[PATCH] Fix boehm-gc DSO checking on Linux (take 2)

[Jakub Jelinek <jakub at redhat dot com>]

On Wed, Aug 08, 2001 at 10:08:51AM -0400, Jakub Jelinek wrote:
> Hi!
> 
> boehm-gc similarly to fde-glibc makes bad assumptions about struct
> link_map's l_addr field, particularly that it is ok to cast this to
> ElfW(Ehdr) to get at its ELF headers.

This is updated patch, which makes the decision whether to use
dl_iterate_phdr at compile time rather than at configure time for the sake
of cross-compiling.
Ok to commit?

2001-08-09  Jakub Jelinek  <jakub@redhat.com>

	* dyn_load.c (GC_register_dynlib_callback): New.
	(GC_register_dynamic_libraries): New implementation if
	dl_iterate_phdr exists.

--- boehm-gc/dyn_load.c.jj	Mon Jul 24 00:06:16 2000
+++ boehm-gc/dyn_load.c	Thu Aug  9 04:10:10 2001
@@ -26,6 +26,10 @@
  * None of this is safe with dlclose and incremental collection.
  * But then not much of anything is safe in the presence of dlclose.
  */
+
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE
+#endif
 #ifndef MACOS
 #  include <sys/types.h>
 #endif
@@ -299,14 +303,68 @@ void GC_register_dynamic_libraries()
 
 #if defined(LINUX) && defined(__ELF__) || defined(SCO_ELF)
 
+#include <elf.h>
+#include <link.h>
+
+# if defined(LINUX) \
+     && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \
+         || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG)))
+
+#include <stddef.h>
+
+static int GC_register_dynlib_callback(info, size, ptr)
+     struct dl_phdr_info * info;
+     size_t size;
+     void * ptr;
+{
+  const ElfW(Phdr) * p;
+  char * start;
+  register int i;
+
+  /* Make sure struct dl_phdr_info is at least as big as we need.  */
+  if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
+      + sizeof (info->dlpi_phnum))
+    return -1;
+
+  /* Skip the first object - it is the main program.  */
+  if (*(int *)ptr == 0)
+    {
+      *(int *)ptr = 1;
+      return 0;
+    }
+
+  p = info->dlpi_phdr;
+  for( i = 0; i < (int)(info->dlpi_phnum); ((i++),(p++)) ) {
+    switch( p->p_type ) {
+      case PT_LOAD:
+	{
+	  if( !(p->p_flags & PF_W) ) break;
+	  start = ((char *)(p->p_vaddr)) + info->dlpi_addr;
+	  GC_add_roots_inner(start, start + p->p_memsz, TRUE);
+	}
+      break;
+      default:
+	break;
+    }
+  }
+
+  return 0;
+}     
+
+void GC_register_dynamic_libraries()
+{
+  int tmp = 0;
+
+  dl_iterate_phdr(GC_register_dynlib_callback, &tmp);
+}
+
+#else /* !DL_ITERATE_PHDR */
+
 /* Dynamic loading code for Linux running ELF. Somewhat tested on
  * Linux/x86, untested but hopefully should work on Linux/Alpha. 
  * This code was derived from the Solaris/ELF support. Thanks to
  * whatever kind soul wrote that.  - Patrick Bridges */
 
-#include <elf.h>
-#include <link.h>
-
 /* Newer versions of Linux/Alpha and Linux/x86 define this macro.  We
  * define it for those older versions that don't.  */
 #  ifndef ElfW
@@ -379,6 +437,7 @@ void GC_register_dynamic_libraries()
     }
 }
 
+#endif /* !DL_ITERATE_PHDR */
 #endif
 
 #if defined(IRIX5) || defined(USE_PROC_FOR_LIBRARIES)

	Jakub