Avoid calling OString ctor with null pointer

...in preparation of potential future changes from using OString to using
std::string_view, where OString has an undocumented feature of allowing
construction from a null pointer.

This is mostly the result of a manual audit of potentially problematic getenv
calls across the code base.  But there can be other problematic places too, like
the xmlGetProp call in tools/source/xml/XmlWalker.cxx.  To identify those,
rtl_{string,uString}_newFromStr aborts now in non-production debug builds when a
null pointer is passed(and all places that hit with a full `make check
screenshot` have been addressed here).  Once we are confident that all
problematic places have been identified, we should drop support for the
undocumented feature (see the TODO in sal/rtl/strtmpl.cxx).

Change-Id: I595cc6d4f1cda74add2a3db171323f817d362b08
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/107430
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/sal/osl/w32/socket.cxx b/sal/osl/w32/socket.cxx
index ba96cc5ed838..9e819beaa61f 100644
--- a/sal/osl/w32/socket.cxx
+++ b/sal/osl/w32/socket.cxx
@@ -512,7 +512,11 @@ oslHostAddr SAL_CALL osl_createHostAddrByName(rtl_uString *strHostname)
             {
                 pRet = static_cast<oslHostAddr>(
                     rtl_allocateZeroMemory(sizeof(struct oslHostAddrImpl)));
-                rtl_uString_newFromStr(&pRet->pHostName, o3tl::toU(pIter->ai_canonname));
+                if (pIter->ai_canonname == nullptr) {
+                    rtl_uString_new(&pRet->pHostName);
+                } else {
+                    rtl_uString_newFromStr(&pRet->pHostName, o3tl::toU(pIter->ai_canonname));
+                }
                 pRet->pSockAddr = createSocketAddr();
                 memcpy(& pRet->pSockAddr->m_sockaddr,
                        pIter->ai_addr, pIter->ai_addrlen);