[binutils-gdb] Empty hash table fix in .debug_names reader

[binutils-gdb] Empty hash table fix in .debug_names reader

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=3a862152958a1d17742cef7fc43c4d51dd2dcbab

commit 3a862152958a1d17742cef7fc43c4d51dd2dcbab
Author: Tom Tromey <tom@tromey.com>
Date:   Mon Dec 4 07:58:48 2023 -0700

    Empty hash table fix in .debug_names reader
    
    The handling of an empty hash table in the .debug_names reader is
    slightly wrong.
    
    Currently the code assumes there is always an array of hashes.
    However, section 6.1.1.4.5 Hash Lookup Table says:
    
        The optional hash lookup table immediately follows the list of
        type signatures.
    
    and then:
    
        The hash lookup table is actually two separate arrays: an array of
        buckets, followed immediately by an array of hashes.
    
    My reading of this is that the hash table as a whole is optional, and
    so the hashes will not exist in this case.  (This also makes sense
    because the hashes are not useful without the buckets anyway.)
    
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=25950

Diff:
---
 gdb/dwarf2/read-debug-names.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gdb/dwarf2/read-debug-names.c b/gdb/dwarf2/read-debug-names.c
index a2a9fd425ae..b4ff36f0ed6 100644
--- a/gdb/dwarf2/read-debug-names.c
+++ b/gdb/dwarf2/read-debug-names.c
@@ -294,7 +294,8 @@ read_debug_names_from_section (struct objfile *objfile,
   map.bucket_table_reordered = reinterpret_cast<const uint32_t *> (addr);
   addr += map.bucket_count * 4;
   map.hash_table_reordered = reinterpret_cast<const uint32_t *> (addr);
-  addr += map.name_count * 4;
+  if (map.bucket_count != 0)
+    addr += map.name_count * 4;
 
   /* Name Table */
   map.name_table_string_offs_reordered = addr;