Decode ELF GNU ABI tag and build ID.

libexeinfo/ELF/ELF.cs

@@ -4,7 +4,6 @@ using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
 using System.Text;
-using System.Threading;
 
 namespace libexeinfo
 {
@@ -13,9 +12,9 @@ namespace libexeinfo
         List<Architecture>          architectures;
         Elf64_Ehdr                  Header;
         string                      interpreter;
+        Dictionary<string, ElfNote> notes;
         string[]                    sectionNames;
         Elf64_Shdr[]                sections;
-        Dictionary<string, ElfNote> notes;
 
         /// <summary>
         ///     Initializes a new instance of the <see cref="T:libexeinfo.ELF" /> class.
@@ -58,7 +57,7 @@ namespace libexeinfo
         public IEnumerable<Architecture> Architectures           => architectures;
         public OperatingSystem           RequiredOperatingSystem { get; private set; }
         public IEnumerable<string>       Strings                 { get; private set; }
-        public IEnumerable<Segment>      Segments                { get; }
+        public IEnumerable<Segment>      Segments { get; private set; }
 
         /// <summary>
         ///     The <see cref="FileStream" /> that contains the executable represented by this instance
@@ -235,10 +234,13 @@ namespace libexeinfo
 
                     pos += (int)namesz;
 
-                    switch(Header.ei_class) {
+                    switch(Header.ei_class)
-                        case eiClass.ELFCLASS32: pos += pos % 4;
+                    {
+                        case eiClass.ELFCLASS32:
+                            pos += pos % 4;
                             break;
-                        case eiClass.ELFCLASS64: pos += pos % 8;
+                        case eiClass.ELFCLASS64:
+                            pos += pos % 8;
                             break;
                     }
 
@@ -248,6 +250,18 @@ namespace libexeinfo
                 }
             }
 
+            if(notes.TryGetValue(".note.ABI-tag", out ElfNote abiTag))
+            {
+                GnuAbiTag gnuAbiTag = DecodeGnuAbiTag(abiTag, IsBigEndian);
+                if(gnuAbiTag != null)
+                    RequiredOperatingSystem = new OperatingSystem
+                    {
+                        Name         = $"{gnuAbiTag.system}",
+                        MajorVersion = (int)gnuAbiTag.major,
+                        MinorVersion = (int)gnuAbiTag.minor
+                    };
+            }
+
             if(strings.Count > 0)
             {
                 strings.Remove(null);
@@ -255,6 +269,8 @@ namespace libexeinfo
                 strings.Sort();
                 Strings = strings.Distinct();
             }
+
+            Segments = segments;
         }
 
         static Elf64_Ehdr UpBits(byte[] buffer, bool bigEndian)

libexeinfo/ELF/Enums.cs

@@ -941,5 +941,10 @@ namespace libexeinfo
             /// <summary>PA-RISC 2.0</summary>
             EFA_PARISC_2_0 = 0x0214
         }
+
+        enum GnuAbiSystem : uint
+        {
+            Linux = 0
+        }
     }
 }

libexeinfo/ELF/GNU.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Text;
+
+namespace libexeinfo
+{
+    public partial class ELF
+    {
+        static GnuAbiTag DecodeGnuAbiTag(ElfNote note, bool bigEndian)
+        {
+            if(note.name != "GNU") return null;
+
+            return bigEndian
+                       ? new GnuAbiTag
+                       {
+                           system   = (GnuAbiSystem)Swapping.Swap(BitConverter.ToUInt32(note.contents, 0)),
+                           major    = Swapping.Swap(BitConverter.ToUInt32(note.contents, 4)),
+                           minor    = Swapping.Swap(BitConverter.ToUInt32(note.contents, 8)),
+                           revision = Swapping.Swap(BitConverter.ToUInt32(note.contents, 0))
+                       }
+                       : new GnuAbiTag
+                       {
+                           system   = (GnuAbiSystem)BitConverter.ToUInt32(note.contents, 0),
+                           major    = BitConverter.ToUInt32(note.contents, 4),
+                           minor    = BitConverter.ToUInt32(note.contents, 8),
+                           revision = BitConverter.ToUInt32(note.contents, 0)
+                       };
+        }
+
+        static string DecodeGnuBuildId(ElfNote note)
+        {
+            StringBuilder sb = new StringBuilder();
+            foreach(byte b in note.contents) { sb.AppendFormat("{0:x2}", b); }
+
+            return sb.ToString();
+        }
+    }
+} 

libexeinfo/ELF/Info.cs

@@ -83,6 +83,17 @@ namespace libexeinfo
                     sb.AppendFormat("\t\t\tLength: {0} bytes", note.contents.Length).AppendLine();
                 }
 
+                if(notes.TryGetValue(".note.ABI-tag", out ElfNote abiTag))
+                {
+                    GnuAbiTag gnuAbiTag = DecodeGnuAbiTag(abiTag, IsBigEndian);
+                    if(gnuAbiTag != null)
+                        sb.AppendFormat("\tGNU ABI tag: Requires {0} version {1}.{2}.{3}", gnuAbiTag.system,
+                                        gnuAbiTag.major, gnuAbiTag.minor, gnuAbiTag.revision).AppendLine();
+                }
+
+                if(notes.TryGetValue(".note.gnu.build-id", out ElfNote buildId))
+                    sb.AppendFormat("\tGNU build ID: {0}", DecodeGnuBuildId(buildId));
+
                 return sb.ToString();
             }
         }

libexeinfo/ELF/Structs.cs

@@ -376,5 +376,13 @@ namespace libexeinfo
             public uint    type;
             public byte[] contents;
         }
+
+        class GnuAbiTag
+        {
+            public GnuAbiSystem system;
+            public uint major;
+            public uint minor;
+            public uint revision;
+        }
     }
 }

libexeinfo/libexeinfo.csproj

@@ -57,6 +57,7 @@
     <Compile Include="ELF\Consts.cs" />
     <Compile Include="ELF\ELF.cs" />
     <Compile Include="ELF\Enums.cs" />
+    <Compile Include="ELF\GNU.cs" />
     <Compile Include="ELF\Info.cs" />
     <Compile Include="ELF\Structs.cs" />
     <Compile Include="Enums.cs" />