Make dwfl_module_getsym yield shndx -1 for any non-allocated section.

2 files changed, 20 insertions, 6 deletions

diff --git a/libdwfl/dwfl_module_getsym.c b/libdwfl/dwfl_module_getsym.c
index 8f02d71f..816d2143 100644
--- a/libdwfl/dwfl_module_getsym.c
+++ b/libdwfl/dwfl_module_getsym.c
@@ -75,7 +75,20 @@ dwfl_module_getsym (Dwfl_Module *mod, int ndx,
     shndx = sym->st_shndx;
 
   if (shndxp != NULL)
-    *shndxp = shndx;
+    {
+      *shndxp = shndx;
+
+      /* Yield -1 in case of a non-SHF_ALLOC section.  */
+      if (sym->st_shndx == SHN_XINDEX
+	  || (sym->st_shndx < SHN_LORESERVE && sym->st_shndx != SHN_UNDEF))
+	{
+	  GElf_Shdr shdr_mem;
+	  GElf_Shdr *shdr = gelf_getshdr (elf_getscn (mod->symfile->elf, shndx),
+					  &shdr_mem);
+	  if (unlikely (shdr == NULL) || !(shdr->sh_flags & SHF_ALLOC))
+	    *shndxp = (GElf_Word) -1;
+	}
+    }
 
   switch (sym->st_shndx)
     {
diff --git a/libdwfl/libdwfl.h b/libdwfl/libdwfl.h
index b6ae7765..91d43802 100644
--- a/libdwfl/libdwfl.h
+++ b/libdwfl/libdwfl.h
@@ -1,5 +1,5 @@
 /* Interfaces for libdwfl.
-   Copyright (C) 2005, 2006, 2007, 2008 Red Hat, Inc.
+   Copyright (C) 2005-2009 Red Hat, Inc.
    This file is part of Red Hat elfutils.
 
    Red Hat elfutils is free software; you can redistribute it and/or modify
@@ -423,10 +423,11 @@ extern int dwfl_module_getsymtab (Dwfl_Module *mod);
 
 /* Fetch one entry from the module's symbol table.  On errors, returns
    NULL.  If successful, fills in *SYM and returns the string for st_name.
-   This works like gelf_getsym except that st_value is always adjusted
-   to an absolute value based on the module's location.  If SHNDXP is
-   non-null, it's set with the section index (whether from st_shndx or
-   extended index table).  */
+   This works like gelf_getsym except that st_value is always adjusted to
+   an absolute value based on the module's location, when the symbol is in
+   an SHF_ALLOC section.  If SHNDXP is non-null, it's set with the section
+   index (whether from st_shndx or extended index table); in case of a
+   symbol in a non-allocated section, *SHNDXP is instead set to -1.  */
 extern const char *dwfl_module_getsym (Dwfl_Module *mod, int ndx,
 				       GElf_Sym *sym, GElf_Word *shndxp)
   __nonnull_attribute__ (3);