From ad7ff82771b44ad36d2a66c2413dffaff20816e9 Mon Sep 17 00:00:00 2001
From: Nick Kralevich <nnk@google.com>
Date: Tue, 10 Apr 2012 13:42:06 -0700
Subject: [PATCH] Revert "linker: remove STB_LOCAL hack"

This reverts commit 61ff83475c6f3a3bb05a01ac89d668a331bfe9e9.

This code is harmless, and only applies to the linker, so
there's no harm in keeping it in the tree a little bit longer.
Let's roll this back while we try to figure out the root cause
of bug 6314858.

Bug: 6314858
Change-Id: I9f5ed81d23a7abe273baf792aa8a0a2839ef094c
---
 linker/linker.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/linker/linker.c b/linker/linker.c
index ac183fdaa..9805b35e3 100644
--- a/linker/linker.c
+++ b/linker/linker.c
@@ -408,6 +408,33 @@ static Elf32_Sym *_elf_lookup(soinfo *si, unsigned hash, const char *name)
     return NULL;
 }
 
+/*
+ * Essentially the same method as _elf_lookup() above, but only
+ * searches for LOCAL symbols
+ */
+static Elf32_Sym *_elf_lookup_local(soinfo *si, unsigned hash, const char *name)
+{
+    Elf32_Sym *symtab = si->symtab;
+    const char *strtab = si->strtab;
+    unsigned n = hash % si->nbucket;;
+
+    TRACE_TYPE(LOOKUP, "%5d LOCAL SEARCH %s in %s@0x%08x %08x %d\n", pid,
+               name, si->name, si->base, hash, hash % si->nbucket);
+    for(n = si->bucket[hash % si->nbucket]; n != 0; n = si->chain[n]){
+        Elf32_Sym *s = symtab + n;
+        if (strcmp(strtab + s->st_name, name)) continue;
+        if (ELF32_ST_BIND(s->st_info) != STB_LOCAL) continue;
+        /* no section == undefined */
+        if(s->st_shndx == 0) continue;
+
+        TRACE_TYPE(LOOKUP, "%5d FOUND LOCAL %s in %s (%08x) %d\n", pid,
+                   name, si->name, s->st_value, s->st_size);
+        return s;
+    }
+
+    return NULL;
+}
+
 static unsigned elfhash(const char *_name)
 {
     const unsigned char *name = (const unsigned char *) _name;
@@ -431,6 +458,16 @@ _do_lookup(soinfo *si, const char *name, unsigned *base)
     soinfo *lsi = si;
     int i;
 
+    /* If we are trying to find a symbol for the linker itself, look
+     * for LOCAL symbols first. Avoid using LOCAL symbols for other
+     * shared libraries until we have a better understanding of what
+     * might break by doing so. */
+    if (si->flags & FLAG_LINKER) {
+        s = _elf_lookup_local(si, elf_hash, name);
+        if(s != NULL)
+            goto done;
+    }
+
     /* Look for symbols in the local scope (the object who is
      * searching). This happens with C++ templates on i386 for some
      * reason.