{$file} and $STACK{$file} eq 0) {
 	    m/\sflags\s+(\S+)/o;
@@ -440,6 +443,42 @@ if (-f $preinst) {
     }
 }
 
+# 7th step: check libc dependency indicating broken ${shlibs:Depends} usage
+if (keys %NEEDED) {
+    my $depends = "";
+	if (open (DEPENDS, '<', 'fields/depends')) {
+	    $depends = <DEPENDS>;
+	    chomp $depends;
+	    close DEPENDS;
+	}
+    my $predepends = "";
+	if (open (PREDEPENDS, '<', 'fields/pre-depends')) {
+	    $predepends = <PREDEPENDS>;
+	    chomp $predepends;
+	    close PREDEPENDS;
+	}
+    $depends = Dep::parse($depends);
+    $predepends = Dep::parse($predepends);
+
+    my ($libc_filename, $libc_package);
+    for (keys %NEEDED) {
+        if (/^libc\.so\.(\d+.*)/) {
+            $libc_package  = "libc$1";
+            $libc_filename = $_;
+            last;
+        }
+    }
+
+    if (defined $libc_filename) {
+        my $elffile = $NEEDED{$libc_filename};
+        if ($elffile && ! (Dep::implies($depends,    Dep::parse($libc_package)) ||
+                           Dep::implies($predepends, Dep::parse($libc_package)))) {
+            tag "missing-dep-on-libc", $file;
+        }
+    }
+}
+
+
 my $we_call_postinst=0;
 if (-f $postinst) {
     local $_ = slurp_entire_file($postinst);
diff --git a/checks/shared-libs.desc b/checks/shared-libs.desc
index dfc4951..776a7e3 100644
--- a/checks/shared-libs.desc
+++ b/checks/shared-libs.desc
@@ -230,3 +230,16 @@ Info: Debian revisions should be stripped from versions in symbols files.
  be stripped because the symbol really appearead between two specific
  Debian revisions, you should postfix the version with a single "~"
  (example: 1.0-3~ if the symbol appeared in 1.0-3).
+
+Tag: missing-dep-on-libc
+Type: error
+Ref: policy 8.6
+Info: All shared libraries and compiled binaries must be run through
+ dpkg-shlibdeps to find out any libraries they are linked against, usually
+ with the dh_shlibdeps debhelper command.  The package containing these
+ files must use ${shlibs:Depends} to depend on the corresponding set
+ of packages.
+ .
+ The listed file is linked against the system C library, but the
+ package doesn't depend on the C library package. This indicates that
+ the ${shlibs:Depends} mechanism is not used correctly.