corpus: Handle empty symbol table cases

There can be cases where the symbol table associated with a given
corpus is empty.  This patch handles those cases to avoid crashes.

	* src/abg-corpus.cc (corpus::priv::{get_sorted_fun_symbols,
	get_sorted_undefined_fun_symbols, get_sorted_var_symbols,
	get_sorted_undefined_var_symbols}): If the symbol is null, then
	return an empty vector of symbols.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>

diff --git a/src/abg-corpus.cc b/src/abg-corpus.cc
index b6f760bb574c40fb175b3a184e3f3daed5508df6..4f20a8883c567cd1dd4d857fdc0cbcf3e7042b3f 100644 (file)
--- a/src/abg-corpus.cc
+++ b/src/abg-corpus.cc
@@ -313,9 +313,15 @@ corpus::priv::get_sorted_fun_symbols() const
 {
   if (!sorted_fun_symbols)
     {
-      auto filter = symtab_->make_filter();
-      filter.set_functions();
-      sorted_fun_symbols = elf_symbols(symtab_->begin(filter), symtab_->end());
+      if (symtab_)
+       {
+         auto filter = symtab_->make_filter();
+         filter.set_functions();
+         sorted_fun_symbols = elf_symbols(symtab_->begin(filter),
+                                          symtab_->end());
+       }
+      else
+       sorted_fun_symbols = elf_symbols();
     }
   return *sorted_fun_symbols;
 }
@@ -349,13 +355,18 @@ corpus::priv::get_sorted_undefined_fun_symbols() const
 {
   if (!sorted_undefined_fun_symbols)
     {
-      auto filter = symtab_->make_filter();
-      filter.set_functions();
-      filter.set_undefined_symbols();
-      filter.set_public_symbols(false);
+      if (symtab_)
+       {
+         auto filter = symtab_->make_filter();
+         filter.set_functions();
+         filter.set_undefined_symbols();
+         filter.set_public_symbols(false);
 
-      sorted_undefined_fun_symbols =
-       elf_symbols(symtab_->begin(filter), symtab_->end());
+         sorted_undefined_fun_symbols =
+           elf_symbols(symtab_->begin(filter), symtab_->end());
+       }
+      else
+       sorted_undefined_fun_symbols = elf_symbols();
     }
   return *sorted_undefined_fun_symbols;
 }
@@ -446,10 +457,16 @@ corpus::priv::get_sorted_var_symbols() const
 {
   if (!sorted_var_symbols)
     {
-      auto filter = symtab_->make_filter();
-      filter.set_variables();
+      if (symtab_)
+       {
+         auto filter = symtab_->make_filter();
+         filter.set_variables();
 
-      sorted_var_symbols = elf_symbols(symtab_->begin(filter), symtab_->end());
+         sorted_var_symbols = elf_symbols(symtab_->begin(filter),
+                                          symtab_->end());
+       }
+      else
+       sorted_var_symbols = elf_symbols();
     }
   return *sorted_var_symbols;
 }
@@ -483,13 +500,18 @@ corpus::priv::get_sorted_undefined_var_symbols() const
 {
   if (!sorted_undefined_var_symbols)
     {
-      auto filter = symtab_->make_filter();
-      filter.set_variables();
-      filter.set_undefined_symbols();
-      filter.set_public_symbols(false);
+      if (symtab_)
+       {
+         auto filter = symtab_->make_filter();
+         filter.set_variables();
+         filter.set_undefined_symbols();
+         filter.set_public_symbols(false);
 
-      sorted_undefined_var_symbols =
-         elf_symbols(symtab_->begin(filter), symtab_->end());
+         sorted_undefined_var_symbols =
+           elf_symbols(symtab_->begin(filter), symtab_->end());
+       }
+      else
+       sorted_undefined_var_symbols = elf_symbols();
     }
   return *sorted_undefined_var_symbols;
 }