[pushed] Only make a nullterminated string if we need to
Commit Message
Sourceware to Gerrit sync has submitted this change.
Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/222
......................................................................
Only make a nullterminated string if we need to
As of 7bb43059820c5febb4509b15202a93efde442bc6, we no longer need
a nullterminated linkage_name to look up the entry in the hash table.
So this patch makes it so we only make the copy if the entry was
not found.
By auditing all callers of symbol_set_names, I found out that all cases
where the string may not be nullterminated already pass true for COPY_NAME.
So here, I am documenting that as a requirement and am removing the code
that relies on undefined behavior in symbol_set_names (it accessed the string
past the provided length to check for nulltermination). Note that the Ada
case at the beginning of symbol_set_names was already relying on this.
gdb/ChangeLog:
2019-10-29 Christian Biesinger <cbiesinger@google.com>
* symtab.h (symbol_set_names): Document that copy_name must be
set to true for non-nullterminated strings.
* symtab.c (symbol_set_names): Only make a nullterminated copy of
linkage_name if the entry was not found and we need to demangle.
Change-Id: I183302e1f51483ff6dff0fd5c3b0f32f0f04a5d2
---
M gdb/ChangeLog
M gdb/symtab.c
M gdb/symtab.h
3 files changed, 28 insertions(+), 19 deletions(-)
@@ -1,5 +1,12 @@
2019-10-29 Christian Biesinger <cbiesinger@google.com>
+ * symtab.h (symbol_set_names): Document that copy_name must be
+ set to true for non-nullterminated strings.
+ * symtab.c (symbol_set_names): Only make a nullterminated copy of
+ linkage_name if the entry was not found and we need to demangle.
+
+2019-10-29 Christian Biesinger <cbiesinger@google.com>
+
* Makefile.in (HFILES_NO_SRCDIR): Add gdb_binary_search.h.
* dwarf2-frame.c (bsearch_fde_cmp): Update.
(dwarf2_frame_find_fde): Replace bsearch with gdb::binary_search.
@@ -832,8 +832,6 @@
struct objfile_per_bfd_storage *per_bfd)
{
struct demangled_name_entry **slot;
- /* A 0-terminated copy of the linkage name. */
- const char *linkage_name_copy;
if (gsymbol->language == language_ada)
{
@@ -858,20 +856,7 @@
if (per_bfd->demangled_names_hash == NULL)
create_demangled_names_hash (per_bfd);
- if (linkage_name[len] != '\0')
- {
- char *alloc_name;
-
- alloc_name = (char *) alloca (len + 1);
- memcpy (alloc_name, linkage_name, len);
- alloc_name[len] = '\0';
-
- linkage_name_copy = alloc_name;
- }
- else
- linkage_name_copy = linkage_name;
-
- struct demangled_name_entry entry (gdb::string_view (linkage_name_copy, len));
+ struct demangled_name_entry entry (gdb::string_view (linkage_name, len));
slot = ((struct demangled_name_entry **)
htab_find_slot (per_bfd->demangled_names_hash.get (),
&entry, INSERT));
@@ -882,6 +867,21 @@
This happens to, e.g., main.init (__go_init_main). Cope. */
|| (gsymbol->language == language_go && (*slot)->demangled == nullptr))
{
+ /* A 0-terminated copy of the linkage name. Callers must set COPY_NAME
+ to true if the string might not be nullterminated. We have to make
+ this copy because demangling needs a nullterminated string. */
+ const char *linkage_name_copy;
+ if (copy_name)
+ {
+ char *alloc_name = (char *) alloca (len + 1);
+ memcpy (alloc_name, linkage_name, len);
+ alloc_name[len] = '\0';
+
+ linkage_name_copy = alloc_name;
+ }
+ else
+ linkage_name_copy = linkage_name;
+
gdb::unique_xmalloc_ptr<char> demangled_name_ptr
(symbol_find_demangled_name (gsymbol, linkage_name_copy));
@@ -894,7 +894,7 @@
It turns out that it is actually important to still save such
an entry in the hash table, because storing this name gives
us better bcache hit rates for partial symbols. */
- if (!copy_name && linkage_name_copy == linkage_name)
+ if (!copy_name)
{
*slot
= ((struct demangled_name_entry *)
@@ -912,7 +912,8 @@
obstack_alloc (&per_bfd->storage_obstack,
sizeof (demangled_name_entry) + len + 1));
char *mangled_ptr = reinterpret_cast<char *> (*slot + 1);
- strcpy (mangled_ptr, linkage_name_copy);
+ memcpy (mangled_ptr, linkage_name, len);
+ mangled_ptr [len] = '\0';
new (*slot) demangled_name_entry
(gdb::string_view (mangled_ptr, len));
}
@@ -504,7 +504,8 @@
(symbol)->ginfo.name = (linkage_name)
/* Set the linkage and natural names of a symbol, by demangling
- the linkage name. */
+ the linkage name. If linkage_name may not be nullterminated,
+ copy_name must be set to true. */
#define SYMBOL_SET_NAMES(symbol,linkage_name,len,copy_name,objfile) \
symbol_set_names (&(symbol)->ginfo, linkage_name, len, copy_name, \
(objfile)->per_bfd)