[RFC][BZ #11064] Warn when ldconfig encounters ambiguous SONAME.

[OndÅej BÃlka <neleai at seznam dot cz>]

Hi,

This adds warning when there are two libraries that conflict in soname.

For simplicity I check that link was created before a ldconfig started
running and report ambiguity otherwise. 

Comments?

diff --git a/elf/ldconfig.c b/elf/ldconfig.c
index 21da007..ea039aa 100644
--- a/elf/ldconfig.c
+++ b/elf/ldconfig.c
@@ -460,6 +460,8 @@ create_links (const char *real_path, const char *path, const char *libname,
   struct stat64 stat_lib, stat_so, lstat_so;
   int do_link = 1;
   int do_remove = 1;
+  static int first = 1;
+  struct stat64 first_stat;
   /* XXX: The logics in this function should be simplified.  */
 
   /* Get complete path.  */
@@ -512,17 +514,37 @@ create_links (const char *real_path, const char *path, const char *libname,
     {
       /* Remove old link.  */
       if (do_remove)
-	if (unlink (real_full_soname))
-	  {
-	    error (0, 0, _("Can't unlink %s"), full_soname);
-	    do_link = 0;
-	  }
+        {
+
+	  /* Check if we create duplicate symlink.  */
+	  if (!first && !lstat64 (full_soname, &lstat_so))
+	    if (lstat_so.st_mtim.tv_sec > first_stat.st_mtim.tv_sec ||
+		(lstat_so.st_mtim.tv_sec == first_stat.st_mtim.tv_sec &&
+		 lstat_so.st_mtim.tv_nsec >= first_stat.st_mtim.tv_nsec))
+		   {
+		     error (0, 0, _("Ambiguous link from %s to %s"),
+			    full_soname, libname);
+		     do_link = 0;
+		   }
+
+	  if (unlink (real_full_soname))
+	    {
+	      error (0, 0, _("Can't unlink %s"), full_soname);
+	      do_link = 0;
+	    }
+	}
       /* Create symbolic link.  */
       if (do_link && symlink (libname, real_full_soname))
 	{
 	  error (0, 0, _("Can't link %s to %s"), full_soname, libname);
 	  do_link = 0;
 	}
+
+      /* Get timestamp of first change.  */
+      if (first)
+	if (!lstat64 (real_full_soname, &first_stat))
+	  first = 0;
+
       if (opt_verbose)
 	{
 	  if (do_link)