Add ELF dynamic linking table (SHT_DYNAMIC) support

readme.md

@@ -49,6 +49,7 @@ elf.Write(outStream);
     - Symbol Table
     - Relocation Table: supported I386, X86_64, ARM and AARCH64 relocations (others can be exposed by adding some mappings)
     - Note Table
+    - Dynamic Linking Table (`SHT_DYNAMIC`)
     - Other sections fallback to `ElfCustomSection`
   - Program headers with or without sections
   - Print with `readelf` similar output

src/LibObjectFile.Tests/Elf/ElfSimpleTests.cs

@@ -438,6 +438,131 @@ public async Task SimpleProgramHeaderAndCodeSectionAndSymbolSectionAndRelocation
     }
 
 
+    [TestMethod]
+    public async Task SimpleDynamicSection()
+    {
+        var elf = new ElfFile(ElfArch.X86_64);
+
+        var dynstr = new ElfStringTable() { Name = ".dynstr" };
+        elf.Add(dynstr);
+
+        var dynamic = new ElfDynamicLinkingTable() { Link = dynstr };
+        dynamic.AddNeededLibrary("libc.so.6");
+        dynamic.AddNeededLibrary("libm.so.6");
+        dynamic.Entries.Add(new ElfDynamic { Tag = (long)ElfDynamicTag.Flags1, Value = 0x08000001 });
+        dynamic.Entries.Add(new ElfDynamic { Tag = (long)ElfDynamicTag.Null });
+        elf.Add(dynamic);
+
+        elf.Add(new ElfSectionHeaderStringTable());
+        elf.Add(new ElfSectionHeaderTable());
+
+        // The read helpers resolve DT_NEEDED offsets through the linked .dynstr.
+        CollectionAssert.AreEqual(new[] { "libc.so.6", "libm.so.6" }, dynamic.GetNeededLibraries().ToList());
+
+        await AssertReadElf(elf, "test_dynamic.elf");
+
+        // Round-trip the entries and confirm the resolved library names survive write -> read.
+        var memoryStream = new MemoryStream();
+        elf.Write(memoryStream);
+        memoryStream.Position = 0;
+        var roundTrip = ElfFile.Read(memoryStream);
+        var roundTripDynamic = roundTrip.Sections.OfType<ElfDynamicLinkingTable>().Single();
+        Assert.AreEqual(dynamic.Entries.Count, roundTripDynamic.Entries.Count);
+        CollectionAssert.AreEqual(new[] { "libc.so.6", "libm.so.6" }, roundTripDynamic.GetNeededLibraries().ToList());
+    }
+
+    [TestMethod]
+    public void DynamicSectionStreamRoundTrip()
+    {
+        var elf = new ElfFile(ElfArch.X86_64);
+        var dynstr = new ElfStringTable() { Name = ".dynstr" };
+        elf.Add(dynstr);
+
+        var dynamic = new ElfDynamicLinkingTable() { Link = dynstr };
+        dynamic.AddNeededLibrary("libc.so.6");
+        dynamic.Entries.Add(new ElfDynamic { Tag = (long)ElfDynamicTag.Flags1, Value = 0x08000001 });
+        dynamic.Entries.Add(new ElfDynamic { Tag = (long)ElfDynamicTag.Null });
+        elf.Add(dynamic);
+
+        // Serialize just the .dynamic entries to a standalone stream (64-bit -> 16 bytes each).
+        var stream = new MemoryStream();
+        dynamic.Write(stream);
+        Assert.AreEqual(dynamic.Entries.Count * 16, stream.Length);
+
+        // Read them back into a fresh table attached to another file and confirm value equality.
+        var elf2 = new ElfFile(ElfArch.X86_64);
+        var dynamic2 = new ElfDynamicLinkingTable();
+        elf2.Add(dynamic2);
+        stream.Position = 0;
+        dynamic2.Read(stream);
+
+        CollectionAssert.AreEqual(dynamic.Entries, dynamic2.Entries);
+    }
+
+    [TestMethod]
+    public void DynamicSection32Bit()
+    {
+        var elf = new ElfFile(ElfArch.I386);
+        var dynstr = new ElfStringTable() { Name = ".dynstr" };
+        elf.Add(dynstr);
+
+        var dynamic = new ElfDynamicLinkingTable() { Link = dynstr };
+        dynamic.AddNeededLibrary("libc.so.6");
+        dynamic.Entries.Add(new ElfDynamic { Tag = (long)ElfDynamicTag.Flags, Value = 0x8 }); // DF_BIND_NOW
+        dynamic.Entries.Add(new ElfDynamic { Tag = (long)ElfDynamicTag.Null });
+        elf.Add(dynamic);
+
+        // The printer uses 8-digit tag hex for 32-bit files.
+        var writer = new StringWriter();
+        ElfPrinter.PrintDynamicSections(elf, writer);
+        var text = writer.ToString();
+        StringAssert.Contains(text, " 0x00000001 (NEEDED)");
+        StringAssert.Contains(text, "Shared library: [libc.so.6]");
+        StringAssert.Contains(text, " 0x0000001e (FLAGS)");
+        StringAssert.Contains(text, "BIND_NOW");
+
+        // The Read32/Write32 path uses 8-byte Elf32_Dyn records.
+        var stream = new MemoryStream();
+        dynamic.Write(stream);
+        Assert.AreEqual(dynamic.Entries.Count * 8, stream.Length);
+
+        var elf2 = new ElfFile(ElfArch.I386);
+        var dynamic2 = new ElfDynamicLinkingTable();
+        elf2.Add(dynamic2);
+        stream.Position = 0;
+        dynamic2.Read(stream);
+
+        CollectionAssert.AreEqual(dynamic.Entries, dynamic2.Entries);
+    }
+
+    [TestMethod]
+    public void SectionHeader64BitFieldsNotTruncated()
+    {
+        // Regression: the 64-bit section header writer cast sh_addr/sh_offset/sh_size/etc. to uint,
+        // truncating any value >= 4 GiB. A NOBITS section declares a huge address/size with no file bytes.
+        var elf = new ElfFile(ElfArch.X86_64);
+
+        var bss = new ElfNoBitsSection
+        {
+            Name = ".hugebss",
+            VirtualAddress = 0x1_0000_2000UL, // > 4 GiB
+            Size = 0x2_0000_1000UL,           // > 4 GiB
+            VirtualAddressAlignment = 0x1000,
+        };
+        elf.Add(bss);
+        elf.Add(new ElfSectionHeaderStringTable());
+        elf.Add(new ElfSectionHeaderTable());
+
+        var stream = new MemoryStream();
+        elf.Write(stream);
+        stream.Position = 0;
+        var roundTrip = ElfFile.Read(stream);
+
+        var bss2 = roundTrip.Sections.OfType<ElfNoBitsSection>().Single();
+        Assert.AreEqual(0x1_0000_2000UL, bss2.VirtualAddress);
+        Assert.AreEqual(0x2_0000_1000UL, bss2.Size);
+    }
+
     [TestMethod]
     public async Task TestAlignedSection()
     {

src/LibObjectFile.Tests/Verified/ElfSimpleTests.SimpleDynamicSection.verified.txt

@@ -0,0 +1,48 @@
+ELF Header:
+  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 
+  Class:                             ELF64
+  Data:                              2's complement, little endian
+  Version:                           1 (current)
+  OS/ABI:                            UNIX - System V
+  ABI Version:                       0
+  Type:                              REL (Relocatable file)
+  Machine:                           Advanced Micro Devices X86-64
+  Version:                           0x1
+  Entry point address:               0x0
+  Start of program headers:          0 (bytes into file)
+  Start of section headers:          0 (bytes into file)
+  Flags:                             0x0
+  Size of this header:               0 (bytes)
+  Size of program headers:           0 (bytes)
+  Number of program headers:         0
+  Size of section headers:           0 (bytes)
+  Number of section headers:         4
+  Section header string table index: 3
+
+Section Headers:
+  [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
+  [ 0]                   NULL            0000000000000000 000000 000000 00      0   0  0
+  [ 1] .dynstr           STRTAB          0000000000000000 000000 000000 00      0   0  0
+  [ 2] .dynamic          DYNAMIC         0000000000000000 000000 000000 10   A  1   0  0
+  [ 3] .shstrtab         STRTAB          0000000000000000 000000 000000 00      0   0  0
+Key to Flags:
+  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
+  L (link order), O (extra OS processing required), G (group), T (TLS),
+  C (compressed), x (unknown), o (OS specific), E (exclude),
+  D (mbind), l (large), p (processor specific)
+
+There are no section groups in this file.
+
+There are no program headers in this file.
+
+Dynamic section at offset 0x0 contains 4 entries:
+  Tag        Type                         Name/Value
+ 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
+ 0x0000000000000001 (NEEDED)             Shared library: [libm.so.6]
+ 0x000000006ffffffb (FLAGS_1)            Flags: NOW PIE
+ 0x0000000000000000 (NULL)               0x0
+
+There are no relocations in this file.
+No processor specific unwind information to decode
+
+No version information found in this file.

src/LibObjectFile.Tests/Verified/ElfSimpleTests.TestElf_name=helloworld.verified.txt

@@ -92,7 +92,35 @@ Program Headers:
    11      
    12     .init_array .fini_array .dynamic .got 
 
-There is no dynamic section in this file.
+Dynamic section at offset 0x2dc8 contains 27 entries:
+  Tag        Type                         Name/Value
+ 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
+ 0x000000000000000c (INIT)               0x1000
+ 0x000000000000000d (FINI)               0x1174
+ 0x0000000000000019 (INIT_ARRAY)         0x3db8
+ 0x000000000000001b (INIT_ARRAYSZ)       8 (bytes)
+ 0x000000000000001a (FINI_ARRAY)         0x3dc0
+ 0x000000000000001c (FINI_ARRAYSZ)       8 (bytes)
+ 0x000000006ffffef5 (GNU_HASH)           0x3b0
+ 0x0000000000000005 (STRTAB)             0x480
+ 0x0000000000000006 (SYMTAB)             0x3d8
+ 0x000000000000000a (STRSZ)              141 (bytes)
+ 0x000000000000000b (SYMENT)             24 (bytes)
+ 0x0000000000000015 (DEBUG)              0x0
+ 0x0000000000000003 (PLTGOT)             0x3fb8
+ 0x0000000000000002 (PLTRELSZ)           24 (bytes)
+ 0x0000000000000014 (PLTREL)             RELA
+ 0x0000000000000017 (JMPREL)             0x610
+ 0x0000000000000007 (RELA)               0x550
+ 0x0000000000000008 (RELASZ)             192 (bytes)
+ 0x0000000000000009 (RELAENT)            24 (bytes)
+ 0x000000000000001e (FLAGS)              BIND_NOW
+ 0x000000006ffffffb (FLAGS_1)            Flags: NOW PIE
+ 0x000000006ffffffe (VERNEED)            0x520
+ 0x000000006fffffff (VERNEEDNUM)         1
+ 0x000000006ffffff0 (VERSYM)             0x50e
+ 0x000000006ffffff9 (RELACOUNT)          3
+ 0x0000000000000000 (NULL)               0x0
 
 Relocation section '.rela.dyn' at offset 0x550 contains 8 entries:
     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend

src/LibObjectFile.Tests/Verified/ElfSimpleTests.TestElf_name=helloworld_debug.verified.txt

@@ -97,7 +97,35 @@ Program Headers:
    11      
    12     .init_array .fini_array .dynamic .got 
 
-There is no dynamic section in this file.
+Dynamic section at offset 0x2dc8 contains 27 entries:
+  Tag        Type                         Name/Value
+ 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
+ 0x000000000000000c (INIT)               0x1000
+ 0x000000000000000d (FINI)               0x1174
+ 0x0000000000000019 (INIT_ARRAY)         0x3db8
+ 0x000000000000001b (INIT_ARRAYSZ)       8 (bytes)
+ 0x000000000000001a (FINI_ARRAY)         0x3dc0
+ 0x000000000000001c (FINI_ARRAYSZ)       8 (bytes)
+ 0x000000006ffffef5 (GNU_HASH)           0x3b0
+ 0x0000000000000005 (STRTAB)             0x480
+ 0x0000000000000006 (SYMTAB)             0x3d8
+ 0x000000000000000a (STRSZ)              141 (bytes)
+ 0x000000000000000b (SYMENT)             24 (bytes)
+ 0x0000000000000015 (DEBUG)              0x0
+ 0x0000000000000003 (PLTGOT)             0x3fb8
+ 0x0000000000000002 (PLTRELSZ)           24 (bytes)
+ 0x0000000000000014 (PLTREL)             RELA
+ 0x0000000000000017 (JMPREL)             0x610
+ 0x0000000000000007 (RELA)               0x550
+ 0x0000000000000008 (RELASZ)             192 (bytes)
+ 0x0000000000000009 (RELAENT)            24 (bytes)
+ 0x000000000000001e (FLAGS)              BIND_NOW
+ 0x000000006ffffffb (FLAGS_1)            Flags: NOW PIE
+ 0x000000006ffffffe (VERNEED)            0x520
+ 0x000000006fffffff (VERNEEDNUM)         1
+ 0x000000006ffffff0 (VERSYM)             0x50e
+ 0x000000006ffffff9 (RELACOUNT)          3
+ 0x0000000000000000 (NULL)               0x0
 
 Relocation section '.rela.dyn' at offset 0x550 contains 8 entries:
     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend

src/LibObjectFile.Tests/Verified/ElfSimpleTests.TestElf_name=lib_debug.so.verified.txt

@@ -87,7 +87,25 @@ Program Headers:
    09      
    10     .init_array .fini_array .dynamic .got 
 
-There is no dynamic section in this file.
+Dynamic section at offset 0x2e90 contains 17 entries:
+  Tag        Type                         Name/Value
+ 0x000000000000000c (INIT)               0x1000
+ 0x000000000000000d (FINI)               0x1130
+ 0x0000000000000019 (INIT_ARRAY)         0x3e80
+ 0x000000000000001b (INIT_ARRAYSZ)       8 (bytes)
+ 0x000000000000001a (FINI_ARRAY)         0x3e88
+ 0x000000000000001c (FINI_ARRAYSZ)       8 (bytes)
+ 0x000000006ffffef5 (GNU_HASH)           0x2f0
+ 0x0000000000000005 (STRTAB)             0x3c0
+ 0x0000000000000006 (SYMTAB)             0x318
+ 0x000000000000000a (STRSZ)              122 (bytes)
+ 0x000000000000000b (SYMENT)             24 (bytes)
+ 0x0000000000000003 (PLTGOT)             0x4000
+ 0x0000000000000007 (RELA)               0x440
+ 0x0000000000000008 (RELASZ)             168 (bytes)
+ 0x0000000000000009 (RELAENT)            24 (bytes)
+ 0x000000006ffffff9 (RELACOUNT)          3
+ 0x0000000000000000 (NULL)               0x0
 
 Relocation section '.rela.dyn' at offset 0x440 contains 7 entries:
     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend

src/LibObjectFile.Tests/Verified/ElfSimpleTests.TestElf_name=libstdc++.so.verified.txt

@@ -93,7 +93,38 @@ Program Headers:
    10      
    11     .init_array .fini_array .data.rel.ro .dynamic .got 
 
-There is no dynamic section in this file.
+Dynamic section at offset 0x223c90 contains 30 entries:
+  Tag        Type                         Name/Value
+ 0x0000000000000001 (NEEDED)             Shared library: [libm.so.6]
+ 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
+ 0x0000000000000001 (NEEDED)             Shared library: [ld-linux-x86-64.so.2]
+ 0x0000000000000001 (NEEDED)             Shared library: [libgcc_s.so.1]
+ 0x000000000000000e (SONAME)             Library soname: [libstdc++.so.6]
+ 0x000000000000000c (INIT)               0x9a000
+ 0x000000000000000d (FINI)               0x1aafc4
+ 0x0000000000000019 (INIT_ARRAY)         0x21b880
+ 0x000000000000001b (INIT_ARRAYSZ)       120 (bytes)
+ 0x000000000000001a (FINI_ARRAY)         0x21b8f8
+ 0x000000000000001c (FINI_ARRAYSZ)       8 (bytes)
+ 0x000000006ffffef5 (GNU_HASH)           0x328
+ 0x0000000000000005 (STRTAB)             0x2d310
+ 0x0000000000000006 (SYMTAB)             0x90a0
+ 0x000000000000000a (STRSZ)              302456 (bytes)
+ 0x000000000000000b (SYMENT)             24 (bytes)
+ 0x0000000000000003 (PLTGOT)             0x226000
+ 0x0000000000000002 (PLTRELSZ)           25032 (bytes)
+ 0x0000000000000014 (PLTREL)             RELA
+ 0x0000000000000017 (JMPREL)             0x92f78
+ 0x0000000000000007 (RELA)               0x7a8e8
+ 0x0000000000000008 (RELASZ)             99984 (bytes)
+ 0x0000000000000009 (RELAENT)            24 (bytes)
+ 0x000000006ffffffc (VERDEF)             0x7a0c0
+ 0x000000006ffffffd (VERDEFNUM)          48
+ 0x000000006ffffffe (VERNEED)            0x7a758
+ 0x000000006fffffff (VERNEEDNUM)         4
+ 0x000000006ffffff0 (VERSYM)             0x77088
+ 0x000000006ffffff9 (RELACOUNT)          899
+ 0x0000000000000000 (NULL)               0x0
 
 Relocation section '.rela.dyn' at offset 0x7a8e8 contains 4166 entries:
     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend