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[mach-o] get rid of current_oso global 

This current_oso global was used to store the OSO's symbol table
in order to relocate common symbols.  But it is also making the
assumption that all sections are going to be immediately relocated
as macho_add_oso_symfile does:
  - Initialize the current_oso
  - Use it through symbol_file_add_from_bfd
  - Reset the current_oso (to all fields NULL)

What actually happens is that the .debug_frame section gets read
lazily, and thus relocated at a later time.  This relocation causes
current_oso.symbol_table to be initialized (see macho_symfile_relocate)
again.  And this eventually causes to trip the...

        gdb_assert (current_oso.symbol_table == NULL);

...assertion to fail because the symbol_table was never free'ed.
To be complete, this happens because macho_symfile_relocate was
called outside of macho_add_oso_symfile's control, where the
set-global/use/unset-global dance happens.

But it looks like keeping this global around is not necessary, as
this symbol table is only used to relocate the common symbols.
We can do that prior to relocating the rest of the symbols.

gdb/ChangeLog:

        * machoread.c (struct macho_oso_data): Delete.
        (current_oso): Delete.
        (macho_relocate_common_syms): New function, mostly extracted
        out of
        (macho_add_oso_symfile): Call macho_relocate_common_syms.
        Remove code that sets and unset current_oso.
        (macho_symfile_relocate): Delete handling of common symbols,
        now moved to macho_relocate_common_syms.
This commit is contained in:
Joel Brobecker 2011-07-01 18:36:36 +00:00
parent a7aa0d73a2
commit 38947ccadc
2 changed files with 75 additions and 68 deletions
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11
gdb/ChangeLog
View File

@ -1,3 +1,14 @@
2011-07-01 Joel Brobecker <brobecker@adacore.com>
* machoread.c (struct macho_oso_data): Delete.
(current_oso): Delete.
(macho_relocate_common_syms): New function, mostly extracted
out of
(macho_add_oso_symfile): Call macho_relocate_common_syms.
Remove code that sets and unset current_oso.
(macho_symfile_relocate): Delete handling of common symbols,
now moved to macho_relocate_common_syms.
2011-07-01 Joel Brobecker <brobecker@adacore.com>
* darwin-nat.c (darwin_ptrace): Add documentation.

132
gdb/machoread.c
View File

@ -71,23 +71,6 @@ oso_el;
DEF_VEC_O (oso_el);
static VEC (oso_el) *oso_vector;
struct macho_oso_data
{
/* Per objfile symbol table. This is used to apply relocation to sections
It is loaded only once, then relocated, and free after sections are
relocated. */
asymbol **symbol_table;
/* The offsets for this objfile. Used to relocate the symbol_table. */
struct oso_el *oso;
struct objfile *main_objfile;
};
/* Data for OSO being processed. */
static struct macho_oso_data current_oso;
static void
macho_new_init (struct objfile *objfile)
{
@ -308,6 +291,65 @@ oso_el_compare_name (const void *vl, const void *vr)
return strcmp (l->name, r->name);
}
/* Relocate all of ABFD's common symbols immediately.
This modifies the section and address of all common symbols to become
absolute symbols with their address set to match the address given by
the main objfile's symbol table.
The reason why the common symbols have to be handled separately
is because relocation is performed relative to section start.
But there is no section in this case. So the "relocation" of
these common symbols is performed by finding their address in
the main objfile's symbol table, where we know it's been relocated.
ABFD is an OSO's bfd.
MAIN_OBJFILE is the object file from which the OSO is a part. */
static void
macho_relocate_common_syms(bfd *abfd, struct objfile *main_objfile)
{
int storage;
int i;
char leading_char;
asymbol **symbol_table;
storage = bfd_get_symtab_upper_bound (abfd);
symbol_table = (asymbol **) xmalloc (storage);
bfd_canonicalize_symtab (abfd, symbol_table);
leading_char = bfd_get_symbol_leading_char (abfd);
for (i = 0; symbol_table[i]; i++)
{
asymbol *sym = symbol_table[i];
if (bfd_is_com_section (sym->section))
{
/* This one must be solved. */
struct minimal_symbol *msym;
const char *name = sym->name;
if (name[0] == leading_char)
name++;
msym = lookup_minimal_symbol (name, NULL, main_objfile);
if (msym == NULL)
{
warning (_("can't find symbol '%s' in minsymtab"), name);
continue;
}
else
{
sym->section = &bfd_abs_section;
sym->value = SYMBOL_VALUE_ADDRESS (msym);
}
}
}
xfree (symbol_table);
}
/* Add an oso file as a symbol file. */
static void
@ -384,14 +426,16 @@ macho_add_oso_symfile (oso_el *oso, bfd *abfd,
core_addr_to_string (vma), sectname);
}
/* Deal with the common symbols now, as they need special handing.
Doing it now sets them up so that we don't accidently try to
relocate them during the normal relocation phase. */
macho_relocate_common_syms (abfd, main_objfile);
/* Make sure that the filename was malloc'ed. The current filename comes
either from an OSO symbol name or from an archive name. Memory for both
is not managed by gdb. */
abfd->filename = xstrdup (abfd->filename);
gdb_assert (current_oso.symbol_table == NULL);
current_oso.main_objfile = main_objfile;
/* We need to clear SYMFILE_MAINLINE to avoid interractive question
from symfile.c:symbol_file_add_with_addrs_or_offsets. */
objfile = symbol_file_add_from_bfd
@ -399,13 +443,6 @@ macho_add_oso_symfile (oso_el *oso, bfd *abfd,
main_objfile->flags & (OBJF_REORDERED | OBJF_SHARED
| OBJF_READNOW | OBJF_USERLOADED),
main_objfile);
current_oso.main_objfile = NULL;
if (current_oso.symbol_table)
{
xfree (current_oso.symbol_table);
current_oso.symbol_table = NULL;
}
}
/* Read symbols from the vector of oso files. */
@ -731,47 +768,6 @@ macho_symfile_relocate (struct objfile *objfile, asection *sectp,
printf_unfiltered (_("Relocate section '%s' of %s\n"),
sectp->name, objfile->name);
if (current_oso.symbol_table == NULL)
{
int storage;
int i;
char leading_char;
storage = bfd_get_symtab_upper_bound (abfd);
current_oso.symbol_table = (asymbol **) xmalloc (storage);
bfd_canonicalize_symtab (abfd, current_oso.symbol_table);
leading_char = bfd_get_symbol_leading_char (abfd);
for (i = 0; current_oso.symbol_table[i]; i++)
{
asymbol *sym = current_oso.symbol_table[i];
if (bfd_is_com_section (sym->section))
{
/* This one must be solved. */
struct minimal_symbol *msym;
const char *name = sym->name;
if (name[0] == leading_char)
name++;
msym = lookup_minimal_symbol
(name, NULL, current_oso.main_objfile);
if (msym == NULL)
{
warning (_("can't find symbol '%s' in minsymtab"), name);
continue;
}
else
{
sym->section = &bfd_abs_section;
sym->value = SYMBOL_VALUE_ADDRESS (msym);
}
}
}
}
return bfd_simple_get_relocated_section_contents (abfd, sectp, buf, NULL);
}