Index: gdb-7.6/gdb/corelow.c

===================================================================

--- gdb-7.6.orig/gdb/corelow.c	2013-01-31 19:37:37.000000000 +0100

+++ gdb-7.6/gdb/corelow.c	2013-08-06 16:57:14.832517976 +0200

@@ -46,6 +46,9 @@

 #include "progspace.h"

 #include "objfiles.h"

 #include "gdb_bfd.h"

+#include "auxv.h"

+#include "elf/common.h"

+#include "gdbcmd.h"

 #ifndef O_LARGEFILE

 #define O_LARGEFILE 0

@@ -271,6 +274,53 @@ add_to_thread_list (bfd *abfd, asection

     inferior_ptid = ptid;			/* Yes, make it current.  */

 }

+static int build_id_core_loads = 1;

+

+static void

+build_id_locate_exec (int from_tty)

+{

+  CORE_ADDR at_entry;

+  struct elf_build_id *build_id;

+  char *execfilename, *debug_filename;

+  char *build_id_filename;

+  struct cleanup *back_to;

+

+  if (exec_bfd != NULL || symfile_objfile != NULL)

+    return;

+

+  if (target_auxv_search (&current_target, AT_ENTRY, &at_entry) <= 0)

+    return;

+

+  build_id = build_id_addr_get (at_entry);

+  if (build_id == NULL)

+    return;

+  back_to = make_cleanup (xfree, build_id);

+

+  /* SYMFILE_OBJFILE should refer to the main executable (not only to its

+     separate debug info file).  gcc44+ keeps .eh_frame only in the main

+     executable without its duplicate .debug_frame in the separate debug info

+     file - such .eh_frame would not be found if SYMFILE_OBJFILE would refer

+     directly to the separate debug info file.  */

+

+  execfilename = build_id_to_filename (build_id, &build_id_filename, 0);

+  make_cleanup (xfree, build_id_filename);

+

+  if (execfilename != NULL)

+    {

+      make_cleanup (xfree, execfilename);

+      exec_file_attach (execfilename, from_tty);

+      symbol_file_add_main (execfilename, from_tty);

+      if (symfile_objfile != NULL)

+        symfile_objfile->flags |= OBJF_BUILD_ID_CORE_LOADED;

+    }

+  else

+    debug_print_missing (_("the main executable file"), build_id_filename);

+

+  do_cleanups (back_to);

+

+  /* No automatic SOLIB_ADD as the libraries would get read twice.  */

+}

+

 /* This routine opens and sets up the core file bfd.  */

 static void

@@ -409,6 +459,14 @@ core_open (char *filename, int from_tty)

 	switch_to_thread (thread->ptid);

     }

+  /* Find the build_id identifiers.  If it gets executed after

+     POST_CREATE_INFERIOR we would clash with asking to discard the already

+     loaded VDSO symbols.  If it gets executed before bfd_map_over_sections

+     INFERIOR_PTID is still not set and libthread_db initialization crashes on

+     PID == 0 in ps_pglobal_lookup.  */

+  if (build_id_core_loads != 0)

+    build_id_locate_exec (from_tty);

+

   post_create_inferior (&core_ops, from_tty);

   /* Now go through the target stack looking for threads since there

@@ -978,4 +1036,11 @@ _initialize_corelow (void)

   init_core_ops ();

   add_target (&core_ops);

+

+  add_setshow_boolean_cmd ("build-id-core-loads", class_files,

+			   &build_id_core_loads, _("\

+Set whether CORE-FILE loads the build-id associated files automatically."), _("\

+Show whether CORE-FILE loads the build-id associated files automatically."),

+			   NULL, NULL, NULL,

+			   &setlist, &showlist);

 }

Index: gdb-7.6/gdb/doc/gdb.texinfo

===================================================================

--- gdb-7.6.orig/gdb/doc/gdb.texinfo	2013-08-06 16:57:14.531517553 +0200

+++ gdb-7.6/gdb/doc/gdb.texinfo	2013-08-06 16:57:14.843517992 +0200

@@ -16831,6 +16831,27 @@ information files.

 @end table

+You can also adjust the current verbosity of the @dfn{build id} locating.

+

+@table @code

+

+@kindex set build-id-verbose

+@item set build-id-verbose 0

+No additional messages are printed.

+

+@item set build-id-verbose 1

+Missing separate debug filenames are printed.

+

+@item set build-id-verbose 2

+Missing separate debug filenames are printed and also all the parsing of the

+binaries to find their @dfn{build id} content is printed.

+

+@kindex show build-id-verbose

+@item show build-id-verbose

+Show the current verbosity value for the @dfn{build id} content locating.

+

+@end table

+

 @cindex @code{.gnu_debuglink} sections

 @cindex debug link sections

 A debug link is a special section of the executable file named

Index: gdb-7.6/gdb/solib-svr4.c

===================================================================

--- gdb-7.6.orig/gdb/solib-svr4.c	2013-01-31 14:52:52.000000000 +0100

+++ gdb-7.6/gdb/solib-svr4.c	2013-08-06 16:57:14.917518096 +0200

@@ -1224,9 +1224,52 @@ svr4_read_so_list (CORE_ADDR lm, struct

 	  continue;

 	}

-      strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1);

-      new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';

-      strcpy (new->so_original_name, new->so_name);

+      {

+	struct elf_build_id *build_id;

+

+	strncpy (new->so_original_name, buffer, SO_NAME_MAX_PATH_SIZE - 1);

+	new->so_original_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';

+	/* May get overwritten below.  */

+	strcpy (new->so_name, new->so_original_name);

+

+	build_id = build_id_addr_get (new->lm_info->l_ld);

+	if (build_id != NULL)

+	  {

+	    char *name, *build_id_filename;

+

+	    /* Missing the build-id matching separate debug info file

+	       would be handled while SO_NAME gets loaded.  */

+	    name = build_id_to_filename (build_id, &build_id_filename, 0);

+	    if (name != NULL)

+	      {

+		strncpy (new->so_name, name, SO_NAME_MAX_PATH_SIZE - 1);

+		new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';

+		xfree (name);

+	      }

+	    else

+	      {

+		debug_print_missing (new->so_name, build_id_filename);

+

+		/* In the case the main executable was found according to

+		   its build-id (from a core file) prevent loading

+		   a different build of a library with accidentally the

+		   same SO_NAME.

+

+		   It suppresses bogus backtraces (and prints "??" there

+		   instead) if the on-disk files no longer match the

+		   running program version.  */

+

+		if (symfile_objfile != NULL

+		    && (symfile_objfile->flags

+			& OBJF_BUILD_ID_CORE_LOADED) != 0)

+		  new->so_name[0] = 0;

+	      }

+

+	    xfree (build_id_filename);

+	    xfree (build_id);

+	  }

+      }

+

       xfree (buffer);

       /* If this entry has no name, or its name matches the name

Index: gdb-7.6/gdb/elfread.c

===================================================================

--- gdb-7.6.orig/gdb/elfread.c	2013-03-18 10:20:02.000000000 +0100

+++ gdb-7.6/gdb/elfread.c	2013-08-06 16:57:19.548524529 +0200

@@ -45,6 +45,11 @@

 #include "regcache.h"

 #include "bcache.h"

 #include "gdb_bfd.h"

+#include "libbfd.h"

+#include "gdbcore.h"

+#include "gdbcmd.h"

+#include "observer.h"

+#include <sys/stat.h>

 extern void _initialize_elfread (void);

@@ -1068,10 +1073,59 @@ elf_gnu_ifunc_resolver_return_stop (stru

   update_breakpoint_locations (b, sals, sals_end);

 }

-/* Locate NT_GNU_BUILD_ID from ABFD and return its content.  */

+#define BUILD_ID_VERBOSE_NONE 0

+#define BUILD_ID_VERBOSE_FILENAMES 1

+#define BUILD_ID_VERBOSE_BINARY_PARSE 2

+static int build_id_verbose = BUILD_ID_VERBOSE_FILENAMES;

+static void

+show_build_id_verbose (struct ui_file *file, int from_tty,

+		       struct cmd_list_element *c, const char *value)

+{

+  fprintf_filtered (file, _("Verbosity level of the build-id locator is %s.\n"),

+		    value);

+}

+

+/* Locate NT_GNU_BUILD_ID and return its matching debug filename.

+   FIXME: NOTE decoding should be unified with the BFD core notes decoding.  */

+

+static struct elf_build_id *

+build_id_buf_get (bfd *templ, gdb_byte *buf, bfd_size_type size)

+{

+  bfd_byte *p;

+

+  p = buf;

+  while (p < buf + size)

+    {

+      /* FIXME: bad alignment assumption.  */

+      Elf_External_Note *xnp = (Elf_External_Note *) p;

+      size_t namesz = H_GET_32 (templ, xnp->namesz);

+      size_t descsz = H_GET_32 (templ, xnp->descsz);

+      bfd_byte *descdata = xnp->name + BFD_ALIGN (namesz, 4);

+

+      if (H_GET_32 (templ, xnp->type) == NT_GNU_BUILD_ID

+	  && namesz == sizeof "GNU"

+	  && memcmp (xnp->name, "GNU", sizeof "GNU") == 0)

+	{

+	  size_t size = descsz;

+	  gdb_byte *data = (void *) descdata;

+	  struct elf_build_id *retval;

+

+	  retval = xmalloc (sizeof *retval - 1 + size);

+	  retval->size = size;

+	  memcpy (retval->data, data, size);

+

+	  return retval;

+	}

+      p = descdata + BFD_ALIGN (descsz, 4);

+    }

+  return NULL;

+}

+

+/* Separate debuginfo files have corrupted PHDR but SHDR is correct there.

+   Locate NT_GNU_BUILD_ID from ABFD and return its content.  */

 static const struct elf_build_id *

-build_id_bfd_get (bfd *abfd)

+build_id_bfd_shdr_get (bfd *abfd)

 {

   if (!bfd_check_format (abfd, bfd_object)

       || bfd_get_flavour (abfd) != bfd_target_elf_flavour

@@ -1081,6 +1135,348 @@ build_id_bfd_get (bfd *abfd)

   return elf_tdata (abfd)->build_id;

 }

+/* Core files may have missing (corrupt) SHDR but PDHR is correct there.

+   bfd_elf_bfd_from_remote_memory () has too much overhead by

+   allocating/reading all the available ELF PT_LOADs.  */

+

+static struct elf_build_id *

+build_id_phdr_get (bfd *templ, bfd_vma loadbase, unsigned e_phnum,

+		   Elf_Internal_Phdr *i_phdr)

+{

+  int i;

+  struct elf_build_id *retval = NULL;

+

+  for (i = 0; i < e_phnum; i++)

+    if (i_phdr[i].p_type == PT_NOTE && i_phdr[i].p_filesz > 0)

+      {

+	Elf_Internal_Phdr *hdr = &i_phdr[i];

+	gdb_byte *buf;

+	int err;

+

+	buf = xmalloc (hdr->p_filesz);

+	err = target_read_memory (loadbase + i_phdr[i].p_vaddr, buf,

+				  hdr->p_filesz);

+	if (err == 0)

+	  retval = build_id_buf_get (templ, buf, hdr->p_filesz);

+	else

+	  retval = NULL;

+	xfree (buf);

+	if (retval != NULL)

+	  break;

+      }

+  return retval;

+}

+

+/* First we validate the file by reading in the ELF header and checking

+   the magic number.  */

+

+static inline bfd_boolean

+elf_file_p (Elf64_External_Ehdr *x_ehdrp64)

+{

+  gdb_assert (sizeof (Elf64_External_Ehdr) >= sizeof (Elf32_External_Ehdr));

+  gdb_assert (offsetof (Elf64_External_Ehdr, e_ident)

+	      == offsetof (Elf32_External_Ehdr, e_ident));

+  gdb_assert (sizeof (((Elf64_External_Ehdr *) 0)->e_ident)

+	      == sizeof (((Elf32_External_Ehdr *) 0)->e_ident));

+

+  return ((x_ehdrp64->e_ident[EI_MAG0] == ELFMAG0)

+	  && (x_ehdrp64->e_ident[EI_MAG1] == ELFMAG1)

+	  && (x_ehdrp64->e_ident[EI_MAG2] == ELFMAG2)

+	  && (x_ehdrp64->e_ident[EI_MAG3] == ELFMAG3));

+}

+

+/* Translate an ELF file header in external format into an ELF file header in

+   internal format.  */

+

+#define H_GET_WORD(bfd, ptr) (is64 ? H_GET_64 (bfd, (ptr))		\

+				   : H_GET_32 (bfd, (ptr)))

+#define H_GET_SIGNED_WORD(bfd, ptr) (is64 ? H_GET_S64 (bfd, (ptr))	\

+					  : H_GET_S32 (bfd, (ptr)))

+

+static void

+elf_swap_ehdr_in (bfd *abfd,

+		  const Elf64_External_Ehdr *src64,

+		  Elf_Internal_Ehdr *dst)

+{

+  int is64 = bfd_get_arch_size (abfd) == 64;

+#define SRC(field) (is64 ? src64->field \

+			 : ((const Elf32_External_Ehdr *) src64)->field)

+

+  int signed_vma = get_elf_backend_data (abfd)->sign_extend_vma;

+  memcpy (dst->e_ident, SRC (e_ident), EI_NIDENT);

+  dst->e_type = H_GET_16 (abfd, SRC (e_type));

+  dst->e_machine = H_GET_16 (abfd, SRC (e_machine));

+  dst->e_version = H_GET_32 (abfd, SRC (e_version));

+  if (signed_vma)

+    dst->e_entry = H_GET_SIGNED_WORD (abfd, SRC (e_entry));

+  else

+    dst->e_entry = H_GET_WORD (abfd, SRC (e_entry));

+  dst->e_phoff = H_GET_WORD (abfd, SRC (e_phoff));

+  dst->e_shoff = H_GET_WORD (abfd, SRC (e_shoff));

+  dst->e_flags = H_GET_32 (abfd, SRC (e_flags));

+  dst->e_ehsize = H_GET_16 (abfd, SRC (e_ehsize));

+  dst->e_phentsize = H_GET_16 (abfd, SRC (e_phentsize));

+  dst->e_phnum = H_GET_16 (abfd, SRC (e_phnum));

+  dst->e_shentsize = H_GET_16 (abfd, SRC (e_shentsize));

+  dst->e_shnum = H_GET_16 (abfd, SRC (e_shnum));

+  dst->e_shstrndx = H_GET_16 (abfd, SRC (e_shstrndx));

+

+#undef SRC

+}

+

+/* Translate an ELF program header table entry in external format into an

+   ELF program header table entry in internal format.  */

+

+static void

+elf_swap_phdr_in (bfd *abfd,

+		  const Elf64_External_Phdr *src64,

+		  Elf_Internal_Phdr *dst)

+{

+  int is64 = bfd_get_arch_size (abfd) == 64;

+#define SRC(field) (is64 ? src64->field					\

+			 : ((const Elf32_External_Phdr *) src64)->field)

+

+  int signed_vma = get_elf_backend_data (abfd)->sign_extend_vma;

+

+  dst->p_type = H_GET_32 (abfd, SRC (p_type));

+  dst->p_flags = H_GET_32 (abfd, SRC (p_flags));

+  dst->p_offset = H_GET_WORD (abfd, SRC (p_offset));

+  if (signed_vma)

+    {

+      dst->p_vaddr = H_GET_SIGNED_WORD (abfd, SRC (p_vaddr));

+      dst->p_paddr = H_GET_SIGNED_WORD (abfd, SRC (p_paddr));

+    }

+  else

+    {

+      dst->p_vaddr = H_GET_WORD (abfd, SRC (p_vaddr));

+      dst->p_paddr = H_GET_WORD (abfd, SRC (p_paddr));

+    }

+  dst->p_filesz = H_GET_WORD (abfd, SRC (p_filesz));

+  dst->p_memsz = H_GET_WORD (abfd, SRC (p_memsz));

+  dst->p_align = H_GET_WORD (abfd, SRC (p_align));

+

+#undef SRC

+}

+

+#undef H_GET_SIGNED_WORD

+#undef H_GET_WORD

+

+static Elf_Internal_Phdr *

+elf_get_phdr (bfd *templ, bfd_vma ehdr_vma, unsigned *e_phnum_pointer,

+              bfd_vma *loadbase_pointer)

+{

+  /* sizeof (Elf64_External_Ehdr) >= sizeof (Elf32_External_Ehdr)  */

+  Elf64_External_Ehdr x_ehdr64;	/* Elf file header, external form */

+  Elf_Internal_Ehdr i_ehdr;	/* Elf file header, internal form */

+  bfd_size_type x_phdrs_size;

+  gdb_byte *x_phdrs_ptr;

+  Elf_Internal_Phdr *i_phdrs;

+  int err;

+  unsigned int i;

+  bfd_vma loadbase;

+  int loadbase_set;

+

+  gdb_assert (templ != NULL);

+  gdb_assert (sizeof (Elf64_External_Ehdr) >= sizeof (Elf32_External_Ehdr));

+

+  /* Read in the ELF header in external format.  */

+  err = target_read_memory (ehdr_vma, (bfd_byte *) &x_ehdr64, sizeof x_ehdr64);

+  if (err)

+    {

+      if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)

+        warning (_("build-id: Error reading ELF header at address 0x%lx"),

+		 (unsigned long) ehdr_vma);

+      return NULL;

+    }

+

+  /* Now check to see if we have a valid ELF file, and one that BFD can

+     make use of.  The magic number must match, the address size ('class')

+     and byte-swapping must match our XVEC entry.  */

+

+  if (! elf_file_p (&x_ehdr64)

+      || x_ehdr64.e_ident[EI_VERSION] != EV_CURRENT

+      || !((bfd_get_arch_size (templ) == 64

+            && x_ehdr64.e_ident[EI_CLASS] == ELFCLASS64)

+           || (bfd_get_arch_size (templ) == 32

+	       && x_ehdr64.e_ident[EI_CLASS] == ELFCLASS32)))

+    {

+      if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)

+        warning (_("build-id: Unrecognized ELF header at address 0x%lx"),

+		 (unsigned long) ehdr_vma);

+      return NULL;

+    }

+

+  /* Check that file's byte order matches xvec's */

+  switch (x_ehdr64.e_ident[EI_DATA])

+    {

+    case ELFDATA2MSB:		/* Big-endian */

+      if (! bfd_header_big_endian (templ))

+	{

+	  if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)

+	    warning (_("build-id: Unrecognized "

+		       "big-endian ELF header at address 0x%lx"),

+		     (unsigned long) ehdr_vma);

+	  return NULL;

+	}

+      break;

+    case ELFDATA2LSB:		/* Little-endian */

+      if (! bfd_header_little_endian (templ))

+	{

+	  if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)

+	    warning (_("build-id: Unrecognized "

+		       "little-endian ELF header at address 0x%lx"),

+		     (unsigned long) ehdr_vma);

+	  return NULL;

+	}

+      break;

+    case ELFDATANONE:		/* No data encoding specified */

+    default:			/* Unknown data encoding specified */

+      if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)

+	warning (_("build-id: Unrecognized "

+		   "ELF header endianity at address 0x%lx"),

+		 (unsigned long) ehdr_vma);

+      return NULL;

+    }

+

+  elf_swap_ehdr_in (templ, &x_ehdr64, &i_ehdr);

+

+  /* The file header tells where to find the program headers.

+     These are what we use to actually choose what to read.  */

+

+  if (i_ehdr.e_phentsize != (bfd_get_arch_size (templ) == 64

+                             ? sizeof (Elf64_External_Phdr)

+			     : sizeof (Elf32_External_Phdr))

+      || i_ehdr.e_phnum == 0)

+    {

+      if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)

+	warning (_("build-id: Invalid ELF program headers from the ELF header "

+		   "at address 0x%lx"), (unsigned long) ehdr_vma);

+      return NULL;

+    }

+

+  x_phdrs_size = (bfd_get_arch_size (templ) == 64 ? sizeof (Elf64_External_Phdr)

+						: sizeof (Elf32_External_Phdr));

+

+  i_phdrs = xmalloc (i_ehdr.e_phnum * (sizeof *i_phdrs + x_phdrs_size));

+  x_phdrs_ptr = (void *) &i_phdrs[i_ehdr.e_phnum];

+  err = target_read_memory (ehdr_vma + i_ehdr.e_phoff, (bfd_byte *) x_phdrs_ptr,

+			    i_ehdr.e_phnum * x_phdrs_size);

+  if (err)

+    {

+      free (i_phdrs);

+      if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)

+        warning (_("build-id: Error reading "

+		   "ELF program headers at address 0x%lx"),

+		 (unsigned long) (ehdr_vma + i_ehdr.e_phoff));

+      return NULL;

+    }

+

+  loadbase = ehdr_vma;

+  loadbase_set = 0;

+  for (i = 0; i < i_ehdr.e_phnum; ++i)

+    {

+      elf_swap_phdr_in (templ, (Elf64_External_Phdr *)

+			       (x_phdrs_ptr + i * x_phdrs_size), &i_phdrs[i]);

+      /* IA-64 vDSO may have two mappings for one segment, where one mapping

+	 is executable only, and one is read only.  We must not use the

+	 executable one (PF_R is the first one, PF_X the second one).  */

+      if (i_phdrs[i].p_type == PT_LOAD && (i_phdrs[i].p_flags & PF_R))

+	{

+	  /* Only the first PT_LOAD segment indicates the file bias.

+	     Next segments may have P_VADDR arbitrarily higher.

+	     If the first segment has P_VADDR zero any next segment must not

+	     confuse us, the first one sets LOADBASE certainly enough.  */

+	  if (!loadbase_set && i_phdrs[i].p_offset == 0)

+	    {

+	      loadbase = ehdr_vma - i_phdrs[i].p_vaddr;

+	      loadbase_set = 1;

+	    }

+	}

+    }

+

+  if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)

+    warning (_("build-id: Found ELF header at address 0x%lx, loadbase 0x%lx"),

+	     (unsigned long) ehdr_vma, (unsigned long) loadbase);

+

+  *e_phnum_pointer = i_ehdr.e_phnum;

+  *loadbase_pointer = loadbase;

+  return i_phdrs;

+}

+

+/* BUILD_ID_ADDR_GET gets ADDR located somewhere in the object.

+   Find the first section before ADDR containing an ELF header.

+   We rely on the fact the sections from multiple files do not mix.

+   FIXME: We should check ADDR is contained _inside_ the section with possibly

+   missing content (P_FILESZ < P_MEMSZ).  These omitted sections are currently

+   hidden by _BFD_ELF_MAKE_SECTION_FROM_PHDR.  */

+

+static CORE_ADDR build_id_addr;

+struct build_id_addr_sect

+  {

+    struct build_id_addr_sect *next;

+    asection *sect;

+  };

+static struct build_id_addr_sect *build_id_addr_sect;

+

+static void build_id_addr_candidate (bfd *abfd, asection *sect, void *obj)

+{

+  if (build_id_addr >= bfd_section_vma (abfd, sect))

+    {

+      struct build_id_addr_sect *candidate;

+

+      candidate = xmalloc (sizeof *candidate);

+      candidate->next = build_id_addr_sect;

+      build_id_addr_sect = candidate;

+      candidate->sect = sect;

+    }

+}

+

+struct elf_build_id *

+build_id_addr_get (CORE_ADDR addr)

+{

+  struct build_id_addr_sect *candidate;

+  struct elf_build_id *retval = NULL;

+  Elf_Internal_Phdr *i_phdr = NULL;

+  bfd_vma loadbase = 0;

+  unsigned e_phnum = 0;

+

+  if (core_bfd == NULL)

+    return NULL;

+

+  build_id_addr = addr;

+  gdb_assert (build_id_addr_sect == NULL);

+  bfd_map_over_sections (core_bfd, build_id_addr_candidate, NULL);

+

+  /* Sections are sorted in the high-to-low VMAs order.

+     Stop the search on the first ELF header we find.

+     Do not continue the search even if it does not contain NT_GNU_BUILD_ID.  */

+

+  for (candidate = build_id_addr_sect; candidate != NULL;

+       candidate = candidate->next)

+    {

+      i_phdr = elf_get_phdr (core_bfd,

+			     bfd_section_vma (core_bfd, candidate->sect),

+			     &e_phnum, &loadbase);

+      if (i_phdr != NULL)

+	break;

+    }

+

+  if (i_phdr != NULL)

+    {

+      retval = build_id_phdr_get (core_bfd, loadbase, e_phnum, i_phdr);

+      xfree (i_phdr);

+    }

+

+  while (build_id_addr_sect != NULL)

+    {

+      candidate = build_id_addr_sect;

+      build_id_addr_sect = candidate->next;

+      xfree (candidate);

+    }

+

+  return retval;

+}

+

 /* Return if FILENAME has NT_GNU_BUILD_ID matching the CHECK value.  */

 static int

@@ -1095,7 +1491,7 @@ build_id_verify (const char *filename, c

   if (abfd == NULL)

     return 0;

-  found = build_id_bfd_get (abfd);

+  found = build_id_bfd_shdr_get (abfd);

   if (found == NULL)

     warning (_("File \"%s\" has no build-id, file skipped"), filename);

@@ -1112,16 +1508,53 @@ build_id_verify (const char *filename, c

 }

 static char *

-build_id_to_debug_filename (const struct elf_build_id *build_id)

+link_resolve (const char *symlink, int level)

+{

+  char buf[PATH_MAX + 1], *target, *retval;

+  ssize_t got;

+

+  if (level > 10)

+    return xstrdup (symlink);

+

+  got = readlink (symlink, buf, sizeof (buf));

+  if (got < 0 || got >= sizeof (buf))

+    return xstrdup (symlink);

+  buf[got] = '\0';

+

+  if (IS_ABSOLUTE_PATH (buf))

+    target = xstrdup (buf);

+  else

+    {

+      char *dir = ldirname (symlink);

+

+      if (dir == NULL)

+	return xstrdup (symlink);

+      target = xstrprintf ("%s"

+#ifndef HAVE_DOS_BASED_FILE_SYSTEM

+			   "/"

+#else /* HAVE_DOS_BASED_FILE_SYSTEM */

+			   "\\"

+#endif /* HAVE_DOS_BASED_FILE_SYSTEM */

+			   "%s", dir, buf);

+    }

+

+  retval = link_resolve (target, level + 1);

+  xfree (target);

+  return retval;

+}

+

+char *

+build_id_to_filename (const struct elf_build_id *build_id, char **link_return,

+		      int add_debug_suffix)

 {

   char *link, *debugdir, *retval = NULL;

+  char *link_all = NULL;

   VEC (char_ptr) *debugdir_vec;

   struct cleanup *back_to;

   int ix;

   /* DEBUG_FILE_DIRECTORY/.build-id/ab/cdef */

-  link = alloca (strlen (debug_file_directory) + (sizeof "/.build-id/" - 1) + 1

-		 + 2 * build_id->size + (sizeof ".debug" - 1) + 1);

+  link = xmalloc (strlen (debug_file_directory) + 2 * build_id->size + 50);

   /* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will

      cause "/.build-id/..." lookups.  */

@@ -1134,7 +1567,10 @@ build_id_to_debug_filename (const struct

       size_t debugdir_len = strlen (debugdir);

       const gdb_byte *data = build_id->data;

       size_t size = build_id->size;

-      char *s;

+      unsigned seqno;

+      struct stat statbuf_trash;

+      /* Initialize it just to avoid a GCC false warning.  */

+      char *s, *link0 = NULL, *link0_resolved;

       memcpy (link, debugdir, debugdir_len);

       s = &link[debugdir_len];

@@ -1148,37 +1584,256 @@ build_id_to_debug_filename (const struct

 	*s++ = '/';

       while (size-- > 0)

 	s += sprintf (s, "%02x", (unsigned) *data++);

-      strcpy (s, ".debug");

-      /* lrealpath() is expensive even for the usually non-existent files.  */

-      if (access (link, F_OK) == 0)

-	retval = lrealpath (link);

+      for (seqno = 0;; seqno++)

+	{

+	  char *s2;

+

+	  if (seqno)

+	    {

+	      /* There can be multiple build-id symlinks pointing to real files

+		 with the same build-id (such as hard links).  Some of the real

+		 files may not be installed.  */

+

+	      s2 = s + sprintf (s, ".%u", seqno);

+	    }

+	  else

+	    s2 = s;

+

+	  if (add_debug_suffix)

+	    strcpy (s2, ".debug");

+	  else