[Libguestfs] [PATCH 2/3] lib: improve libdb tools handling at runtime (RHBZ#1409024)

[Pino Toscano]

When built with support for libdb tools (i.e. db_dump was found at
configure time), check for the existance of the db_dumb tool before
attempting to use it: this way the libdb tools can stay an optional
dependency at runtime, and their lack just gives no information on the
applications installed in an RPM-based distro.

Since we don't need the absolute path of db_dumb (nor db_load, used only
in tests), change the GUESTFS_FIND_DB_TOOL m4 macro to give the names
instead.
---
 m4/guestfs-find-db-tool.m4 |  2 +-
 src/inspect-apps.c         | 14 ++++++++++++--
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/m4/guestfs-find-db-tool.m4 b/m4/guestfs-find-db-tool.m4
index ee20301..1026938 100644
--- a/m4/guestfs-find-db-tool.m4
+++ b/m4/guestfs-find-db-tool.m4
@@ -36,7 +36,7 @@ AC_DEFUN([GUESTFS_FIND_DB_TOOL],[
                 exe_list="$exe_list $exe"
             done
         done
-        AC_PATH_PROGS([]VARIABLE[], [$exe_list], [no])
+        AC_CHECK_PROGS([]VARIABLE[], [$exe_list], [no])
     ])
 
     popdef([VARIABLE])
diff --git a/src/inspect-apps.c b/src/inspect-apps.c
index b377f57..78c2711 100644
--- a/src/inspect-apps.c
+++ b/src/inspect-apps.c
@@ -22,6 +22,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
+#include <libintl.h>
 
 #ifdef HAVE_ENDIAN_H
 #include <endian.h>
@@ -109,6 +110,7 @@ guestfs_impl_inspect_list_applications2 (guestfs_h *g, const char *root)
 {
   struct guestfs_application2_list *ret = NULL;
   struct inspect_fs *fs = guestfs_int_search_for_root (g, root);
+  int r;
   if (!fs)
     return NULL;
 
@@ -122,9 +124,17 @@ guestfs_impl_inspect_list_applications2 (guestfs_h *g, const char *root)
       switch (fs->package_format) {
       case OS_PACKAGE_FORMAT_RPM:
 #ifdef DB_DUMP
-        ret = list_applications_rpm (g, fs);
-        if (ret == NULL)
+        r = guestfs_int_find_cmd (g, DB_DUMP, NULL);
+        if (r < 0)
           return NULL;
+        if (r == 0) {
+          debug (g, _("inspection of RPM database cannot be done, as %s is not available"),
+                    DB_DUMP);
+        } else {
+          ret = list_applications_rpm (g, fs);
+          if (ret == NULL)
+            return NULL;
+        }
 #endif
         break;
 
-- 
2.7.4