Add support for the WebAssembly backend to the BFD library.
* wasm-module.c: New file to support WebAssembly modules. * wasm-module.h: New file to support WebAssembly modules. * doc/webassembly.texi: Start documenting wasm-module.c. * config.bfd: Add wasm_vec. * targets.c: Likewise. * configure.ac: Likewise. * Makefile.am: Add entries for wasm-module.c. * Makefile.in: Regenerate. * configure: Regenerate. * po/SRC-POTFILES.in: Regenerate.
This commit is contained in:
Pip Cet
Nick Clifton
parent
210477268d
commit
a6be053897
@ -1,3 +1,16 @@
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2017-03-27 Pip Cet <pipcet@gmail.com>
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* wasm-module.c: New file to support WebAssembly modules.
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* wasm-module.h: New file to support WebAssembly modules.
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* doc/webassembly.texi: Start documenting wasm-module.c.
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* config.bfd: Add wasm_vec.
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* targets.c: Likewise.
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* configure.ac: Likewise.
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* Makefile.am: Add entries for wasm-module.c.
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* Makefile.in: Regenerate.
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* configure: Regenerate.
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* po/SRC-POTFILES.in: Regenerate.
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2017-03-27 Pip Cet <pipcet@gmail.com>
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* cpu-wasm32.c: New file to support wasm32 architecture.
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@ -459,6 +459,7 @@ BFD32_BACKENDS = \
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versados.lo \
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vms-lib.lo \
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vms-misc.lo \
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wasm-module.lo \
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xcofflink.lo \
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xsym.lo \
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xtensa-isa.lo \
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@ -652,6 +653,7 @@ BFD32_BACKENDS_CFILES = \
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versados.c \
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vms-lib.c \
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vms-misc.c \
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wasm-module.c \
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xcofflink.c \
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xsym.c \
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xtensa-isa.c \
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@ -793,6 +793,7 @@ BFD32_BACKENDS = \
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versados.lo \
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vms-lib.lo \
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vms-misc.lo \
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wasm-module.lo \
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xcofflink.lo \
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xsym.lo \
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xtensa-isa.lo \
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@ -986,6 +987,7 @@ BFD32_BACKENDS_CFILES = \
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versados.c \
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vms-lib.c \
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vms-misc.c \
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wasm-module.c \
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xcofflink.c \
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xsym.c \
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xtensa-isa.c \
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@ -1671,6 +1673,7 @@ distclean-compile:
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@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/vms-alpha.Plo@am__quote@
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@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/vms-lib.Plo@am__quote@
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@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/vms-misc.Plo@am__quote@
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@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/wasm-module.Plo@am__quote@
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@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/xcofflink.Plo@am__quote@
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@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/xsym.Plo@am__quote@
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@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/xtensa-isa.Plo@am__quote@
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@ -1796,6 +1796,7 @@ case "${targ}" in
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wasm32-*-*)
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targ_defvec=wasm32_elf32_vec
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targ_selvecs="wasm_vec"
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;;
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we32k-*-*)
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1
bfd/configure
vendored
1
bfd/configure
vendored
@ -14569,6 +14569,7 @@ do
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ft32_elf32_vec) tb="$tb elf32-ft32.lo elf32.lo $elf" ;;
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visium_elf32_vec) tb="$tb elf32-visium.lo elf32.lo $elf" ;;
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w65_coff_vec) tb="$tb coff-w65.lo reloc16.lo $coffgen" ;;
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wasm_vec) tb="$tb wasm-module.lo" ;;
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wasm32_elf32_vec) tb="$tb elf32-wasm32.lo elf32.lo $elf" ;;
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we32k_coff_vec) tb="$tb coff-we32k.lo $coffgen" ;;
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x86_64_coff_vec) tb="$tb coff-x86_64.lo $coff"; target_size=64 ;;
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@ -700,6 +700,7 @@ do
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ft32_elf32_vec) tb="$tb elf32-ft32.lo elf32.lo $elf" ;;
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visium_elf32_vec) tb="$tb elf32-visium.lo elf32.lo $elf" ;;
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w65_coff_vec) tb="$tb coff-w65.lo reloc16.lo $coffgen" ;;
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wasm_vec) tb="$tb wasm-module.lo" ;;
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wasm32_elf32_vec) tb="$tb elf32-wasm32.lo elf32.lo $elf" ;;
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we32k_coff_vec) tb="$tb coff-we32k.lo $coffgen" ;;
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x86_64_coff_vec) tb="$tb coff-x86_64.lo $coff"; target_size=64 ;;
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33
bfd/doc/webassembly.texi
Normal file
33
bfd/doc/webassembly.texi
Normal file
@ -0,0 +1,33 @@
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@section WebAssembly backend
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The WebAssembly module file format, at present, is a very simple
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object file format with up to 11 numbered sections plus named
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``custom'' sections. At present, there is no standard for relocations
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or symbols, though a @code{"name"} subsection can assign names to
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function indices and local variables.
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As such, it offers no real advantages over ELF, and intermediate ELF
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files can be used to produce WebAssembly modules. The WebAssembly
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backend aims to enable the opposite: reading a WebAssembly module and
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producing an ELF file containing the same information, which can then
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be manipulated and inspected with standard tools.
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When writing WebAssembly modules, the WebAssembly backend attempts to
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determine based on the section name whether to use a numeric section
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id, a named section header, or to include the section verbatim,
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assuming it already contains any necessary header.
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Function names are supported as symbols; local names and WebAssembly
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relocation sections are currently unsupported.
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There are slight differences in the LEB128 integer implementations
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between the WebAssembly specification and the BFD code; these result
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in some malformed WebAssembly modules being treated as valid.
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@menu
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* File layout::
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@end menu
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@node File layout, WebAssembly
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@subsection File layout
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For a description of the WebAssembly file format, see
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@url{https://github.com/WebAssembly/design/blob/master/BinaryEncoding.md}.
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@ -386,6 +386,7 @@ vms-alpha.c
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vms-lib.c
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vms-misc.c
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vms.h
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wasm-module.c
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xcofflink.c
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xsym.c
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xsym.h
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1353
bfd/po/bfd.pot
1353
bfd/po/bfd.pot
File diff suppressed because it is too large
Load Diff
@ -893,6 +893,7 @@ extern const bfd_target vax_aout_nbsd_vec;
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extern const bfd_target vax_elf32_vec;
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extern const bfd_target visium_elf32_vec;
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extern const bfd_target w65_coff_vec;
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extern const bfd_target wasm_vec;
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extern const bfd_target wasm32_elf32_vec;
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extern const bfd_target we32k_coff_vec;
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extern const bfd_target x86_64_coff_vec;
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@ -1422,6 +1423,7 @@ static const bfd_target * const _bfd_target_vector[] =
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&w65_coff_vec,
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&wasm_vec,
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&wasm32_elf32_vec,
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&we32k_coff_vec,
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839
bfd/wasm-module.c
Normal file
839
bfd/wasm-module.c
Normal file
@ -0,0 +1,839 @@
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/* BFD back-end for WebAssembly modules.
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Copyright (C) 2017 Free Software Foundation, Inc.
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Based on srec.c, mmo.c, and binary.c
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This file is part of BFD, the Binary File Descriptor library.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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MA 02110-1301, USA. */
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/* The WebAssembly module format is a simple object file format
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including up to 11 numbered sections, plus any number of named
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"custom" sections. It is described at:
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https://github.com/WebAssembly/design/blob/master/BinaryEncoding.md. */
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#include "sysdep.h"
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#include "alloca-conf.h"
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#include "bfd.h"
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#include "sysdep.h"
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#include <limits.h>
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#include "bfd_stdint.h"
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#include "libiberty.h"
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#include "libbfd.h"
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#include "wasm-module.h"
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typedef struct
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{
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asymbol * symbols;
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bfd_size_type symcount;
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} tdata_type;
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static const char * const wasm_numbered_sections[] =
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{
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NULL, /* Custom section, different layout. */
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WASM_SECTION ( 1, "type"),
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WASM_SECTION ( 2, "import"),
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WASM_SECTION ( 3, "function"),
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WASM_SECTION ( 4, "table"),
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WASM_SECTION ( 5, "memory"),
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WASM_SECTION ( 6, "global"),
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WASM_SECTION ( 7, "export"),
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WASM_SECTION ( 8, "start"),
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WASM_SECTION ( 9, "element"),
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WASM_SECTION (10, "code"),
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WASM_SECTION (11, "data"),
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};
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#define WASM_NUMBERED_SECTIONS ARRAY_SIZE (wasm_numbered_sections)
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/* Resolve SECTION_CODE to a section name if there is one, NULL
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otherwise. */
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static const char *
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wasm_section_code_to_name (bfd_byte section_code)
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{
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if (section_code < WASM_NUMBERED_SECTIONS)
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return wasm_numbered_sections[section_code];
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return NULL;
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}
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/* Translate section name NAME to a section code, or 0 if it's a
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custom name. */
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static unsigned int
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wasm_section_name_to_code (const char *name)
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{
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unsigned i;
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for (i = 1; i < WASM_NUMBERED_SECTIONS; i++)
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if (strcmp (name, wasm_numbered_sections[i]) == 0)
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return i;
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return 0;
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}
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/* WebAssembly LEB128 integers are sufficiently like DWARF LEB128
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integers that we use _bfd_safe_read_leb128, but there are two
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points of difference:
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- WebAssembly requires a 32-bit value to be encoded in at most 5
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bytes, etc.
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- _bfd_safe_read_leb128 accepts incomplete LEB128 encodings at the
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end of the buffer, while these are invalid in WebAssembly.
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Those differences mean that we will accept some files that are
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invalid WebAssembly. */
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/* Read an LEB128-encoded integer from ABFD's I/O stream, reading one
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byte at a time. Set ERROR_RETURN if no complete integer could be
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read, LENGTH_RETURN to the number of bytes read (including bytes in
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incomplete numbers). SIGN means interpret the number as SLEB128. */
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static bfd_vma
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wasm_read_leb128 (bfd * abfd,
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bfd_boolean * error_return,
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unsigned int * length_return,
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bfd_boolean sign)
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{
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bfd_vma result = 0;
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unsigned int num_read = 0;
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unsigned int shift = 0;
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unsigned char byte = 0;
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bfd_boolean success = FALSE;
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while (bfd_bread (&byte, 1, abfd) == 1)
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{
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num_read++;
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result |= ((bfd_vma) (byte & 0x7f)) << shift;
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shift += 7;
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if ((byte & 0x80) == 0)
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{
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success = TRUE;
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break;
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}
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}
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if (length_return != NULL)
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*length_return = num_read;
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if (error_return != NULL)
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*error_return = ! success;
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if (sign && (shift < 8 * sizeof (result)) && (byte & 0x40))
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result |= -((bfd_vma) 1 << shift);
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return result;
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}
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/* Encode an integer V as LEB128 and write it to ABFD, return TRUE on
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success. */
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static bfd_boolean
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wasm_write_uleb128 (bfd *abfd, bfd_vma v)
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{
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do
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{
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bfd_byte c = v & 0x7f;
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v >>= 7;
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if (v)
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c |= 0x80;
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if (bfd_bwrite (&c, 1, abfd) != 1)
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return FALSE;
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}
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while (v);
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return TRUE;
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}
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/* Read the LEB128 integer at P, saving it to X; at end of buffer,
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jump to error_return. */
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#define READ_LEB128(x, p, end) \
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do \
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{ \
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unsigned int length_read; \
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(x) = _bfd_safe_read_leb128 (abfd, (p), &length_read, \
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FALSE, (end)); \
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(p) += length_read; \
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if (length_read == 0) \
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goto error_return; \
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} \
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while (0)
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/* Verify the magic number at the beginning of a WebAssembly module
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ABFD, setting ERRORPTR if there's a mismatch. */
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static bfd_boolean
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wasm_read_magic (bfd *abfd, bfd_boolean *errorptr)
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{
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bfd_byte magic_const[SIZEOF_WASM_MAGIC] = WASM_MAGIC;
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bfd_byte magic[SIZEOF_WASM_MAGIC];
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if (bfd_bread (magic, sizeof (magic), abfd) == sizeof (magic)
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&& memcmp (magic, magic_const, sizeof (magic)) == 0)
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return TRUE;
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*errorptr = TRUE;
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return FALSE;
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}
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/* Read the version number from ABFD, returning TRUE if it's a supported
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version. Set ERRORPTR otherwise. */
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static bfd_boolean
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wasm_read_version (bfd *abfd, bfd_boolean *errorptr)
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{
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bfd_byte vers_const[SIZEOF_WASM_VERSION] = WASM_VERSION;
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bfd_byte vers[SIZEOF_WASM_VERSION];
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if (bfd_bread (vers, sizeof (vers), abfd) == sizeof (vers)
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/* Don't attempt to parse newer versions, which are likely to
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require code changes. */
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&& memcmp (vers, vers_const, sizeof (vers)) == 0)
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return TRUE;
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*errorptr = TRUE;
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return FALSE;
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}
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|
||||
/* Read the WebAssembly header (magic number plus version number) from
|
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ABFD, setting ERRORPTR to TRUE if there is a mismatch. */
|
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|
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static bfd_boolean
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wasm_read_header (bfd *abfd, bfd_boolean *errorptr)
|
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{
|
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if (! wasm_read_magic (abfd, errorptr))
|
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return FALSE;
|
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|
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if (! wasm_read_version (abfd, errorptr))
|
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return FALSE;
|
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|
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return TRUE;
|
||||
}
|
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|
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/* Scan the "function" subsection of the "name" section ASECT in the
|
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wasm module ABFD. Create symbols. Return TRUE on success. */
|
||||
|
||||
static bfd_boolean
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wasm_scan_name_function_section (bfd *abfd, sec_ptr asect)
|
||||
{
|
||||
bfd_byte *p;
|
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bfd_byte *end;
|
||||
bfd_vma payload_size;
|
||||
bfd_vma symcount = 0;
|
||||
tdata_type *tdata = abfd->tdata.any;
|
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asymbol *symbols = NULL;
|
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sec_ptr space_function_index;
|
||||
|
||||
if (! asect)
|
||||
return FALSE;
|
||||
|
||||
if (strcmp (asect->name, WASM_NAME_SECTION) != 0)
|
||||
return FALSE;
|
||||
|
||||
p = asect->contents;
|
||||
end = asect->contents + asect->size;
|
||||
|
||||
if (! p)
|
||||
return FALSE;
|
||||
|
||||
while (p < end)
|
||||
{
|
||||
bfd_byte subsection_code = *p++;
|
||||
if (subsection_code == WASM_FUNCTION_SUBSECTION)
|
||||
break;
|
||||
|
||||
/* subsection_code is documented to be a varuint7, meaning that
|
||||
it has to be a single byte in the 0 - 127 range. If it isn't,
|
||||
the spec must have changed underneath us, so give up. */
|
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if (subsection_code & 0x80)
|
||||
return FALSE;
|
||||
|
||||
READ_LEB128 (payload_size, p, end);
|
||||
|
||||
if (p > p + payload_size)
|
||||
return FALSE;
|
||||
|
||||
p += payload_size;
|
||||
}
|
||||
|
||||
if (p >= end)
|
||||
return FALSE;
|
||||
|
||||
READ_LEB128 (payload_size, p, end);
|
||||
|
||||
if (p > p + payload_size)
|
||||
return FALSE;
|
||||
|
||||
if (p + payload_size > end)
|
||||
return FALSE;
|
||||
|
||||
end = p + payload_size;
|
||||
|
||||
READ_LEB128 (symcount, p, end);
|
||||
|
||||
/* Sanity check: each symbol has at least two bytes. */
|
||||
if (symcount > payload_size/2)
|
||||
return FALSE;
|
||||
|
||||
tdata->symcount = symcount;
|
||||
|
||||
space_function_index = bfd_make_section_with_flags
|
||||
(abfd, WASM_SECTION_FUNCTION_INDEX, SEC_READONLY | SEC_CODE);
|
||||
|
||||
if (! space_function_index)
|
||||
space_function_index = bfd_get_section_by_name (abfd, WASM_SECTION_FUNCTION_INDEX);
|
||||
|
||||
if (! space_function_index)
|
||||
return FALSE;
|
||||
|
||||
symbols = bfd_zalloc (abfd, tdata->symcount * sizeof (asymbol));
|
||||
if (! symbols)
|
||||
return FALSE;
|
||||
|
||||
for (symcount = 0; p < end && symcount < tdata->symcount; symcount++)
|
||||
{
|
||||
bfd_vma index;
|
||||
bfd_vma len;
|
||||
char *name;
|
||||
asymbol *sym;
|
||||
|
||||
READ_LEB128 (index, p, end);
|
||||
READ_LEB128 (len, p, end);
|
||||
|
||||
if (p + len < p || p + len > end)
|
||||
goto error_return;
|
||||
|
||||
name = bfd_zalloc (abfd, len + 1);
|
||||
if (! name)
|
||||
goto error_return;
|
||||
|
||||
memcpy (name, p, len);
|
||||
p += len;
|
||||
|
||||
sym = &symbols[symcount];
|
||||
sym->the_bfd = abfd;
|
||||
sym->name = name;
|
||||
sym->value = index;
|
||||
sym->flags = BSF_GLOBAL | BSF_FUNCTION;
|
||||
sym->section = space_function_index;
|
||||
sym->udata.p = NULL;
|
||||
}
|
||||
|
||||
if (symcount < tdata->symcount)
|
||||
goto error_return;
|
||||
|
||||
tdata->symbols = symbols;
|
||||
abfd->symcount = symcount;
|
||||
|
||||
return TRUE;
|
||||
|
||||
error_return:
|
||||
while (symcount)
|
||||
bfd_release (abfd, (void *)symbols[--symcount].name);
|
||||
bfd_release (abfd, symbols);
|
||||
return FALSE;
|
||||
}
|
||||
|
||||
/* Read a byte from ABFD and return it, or EOF for EOF or error.
|
||||
Set ERRORPTR on non-EOF error. */
|
||||
|
||||
static int
|
||||
wasm_read_byte (bfd *abfd, bfd_boolean *errorptr)
|
||||
{
|
||||
bfd_byte byte;
|
||||
|
||||
if (bfd_bread (&byte, (bfd_size_type) 1, abfd) != 1)
|
||||
{
|
||||
if (bfd_get_error () != bfd_error_file_truncated)
|
||||
*errorptr = TRUE;
|
||||
return EOF;
|
||||
}
|
||||
|
||||
return byte;
|
||||
}
|
||||
|
||||
/* Scan the wasm module ABFD, creating sections and symbols.
|
||||
Return TRUE on success. */
|
||||
|
||||
static bfd_boolean
|
||||
wasm_scan (bfd *abfd)
|
||||
{
|
||||
bfd_boolean error = FALSE;
|
||||
/* Fake VMAs for now. Choose 0x80000000 as base to avoid clashes
|
||||
with actual data addresses. */
|
||||
bfd_vma vma = 0x80000000;
|
||||
int section_code;
|
||||
unsigned int bytes_read;
|
||||
char *name = NULL;
|
||||
asection *bfdsec;
|
||||
|
||||
if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
|
||||
goto error_return;
|
||||
|
||||
if (! wasm_read_header (abfd, &error))
|
||||
goto error_return;
|
||||
|
||||
while ((section_code = wasm_read_byte (abfd, &error)) != EOF)
|
||||
{
|
||||
if (section_code != 0)
|
||||
{
|
||||
const char *sname = wasm_section_code_to_name (section_code);
|
||||
|
||||
if (! sname)
|
||||
goto error_return;
|
||||
|
||||
name = strdup (sname);
|
||||
bfdsec = bfd_make_section_anyway_with_flags (abfd, name, SEC_HAS_CONTENTS);
|
||||
if (bfdsec == NULL)
|
||||
goto error_return;
|
||||
name = NULL;
|
||||
|
||||
bfdsec->vma = vma;
|
||||
bfdsec->lma = vma;
|
||||
bfdsec->size = wasm_read_leb128 (abfd, &error, &bytes_read, FALSE);
|
||||
if (error)
|
||||
goto error_return;
|
||||
bfdsec->filepos = bfd_tell (abfd);
|
||||
bfdsec->alignment_power = 0;
|
||||
}
|
||||
else
|
||||
{
|
||||
bfd_vma payload_len;
|
||||
file_ptr section_start;
|
||||
bfd_vma namelen;
|
||||
char *prefix = WASM_SECTION_PREFIX;
|
||||
char *p;
|
||||
int ret;
|
||||
|
||||
payload_len = wasm_read_leb128 (abfd, &error, &bytes_read, FALSE);
|
||||
if (error)
|
||||
goto error_return;
|
||||
section_start = bfd_tell (abfd);
|
||||
namelen = wasm_read_leb128 (abfd, &error, &bytes_read, FALSE);
|
||||
if (error || namelen > payload_len)
|
||||
goto error_return;
|
||||
name = bfd_zmalloc (namelen + strlen (prefix) + 1);
|
||||
if (! name)
|
||||
goto error_return;
|
||||
p = name;
|
||||
ret = sprintf (p, "%s", prefix);
|
||||
if (ret < 0 || (bfd_vma) ret != strlen (prefix))
|
||||
goto error_return;
|
||||
p += ret;
|
||||
if (bfd_bread (p, namelen, abfd) != namelen)
|
||||
goto error_return;
|
||||
|
||||
bfdsec = bfd_make_section_anyway_with_flags (abfd, name, SEC_HAS_CONTENTS);
|
||||
if (bfdsec == NULL)
|
||||
goto error_return;
|
||||
name = NULL;
|
||||
|
||||
bfdsec->vma = vma;
|
||||
bfdsec->lma = vma;
|
||||
bfdsec->filepos = bfd_tell (abfd);
|
||||
bfdsec->size = section_start + payload_len - bfdsec->filepos;
|
||||
bfdsec->alignment_power = 0;
|
||||
}
|
||||
|
||||
if (bfdsec->size != 0)
|
||||
{
|
||||
bfdsec->contents = bfd_zalloc (abfd, bfdsec->size);
|
||||
if (! bfdsec->contents)
|
||||
goto error_return;
|
||||
|
||||
if (bfd_bread (bfdsec->contents, bfdsec->size, abfd) != bfdsec->size)
|
||||
goto error_return;
|
||||
}
|
||||
|
||||
vma += bfdsec->size;
|
||||
}
|
||||
|
||||
/* Make sure we're at actual EOF. There's no indication in the
|
||||
WebAssembly format of how long the file is supposed to be. */
|
||||
if (error)
|
||||
goto error_return;
|
||||
|
||||
return TRUE;
|
||||
|
||||
error_return:
|
||||
if (name)
|
||||
free (name);
|
||||
|
||||
for (bfdsec = abfd->sections; bfdsec; bfdsec = bfdsec->next)
|
||||
free ((void *) bfdsec->name);
|
||||
|
||||
return FALSE;
|
||||
}
|
||||
|
||||
/* Put a numbered section ASECT of ABFD into the table of numbered
|
||||
sections pointed to by FSARG. */
|
||||
|
||||
static void
|
||||
wasm_register_section (bfd *abfd ATTRIBUTE_UNUSED,
|
||||
asection *asect,
|
||||
void *fsarg)
|
||||
{
|
||||
sec_ptr *numbered_sections = fsarg;
|
||||
int index = wasm_section_name_to_code (asect->name);
|
||||
|
||||
if (index == 0)
|
||||
return;
|
||||
|
||||
numbered_sections[index] = asect;
|
||||
}
|
||||
|
||||
struct compute_section_arg
|
||||
{
|
||||
bfd_vma pos;
|
||||
bfd_boolean failed;
|
||||
};
|
||||
|
||||
/* Compute the file position of ABFD's section ASECT. FSARG is a
|
||||
pointer to the current file position.
|
||||
|
||||
We allow section names of the form .wasm.id to encode the numbered
|
||||
section with ID id, if it exists; otherwise, a custom section with
|
||||
ID "id" is produced. Arbitrary section names are for sections that
|
||||
are assumed already to contain a section header; those are appended
|
||||
to the WebAssembly module verbatim. */
|
||||
|
||||
static void
|
||||
wasm_compute_custom_section_file_position (bfd *abfd,
|
||||
sec_ptr asect,
|
||||
void *fsarg)
|
||||
{
|
||||
struct compute_section_arg *fs = fsarg;
|
||||
int index;
|
||||
|
||||
if (fs->failed)
|
||||
return;
|
||||
|
||||
index = wasm_section_name_to_code (asect->name);
|
||||
|
||||
if (index != 0)
|
||||
return;
|
||||
|
||||
if (CONST_STRNEQ (asect->name, WASM_SECTION_PREFIX))
|
||||
{
|
||||
const char *name = asect->name + strlen (WASM_SECTION_PREFIX);
|
||||
bfd_size_type payload_len = asect->size;
|
||||
bfd_size_type name_len = strlen (name);
|
||||
bfd_size_type nl = name_len;
|
||||
|
||||
payload_len += name_len;
|
||||
|
||||
do
|
||||
{
|
||||
payload_len++;
|
||||
nl >>= 7;
|
||||
}
|
||||
while (nl);
|
||||
|
||||
bfd_seek (abfd, fs->pos, SEEK_SET);
|
||||
if (! wasm_write_uleb128 (abfd, 0)
|
||||
|| ! wasm_write_uleb128 (abfd, payload_len)
|
||||
|| ! wasm_write_uleb128 (abfd, name_len)
|
||||
|| bfd_bwrite (name, name_len, abfd) != name_len)
|
||||
goto error_return;
|
||||
fs->pos = asect->filepos = bfd_tell (abfd);
|
||||
}
|
||||
else
|
||||
{
|
||||
asect->filepos = fs->pos;
|
||||
}
|
||||
|
||||
|
||||
fs->pos += asect->size;
|
||||
return;
|
||||
|
||||
error_return:
|
||||
fs->failed = TRUE;
|
||||
}
|
||||
|
||||
/* Compute the file positions for the sections of ABFD. Currently,
|
||||
this writes all numbered sections first, in order, then all custom
|
||||
sections, in section order.
|
||||
|
||||
The spec says that the numbered sections must appear in order of
|
||||
their ids, but custom sections can appear in any position and any
|
||||
order, and more than once. FIXME: support that. */
|
||||
|
||||
static bfd_boolean
|
||||
wasm_compute_section_file_positions (bfd *abfd)
|
||||
{
|
||||
bfd_byte magic[SIZEOF_WASM_MAGIC] = WASM_MAGIC;
|
||||
bfd_byte vers[SIZEOF_WASM_VERSION] = WASM_VERSION;
|
||||
sec_ptr numbered_sections[WASM_NUMBERED_SECTIONS];
|
||||
struct compute_section_arg fs;
|
||||
unsigned int i;
|
||||
|
||||
bfd_seek (abfd, (bfd_vma) 0, SEEK_SET);
|
||||
|
||||
if (bfd_bwrite (magic, sizeof (magic), abfd) != (sizeof magic)
|
||||
|| bfd_bwrite (vers, sizeof (vers), abfd) != sizeof (vers))
|
||||
return FALSE;
|
||||
|
||||
for (i = 0; i < WASM_NUMBERED_SECTIONS; i++)
|
||||
numbered_sections[i] = NULL;
|
||||
|
||||
bfd_map_over_sections (abfd, wasm_register_section, numbered_sections);
|
||||
|
||||
fs.pos = bfd_tell (abfd);
|
||||
for (i = 0; i < WASM_NUMBERED_SECTIONS; i++)
|
||||
{
|
||||
sec_ptr sec = numbered_sections[i];
|
||||
bfd_size_type size;
|
||||
|
||||
if (! sec)
|
||||
continue;
|
||||
size = sec->size;
|
||||
if (bfd_seek (abfd, fs.pos, SEEK_SET) != 0)
|
||||
return FALSE;
|
||||
if (! wasm_write_uleb128 (abfd, i)
|
||||
|| ! wasm_write_uleb128 (abfd, size))
|
||||
return FALSE;
|
||||
fs.pos = sec->filepos = bfd_tell (abfd);
|
||||
fs.pos += size;
|
||||
}
|
||||
|
||||
fs.failed = FALSE;
|
||||
|
||||
bfd_map_over_sections (abfd, wasm_compute_custom_section_file_position, &fs);
|
||||
|
||||
if (fs.failed)
|
||||
return FALSE;
|
||||
|
||||
abfd->output_has_begun = TRUE;
|
||||
|
||||
return TRUE;
|
||||
}
|
||||
|
||||
static bfd_boolean
|
||||
wasm_set_section_contents (bfd *abfd,
|
||||
sec_ptr section,
|
||||
const void *location,
|
||||
file_ptr offset,
|
||||
bfd_size_type count)
|
||||
{
|
||||
if (count == 0)
|
||||
return TRUE;
|
||||
|
||||
if (! abfd->output_has_begun
|
||||
&& ! wasm_compute_section_file_positions (abfd))
|
||||
return FALSE;
|
||||
|
||||
if (bfd_seek (abfd, section->filepos + offset, SEEK_SET) != 0
|
||||
|| bfd_bwrite (location, count, abfd) != count)
|
||||
return FALSE;
|
||||
|
||||
return TRUE;
|
||||
}
|
||||
|
||||
static bfd_boolean
|
||||
wasm_write_object_contents (bfd* abfd)
|
||||
{
|
||||
bfd_byte magic[] = WASM_MAGIC;
|
||||
bfd_byte vers[] = WASM_VERSION;
|
||||
|
||||
if (bfd_seek (abfd, 0, SEEK_SET) != 0)
|
||||
return FALSE;
|
||||
|
||||
if (bfd_bwrite (magic, sizeof (magic), abfd) != sizeof (magic)
|
||||
|| bfd_bwrite (vers, sizeof (vers), abfd) != sizeof (vers))
|
||||
return FALSE;
|
||||
|
||||
return TRUE;
|
||||
}
|
||||
|
||||
static bfd_boolean
|
||||
wasm_mkobject (bfd *abfd)
|
||||
{
|
||||
tdata_type *tdata = (tdata_type *) bfd_alloc (abfd, sizeof (tdata_type));
|
||||
|
||||
if (! tdata)
|
||||
return FALSE;
|
||||
|
||||
tdata->symbols = NULL;
|
||||
tdata->symcount = 0;
|
||||
|
||||
abfd->tdata.any = tdata;
|
||||
|
||||
return TRUE;
|
||||
}
|
||||
|
||||
static long
|
||||
wasm_get_symtab_upper_bound (bfd *abfd)
|
||||
{
|
||||
tdata_type *tdata = abfd->tdata.any;
|
||||
|
||||
return (tdata->symcount + 1) * (sizeof (asymbol *));
|
||||
}
|
||||
|
||||
static long
|
||||
wasm_canonicalize_symtab (bfd *abfd, asymbol **alocation)
|
||||
{
|
||||
tdata_type *tdata = abfd->tdata.any;
|
||||
size_t i;
|
||||
|
||||
for (i = 0; i < tdata->symcount; i++)
|
||||
alocation[i] = &tdata->symbols[i];
|
||||
alocation[i] = NULL;
|
||||
|
||||
return tdata->symcount;
|
||||
}
|
||||
|
||||
static asymbol *
|
||||
wasm_make_empty_symbol (bfd *abfd)
|
||||
{
|
||||
bfd_size_type amt = sizeof (asymbol);
|
||||
asymbol *new_symbol = (asymbol *) bfd_zalloc (abfd, amt);
|
||||
|
||||
if (! new_symbol)
|
||||
return NULL;
|
||||
new_symbol->the_bfd = abfd;
|
||||
return new_symbol;
|
||||
}
|
||||
|
||||
static void
|
||||
wasm_print_symbol (bfd *abfd,
|
||||
void * filep,
|
||||
asymbol *symbol,
|
||||
bfd_print_symbol_type how)
|
||||
{
|
||||
FILE *file = (FILE *) filep;
|
||||
|
||||
switch (how)
|
||||
{
|
||||
case bfd_print_symbol_name:
|
||||
fprintf (file, "%s", symbol->name);
|
||||
break;
|
||||
|
||||
default:
|
||||
bfd_print_symbol_vandf (abfd, filep, symbol);
|
||||
fprintf (file, " %-5s %s", symbol->section->name, symbol->name);
|
||||
}
|
||||
}
|
||||
|
||||
static void
|
||||
wasm_get_symbol_info (bfd *abfd ATTRIBUTE_UNUSED,
|
||||
asymbol *symbol,
|
||||
symbol_info *ret)
|
||||
{
|
||||
bfd_symbol_info (symbol, ret);
|
||||
}
|
||||
|
||||
/* Check whether ABFD is a WebAssembly module; if so, scan it. */
|
||||
|
||||
static const bfd_target *
|
||||
wasm_object_p (bfd *abfd)
|
||||
{
|
||||
bfd_boolean error;
|
||||
|
||||
if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
|
||||
return NULL;
|
||||
|
||||
if (! wasm_read_header (abfd, &error))
|
||||
{
|
||||
bfd_set_error (bfd_error_wrong_format);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
if (! wasm_mkobject (abfd) || ! wasm_scan (abfd))
|
||||
return NULL;
|
||||
|
||||
if (! bfd_default_set_arch_mach (abfd, bfd_arch_wasm32, 0))
|
||||
return NULL;
|
||||
|
||||
if (wasm_scan_name_function_section (abfd, bfd_get_section_by_name (abfd, WASM_NAME_SECTION)))
|
||||
abfd->flags |= HAS_SYMS;
|
||||
|
||||
return abfd->xvec;
|
||||
}
|
||||
|
||||
/* BFD_JUMP_TABLE_WRITE */
|
||||
#define wasm_set_arch_mach _bfd_generic_set_arch_mach
|
||||
|
||||
/* BFD_JUMP_TABLE_SYMBOLS */
|
||||
#define wasm_get_symbol_version_string _bfd_nosymbols_get_symbol_version_string
|
||||
#define wasm_bfd_is_local_label_name bfd_generic_is_local_label_name
|
||||
#define wasm_bfd_is_target_special_symbol ((bfd_boolean (*) (bfd *, asymbol *)) bfd_false)
|
||||
#define wasm_get_lineno _bfd_nosymbols_get_lineno
|
||||
#define wasm_find_nearest_line _bfd_nosymbols_find_nearest_line
|
||||
#define wasm_find_line _bfd_nosymbols_find_line
|
||||
#define wasm_find_inliner_info _bfd_nosymbols_find_inliner_info
|
||||
#define wasm_bfd_make_debug_symbol _bfd_nosymbols_bfd_make_debug_symbol
|
||||
#define wasm_read_minisymbols _bfd_generic_read_minisymbols
|
||||
#define wasm_minisymbol_to_symbol _bfd_generic_minisymbol_to_symbol
|
||||
|
||||
const bfd_target wasm_vec =
|
||||
{
|
||||
"wasm", /* Name. */
|
||||
bfd_target_unknown_flavour,
|
||||
BFD_ENDIAN_LITTLE,
|
||||
BFD_ENDIAN_LITTLE,
|
||||
(HAS_SYMS | WP_TEXT), /* Object flags. */
|
||||
(SEC_CODE | SEC_DATA | SEC_HAS_CONTENTS), /* Section flags. */
|
||||
0, /* Leading underscore. */
|
||||
' ', /* AR_pad_char. */
|
||||
255, /* AR_max_namelen. */
|
||||
0, /* Match priority. */
|
||||
/* Routines to byte-swap various sized integers from the data sections. */
|
||||
bfd_getl64, bfd_getl_signed_64, bfd_putl64,
|
||||
bfd_getl32, bfd_getl_signed_32, bfd_putl32,
|
||||
bfd_getl16, bfd_getl_signed_16, bfd_putl16,
|
||||
|
||||
/* Routines to byte-swap various sized integers from the file headers. */
|
||||
bfd_getl64, bfd_getl_signed_64, bfd_putl64,
|
||||
bfd_getl32, bfd_getl_signed_32, bfd_putl32,
|
||||
bfd_getl16, bfd_getl_signed_16, bfd_putl16,
|
||||
|
||||
{
|
||||
_bfd_dummy_target,
|
||||
wasm_object_p, /* bfd_check_format. */
|
||||
_bfd_dummy_target,
|
||||
_bfd_dummy_target,
|
||||
},
|
||||
{
|
||||
bfd_false,
|
||||
wasm_mkobject,
|
||||
_bfd_generic_mkarchive,
|
||||
bfd_false,
|
||||
},
|
||||
{ /* bfd_write_contents. */
|
||||
bfd_false,
|
||||
wasm_write_object_contents,
|
||||
_bfd_write_archive_contents,
|
||||
bfd_false,
|
||||
},
|
||||
|
||||
BFD_JUMP_TABLE_GENERIC (_bfd_generic),
|
||||
BFD_JUMP_TABLE_COPY (_bfd_generic),
|
||||
BFD_JUMP_TABLE_CORE (_bfd_nocore),
|
||||
BFD_JUMP_TABLE_ARCHIVE (_bfd_noarchive),
|
||||
BFD_JUMP_TABLE_SYMBOLS (wasm),
|
||||
BFD_JUMP_TABLE_RELOCS (_bfd_norelocs),
|
||||
BFD_JUMP_TABLE_WRITE (wasm),
|
||||
BFD_JUMP_TABLE_LINK (_bfd_nolink),
|
||||
BFD_JUMP_TABLE_DYNAMIC (_bfd_nodynamic),
|
||||
|
||||
NULL,
|
||||
|
||||
NULL,
|
||||
};
|
||||
52
bfd/wasm-module.h
Normal file
52
bfd/wasm-module.h
Normal file
@ -0,0 +1,52 @@
|
||||
/* BFD back-end for WebAssembly modules.
|
||||
Copyright (C) 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. */
|
||||
|
||||
#ifndef _WASM_MODULE_H
|
||||
#define _WASM_MODULE_H
|
||||
|
||||
/* WebAssembly module file header. Note that WASM_VERSION is a 32-bit
|
||||
little-endian integer, not an LEB128-encoded integer. */
|
||||
#define SIZEOF_WASM_MAGIC 4
|
||||
#define WASM_MAGIC { 0x00, 'a', 's', 'm' }
|
||||
#define SIZEOF_WASM_VERSION 4
|
||||
#define WASM_VERSION { 0x01, 0x00, 0x00, 0x00 }
|
||||
|
||||
/* Prefix to use to form section names. */
|
||||
#define WASM_SECTION_PREFIX ".wasm."
|
||||
|
||||
/* NUMBER is currently unused, but is included for error checking purposes. */
|
||||
#define WASM_SECTION(number, name) (WASM_SECTION_PREFIX name)
|
||||
|
||||
/* Section names. WASM_NAME_SECTION is the name of the named section
|
||||
named "name". */
|
||||
#define WASM_NAME_SECTION WASM_SECTION (0, "name")
|
||||
#define WASM_RELOC_SECTION_PREFIX WASM_SECTION (0, "reloc.")
|
||||
#define WASM_LINKING_SECTION WASM_SECTION (0, "linking")
|
||||
#define WASM_DYLINK_SECTION WASM_SECTION (0, "dylink")
|
||||
|
||||
/* Subsection indices. Right now, that's subsections of the "name"
|
||||
section only. */
|
||||
#define WASM_FUNCTION_SUBSECTION 1 /* Function names. */
|
||||
#define WASM_LOCALS_SUBSECTION 2 /* Names of locals by function. */
|
||||
|
||||
/* The section to report wasm symbols in. */
|
||||
#define WASM_SECTION_FUNCTION_INDEX ".space.function_index"
|
||||
|
||||
#endif /* _WASM_MODULE_H */
|
||||
Loading…
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Reference in New Issue
Block a user