[PATCH] Fix memory leak of the demangled symbol name

["Christian Biesinger via gdb-patches" <gdb-patches at sourceware dot org>]

compute_and_set_names would only free the name if we did not find the name
in the hashtable, but it needs to always free it.  Solve this by moving the
smart pointer outside the if.

Thanks to PhilippeW for finding this.

gdb/ChangeLog:

2020-01-07  Christian Biesinger  <cbiesinger@google.com>

	* symtab.c (general_symbol_info::compute_and_set_names): Move the
	unique_xmalloc_ptr outside the if to always free the demangled name.

Change-Id: Id7c6b8408432183700ccb5ff634818d6c5a3ac95
---
 gdb/symtab.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/gdb/symtab.c b/gdb/symtab.c
index 88b8faedb5..122f9051af 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -892,6 +892,16 @@ general_symbol_info::compute_and_set_names (gdb::string_view linkage_name,
           htab_find_slot_with_hash (per_bfd->demangled_names_hash.get (),
 				    &entry, *hash, INSERT));
 
+  /* The const_cast is safe because the only reason it is already
+     initialized is if we purposefully set it from a background
+     thread to avoid doing the work here.  However, it is still
+     allocated from the heap and needs to be freed by us, just
+     like if we called symbol_find_demangled_name here.  If this is
+     nullptr, we call symbol_find_demangled_name below, but we put
+     this smart pointer here to be sure that we don't leak this name.  */
+  gdb::unique_xmalloc_ptr<char> demangled_name
+    (const_cast<char *> (language_specific.demangled_name));
+
   /* If this name is not in the hash table, add it.  */
   if (*slot == NULL
       /* A C version of the symbol may have already snuck into the table.
@@ -914,15 +924,9 @@ general_symbol_info::compute_and_set_names (gdb::string_view linkage_name,
       else
 	linkage_name_copy = linkage_name;
 
-      /* The const_cast is safe because the only reason it is already
-         initialized is if we purposefully set it from a background
-         thread to avoid doing the work here.  However, it is still
-         allocated from the heap and needs to be freed by us, just
-         like if we called symbol_find_demangled_name here.  */
-      gdb::unique_xmalloc_ptr<char> demangled_name
-	(language_specific.demangled_name
-	 ? const_cast<char *> (language_specific.demangled_name)
-	 : symbol_find_demangled_name (this, linkage_name_copy.data ()));
+      if (demangled_name.get () == nullptr)
+	 demangled_name.reset
+	   (symbol_find_demangled_name (this, linkage_name_copy.data ()));
 
       /* Suppose we have demangled_name==NULL, copy_name==0, and
 	 linkage_name_copy==linkage_name.  In this case, we already have the
-- 
2.24.1.735.g03f4e72817-goog