3 files changed, 92 insertions, 8 deletions

diff --git a/lldb/source/Plugins/ObjectFile/ELF/ELFHeader.cpp b/lldb/source/Plugins/ObjectFile/ELF/ELFHeader.cpp
index a3e82390d26..34b32a10b67 100644
--- a/lldb/source/Plugins/ObjectFile/ELF/ELFHeader.cpp
+++ b/lldb/source/Plugins/ObjectFile/ELF/ELFHeader.cpp
@@ -81,6 +81,39 @@ ByteOrder ELFHeader::GetByteOrder() const {
   return eByteOrderInvalid;
 }
 
+bool ELFHeader::HasHeaderExtension() const {
+  bool result = false;
+
+  // Check if any of these values looks like sentinel.
+  result |= e_phnum_hdr == 0xFFFF; // PN_XNUM
+  result |= e_shnum_hdr == SHN_UNDEF;
+  result |= e_shstrndx_hdr == SHN_XINDEX;
+
+  // If header extension is present, the section offset cannot be null.
+  result &= e_shoff != 0;
+
+  // Done.
+  return result;
+}
+
+void ELFHeader::ParseHeaderExtension(lldb_private::DataExtractor &data) {
+  // Extract section #0 header.
+  ELFSectionHeader section_zero;
+  lldb::offset_t offset = 0;
+  lldb_private::DataExtractor sh_data(data, e_shoff, e_shentsize);
+  bool ok = section_zero.Parse(sh_data, &offset);
+
+  // If we succeeded, fix the header.
+  if (ok) {
+    if (e_phnum_hdr == 0xFFFF) // PN_XNUM
+      e_phnum = section_zero.sh_info;
+    if (e_shnum_hdr == SHN_UNDEF)
+      e_shnum = section_zero.sh_size;
+    if (e_shstrndx_hdr == SHN_XINDEX)
+      e_shstrndx = section_zero.sh_link;
+  }
+}
+
 bool ELFHeader::Parse(lldb_private::DataExtractor &data,
                       lldb::offset_t *offset) {
   // Read e_ident.  This provides byte order and address size info.
@@ -112,6 +145,16 @@ bool ELFHeader::Parse(lldb_private::DataExtractor &data,
   if (data.GetU16(offset, &e_ehsize, 6) == NULL)
     return false;
 
+  // Initialize e_phnum, e_shnum, and e_shstrndx with the values
+  // read from the header.
+  e_phnum = e_phnum_hdr;
+  e_shnum = e_shnum_hdr;
+  e_shstrndx = e_shstrndx_hdr;
+
+  // See if we have extended header in section #0.
+  if (HasHeaderExtension())
+    ParseHeaderExtension(data);
+
   return true;
 }
 
diff --git a/lldb/source/Plugins/ObjectFile/ELF/ELFHeader.h b/lldb/source/Plugins/ObjectFile/ELF/ELFHeader.h
index 71b200f1c16..e6738a1ecb2 100644
--- a/lldb/source/Plugins/ObjectFile/ELF/ELFHeader.h
+++ b/lldb/source/Plugins/ObjectFile/ELF/ELFHeader.h
@@ -24,6 +24,7 @@
 #include "llvm/Support/ELF.h"
 
 #include "lldb/lldb-enumerations.h"
+#include "lldb/lldb-types.h"
 
 namespace lldb_private {
 class DataExtractor;
@@ -65,10 +66,17 @@ struct ELFHeader {
   elf_half e_machine;   ///< Target architecture.
   elf_half e_ehsize;    ///< Byte size of the ELF header.
   elf_half e_phentsize; ///< Size of a program header table entry.
-  elf_half e_phnum;     ///< Number of program header entries.
+  elf_half e_phnum_hdr; ///< Number of program header entries.
   elf_half e_shentsize; ///< Size of a section header table entry.
-  elf_half e_shnum;     ///< Number of section header entries.
-  elf_half e_shstrndx;  ///< String table section index.
+  elf_half e_shnum_hdr; ///< Number of section header entries.
+  elf_half e_shstrndx_hdr; ///< String table section index.
+
+  // In some cases these numbers do not fit in 16 bits and they are
+  // stored outside of the header in section #0. Here are the actual
+  // values.
+  elf_word e_phnum;     ///< Number of program header entries.
+  elf_word e_shnum;     ///< Number of section header entries.
+  elf_word e_shstrndx;  ///< String table section index.
 
   ELFHeader();
 
@@ -102,6 +110,14 @@ struct ELFHeader {
   unsigned GetRelocationJumpSlotType() const;
 
   //--------------------------------------------------------------------------
+  /// Check if there should be header extension in section header #0
+  ///
+  /// @return
+  ///    True if parsing the ELFHeader requires reading header extension
+  ///    and false otherwise.
+  bool HasHeaderExtension() const;
+
+  //--------------------------------------------------------------------------
   /// Parse an ELFHeader entry starting at position \p offset and
   /// update the data extractor with the address size and byte order
   /// attributes as defined by the header.
@@ -137,6 +153,16 @@ struct ELFHeader {
   ///    The number of bytes forming an address in the ELF file (either 4 or
   ///    8), else zero if the address size could not be determined.
   static unsigned AddressSizeInBytes(const uint8_t *magic);
+
+private:
+
+  //--------------------------------------------------------------------------
+  /// Parse an ELFHeader header extension entry.  This method is called
+  /// by Parse().
+  ///
+  /// @param[in] data
+  ///    The DataExtractor to read from.
+  void ParseHeaderExtension(lldb_private::DataExtractor &data);
 };
 
 //------------------------------------------------------------------------------
diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
index fa79b24c481..44ea01dbe16 100644
--- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -610,7 +610,8 @@ size_t ObjectFileELF::GetModuleSpecifications(
     DataExtractor data;
     data.SetData(data_sp);
     elf::ELFHeader header;
-    if (header.Parse(data, &data_offset)) {
+    lldb::offset_t header_offset = data_offset;
+    if (header.Parse(data, &header_offset)) {
       if (data_sp) {
         ModuleSpec spec(file);
 
@@ -645,10 +646,24 @@ size_t ObjectFileELF::GetModuleSpecifications(
                           __FUNCTION__, file.GetPath().c_str());
           }
 
+          // In case there is header extension in the section #0, the header
+          // we parsed above could have sentinel values for e_phnum, e_shnum,
+          // and e_shstrndx.  In this case we need to reparse the header
+          // with a bigger data source to get the actual values.
+          size_t section_header_end = header.e_shoff + header.e_shentsize;
+          if (header.HasHeaderExtension() &&
+            section_header_end > data_sp->GetByteSize()) {
+            data_sp = file.MemoryMapFileContentsIfLocal (file_offset,
+                                                         section_header_end);
+            data.SetData(data_sp);
+            lldb::offset_t header_offset = data_offset;
+            header.Parse(data, &header_offset);
+          }
+
           // Try to get the UUID from the section list. Usually that's at the
           // end, so
           // map the file in if we don't have it already.
-          size_t section_header_end =
+          section_header_end =
               header.e_shoff + header.e_shnum * header.e_shentsize;
           if (section_header_end > data_sp->GetByteSize()) {
             data_sp = file.MemoryMapFileContentsIfLocal(file_offset,
@@ -3067,10 +3082,10 @@ void ObjectFileELF::DumpELFHeader(Stream *s, const ELFHeader &header) {
   s->Printf("e_flags     = 0x%8.8x\n", header.e_flags);
   s->Printf("e_ehsize    = 0x%4.4x\n", header.e_ehsize);
   s->Printf("e_phentsize = 0x%4.4x\n", header.e_phentsize);
-  s->Printf("e_phnum     = 0x%4.4x\n", header.e_phnum);
+  s->Printf("e_phnum     = 0x%8.8x\n", header.e_phnum);
   s->Printf("e_shentsize = 0x%4.4x\n", header.e_shentsize);
-  s->Printf("e_shnum     = 0x%4.4x\n", header.e_shnum);
-  s->Printf("e_shstrndx  = 0x%4.4x\n", header.e_shstrndx);
+  s->Printf("e_shnum     = 0x%8.8x\n", header.e_shnum);
+  s->Printf("e_shstrndx  = 0x%8.8x\n", header.e_shstrndx);
 }
 
 //----------------------------------------------------------------------