rgw: Fix potential null pointer dereferences where `RGWEnv::get()` is called

Here are the changes I've made:
- Added `RGWEnv::get_optional` with the similar implementation to the `RGWHTTPArgs::get_optional`
- Replaced `RGWEnv::get` in the RGW code where null pointer derefence happens with `RGWEnv::get_optional` as long as it accepts `std::string`
- Otherwise if calling function of `RGWEnv::get` accepts `char*` I leave it as it is
- Added null pointer checks to avoid the null pointer dereference

This commit addresses the following Coverity CIDs:
- "1510310"
- "1510928"
- "1511097"
- "1511555"
- "1511760"
- "1511951"
- "1512003"
- "1512138"
- "1512398"

Fixes: https://tracker.ceph.com/issues/57347
Signed-off-by: Mohamed Awnallah <mohamedmohey2352@gmail.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/src/rgw/rgw_env.cc b/src/rgw/rgw_env.cc
index bb45ee8d36a..d528f0e6d47 100644
--- a/src/rgw/rgw_env.cc
+++ b/src/rgw/rgw_env.cc
@@ -52,11 +52,26 @@ const char *rgw_conf_get(const map<string, string, ltstr_nocase>& conf_map, cons
   return iter->second.c_str();
 }
 
+boost::optional<const std::string&> rgw_conf_get_optional(const map<string, string, ltstr_nocase>& conf_map, const std::string& name)
+{
+  auto iter = conf_map.find(name);
+  if (iter == conf_map.end())
+    return boost::none;
+
+  return boost::optional<const std::string&>(iter->second);
+}
+
 const char *RGWEnv::get(const char *name, const char *def_val) const
 {
   return rgw_conf_get(env_map, name, def_val);
 }
 
+boost::optional<const std::string&>
+RGWEnv::get_optional(const std::string& name) const
+{
+  return rgw_conf_get_optional(env_map, name);
+}
+
 int rgw_conf_get_int(const map<string, string, ltstr_nocase>& conf_map, const char *name, int def_val)
 {
   auto iter = conf_map.find(name);