MINOR: debug: add ability to dump loaded shared libraries
Many times core dumps reported by users who experience trouble are
difficult to exploit due to missing system libraries. Sometimes,
having just a list of loaded libraries and their respective addresses
can already provide some hints about some problems.
This patch makes a step in that direction by adding a new "show libs"
command that will try to enumerate the list of object files that are
loaded in memory, relying on the dynamic linker for this. It may also
be used to detect that some foreign code embarks other undesired libs
(e.g. some external Lua modules).
At the moment it's only supported on glibc when USE_DL is set, but it's
implemented in a way that ought to make it reasonably easy to be extended
to other platforms.
diff --git a/src/debug.c b/src/debug.c
index 0561992..5accb0b 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -305,6 +305,21 @@
return 1;
}
+#if defined(HA_HAVE_DUMP_LIBS)
+/* parse a "show libs" command. It returns 1 if it emits anything otherwise zero. */
+static int debug_parse_cli_show_libs(char **args, char *payload, struct appctx *appctx, void *private)
+{
+ if (!cli_has_level(appctx, ACCESS_LVL_OPER))
+ return 1;
+
+ chunk_reset(&trash);
+ if (dump_libs(&trash, 1))
+ return cli_msg(appctx, LOG_INFO, trash.area);
+ else
+ return 0;
+}
+#endif
+
/* dumps a state of all threads into the trash and on fd #2, then aborts. */
void ha_panic()
{
@@ -1204,6 +1219,9 @@
{{ "debug", "dev", "sym", NULL }, "debug dev sym <addr> : resolve symbol address", debug_parse_cli_sym, NULL, NULL, NULL, ACCESS_EXPERT },
{{ "debug", "dev", "tkill", NULL }, "debug dev tkill [thr] [sig] : send signal to thread", debug_parse_cli_tkill, NULL, NULL, NULL, ACCESS_EXPERT },
{{ "debug", "dev", "write", NULL }, "debug dev write [size] : write that many bytes in return", debug_parse_cli_write, NULL, NULL, NULL, ACCESS_EXPERT },
+#if defined(HA_HAVE_DUMP_LIBS)
+ {{ "show", "libs", NULL, NULL }, "show libs : show loaded object files and libraries", debug_parse_cli_show_libs, NULL, NULL },
+#endif
{{ "show", "threads", NULL, NULL }, "show threads : show some threads debugging information", NULL, cli_io_handler_show_threads, NULL },
{{},}
}};