Refactor the ELF support to allow ELF write suppport.

The refactoring allows better reuse of the ELF support and cleans up
some hacks from the generic file and archive handling improving the
separation of the file handling from the file format, ie ELF. The
handling of ELF object files and ELF object files inside archives
is cleaner.

The refactor cleaned up the symbol handling where the symbols now
reside in the ELF file object and references are take in symbol
pointer containers and symbol table containers.

The main purpose of the refactor is to allow support for creating
and writing ELF files.

Also added an rtems-syms command where special symbol support
can be added.

1 files changed, 145 insertions, 69 deletions

diff --git a/rld-files.cpp b/rld-files.cpp
index d44474b..108f920 100644
--- a/rld-files.cpp
+++ b/rld-files.cpp
@@ -1,10 +1,10 @@
 /*
- * Copyright (c) 2011, Chris Johns <chrisj@rtems.org> 
+ * Copyright (c) 2011, Chris Johns <chrisj@rtems.org>
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.
- * 
+ *
  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
@@ -45,7 +45,7 @@ namespace rld
     scan_decimal (const uint8_t* string, size_t len)
     {
       uint64_t value = 0;
-      
+
       while (len && (*string != ' '))
       {
         value *= 10;
@@ -104,7 +104,7 @@ namespace rld
         joined = path_ + RLD_PATH_SEPARATOR + file_;
       else if ((path_[path_.size () - 1] == RLD_PATH_SEPARATOR) &&
                (file_[0] == RLD_PATH_SEPARATOR))
-        joined = path_ + &file_[1];        
+        joined = path_ + &file_[1];
       else
         joined = path_ + file_;
     }
@@ -147,7 +147,7 @@ namespace rld
                 const std::string& oname,
                 off_t              offset,
                 size_t             size)
-      : aname_ (aname), 
+      : aname_ (aname),
         oname_ (oname),
         offset_ (offset),
         size_ (size)
@@ -246,8 +246,8 @@ namespace rld
         return aname_;
       return oname_;
     }
-    
-    const std::string 
+
+    const std::string
     file::full () const
     {
       std::string f;
@@ -297,8 +297,7 @@ namespace rld
     image::image (file& name)
       : name_ (name),
         references_ (0),
-        fd_ (-1),
-        elf_ (0)
+        fd_ (-1)
     {
     }
 
@@ -306,15 +305,14 @@ namespace rld
       : name_ (path, is_object),
         references_ (0),
         fd_ (-1),
-        elf_ (0),
-        symbol_refs (0)
+        symbol_refs (0),
+        writeable (false)
     {
     }
 
     image::image ()
       : references_ (0),
         fd_ (-1),
-        elf_ (0),
         symbol_refs (0)
     {
     }
@@ -335,26 +333,34 @@ namespace rld
     }
 
     void
-    image::open (bool writable)
+    image::open (bool writeable_)
     {
       const std::string path = name_.path ();
 
       if (path.empty ())
-        throw rld::error ("No file name", "open" + path);
+        throw rld::error ("No file name", "open:" + path);
 
       if (rld::verbose () >= RLD_VERBOSE_DETAILS)
         std::cout << "image::open: " << name (). full ()
+                  << " writable:" << (char*) (writeable_ ? "yes" : "no")
                   << " refs:" << references_ + 1 << std::endl;
 
       if (fd_ < 0)
       {
-        if (writable)
+        writeable = writeable_;
+
+        if (writeable)
           fd_ = ::open (path.c_str (), OPEN_FLAGS | O_RDWR | O_CREAT | O_TRUNC, CREATE_MODE);
         else
           fd_ = ::open (path.c_str (), OPEN_FLAGS | O_RDONLY);
         if (fd_ < 0)
           throw rld::error (::strerror (errno), "open:" + path);
       }
+      else
+      {
+        if (writeable_ != writeable)
+          throw rld::error ("Cannot change write status", "open:" + path);
+      }
 
       ++references_;
     }
@@ -385,7 +391,7 @@ namespace rld
         throw rld::error (strerror (errno), "read:" + name ().path ());
       return rsize;
     }
- 
+
     ssize_t
     image::write (const void* buffer, size_t size)
     {
@@ -394,28 +400,28 @@ namespace rld
         throw rld::error (strerror (errno), "write:" + name ().path ());
       return wsize;
     }
- 
+
     void
     image::seek (off_t offset)
     {
       if (::lseek (fd (), name_.offset () + offset, SEEK_SET) < 0)
         throw rld::error (strerror (errno), "lseek:" + name ().path ());
     }
- 
+
     bool
     image::seek_read (off_t offset, uint8_t* buffer, size_t size)
     {
       seek (offset);
       return size == (size_t) read (buffer, size);
     }
- 
+
     bool
     image::seek_write (off_t offset, const void* buffer, size_t size)
     {
       seek (offset);
       return size == (size_t) write (buffer, size);
     }
- 
+
     const file&
     image::name () const
     {
@@ -423,41 +429,35 @@ namespace rld
     }
 
     int
-    image::references () const 
+    image::references () const
     {
       return references_;
     }
 
     size_t
-    image::size () const 
+    image::size () const
     {
       return name ().size ();
     }
 
     int
-    image::fd () const 
+    image::fd () const
     {
       return fd_;
     }
 
-    rld::elf::elf*
-    image::elf (bool )
+    rld::elf::file&
+    image::elf ()
     {
       return elf_;
     }
 
     void
-    image::set_elf (rld::elf::elf* elf)
-    {
-      elf_ = elf;
-    }
-
-    void
     image::symbol_referenced ()
     {
       ++symbol_refs;
     }
-    
+
     int
     image::symbol_references () const
     {
@@ -474,6 +474,10 @@ namespace rld
         buffer = new uint8_t[COPY_FILE_BUFFER_SIZE];
         while (size)
         {
+          /*
+           * @fixme the reading and writing are not POSIX; sigints could split them.
+           */
+
           size_t l = size < COPY_FILE_BUFFER_SIZE ? size : COPY_FILE_BUFFER_SIZE;
           ssize_t r = ::read (in.fd (), buffer, l);
 
@@ -545,6 +549,25 @@ namespace rld
       close ();
     }
 
+    void
+    archive::begin ()
+    {
+      elf ().begin (name ().full (), fd ());
+
+      /*
+       * Make sure it is an archive.
+       */
+      if (!elf ().is_archive ())
+        throw rld::error ("Not an archive.",
+                          "archive-begin:" + name ().full ());
+    }
+
+    void
+    archive::end ()
+    {
+      elf ().end ();
+    }
+
     bool
     archive::is (const std::string& path) const
     {
@@ -580,8 +603,8 @@ namespace rld
         /*
          * The archive file headers are always aligned to an even address.
          */
-        size = 
-          (scan_decimal (&header[rld_archive_size], 
+        size =
+          (scan_decimal (&header[rld_archive_size],
                          rld_archive_size_size) + 1) & ~1;
 
         /*
@@ -625,15 +648,15 @@ namespace rld
                 off_t off = offset;
                 while (extended_file_names == 0)
                 {
-                  size_t esize = 
+                  size_t esize =
                     (scan_decimal (&header[rld_archive_size],
                                    rld_archive_size_size) + 1) & ~1;
                   off += esize + rld_archive_fhdr_size;
-                    
+
                   if (!read_header (off, &header[0]))
                     throw rld::error ("No GNU extended file name section found",
                                       "get-names:" + name ().path ());
-              
+
                   if ((header[0] == '/') && (header[1] == '/'))
                   {
                     extended_file_names = off + rld_archive_fhdr_size;
@@ -693,7 +716,7 @@ namespace rld
           (header[rld_archive_magic + 1] != 0x0a))
         throw rld::error ("Invalid header magic numbers at " +
                           rld::to_string (offset), "read-header:" + name ().path ());
-      
+
       return true;
     }
 
@@ -725,7 +748,7 @@ namespace rld
         uint8_t header[rld_archive_fhdr_size];
 
         memset (header, ' ', sizeof (header));
-        
+
         size_t len = name.length ();
         if (len > rld_archive_fname_size)
           len = rld_archive_fname_size;
@@ -756,7 +779,7 @@ namespace rld
          * GNU extended filenames.
          */
         std::string extended_file_names;
-        
+
         for (object_list::iterator oi = objects.begin ();
              oi != objects.end ();
              ++oi)
@@ -818,7 +841,7 @@ namespace rld
         close ();
         throw;
       }
-      
+
       close ();
     }
 
@@ -877,16 +900,34 @@ namespace rld
     object::begin ()
     {
       /*
-       * Begin an ELF session and get the ELF header.
+       * Begin a session.
+       */
+      if (archive_)
+        elf ().begin (name ().full (), archive_->elf(), name ().offset ());
+      else
+        elf ().begin (name ().full (), fd ());
+
+      /*
+       * Cannot be an archive.
        */
-      rld::elf::begin (*this);
-      rld::elf::get_header (*this, ehdr);
+      if (elf ().is_archive ())
+        throw rld::error ("Is an archive not an object file.",
+                          "object-begin:" + name ().full ());
+
+      /*
+       * We only support executable or relocatable ELF files.
+       */
+      if (!elf ().is_executable () && !elf ().is_relocatable ())
+        throw rld::error ("Invalid ELF type (only ET_EXEC/ET_REL supported).",
+                          "object-begin:" + name ().full ());
+
+      elf::check_file (elf ());
     }
 
     void
     object::end ()
     {
-      rld::elf::end (*this);
+      elf ().end ();
     }
 
     void
@@ -894,17 +935,58 @@ namespace rld
     {
       if (rld::verbose () >= RLD_VERBOSE_DETAILS)
         std::cout << "object:load-sym: " << name ().full () << std::endl;
-      rld::elf::load_symbols (symbols, *this, local);
-    }
 
-    std::string
-    object::get_string (int section, size_t offset)
-    {
-      return rld::elf::get_string (*this, section, offset);
+      rld::symbols::pointers syms;
+
+      elf ().get_symbols (syms, false, local);
+
+      if (rld::verbose () >= RLD_VERBOSE_DETAILS)
+        std::cout << "object:load-sym: exported: total "
+                  << syms.size () << std::endl;
+
+      for (symbols::pointers::iterator si = syms.begin ();
+           si != syms.end ();
+           ++si)
+      {
+        symbols::symbol& sym = *(*si);
+
+        if (rld::verbose () >= RLD_VERBOSE_DETAILS)
+        {
+          std::cout << "object:load-sym: exported: ";
+          sym.output (std::cout);
+          std::cout << std::endl;
+        }
+
+        sym.set_object (*this);
+        symbols[sym.name ()] = &sym;
+        externals.push_back (&sym);
+      }
+
+      elf ().get_symbols (syms, true);
+
+      if (rld::verbose () >= RLD_VERBOSE_DETAILS)
+        std::cout << "object:load-sym: unresolved: total "
+                  << syms.size () << std::endl;
+
+      for (symbols::pointers::iterator si = syms.begin ();
+           si != syms.end ();
+           ++si)
+      {
+        symbols::symbol& sym = *(*si);
+
+        if (rld::verbose () >= RLD_VERBOSE_DETAILS)
+        {
+          std::cout << "object:load-sym: unresolved: ";
+          sym.output (std::cout);
+          std::cout << std::endl;
+        }
+
+        unresolved[sym.name ()] = &sym;
+      }
     }
-    
+
     int
-    object::references () const 
+    object::references () const
     {
       if (archive_)
         return archive_->references ();
@@ -912,7 +994,7 @@ namespace rld
     }
 
     size_t
-    object::size () const 
+    object::size () const
     {
       if (archive_)
         return archive_->size ();
@@ -920,21 +1002,13 @@ namespace rld
     }
 
     int
-    object::fd () const 
+    object::fd () const
     {
       if (archive_)
         return archive_->fd ();
       return image::fd ();
     }
 
-    rld::elf::elf* 
-    object::elf (bool archive__)
-    {
-      if (archive__ && archive_)
-        return archive_->elf ();
-      return image::elf ();
-    }
-
     void
     object::symbol_referenced ()
     {
@@ -942,13 +1016,14 @@ namespace rld
       if (archive_)
         archive_->symbol_referenced ();
     }
-    
+
     archive*
     object::get_archive ()
     {
       return archive_;
     }
 
+#if 0
     int
     object::sections () const
     {
@@ -960,6 +1035,7 @@ namespace rld
     {
       return ehdr.e_shstrndx;
     }
+#endif
 
     rld::symbols::table&
     object::unresolved_symbols ()
@@ -967,7 +1043,7 @@ namespace rld
       return unresolved;
     }
 
-    rld::symbols::list&
+    rld::symbols::pointers&
     object::external_symbols ()
     {
       return externals;
@@ -1047,7 +1123,7 @@ namespace rld
           if (rld::verbose () >= RLD_VERBOSE_TRACE)
             std::cout << "cache:archive-begin: " << path << std::endl;
           ar->open ();
-          rld::elf::begin (*ar);
+          ar->begin ();
         }
       }
     }
@@ -1063,7 +1139,7 @@ namespace rld
         {
           if (rld::verbose () >= RLD_VERBOSE_TRACE)
             std::cout << "cache:archive-end: " << path << std::endl;
-          rld::elf::end (*ar);
+          ar->end ();
           ar->close ();
         }
       }
@@ -1082,7 +1158,7 @@ namespace rld
       for (archives::iterator ai = archives_.begin (); ai != archives_.end (); ++ai)
         archive_end (((*ai).second)->path ());
     }
-    
+
     void
     cache::collect_object_files ()
     {
@@ -1173,7 +1249,7 @@ namespace rld
     {
       return archives_;
     }
- 
+
     objects&
     cache::get_objects ()
     {