Preliminary support for generating shared libraries, from Eric

	Youngdale <ericy@cais.cais.com>.
	* elfcode.h (prep_headers): If DYNAMIC, set e_type to ET_DYN.
	(elf_link_add_object_symbols): If generating a shared library,
	create dynamic sections for first input BFD with the right format.
	(elf_link_create_dynamic_sections): Don't create .interp section
	if creating a shared library.
	(elf_link_input_bfd): Skip dynamic sections in input file.
	(elf_bfd_final_link): If creating a shared library, it's OK for
	dynobj to have sections which are not SEC_IN_MEMORY.
	* elf32-i386.c (elf_i386_size_dynamic_sections): Only set .interp
	section if not creating a shared library.
	* elf32-sparc.c (elf_sparc_size_dynamic_sections): Likewise.

4 files changed, 85 insertions, 22 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 4e6d161..7c6e3cb 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,5 +1,19 @@
 Thu Jun 23 15:31:28 1994  Ian Lance Taylor  (ian@sanguine.cygnus.com)
 
+	Preliminary support for generating shared libraries, from Eric
+	Youngdale <ericy@cais.cais.com>.
+	* elfcode.h (prep_headers): If DYNAMIC, set e_type to ET_DYN.
+	(elf_link_add_object_symbols): If generating a shared library,
+	create dynamic sections for first input BFD with the right format.
+	(elf_link_create_dynamic_sections): Don't create .interp section
+	if creating a shared library.
+	(elf_link_input_bfd): Skip dynamic sections in input file.
+	(elf_bfd_final_link): If creating a shared library, it's OK for
+	dynobj to have sections which are not SEC_IN_MEMORY.
+	* elf32-i386.c (elf_i386_size_dynamic_sections): Only set .interp
+	section if not creating a shared library.
+	* elf32-sparc.c (elf_sparc_size_dynamic_sections): Likewise.
+
 	* elfcode.h (elf_object_p): Don't set DYNAMIC just because there
 	is an SHT_DYNAMIC section.
 
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index 6e942a5..5643c7a 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -488,10 +488,13 @@ elf_i386_size_dynamic_sections (output_bfd, info)
   BFD_ASSERT (dynobj != NULL);
 
   /* Set the contents of the .interp section to the interpreter.  */
-  s = bfd_get_section_by_name (dynobj, ".interp");
-  BFD_ASSERT (s != NULL);
-  s->_raw_size = sizeof ELF_DYNAMIC_INTERPRETER;
-  s->contents = (unsigned char *) ELF_DYNAMIC_INTERPRETER;
+  if (! info->shared)
+    {
+      s = bfd_get_section_by_name (dynobj, ".interp");
+      BFD_ASSERT (s != NULL);
+      s->_raw_size = sizeof ELF_DYNAMIC_INTERPRETER;
+      s->contents = (unsigned char *) ELF_DYNAMIC_INTERPRETER;
+    }
 
   /* The adjust_dynamic_symbol entry point has determined the sizes of
      the various dynamic sections.  Allocate some memory for them to
@@ -505,8 +508,10 @@ elf_i386_size_dynamic_sections (output_bfd, info)
   /* Add some entries to the .dynamic section.  We fill in the values
      later, in elf_i386_finish_dynamic_sections, but we must add the
      entries now so that we get the correct size for the .dynamic
-     section.  */
-  if (! bfd_elf32_add_dynamic_entry (info, DT_PLTGOT, 0))
+     section.  The DT_DEBUG entry is filled in by the dynamic linker
+     and used by the debugger.  */
+  if (! bfd_elf32_add_dynamic_entry (info, DT_DEBUG, 0)
+      || ! bfd_elf32_add_dynamic_entry (info, DT_PLTGOT, 0))
     return false;
 
   s = bfd_get_section_by_name (dynobj, ".plt");
diff --git a/bfd/elf32-sparc.c b/bfd/elf32-sparc.c
index 4256878..2733a1e 100644
--- a/bfd/elf32-sparc.c
+++ b/bfd/elf32-sparc.c
@@ -472,10 +472,13 @@ elf32_sparc_size_dynamic_sections (output_bfd, info)
   BFD_ASSERT (dynobj != NULL);
 
   /* Set the contents of the .interp section to the interpreter.  */
-  s = bfd_get_section_by_name (dynobj, ".interp");
-  BFD_ASSERT (s != NULL);
-  s->_raw_size = sizeof ELF_DYNAMIC_INTERPRETER;
-  s->contents = (unsigned char *) ELF_DYNAMIC_INTERPRETER;
+  if (! info->shared)
+    {
+      s = bfd_get_section_by_name (dynobj, ".interp");
+      BFD_ASSERT (s != NULL);
+      s->_raw_size = sizeof ELF_DYNAMIC_INTERPRETER;
+      s->contents = (unsigned char *) ELF_DYNAMIC_INTERPRETER;
+    }
 
   /* Make space for the trailing nop in .plt.  */
   s = bfd_get_section_by_name (dynobj, ".plt");
@@ -492,10 +495,12 @@ elf32_sparc_size_dynamic_sections (output_bfd, info)
     return false;
 
   /* Add some entries to the .dynamic section.  We fill in the values
-     later, in elf32_sparc_finish_dynamic_sections, but we must add the
-     entries now so that we get the correct size for the .dynamic
-     section.  */
-  if (! bfd_elf32_add_dynamic_entry (info, DT_PLTGOT, 0)
+     later, in elf32_sparc_finish_dynamic_sections, but we must add
+     the entries now so that we get the correct size for the .dynamic
+     section.  The DT_DEBUG entry is filled in by the dynamic linker
+     and used by the debugger.  */
+  if (! bfd_elf32_add_dynamic_entry (info, DT_DEBUG, 0)
+      || ! bfd_elf32_add_dynamic_entry (info, DT_PLTGOT, 0)
       || ! bfd_elf32_add_dynamic_entry (info, DT_PLTRELSZ, 0)
       || ! bfd_elf32_add_dynamic_entry (info, DT_PLTREL, DT_RELA)
       || ! bfd_elf32_add_dynamic_entry (info, DT_JMPREL, 0)
diff --git a/bfd/elfcode.h b/bfd/elfcode.h
index 85d5fd9..8286d4e 100644
--- a/bfd/elfcode.h
+++ b/bfd/elfcode.h
@@ -2125,7 +2125,13 @@ prep_headers (abfd)
   for (count = EI_PAD; count < EI_NIDENT; count++)
     i_ehdrp->e_ident[count] = 0;
 
-  i_ehdrp->e_type = (abfd->flags & EXEC_P) ? ET_EXEC : ET_REL;
+  if ((abfd->flags & DYNAMIC) != 0)
+    i_ehdrp->e_type = ET_DYN;
+  else if ((abfd->flags & EXEC_P) != 0)
+    i_ehdrp->e_type = ET_EXEC;
+  else
+    i_ehdrp->e_type = ET_REL;
+
   switch (bfd_get_arch (abfd))
     {
     case bfd_arch_unknown:
@@ -4131,7 +4137,23 @@ elf_link_add_object_symbols (abfd, info)
   elf_sym_hashes (abfd) = sym_hash;
 
   if (elf_elfheader (abfd)->e_type != ET_DYN)
-    dynamic = false;
+    {
+      dynamic = false;
+
+      /* If we are creating a shared library, create all the dynamic
+         sections immediately.  We need to attach them to something,
+         so we attach them to this BFD, provided it is the right
+         format.  FIXME: If there are no input BFD's of the same
+         format as the output, we can't make a shared library.  */
+      if (info->shared
+	  && elf_hash_table (info)->dynobj == NULL
+	  && abfd->xvec == info->hash->creator)
+	{
+	  if (! elf_link_create_dynamic_sections (abfd, info))
+	    goto error_return;
+	  elf_hash_table (info)->dynobj = abfd;
+	}
+    }
   else
     {
       asection *s;
@@ -4571,10 +4593,15 @@ elf_link_create_dynamic_sections (abfd, info)
      sections.  */
   flags = SEC_ALLOC | SEC_LOAD | SEC_HAS_CONTENTS | SEC_IN_MEMORY;
 
-  s = bfd_make_section (abfd, ".interp");
-  if (s == NULL
-      || ! bfd_set_section_flags (abfd, s, flags | SEC_READONLY))
-    return false;
+  /* A dynamically linked executable has a .interp section, but a
+     shared library does not.  */
+  if (! info->shared)
+    {
+      s = bfd_make_section (abfd, ".interp");
+      if (s == NULL
+	  || ! bfd_set_section_flags (abfd, s, flags | SEC_READONLY))
+	return false;
+    }
 
   s = bfd_make_section (abfd, ".dynamic");
   if (s == NULL
@@ -4755,7 +4782,7 @@ NAME(bfd_elf,size_dynamic_sections) (output_bfd, info, sinterpptr)
     return true;
 
   *sinterpptr = bfd_get_section_by_name (dynobj, ".interp");
-  BFD_ASSERT (*sinterpptr != NULL);
+  BFD_ASSERT (*sinterpptr != NULL || info->shared);
 
   /* Set the size of the .dynsym and .hash sections.  We counted the
      number of dynamic symbols in elf_link_add_object_symbols.  We
@@ -5515,7 +5542,11 @@ elf_bfd_final_link (abfd, info)
 	{
 	  if ((o->flags & SEC_HAS_CONTENTS) == 0)
 	    continue;
-	  BFD_ASSERT ((o->flags & SEC_IN_MEMORY) != 0);
+	  if ((o->flags & SEC_IN_MEMORY) == 0)
+	    {
+	      BFD_ASSERT (info->shared);
+	      continue;
+	    }
 	  if (! bfd_set_section_contents (abfd, o->output_section,
 					  o->contents, o->output_offset,
 					  o->_raw_size))
@@ -5965,6 +5996,14 @@ elf_link_input_bfd (finfo, input_bfd)
       if ((o->flags & SEC_HAS_CONTENTS) == 0)
 	continue;
 
+      if ((o->flags & SEC_IN_MEMORY) != 0
+	  && input_bfd == elf_hash_table (finfo->info)->dynobj)
+	{
+	  /* Section was created by elf_link_create_dynamic_sections.
+             FIXME: This test is fragile.  */
+	  continue;
+	}
+
       /* Read the contents of the section.  */
       if (! bfd_get_section_contents (input_bfd, o, finfo->contents,
 				      (file_ptr) 0, o->_raw_size))