Re: [patch 1/2] build id

Joel Brobecker
2010-11-24T18:02:50Z

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> This patch comes from the Fedora rpm and supports the use of build
> id for locating and loading core file executables, and printing
> information about missing debug info files.
>
> I will post the patch in this message and the next message will
> contain my modifications to the patch based on my understanding of
> it.

A lot of the modifications in the second patch seem to be fixes to better
conform to the GDB coding standards, so I found it easier to read both
patches merged into 1. For anyone else who would want to review them
as one patch, here it is...

(I will review this patch is no one else does, but it'll take me a few
days)

--
Joel

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commit 8b74c8e7e02491a6af18f0fe445273eddd6a814a
Author: Joel Brobecker <brobecker@adacore.com>
Date: Wed Nov 24 09:57:49 2010 -0800

Sami's build-id 2 patches merged into 1

diff --git a/gdb/corelow.c b/gdb/corelow.c
index e138ff2..c82dd13 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -47,6 +47,9 @@
#include "filenames.h"
#include "progspace.h"
#include "objfiles.h"
+#include "auxv.h"
+#include "elf/common.h"
+#include "gdbcmd.h"

#ifndef O_LARGEFILE
@@ -275,6 +278,57 @@ add_to_thread_list (bfd *abfd, asection *asect, void *reg_sect_arg)
inferior_ptid = ptid; /* Yes, make it current */
}

+/* Boolean which indicates whether files associated through build id
+ with the current core file should be loaded. */
+static int build_id_core_loads = 1;
+
+/* Using build_id of the current target find the corresponding executable file,
+ and set it as the current executable file. */
+
+static void
+build_id_locate_exec (int from_tty)
+{
+ CORE_ADDR at_entry;
+ struct build_id *build_id;
+ char *exec_filename, *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;
+
+ /* 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. */
+
+ exec_filename = build_id_to_filename (build_id, &build_id_filename, 0);
+ back_to = make_cleanup (xfree, build_id_filename);
+
+ if (exec_filename != NULL)
+ {
+ make_cleanup (xfree, exec_filename);
+ exec_file_attach (exec_filename, from_tty);
+ symbol_file_add_main (exec_filename, 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
@@ -372,6 +426,12 @@ core_open (char *filename, int from_tty)
push_target (&core_ops);
discard_cleanups (old_chain);

+ /* 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 (build_id_core_loads != 0)
+ build_id_locate_exec (from_tty);
+
/* Do this before acknowledging the inferior, so if
post_create_inferior throws (can happen easilly if you're loading
a core file with the wrong exec), we aren't left with threads
@@ -913,4 +973,11 @@ _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);
}
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 5550f51..131c88a 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -15243,6 +15243,48 @@ 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
+
+For corefiles the @dfn{build id} can be used to load the corresponding
+executable. This feature can be turned on or off through the following
+options:
+
+@table @code
+
+@kindex set build-id-core-loads on
+@item set build-id-core-loads on
+Automatically load files associated with a corefile's build id.
+
+@kindex set build-id-core-loads off
+@item set build-id-core-loads off
+Do not load files associated with a corefile's build id.
+
+@kindex show build-id-core-loads
+@item show build-id-core-loads
+Show whether @dfn{build id} will be used to load files asscociated with the
+corefile being inspected.
+
+@end table
+
@cindex @code{.gnu_debuglink} sections
@cindex debug link sections
A debug link is a special section of the executable file named
diff --git a/gdb/elfread.c b/gdb/elfread.c
index d607b87..a26e1ef 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -37,6 +37,10 @@
#include "complaints.h"
#include "demangle.h"
#include "psympriv.h"
+#include "libbfd.h"
+#include "gdbcore.h"
+#include "gdbcmd.h"
+#include "observer.h"

extern void _initialize_elfread (void);

@@ -572,16 +576,68 @@ elf_symtab_read (struct objfile *objfile, int type,
}
}

+/* Locate NT_GNU_BUILD_ID and return its matching debug filename.
+ FIXME: NOTE decoding should be unified with the BFD core notes decoding. */
+
+#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);
+}
+
struct build_id
{
size_t size;
gdb_byte data[1];
};

-/* Locate NT_GNU_BUILD_ID from ABFD and return its content. */
+/* Scan the given buffer for NT_GNU_BUILD_ID return it its content if found
+ otherwise return NULL. */
+
+struct 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 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 struct build_id *
-build_id_bfd_get (bfd *abfd)
+build_id_bfd_shdr_get (bfd *abfd)
{
struct build_id *retval;

@@ -597,6 +653,361 @@ build_id_bfd_get (bfd *abfd)
return retval;
}

+/* Starting at program header I_PHDR search each program header for
+ the one containing build-id. Return it if found otherwise return
+ NULL.
+ 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 build_id *
+build_id_phdr_get (bfd *templ, bfd_vma loadbase, unsigned e_phnum,
+ Elf_Internal_Phdr *i_phdr)
+{
+ int i;
+ struct 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;
+}
+
+/* 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)))
+
+/* Translate an ELF header table entry in external format into an ELF header
+ table entry in internal format. */
+
+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. */
+
+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
+
+/* Get an array of program file headers of TEMPL. Store the number of
+ headers in address pointed to by E_PHNUM_POINTER. */
+
+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;
+
+/* Construct a list of candidate sections which can contain build-id. */
+
+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;
+ }
+}
+
+/* Find and return the build_id for the object file containing ADDR. */
+
+struct build_id *
+build_id_addr_get (CORE_ADDR addr)
+{
+ struct build_id_addr_sect *candidate;
+ struct 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
@@ -611,7 +1022,7 @@ build_id_verify (const char *filename, struct build_id *check)
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);
@@ -628,14 +1039,19 @@ build_id_verify (const char *filename, struct build_id *check)
return retval;
}

-static char *
-build_id_to_debug_filename (struct build_id *build_id)
+/* Return the file name of the debug info file or executable associated with
+ BUILD_ID. If ADD_DEBUG_SUFFIX is false do not append the .debug suffix. */
+
+char *
+build_id_to_filename (struct build_id *build_id, char **link_return,
+ int add_debug_suffix)
{
char *link, *debugdir, *retval = NULL;
+ char *link_all = NULL;

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

/* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will
cause "/.build-id/..." lookups. */
@@ -666,7 +1082,10 @@ build_id_to_debug_filename (struct build_id *build_id)
*s++ = '/';
while (size-- > 0)
s += sprintf (s, "%02x", (unsigned) *data++);
- strcpy (s, ".debug");
+ if (add_debug_suffix)
+ strcpy (s, ".debug");
+ else
+ *s = 0;

/* lrealpath() is expensive even for the usually non-existent files. */
if (access (link, F_OK) == 0)
@@ -679,26 +1098,211 @@ build_id_to_debug_filename (struct build_id *build_id)
}

if (retval != NULL)
- break;
+ {
+ /* LINK_ALL is not used below in this non-NULL RETVAL case. */
+ break;
+ }
+
+ if (link_all == NULL)
+ link_all = xstrdup (link);
+ else
+ {
+ size_t len_orig = strlen (link_all);
+
+ link_all = xrealloc (link_all, len_orig + 1 + strlen (link) + 1);
+
+ /* Use whitespace instead of DIRNAME_SEPARATOR to be compatible with
+ its possible use as an argument for installation command. */
+ link_all[len_orig] = ' ';
+
+ strcpy (&link_all[len_orig + 1], link);
+ }

debugdir = debugdir_end;
}
while (*debugdir != 0);

+ if (link_return != NULL)
+ {
+ if (retval != NULL)
+ {
+ *link_return = link;
+ link = NULL;
+ }
+ else
+ {
+ *link_return = link_all;
+ link_all = NULL;
+ }
+ }
+ xfree (link);
+ xfree (link_all);
+
return retval;
}

+/* This MISSING_FILEPAIR_HASH tracker is used only for the duplicite messages
+ Try to install the hash file ...
+ avoidance. */
+
+struct missing_filepair
+ {
+ char *binary;
+ char *debug;
+ char data[1];
+ };
+
+static struct htab *missing_filepair_hash;
+static struct obstack missing_filepair_obstack;
+
+/* Allocate a missing_filepair entry. */
+
+static void *
+missing_filepair_xcalloc (size_t nmemb, size_t nmemb_size)
+{
+ void *retval;
+ size_t size = nmemb * nmemb_size;
+
+ retval = obstack_alloc (&missing_filepair_obstack, size);
+ memset (retval, 0, size);
+ return retval;
+}
+
+/* Hash function for missing_filepair. */
+
+static hashval_t
+missing_filepair_hash_func (const struct missing_filepair *elem)
+{
+ hashval_t retval = 0;
+
+ retval ^= htab_hash_string (elem->binary);
+ if (elem->debug != NULL)
+ retval ^= htab_hash_string (elem->debug);
+
+ return retval;
+}
+
+/* Comparison function for missing_filepair. */
+
+static int
+missing_filepair_eq (const struct missing_filepair *elem1,
+ const struct missing_filepair *elem2)
+{
+ return strcmp (elem1->binary, elem2->binary) == 0
+ && ((elem1->debug == NULL) == (elem2->debug == NULL))
+ && (elem1->debug == NULL || strcmp (elem1->debug, elem2->debug) == 0);
+}
+
+/* Free missing_filepair obstack. */
+
+static void
+missing_filepair_changed (void)
+{
+ if (missing_filepair_hash != NULL)
+ {
+ obstack_free (&missing_filepair_obstack, NULL);
+ /* All their memory came just from missing_filepair_OBSTACK. */
+ missing_filepair_hash = NULL;
+ }
+}
+
+static void
+debug_print_executable_changed (void)
+{
+ missing_filepair_changed ();
+}
+
+/* Notify user the file BINARY with (possibly NULL) associated separate debug
+ information file DEBUG is missing. DEBUG may or may not be the build-id
+ file such as would be:
+ /usr/lib/debug/.build-id/dd/b1d2ce632721c47bb9e8679f369e2295ce71be.debug
+ */
+
+void
+debug_print_missing (const char *binary, const char *debug)
+{
+ size_t binary_len0 = strlen (binary) + 1;
+ size_t debug_len0 = debug ? strlen (debug) + 1 : 0;
+ struct missing_filepair missing_filepair_find;
+ struct missing_filepair *missing_filepair;
+ struct missing_filepair **slot;
+
+ if (build_id_verbose < BUILD_ID_VERBOSE_FILENAMES)
+ return;
+
+ if (missing_filepair_hash == NULL)
+ {
+ obstack_init (&missing_filepair_obstack);
+ missing_filepair_hash = htab_create_alloc (64,
+ (hashval_t (*) (const void *)) missing_filepair_hash_func,
+ (int (*) (const void *, const void *)) missing_filepair_eq, NULL,
+ missing_filepair_xcalloc, NULL);
+ }
+
+ /* Use MISSING_FILEPAIR_FIND first instead of calling obstack_alloc with
+ obstack_free in the case of a (rare) match. The problem is ALLOC_F for
+ MISSING_FILEPAIR_HASH allocates from MISSING_FILEPAIR_OBSTACK maintenance
+ structures for MISSING_FILEPAIR_HASH. Calling obstack_free would possibly
+ not to free only MISSING_FILEPAIR but also some such structures (allocated
+ during the htab_find_slot call). */
+
+ missing_filepair_find.binary = (char *) binary;
+ missing_filepair_find.debug = (char *) debug;
+ slot = (struct missing_filepair **) htab_find_slot (missing_filepair_hash,
+ &missing_filepair_find,
+ INSERT);
+
+ /* While it may be still printed duplicitely with the missing debuginfo file
+ * it is due to once printing about the binary file build-id link and once
+ * about the .debug file build-id link as both the build-id symlinks are
+ * located in the debuginfo package. */
+
+ if (*slot != NULL)
+ return;
+
+ missing_filepair = obstack_alloc (&missing_filepair_obstack,
+ sizeof (*missing_filepair) - 1
+ + binary_len0 + debug_len0);
+ missing_filepair->binary = missing_filepair->data;
+ memcpy (missing_filepair->binary, binary, binary_len0);
+ if (debug != NULL)
+ {
+ missing_filepair->debug = missing_filepair->binary + binary_len0;
+ memcpy (missing_filepair->debug, debug, debug_len0);
+ }
+ else
+ missing_filepair->debug = NULL;
+
+ *slot = missing_filepair;
+
+ /* We do not collect and flush these messages as each such message
+ already requires its own separate lines. */
+
+ fprintf_unfiltered (gdb_stdlog,
+ _("Missing separate debuginfo for %s\n"), binary);
+ if (debug != NULL)
+ fprintf_unfiltered (gdb_stdlog, _("Try to install the hash file %s\n"),
+ debug);
+}
+
+/* Using the build id of OBJFILE find its separate debug info file. */
+
static char *
-find_separate_debug_file_by_buildid (struct objfile *objfile)
+find_separate_debug_file_by_buildid (struct objfile *objfile,
+ char **build_id_filename_return)
{
struct build_id *build_id;

- build_id = build_id_bfd_get (objfile->obfd);
+ if (build_id_filename_return)
+ *build_id_filename_return = NULL;
+
+ build_id = build_id_bfd_shdr_get (objfile->obfd);
if (build_id != NULL)
{
char *build_id_name;

- build_id_name = build_id_to_debug_filename (build_id);
+ build_id_name = build_id_to_filename (build_id, build_id_filename_return,
+ 1);
xfree (build_id);
/* Prevent looping on a stripped .debug file. */
if (build_id_name != NULL && strcmp (build_id_name, objfile->name) == 0)
@@ -708,7 +1312,7 @@ find_separate_debug_file_by_buildid (struct objfile *objfile)
xfree (build_id_name);
}
else if (build_id_name != NULL)
- return build_id_name;
+ return build_id_name;
}
return NULL;
}
@@ -887,9 +1491,10 @@ elf_symfile_read (struct objfile *objfile, int symfile_flags)
`.gnu_debuglink' may no longer be present with `.note.gnu.build-id'. */
if (!objfile_has_partial_symbols (objfile))
{
- char *debugfile;
+ char *debugfile, *build_id_filename;

- debugfile = find_separate_debug_file_by_buildid (objfile);
+ debugfile = find_separate_debug_file_by_buildid (objfile,
+ &build_id_filename);

if (debugfile == NULL)
debugfile = find_separate_debug_file_by_debuglink (objfile);
@@ -901,6 +1506,12 @@ elf_symfile_read (struct objfile *objfile, int symfile_flags)
symbol_file_add_separate (abfd, symfile_flags, objfile);
xfree (debugfile);
}
+ /* Check if any separate debug info has been extracted out. */
+ else if (bfd_get_section_by_name (objfile->obfd, ".gnu_debuglink")
+ != NULL)
+ debug_print_missing (objfile->name, build_id_filename);
+
+ xfree (build_id_filename);
}
}

@@ -1076,4 +1687,16 @@ void
_initialize_elfread (void)
{
add_symtab_fns (&elf_sym_fns);
+
+ add_setshow_zinteger_cmd ("build-id-verbose", no_class, &build_id_verbose,
+ _("\
+Set debugging level of the build-id locator."), _("\
+Show debugging level of the build-id locator."), _("\
+Level 1 (default) enables printing the missing debug filenames,\n\
+level 2 also prints the parsing of binaries to find the identificators."),
+ NULL,
+ show_build_id_verbose,
+ &setlist, &showlist);
+
+ observer_attach_executable_changed (debug_print_executable_changed);
}
diff --git a/gdb/exec.c b/gdb/exec.c
index de0c459..1dfa253 100644
--- a/gdb/exec.c
+++ b/gdb/exec.c
@@ -177,15 +177,16 @@ exec_file_clear (int from_tty)
printf_unfiltered (_("No executable file now.\n"));
}

-/* Set FILENAME as the new exec file.
+/* Set FILENAME as the new exec file. Open and process the give
+ executable file.

- This function is intended to be behave essentially the same
+ This function is intended to behave essentially the same
as exec_file_command, except that the latter will detect when
a target is being debugged, and will ask the user whether it
should be shut down first. (If the answer is "no", then the
new file is ignored.)

- This file is used by exec_file_command, to do the work of opening
+ This function is used by exec_file_command, to do the work of opening
and processing the exec file after any prompting has happened.

And, it is used by child_attach, when the attach command was
diff --git a/gdb/objfiles.h b/gdb/objfiles.h
index 130ae26..f004ff1 100644
--- a/gdb/objfiles.h
+++ b/gdb/objfiles.h
@@ -432,6 +432,10 @@ struct objfile

#define OBJF_USERLOADED (1 << 3) /* User loaded */

+/* This file was loaded according to the BUILD_ID_CORE_LOADS rules. */
+
+#define OBJF_BUILD_ID_CORE_LOADED (1 << 12)
+
/* The object file that contains the runtime common minimal symbols
for SunOS4. Note that this objfile has no associated BFD. */

diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index db21360..df60943 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -1179,9 +1179,51 @@ svr4_current_sos (void)
safe_strerror (errcode));
else
{
- 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);
+ /* Set so_name using build_id. */
+
+ struct 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 (LM_DYNAMIC_FROM_LINK_MAP (new));
+ 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);

diff --git a/gdb/symfile.h b/gdb/symfile.h
index c9f4e65..0df6883 100644
--- a/gdb/symfile.h
+++ b/gdb/symfile.h
@@ -546,6 +546,13 @@ void free_symfile_segment_data (struct symfile_segment_data *data);

extern struct cleanup *increment_reading_symtab (void);

+/* build-id support. */
+struct build_id;
+extern struct build_id *build_id_addr_get (CORE_ADDR addr);
+extern char *build_id_to_filename (struct build_id *build_id,
+ char **link_return, int add_debug_suffix);
+extern void debug_print_missing (const char *binary, const char *debug);
+
/* From dwarf2read.c */

extern int dwarf2_has_info (struct objfile *);
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index ab54c25..8d98b5e 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -1375,6 +1375,16 @@ proc default_gdb_start { } {
warning "Couldn't set the width to 0."
}
}
+ # Turn off the missing warnings as the testsuite does not expect it.
+ send_gdb "set build-id-verbose 0\n"
+ gdb_expect 10 {
+ -re "$gdb_prompt $" {
+ verbose "Disabled the missing debug infos warnings." 2
+ }
+ timeout {
+ warning "Could not disable the missing debug infos warnings.."
+ }
+ }
return 0;
}

diff --git a/gdb/testsuite/lib/mi-support.exp b/gdb/testsuite/lib/mi-support.exp
index 5de3183..2c046f7 100644
--- a/gdb/testsuite/lib/mi-support.exp
+++ b/gdb/testsuite/lib/mi-support.exp
@@ -221,6 +221,16 @@ proc default_mi_gdb_start { args } {
}
}
}
+ # Turn off the missing warnings as the testsuite does not expect it.
+ send_gdb "190-gdb-set build-id-verbose 0\n"
+ gdb_expect 10 {
+ -re ".*190-gdb-set build-id-verbose 0\r\n190\\\^done\r\n$mi_gdb_prompt$" {
+ verbose "Disabled the missing debug infos warnings." 2
+ }
+ timeout {
+ warning "Could not disable the missing debug infos warnings.."
+ }
+ }

detect_async