Avoid core dump after getpwuid_r failure.

Looking up a nonexistent user ID would lead to a null pointer
dereference.  That's unlikely to happen here, but perhaps
not impossible.

Thinko in commit 4d5111b3f, noticed by Coverity.

diff --git a/src/interfaces/libpq/fe-auth.c b/src/interfaces/libpq/fe-auth.c
index 4904d38ce1c2888510fdb2ad2e8fceaf9bf2ca35..20d3427e943adf623719ae58a831539d558f4f74 100644 (file)
--- a/src/interfaces/libpq/fe-auth.c
+++ b/src/interfaces/libpq/fe-auth.c
@@ -1205,7 +1205,7 @@ pg_fe_getusername(uid_t user_id, PQExpBuffer errorMessage)
        DWORD           namesize = sizeof(username);
 #else
        struct passwd pwbuf;
-       struct passwd *pw;
+       struct passwd *pw = NULL;
        char            buf[1024];
        int                     rc;
 #endif
@@ -1230,7 +1230,8 @@ pg_fe_getusername(uid_t user_id, PQExpBuffer errorMessage)
                if (errorMessage)
                        libpq_append_error(errorMessage, "local user with ID %ld does not exist", (long) user_id);
        }
-       name = pw->pw_name;
+       else
+               name = pw->pw_name;
 #endif
 
        if (name)