Added support for ".gnu.version_d"

serge1 · Oct 23, 2024 · 647aba7 · 647aba7
1 parent 41f4012
commit 647aba7
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diff --git a/elfio/elf_types.hpp b/elfio/elf_types.hpp
@@ -1349,6 +1349,23 @@ struct Elf64_Dyn
     } d_un;
 };
 
+struct Elfxx_Verdef
+{
+    Elf_Half vd_version;
+    Elf_Half vd_flags;
+    Elf_Half vd_ndx;
+    Elf_Half vd_cnt;
+    Elf_Word vd_hash;
+    Elf_Word vd_aux;
+    Elf_Word vd_next;
+};
+
+struct Elfxx_Verdaux
+{
+    Elf_Word vda_name;
+    Elf_Word vda_next;
+};
+
 struct Elfxx_Verneed
 {
     Elf_Half vn_version;

diff --git a/elfio/elfio_versym.hpp b/elfio/elfio_versym.hpp
@@ -174,6 +174,88 @@ using versym_r_section_accessor = versym_r_section_accessor_template<section>;
 using const_versym_r_section_accessor =
     versym_r_section_accessor_template<const section>;
 
+//------------------------------------------------------------------------------
+template <class S> class versym_d_section_accessor_template
+{
+  public:
+    //------------------------------------------------------------------------------
+    versym_d_section_accessor_template( const elfio& elf_file,
+                                        S*           versym_d_section )
+        : elf_file( elf_file ), versym_d_section( versym_d_section ),
+          entries_num( 0 )
+    {
+        // Find .dynamic section
+        const section* dynamic_section = elf_file.sections[".dynamic"];
+
+        if ( dynamic_section == nullptr ) {
+            return;
+        }
+
+        const_dynamic_section_accessor dynamic_section_acc( elf_file,
+                                                            dynamic_section );
+        Elf_Xword dyn_sec_num = dynamic_section_acc.get_entries_num();
+        for ( Elf_Xword i = 0; i < dyn_sec_num; ++i ) {
+            Elf_Xword   tag;
+            Elf_Xword   value;
+            std::string str;
+
+            if ( dynamic_section_acc.get_entry( i, tag, value, str ) &&
+                 tag == DT_VERDEFNUM ) {
+                entries_num = (Elf_Word)value;
+                break;
+            }
+        }
+    }
+
+    //------------------------------------------------------------------------------
+    Elf_Word get_entries_num() const { return entries_num; }
+
+    //------------------------------------------------------------------------------
+    bool get_entry( Elf_Word     no,
+                    Elf_Half&    flags,
+                    Elf_Half&    version_index,
+                    Elf_Word&    hash,
+                    std::string& dep_name ) const
+    {
+        if ( versym_d_section == nullptr || ( no >= get_entries_num() ) ) {
+            return false;
+        }
+
+        const_string_section_accessor string_section_acc(
+            elf_file.sections[versym_d_section->get_link()] );
+
+        Elfxx_Verdef*  verdef = (Elfxx_Verdef*)versym_d_section->get_data();
+        Elfxx_Verdaux* verdaux =
+            (Elfxx_Verdaux*)( (char*)verdef + verdef->vd_aux );
+        for ( Elf_Word i = 0; i < no; ++i ) {
+            verdef  = (Elfxx_Verdef*)( (char*)verdef + verdef->vd_next );
+            verdaux = (Elfxx_Verdaux*)( (char*)verdef + verdef->vd_aux );
+        }
+
+        // verdef->vd_version should always be 1
+        // see https://refspecs.linuxfoundation.org/LSB_3.0.0/LSB-PDA/LSB-PDA.junk/symversion.html#VERDEFENTRIES
+        // verdef->vd_cnt should always be 1.
+        // see https://maskray.me/blog/2020-11-26-all-about-symbol-versioning
+
+        flags         = verdef->vd_flags;
+        version_index = verdef->vd_ndx;
+        hash          = verdef->vd_hash;
+        dep_name      = string_section_acc.get_string( verdaux->vda_name );
+
+        return true;
+    }
+
+    //------------------------------------------------------------------------------
+  private:
+    const elfio& elf_file;
+    S*           versym_d_section = nullptr;
+    Elf_Word     entries_num      = 0;
+};
+
+using versym_d_section_accessor = versym_d_section_accessor_template<section>;
+using const_versym_d_section_accessor =
+    versym_d_section_accessor_template<const section>;
+
 } // namespace ELFIO
 
 #endif // ELFIO_VERSYM_HPP
diff --git a/tests/ELFIOTest2.cpp b/tests/ELFIOTest2.cpp
@@ -416,6 +416,78 @@ TEST( ELFIOTest, gnu_version_64_le )
     EXPECT_EQ( dep_name, "GLIBC_2.2.5" );
 }
 
+////////////////////////////////////////////////////////////////////////////////
+TEST( ELFIOTest, gnu_version_d_64_le )
+{
+    elfio reader;
+    // Load ELF data
+
+    ASSERT_EQ( reader.load( "elf_examples/libversion_d.so" ), true );
+
+    section*                      dynsym = reader.sections[".dynsym"];
+    const_symbol_section_accessor dynsym_acc( reader, dynsym );
+
+    section*                      gnu_version = reader.sections[".gnu.version"];
+    const_versym_section_accessor gnu_version_arr( gnu_version );
+
+    const section* gnu_version_d = reader.sections[".gnu.version_d"];
+    const_versym_d_section_accessor gnu_version_d_arr( reader, gnu_version_d );
+
+    section* dynstr = reader.sections[".dynstr"];
+
+    EXPECT_EQ( gnu_version_d->get_link(), dynstr->get_index() );
+
+    EXPECT_EQ( dynsym_acc.get_symbols_num(),
+               gnu_version_arr.get_entries_num() );
+
+    EXPECT_EQ( dynsym_acc.get_symbols_num(), 10 );
+
+    EXPECT_EQ( gnu_version_d_arr.get_entries_num(), 3 );
+
+    auto v_check = [&]( const std::string& symbol,
+                        const std::string& vername ) -> void {
+        std::string   name;
+        Elf64_Addr    value;
+        Elf_Xword     size;
+        unsigned char bind;
+        unsigned char type;
+        Elf_Half      section_index;
+        unsigned char other;
+        Elf64_Half    verindex;
+
+        for ( Elf64_Word i = 0; i < dynsym_acc.get_symbols_num(); i++ ) {
+            ASSERT_EQ( dynsym_acc.get_symbol( i, name, value, size, bind, type,
+                                              section_index, other ),
+                       true );
+
+            Elf64_Half vi;
+            ASSERT_EQ( gnu_version_arr.get_entry( i, vi ), true );
+            if ( name == symbol ) {
+                verindex = vi;
+            }
+        }
+        ASSERT_NE( verindex, 0 );
+
+        for ( Elf64_Word i = 0; i < gnu_version_d_arr.get_entries_num(); i++ ) {
+            Elf_Half    flags;
+            Elf_Half    version_index;
+            Elf_Word    hash;
+            std::string dep_name;
+            ASSERT_EQ( gnu_version_d_arr.get_entry( i, flags, version_index,
+                                                    hash, dep_name ),
+                       true );
+            if ( version_index == verindex ) {
+                EXPECT_EQ( flags, 0 );
+                EXPECT_EQ( dep_name, vername );
+                return;
+            }
+        }
+        FAIL() << "version entry is not found";
+    };
+    v_check( "_Z20print_hello_world_v1v", "HELLO_1.0" );
+    v_check( "_Z20print_hello_world_v2v", "HELLO_2.0" );
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // TEST( ELFIOTest, gnu_version_64_le_modify )
 // {

diff --git a/tests/elf_examples/version_d.cpp b/tests/elf_examples/version_d.cpp
@@ -0,0 +1,5 @@
+#include <stdio.h>
+
+void print_hello_world_v1() { printf( "hello v1" ); }
+
+void print_hello_world_v2() { printf( "hello v2" ); }
diff --git a/tests/elf_examples/version_d.map b/tests/elf_examples/version_d.map
@@ -0,0 +1,9 @@
+HELLO_1.0 {
+  global:
+  _Z20print_hello_world_v1v;
+};
+
+HELLO_2.0 {
+global:
+_Z20print_hello_world_v2v;
+};