ENH: Improve linking to third-party shared libraries on soname platforms

  - Reduce false positives in cases of unknown soname
  - Make library extension regular expressions match only at end of string
  - When linking to libraries in implicit dirs convert to the -l option
    only if the file name is one that can be found by the linker
    (ex. /usr/lib/libfoo.so.1 should be linked by full path)
  - Add cmSystemTools::GuessLibrarySOName to guess the soname of a
    library based on presence of a symlink
  - In cmComputeLinkInformation try to guess an soname before assuming
    that a third-party library is built without an soname
  - In cmOrderDirectories guess the soname of shared libraries in cases
    it is otherwise unknown

1 files changed, 31 insertions, 0 deletions

diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 002dc0b..8d13e11 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -2150,3 +2150,34 @@ void cmSystemTools::MakefileColorEcho(int color, const char* message,
     }
 }
 #endif
+
+//----------------------------------------------------------------------------
+bool cmSystemTools::GuessLibrarySOName(std::string const& fullPath,
+                                       std::string& soname)
+{
+  // If the file is not a symlink we have no guess for its soname.
+  if(!cmSystemTools::FileIsSymlink(fullPath.c_str()))
+    {
+    return false;
+    }
+  if(!cmSystemTools::ReadSymlink(fullPath.c_str(), soname))
+    {
+    return false;
+    }
+
+  // If the symlink has a path component we have no guess for the soname.
+  if(!cmSystemTools::GetFilenamePath(soname).empty())
+    {
+    return false;
+    }
+
+  // If the symlink points at an extended version of the same name
+  // assume it is the soname.
+  std::string name = cmSystemTools::GetFilenameName(fullPath);
+  if(soname.length() > name.length() &&
+     soname.substr(0, name.length()) == name)
+    {
+    return true;
+    }
+  return false;
+}