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binutils-gdb/bfd/elf-attrs.c

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/* ELF attributes support (based on ARM EABI attributes).
Copyright (C) 2005-2017 Free Software Foundation, Inc.
This file is part of BFD, the Binary File Descriptor library.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
MA 02110-1301, USA. */
#include "sysdep.h"
#include "bfd.h"
#include "libiberty.h"
#include "libbfd.h"
#include "elf-bfd.h"
/* Return the number of bytes needed by I in uleb128 format. */
static int
uleb128_size (unsigned int i)
{
int size;
size = 1;
while (i >= 0x80)
{
i >>= 7;
size++;
}
return size;
}
/* Return TRUE if the attribute has the default value (0/""). */
static bfd_boolean
is_default_attr (obj_attribute *attr)
{
if (ATTR_TYPE_HAS_INT_VAL (attr->type) && attr->i != 0)
return FALSE;
if (ATTR_TYPE_HAS_STR_VAL (attr->type) && attr->s && *attr->s)
return FALSE;
if (ATTR_TYPE_HAS_NO_DEFAULT (attr->type))
return FALSE;
return TRUE;
}
/* Return the size of a single attribute. */
static bfd_vma
obj_attr_size (unsigned int tag, obj_attribute *attr)
{
bfd_vma size;
if (is_default_attr (attr))
return 0;
size = uleb128_size (tag);
if (ATTR_TYPE_HAS_INT_VAL (attr->type))
size += uleb128_size (attr->i);
if (ATTR_TYPE_HAS_STR_VAL (attr->type))
size += strlen ((char *)attr->s) + 1;
return size;
}
/* Return the vendor name for a given object attributes section. */
static const char *
vendor_obj_attr_name (bfd *abfd, int vendor)
{
return (vendor == OBJ_ATTR_PROC
? get_elf_backend_data (abfd)->obj_attrs_vendor
: "gnu");
}
/* Return the size of the object attributes section for VENDOR
(OBJ_ATTR_PROC or OBJ_ATTR_GNU), or 0 if there are no attributes
for that vendor to record and the vendor is OBJ_ATTR_GNU. */
static bfd_vma
vendor_obj_attr_size (bfd *abfd, int vendor)
{
bfd_vma size;
obj_attribute *attr;
obj_attribute_list *list;
int i;
const char *vendor_name = vendor_obj_attr_name (abfd, vendor);
if (!vendor_name)
return 0;
attr = elf_known_obj_attributes (abfd)[vendor];
size = 0;
for (i = LEAST_KNOWN_OBJ_ATTRIBUTE; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
size += obj_attr_size (i, &attr[i]);
for (list = elf_other_obj_attributes (abfd)[vendor];
list;
list = list->next)
size += obj_attr_size (list->tag, &list->attr);
/* <size> <vendor_name> NUL 0x1 <size> */
return ((size || vendor == OBJ_ATTR_PROC)
? size + 10 + strlen (vendor_name)
: 0);
}
/* Return the size of the object attributes section. */
bfd_vma
bfd_elf_obj_attr_size (bfd *abfd)
{
bfd_vma size;
size = vendor_obj_attr_size (abfd, OBJ_ATTR_PROC);
size += vendor_obj_attr_size (abfd, OBJ_ATTR_GNU);
/* 'A' <sections for each vendor> */
return (size ? size + 1 : 0);
}
/* Write VAL in uleb128 format to P, returning a pointer to the
following byte. */
static bfd_byte *
write_uleb128 (bfd_byte *p, unsigned int val)
{
bfd_byte c;
do
{
c = val & 0x7f;
val >>= 7;
if (val)
c |= 0x80;
*(p++) = c;
}
while (val);
return p;
}
/* Write attribute ATTR to butter P, and return a pointer to the following
byte. */
static bfd_byte *
write_obj_attribute (bfd_byte *p, unsigned int tag, obj_attribute *attr)
{
/* Suppress default entries. */
if (is_default_attr (attr))
return p;
p = write_uleb128 (p, tag);
if (ATTR_TYPE_HAS_INT_VAL (attr->type))
p = write_uleb128 (p, attr->i);
if (ATTR_TYPE_HAS_STR_VAL (attr->type))
{
int len;
len = strlen (attr->s) + 1;
memcpy (p, attr->s, len);
p += len;
}
return p;
}
/* Write the contents of the object attributes section (length SIZE)
for VENDOR to CONTENTS. */
static void
vendor_set_obj_attr_contents (bfd *abfd, bfd_byte *contents, bfd_vma size,
int vendor)
{
bfd_byte *p;
obj_attribute *attr;
obj_attribute_list *list;
int i;
const char *vendor_name = vendor_obj_attr_name (abfd, vendor);
size_t vendor_length = strlen (vendor_name) + 1;
p = contents;
bfd_put_32 (abfd, size, p);
p += 4;
memcpy (p, vendor_name, vendor_length);
p += vendor_length;
*(p++) = Tag_File;
bfd_put_32 (abfd, size - 4 - vendor_length, p);
p += 4;
attr = elf_known_obj_attributes (abfd)[vendor];
for (i = LEAST_KNOWN_OBJ_ATTRIBUTE; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
{
unsigned int tag = i;
if (get_elf_backend_data (abfd)->obj_attrs_order)
tag = get_elf_backend_data (abfd)->obj_attrs_order (i);
p = write_obj_attribute (p, tag, &attr[tag]);
}
for (list = elf_other_obj_attributes (abfd)[vendor];
list;
list = list->next)
p = write_obj_attribute (p, list->tag, &list->attr);
}
/* Write the contents of the object attributes section to CONTENTS. */
void
bfd_elf_set_obj_attr_contents (bfd *abfd, bfd_byte *contents, bfd_vma size)
{
bfd_byte *p;
int vendor;
bfd_vma my_size;
p = contents;
*(p++) = 'A';
my_size = 1;
for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
{
bfd_vma vendor_size = vendor_obj_attr_size (abfd, vendor);
if (vendor_size)
vendor_set_obj_attr_contents (abfd, p, vendor_size, vendor);
p += vendor_size;
my_size += vendor_size;
}
if (size != my_size)
abort ();
}
/* Allocate/find an object attribute. */
static obj_attribute *
elf_new_obj_attr (bfd *abfd, int vendor, unsigned int tag)
{
obj_attribute *attr;
obj_attribute_list *list;
obj_attribute_list *p;
obj_attribute_list **lastp;
if (tag < NUM_KNOWN_OBJ_ATTRIBUTES)
{
/* Known tags are preallocated. */
attr = &elf_known_obj_attributes (abfd)[vendor][tag];
}
else
{
/* Create a new tag. */
list = (obj_attribute_list *)
bfd_alloc (abfd, sizeof (obj_attribute_list));
memset (list, 0, sizeof (obj_attribute_list));
list->tag = tag;
/* Keep the tag list in order. */
lastp = &elf_other_obj_attributes (abfd)[vendor];
for (p = *lastp; p; p = p->next)
{
if (tag < p->tag)
break;
lastp = &p->next;
}
list->next = *lastp;
*lastp = list;
attr = &list->attr;
}
return attr;
}
/* Return the value of an integer object attribute. */
int
bfd_elf_get_obj_attr_int (bfd *abfd, int vendor, unsigned int tag)
{
obj_attribute_list *p;
if (tag < NUM_KNOWN_OBJ_ATTRIBUTES)
{
/* Known tags are preallocated. */
return elf_known_obj_attributes (abfd)[vendor][tag].i;
}
else
{
for (p = elf_other_obj_attributes (abfd)[vendor];
p;
p = p->next)
{
if (tag == p->tag)
return p->attr.i;
if (tag < p->tag)
break;
}
return 0;
}
}
/* Add an integer object attribute. */
void
bfd_elf_add_obj_attr_int (bfd *abfd, int vendor, unsigned int tag, unsigned int i)
{
obj_attribute *attr;
attr = elf_new_obj_attr (abfd, vendor, tag);
attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
attr->i = i;
}
/* Duplicate an object attribute string value. */
char *
_bfd_elf_attr_strdup (bfd *abfd, const char * s)
{
char * p;
int len;
len = strlen (s) + 1;
p = (char *) bfd_alloc (abfd, len);
return (char *) memcpy (p, s, len);
}
/* Add a string object attribute. */
void
bfd_elf_add_obj_attr_string (bfd *abfd, int vendor, unsigned int tag, const char *s)
{
obj_attribute *attr;
attr = elf_new_obj_attr (abfd, vendor, tag);
attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
attr->s = _bfd_elf_attr_strdup (abfd, s);
}
/* Add a int+string object attribute. */
void
bfd_elf_add_obj_attr_int_string (bfd *abfd, int vendor,
unsigned int tag,
unsigned int i, const char *s)
{
obj_attribute *attr;
attr = elf_new_obj_attr (abfd, vendor, tag);
attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
attr->i = i;
attr->s = _bfd_elf_attr_strdup (abfd, s);
}
/* Copy the object attributes from IBFD to OBFD. */
void
_bfd_elf_copy_obj_attributes (bfd *ibfd, bfd *obfd)
{
obj_attribute *in_attr;
obj_attribute *out_attr;
obj_attribute_list *list;
int i;
int vendor;
if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour
|| bfd_get_flavour (obfd) != bfd_target_elf_flavour)
return;
for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
{
in_attr
= &elf_known_obj_attributes (ibfd)[vendor][LEAST_KNOWN_OBJ_ATTRIBUTE];
out_attr
= &elf_known_obj_attributes (obfd)[vendor][LEAST_KNOWN_OBJ_ATTRIBUTE];
for (i = LEAST_KNOWN_OBJ_ATTRIBUTE; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
{
out_attr->type = in_attr->type;
out_attr->i = in_attr->i;
if (in_attr->s && *in_attr->s)
out_attr->s = _bfd_elf_attr_strdup (obfd, in_attr->s);
in_attr++;
out_attr++;
}
for (list = elf_other_obj_attributes (ibfd)[vendor];
list;
list = list->next)
{
in_attr = &list->attr;
switch (in_attr->type & (ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL))
{
case ATTR_TYPE_FLAG_INT_VAL:
bfd_elf_add_obj_attr_int (obfd, vendor, list->tag, in_attr->i);
break;
case ATTR_TYPE_FLAG_STR_VAL:
bfd_elf_add_obj_attr_string (obfd, vendor, list->tag,
in_attr->s);
break;
case ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL:
bfd_elf_add_obj_attr_int_string (obfd, vendor, list->tag,
in_attr->i, in_attr->s);
break;
default:
abort ();
}
}
}
}
/* Determine whether a GNU object attribute tag takes an integer, a
string or both. */
static int
gnu_obj_attrs_arg_type (unsigned int tag)
{
/* Except for Tag_compatibility, for GNU attributes we follow the
same rule ARM ones > 32 follow: odd-numbered tags take strings
and even-numbered tags take integers. In addition, tag & 2 is
nonzero for architecture-independent tags and zero for
architecture-dependent ones. */
if (tag == Tag_compatibility)
return 3;
else
return (tag & 1) != 0 ? 2 : 1;
}
/* Determine what arguments an attribute tag takes. */
int
_bfd_elf_obj_attrs_arg_type (bfd *abfd, int vendor, unsigned int tag)
{
switch (vendor)
{
case OBJ_ATTR_PROC:
return get_elf_backend_data (abfd)->obj_attrs_arg_type (tag);
break;
case OBJ_ATTR_GNU:
return gnu_obj_attrs_arg_type (tag);
break;
default:
abort ();
}
}
/* Parse an object attributes section. */
void
_bfd_elf_parse_attributes (bfd *abfd, Elf_Internal_Shdr * hdr)
{
bfd_byte *contents;
bfd_byte *p;
bfd_byte *p_end;
bfd_vma len;
const char *std_sec;
/* PR 17512: file: 2844a11d. */
if (hdr->sh_size == 0)
return;
contents = (bfd_byte *) bfd_malloc (hdr->sh_size + 1);
if (!contents)
return;
if (!bfd_get_section_contents (abfd, hdr->bfd_section, contents, 0,
hdr->sh_size))
{
free (contents);
return;
}
/* Ensure that the buffer is NUL terminated. */
contents[hdr->sh_size] = 0;
p = contents;
p_end = p + hdr->sh_size;
std_sec = get_elf_backend_data (abfd)->obj_attrs_vendor;
if (*(p++) == 'A')
{
len = hdr->sh_size - 1;
while (len > 0 && p < p_end - 4)
{
unsigned namelen;
bfd_vma section_len;
int vendor;
section_len = bfd_get_32 (abfd, p);
p += 4;
if (section_len == 0)
break;
if (section_len > len)
section_len = len;
len -= section_len;
if (section_len <= 4)
{
_bfd_error_handler (_("%B: error: attribute section length too small: %ld"),
abfd, section_len);
break;
}
section_len -= 4;
namelen = strnlen ((char *) p, section_len) + 1;
if (namelen == 0 || namelen >= section_len)
break;
section_len -= namelen;
if (std_sec && strcmp ((char *) p, std_sec) == 0)
vendor = OBJ_ATTR_PROC;
else if (strcmp ((char *) p, "gnu") == 0)
vendor = OBJ_ATTR_GNU;
else
{
/* Other vendor section. Ignore it. */
p += namelen + section_len;
continue;
}
p += namelen;
while (section_len > 0 && p < p_end)
{
unsigned int tag;
unsigned int n;
unsigned int val;
bfd_vma subsection_len;
bfd_byte *end;
tag = _bfd_safe_read_leb128 (abfd, p, &n, FALSE, p_end);
p += n;
if (p < p_end - 4)
subsection_len = bfd_get_32 (abfd, p);
else
subsection_len = 0;
p += 4;
if (subsection_len == 0)
break;
if (subsection_len > section_len)
subsection_len = section_len;
section_len -= subsection_len;
subsection_len -= n + 4;
end = p + subsection_len;
/* PR 17512: file: 0e8c0c90. */
if (end > p_end)
end = p_end;
switch (tag)
{
case Tag_File:
while (p < end)
{
int type;
tag = _bfd_safe_read_leb128 (abfd, p, &n, FALSE, end);
p += n;
type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
switch (type & (ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL))
{
case ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL:
val = _bfd_safe_read_leb128 (abfd, p, &n, FALSE, end);
p += n;
bfd_elf_add_obj_attr_int_string (abfd, vendor, tag,
val, (char *) p);
p += strlen ((char *)p) + 1;
break;
case ATTR_TYPE_FLAG_STR_VAL:
bfd_elf_add_obj_attr_string (abfd, vendor, tag,
(char *) p);
p += strlen ((char *)p) + 1;
break;
case ATTR_TYPE_FLAG_INT_VAL:
val = _bfd_safe_read_leb128 (abfd, p, &n, FALSE, end);
p += n;
bfd_elf_add_obj_attr_int (abfd, vendor, tag, val);
break;
default:
abort ();
}
}
break;
case Tag_Section:
case Tag_Symbol:
/* Don't have anywhere convenient to attach these.
Fall through for now. */
default:
/* Ignore things we don't kow about. */
p += subsection_len;
subsection_len = 0;
break;
}
}
}
}
free (contents);
}
/* Merge common object attributes from IBFD into OBFD. Raise an error
if there are conflicting attributes. Any processor-specific
attributes have already been merged. This must be called from the
bfd_elfNN_bfd_merge_private_bfd_data hook for each individual
target, along with any target-specific merging. Because there are
no common attributes other than Tag_compatibility at present, and
non-"gnu" Tag_compatibility is not expected in "gnu" sections, this
is not presently called for targets without their own
attributes. */
bfd_boolean
_bfd_elf_merge_object_attributes (bfd *ibfd, struct bfd_link_info *info)
{
bfd *obfd = info->output_bfd;
obj_attribute *in_attr;
obj_attribute *out_attr;
int vendor;
/* The only common attribute is currently Tag_compatibility,
accepted in both processor and "gnu" sections. */
for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
{
/* Handle Tag_compatibility. The tags are only compatible if the flags
are identical and, if the flags are '1', the strings are identical.
If the flags are non-zero, then we can only use the string "gnu". */
in_attr = &elf_known_obj_attributes (ibfd)[vendor][Tag_compatibility];
out_attr = &elf_known_obj_attributes (obfd)[vendor][Tag_compatibility];
if (in_attr->i > 0 && strcmp (in_attr->s, "gnu") != 0)
{
_bfd_error_handler
/* xgettext:c-format */
(_("error: %B: Object has vendor-specific contents that "
"must be processed by the '%s' toolchain"),
ibfd, in_attr->s);
return FALSE;
}
if (in_attr->i != out_attr->i
|| (in_attr->i != 0 && strcmp (in_attr->s, out_attr->s) != 0))
{
/* xgettext:c-format */
_bfd_error_handler (_("error: %B: Object tag '%d, %s' is "
"incompatible with tag '%d, %s'"),
ibfd,
in_attr->i, in_attr->s ? in_attr->s : "",
out_attr->i, out_attr->s ? out_attr->s : "");
return FALSE;
}
}
return TRUE;
}
/* Merge an unknown processor-specific attribute TAG, within the range
of known attributes, from IBFD into OBFD; return TRUE if the link
is OK, FALSE if it must fail. */
bfd_boolean
_bfd_elf_merge_unknown_attribute_low (bfd *ibfd, bfd *obfd, int tag)
{
obj_attribute *in_attr;
obj_attribute *out_attr;
bfd *err_bfd = NULL;
bfd_boolean result = TRUE;
in_attr = elf_known_obj_attributes_proc (ibfd);
out_attr = elf_known_obj_attributes_proc (obfd);
if (out_attr[tag].i != 0 || out_attr[tag].s != NULL)
err_bfd = obfd;
else if (in_attr[tag].i != 0 || in_attr[tag].s != NULL)
err_bfd = ibfd;
if (err_bfd != NULL)
result
= get_elf_backend_data (err_bfd)->obj_attrs_handle_unknown (err_bfd, tag);
/* Only pass on attributes that match in both inputs. */
if (in_attr[tag].i != out_attr[tag].i
|| (in_attr[tag].s == NULL) != (out_attr[tag].s == NULL)
|| (in_attr[tag].s != NULL && out_attr[tag].s != NULL
&& strcmp (in_attr[tag].s, out_attr[tag].s) != 0))
{
out_attr[tag].i = 0;
out_attr[tag].s = NULL;
}
return result;
}
/* Merge the lists of unknown processor-specific attributes, outside
the known range, from IBFD into OBFD; return TRUE if the link is
OK, FALSE if it must fail. */
bfd_boolean
_bfd_elf_merge_unknown_attribute_list (bfd *ibfd, bfd *obfd)
{
obj_attribute_list *in_list;
obj_attribute_list *out_list;
obj_attribute_list **out_listp;
bfd_boolean result = TRUE;
in_list = elf_other_obj_attributes_proc (ibfd);
out_listp = &elf_other_obj_attributes_proc (obfd);
out_list = *out_listp;
for (; in_list || out_list; )
{
bfd *err_bfd = NULL;
unsigned int err_tag = 0;
/* The tags for each list are in numerical order. */
/* If the tags are equal, then merge. */
if (out_list && (!in_list || in_list->tag > out_list->tag))
{
/* This attribute only exists in obfd. We can't merge, and we don't
know what the tag means, so delete it. */
err_bfd = obfd;
err_tag = out_list->tag;
*out_listp = out_list->next;
out_list = *out_listp;
}
else if (in_list && (!out_list || in_list->tag < out_list->tag))
{
/* This attribute only exists in ibfd. We can't merge, and we don't
know what the tag means, so ignore it. */
err_bfd = ibfd;
err_tag = in_list->tag;
in_list = in_list->next;
}
else /* The tags are equal. */
{
/* As present, all attributes in the list are unknown, and
therefore can't be merged meaningfully. */
err_bfd = obfd;
err_tag = out_list->tag;
/* Only pass on attributes that match in both inputs. */
if (in_list->attr.i != out_list->attr.i
|| (in_list->attr.s == NULL) != (out_list->attr.s == NULL)
|| (in_list->attr.s && out_list->attr.s
&& strcmp (in_list->attr.s, out_list->attr.s) != 0))
{
/* No match. Delete the attribute. */
*out_listp = out_list->next;
out_list = *out_listp;
}
else
{
/* Matched. Keep the attribute and move to the next. */
out_list = out_list->next;
in_list = in_list->next;
}
}
if (err_bfd)
result = result
&& get_elf_backend_data (err_bfd)->obj_attrs_handle_unknown (err_bfd,
err_tag);
}
return result;
}
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