On Debian/Ubuntu distributions, the standard for files in /usr/lib/debug does

From:  <>

not involve appending .debug to the filename.  It appears that the Fedora/RH
standard is to append .debug, which is what is currently implemented in
chronicle-query.  This patch rather simply adds an additional attempt to open
the debian-style standard before giving up.  The additional check should not
be dangerous, as Fedora/RH packages don't seem to install any files that would
match the second check attempt.

The documentation for the Debian policy is found here:
http://www.debian.org/doc/developers-reference/ch-best-pkging-practices.en.html#s-bpp-dbg
---

 chronicle/query/debug.c |   22 +++++++++++++++++++---
 1 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/chronicle/query/debug.c b/chronicle/query/debug.c
index 5bb92cc..65d6e2b 100644
--- a/chronicle/query/debug.c
+++ b/chronicle/query/debug.c
@@ -857,13 +857,29 @@ static CH_DbgDwarf2Object* load_dwarf2_for(int fd, const char* name) {
   if (obj)
     return obj;
 
-  /* fd was closed. Try to open external debug info. */
+  /* fd was closed. Try to open external debug info.  We use two simple
+     heuristics here because it is reasonably simple.  The official way
+     to do this is to look for a .gnu_debuglink section in an object,
+     but that still requires heuristics after the fact too, because you
+     have to know what path to look on; all it gives you are the filename
+     (no path) and a CRC32. */
+  /* on fedora/red hat platforms, debug packages are installed into
+     /usr/lib/debug with the same path as the actual binary and ".debug"
+     appended.  So /usr/bin/python2.5 becomes
+     /usr/lib/debug/usr/bin/python2.5.debug. */
   snprintf(buf, sizeof(buf), "/usr/lib/debug%s.debug", name);
   buf[sizeof(buf) - 1] = 0;
   fd = open(buf, O_RDONLY);
   if (fd < 0) {
-    errno = 0;
-    return NULL;
+    /* wasn't there, try the debian/ubuntu standard which is the same place
+       but we don't append ".debug" */
+    snprintf(buf, sizeof(buf), "/usr/lib/debug%s", name);
+    buf[sizeof(buf) - 1] = 0;
+    fd = open(buf, O_RDONLY);
+    if (fd < 0) {
+      errno = 0;
+      return NULL;
+    }
   }
   return dwarf2_load(fd, buf);
 }