Do not obliterate old rpath because it might be used due to read only data sharing. Closes #1619.

mesonbuild/scripts/depfixer.py

@@ -297,11 +297,20 @@ class Elf(DataSizes):
         old_rpath = self.read_str()
         if len(old_rpath) < len(new_rpath):
             sys.exit("New rpath must not be longer than the old one.")
-        self.bf.seek(rp_off)
-        self.bf.write(new_rpath)
-        self.bf.write(b'\0' * (len(old_rpath) - len(new_rpath) + 1))
+        # The linker does read-only string deduplication. If there is a
+        # string that shares a suffix with the rpath, they might get
+        # dedupped. This means changing the rpath string might break something
+        # completely unrelated. This has already happened once with X.org.
+        # Thus we want to keep this change as small as possible to minimize
+        # the chance of obliterating other strings. It might still happen
+        # but our behaviour is identical to what chrpath does and it has
+        # been in use for ages so based on that this should be rare.
         if len(new_rpath) == 0:
             self.remove_rpath_entry(entrynum)
+        else:
+            self.bf.seek(rp_off)
+            self.bf.write(new_rpath)
+            self.bf.write(b'\0')
 
     def remove_rpath_entry(self, entrynum):
         sec = self.find_section(b'.dynamic')

run_unittests.py

@@ -1460,6 +1460,28 @@ class LinuxlikeTests(BasePlatformTests):
         self.assertIn('-Werror', plain_comp)
         self.assertNotIn('-Werror', c03_comp)
 
+    def test_run_installed(self):
+        testdir = os.path.join(self.unit_test_dir, '7 run installed')
+        self.init(testdir)
+        self.build()
+        self.install()
+        installed_exe = os.path.join(self.installdir, 'usr/bin/prog')
+        installed_libdir = os.path.join(self.installdir, 'usr/foo')
+        installed_lib = os.path.join(installed_libdir, 'libfoo.so')
+        self.assertTrue(os.path.isfile(installed_exe))
+        self.assertTrue(os.path.isdir(installed_libdir))
+        self.assertTrue(os.path.isfile(installed_lib))
+        # Must fail when run without LD_LIBRARY_PATH to ensure that
+        # rpath has been properly stripped rather than pointing to the builddir.
+        self.assertNotEqual(subprocess.call(installed_exe, stderr=subprocess.DEVNULL), 0)
+        # When LD_LIBRARY_PATH is set it should start working.
+        # For some reason setting LD_LIBRARY_PATH in os.environ fails
+        # when all tests are run (but works when only this test is run),
+        # but doing this explicitly works.
+        env = os.environ.copy()
+        env['LD_LIBRARY_PATH'] = installed_libdir
+        self.assertEqual(subprocess.call(installed_exe, env=env), 0)
+
 class RewriterTests(unittest.TestCase):
 
     def setUp(self):

test cases/unit/7 run installed/foo/foo.c

@@ -0,0 +1,3 @@
+int foo() {
+    return 0;
+}

test cases/unit/7 run installed/foo/meson.build

@@ -0,0 +1,7 @@
+# Try to invoke linker constant string deduplication,
+# to ensure we are not clobbering shared strings.
+# Name everything possible just as "foo".
+foolib = shared_library('foo', 'foo.c',
+  install_dir : 'foo',
+  install : true)
+

test cases/unit/7 run installed/meson.build

@@ -0,0 +1,9 @@
+project('foo', 'c',
+  default_options : 'libdir=lib')
+
+subdir('foo')
+
+executable('prog', 'prog.c',
+  link_with : foolib,
+  install : true)
+

test cases/unit/7 run installed/prog.c

@@ -0,0 +1,5 @@
+int foo();
+
+int main(int argc, char **argv) {
+    return foo();
+}