authorgravatar for jay@jayschwa.netJay Petacat <jay@jayschwa.net> 2020-07-31 20:37:02-04:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2020-08-01 16:01:48+00:00
logcf15b4c2690ae7884e7bdb9259e6497c18213d35
treeaf882c0bd2808d7862db5914cfee48ab66cfc47a
parent0d31877444bf6c21307dfd3c412f9673dfd8acab

elf: Iterate over headers w/o need for allocator

2 files changed, 140 insertions(+), 131 deletions(-)

lib/std/build/emit_raw.zig+5-3
......@@ -46,9 +46,10 @@ const BinaryElfOutput = struct {
4646 .segments = ArrayList(*BinaryElfSegment).init(allocator),
4747 .sections = ArrayList(*BinaryElfSection).init(allocator),
4848 };
49 const elf_hdrs = try std.elf.readAllHeaders(allocator, elf_file);
49 const elf_hdr = try std.elf.readHeader(elf_file);
5050
51 for (elf_hdrs.section_headers) |section, i| {
51 var section_headers = elf_hdr.section_header_iterator(elf_file);
52 while (try section_headers.next()) |section| {
5253 if (sectionValidForOutput(section)) {
5354 const newSection = try allocator.create(BinaryElfSection);
5455
......@@ -61,7 +62,8 @@ const BinaryElfOutput = struct {
6162 }
6263 }
6364
64 for (elf_hdrs.program_headers) |phdr, i| {
65 var program_headers = elf_hdr.program_header_iterator(elf_file);
66 while (try program_headers.next()) |phdr| {
6567 if (phdr.p_type == elf.PT_LOAD) {
6668 const newSegment = try allocator.create(BinaryElfSegment);
6769
lib/std/elf.zig+135-128
......@@ -341,6 +341,20 @@ const Header = struct {
341341 shentsize: u16,
342342 shnum: u16,
343343 shstrndx: u16,
344
345 pub fn program_header_iterator(self: Header, file: File) ProgramHeaderIterator {
346 return .{
347 .elf_header = self,
348 .file = file,
349 };
350 }
351
352 pub fn section_header_iterator(self: Header, file: File) SectionHeaderIterator {
353 return .{
354 .elf_header = self,
355 .file = file,
356 };
357 }
344358};
345359
346360pub fn readHeader(file: File) !Header {
......@@ -378,144 +392,137 @@ pub fn readHeader(file: File) !Header {
378392 });
379393}
380394
381/// All integers are native endian.
382pub const AllHeaders = struct {
383 header: Header,
384 section_headers: []Elf64_Shdr,
385 program_headers: []Elf64_Phdr,
386 allocator: *mem.Allocator,
387};
388
389pub fn readAllHeaders(allocator: *mem.Allocator, file: File) !AllHeaders {
390 var hdrs: AllHeaders = .{
391 .allocator = allocator,
392 .header = try readHeader(file),
393 .section_headers = undefined,
394 .program_headers = undefined,
395 };
396 const is_64 = hdrs.header.is_64;
397 const need_bswap = hdrs.header.endian != std.builtin.endian;
398
399 hdrs.section_headers = try allocator.alloc(Elf64_Shdr, hdrs.header.shnum);
400 errdefer allocator.free(hdrs.section_headers);
401
402 hdrs.program_headers = try allocator.alloc(Elf64_Phdr, hdrs.header.phnum);
403 errdefer allocator.free(hdrs.program_headers);
404
405 // If the ELF file is 64-bit and same-endianness, then all we have to do is
406 // yeet the bytes into memory.
407 // If only the endianness is different, they can be simply byte swapped.
408 if (is_64) {
409 const shdr_buf = std.mem.sliceAsBytes(hdrs.section_headers);
410 const phdr_buf = std.mem.sliceAsBytes(hdrs.program_headers);
411 try preadNoEof(file, shdr_buf, hdrs.header.shoff);
412 try preadNoEof(file, phdr_buf, hdrs.header.phoff);
395pub const ProgramHeaderIterator = struct {
396 elf_header: Header,
397 file: File,
398 index: usize = 0,
399
400 pub fn next(self: *ProgramHeaderIterator) !?Elf64_Phdr {
401 if (self.index >= self.elf_header.phnum) return null;
402 defer self.index += 1;
403
404 if (self.elf_header.is_64) {
405 var phdr: Elf64_Phdr = undefined;
406 const offset = self.elf_header.phoff + @sizeOf(@TypeOf(phdr)) * self.index;
407 try preadNoEof(self.file, mem.asBytes(&phdr), offset);
408
409 // ELF endianness matches native endianness.
410 if (self.elf_header.endian == std.builtin.endian) return phdr;
411
412 // Convert fields to native endianness.
413 return Elf64_Phdr{
414 .p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
415 .p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
416 .p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
417 .p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
418 .p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
419 .p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
420 .p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
421 .p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
422 };
423 }
413424
414 if (need_bswap) {
415 for (hdrs.section_headers) |*shdr| {
416 shdr.* = .{
417 .sh_name = @byteSwap(@TypeOf(shdr.sh_name), shdr.sh_name),
418 .sh_type = @byteSwap(@TypeOf(shdr.sh_type), shdr.sh_type),
419 .sh_flags = @byteSwap(@TypeOf(shdr.sh_flags), shdr.sh_flags),
420 .sh_addr = @byteSwap(@TypeOf(shdr.sh_addr), shdr.sh_addr),
421 .sh_offset = @byteSwap(@TypeOf(shdr.sh_offset), shdr.sh_offset),
422 .sh_size = @byteSwap(@TypeOf(shdr.sh_size), shdr.sh_size),
423 .sh_link = @byteSwap(@TypeOf(shdr.sh_link), shdr.sh_link),
424 .sh_info = @byteSwap(@TypeOf(shdr.sh_info), shdr.sh_info),
425 .sh_addralign = @byteSwap(@TypeOf(shdr.sh_addralign), shdr.sh_addralign),
426 .sh_entsize = @byteSwap(@TypeOf(shdr.sh_entsize), shdr.sh_entsize),
427 };
428 }
429 for (hdrs.program_headers) |*phdr| {
430 phdr.* = .{
431 .p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
432 .p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
433 .p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
434 .p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
435 .p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
436 .p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
437 .p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
438 .p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
439 };
440 }
425 var phdr: Elf32_Phdr = undefined;
426 const offset = self.elf_header.phoff + @sizeOf(@TypeOf(phdr)) * self.index;
427 try preadNoEof(self.file, mem.asBytes(&phdr), offset);
428
429 // ELF endianness does NOT match native endianness.
430 if (self.elf_header.endian != std.builtin.endian) {
431 // Convert fields to native endianness.
432 phdr = .{
433 .p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
434 .p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
435 .p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
436 .p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
437 .p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
438 .p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
439 .p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
440 .p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
441 };
441442 }
442443
443 return hdrs;
444 // Convert 32-bit header to 64-bit.
445 return Elf64_Phdr{
446 .p_type = phdr.p_type,
447 .p_offset = phdr.p_offset,
448 .p_vaddr = phdr.p_vaddr,
449 .p_paddr = phdr.p_paddr,
450 .p_filesz = phdr.p_filesz,
451 .p_memsz = phdr.p_memsz,
452 .p_flags = phdr.p_flags,
453 .p_align = phdr.p_align,
454 };
444455 }
456};
445457
446 const shdrs_32 = try allocator.alloc(Elf32_Shdr, hdrs.header.shnum);
447 defer allocator.free(shdrs_32);
448
449 const phdrs_32 = try allocator.alloc(Elf32_Phdr, hdrs.header.phnum);
450 defer allocator.free(phdrs_32);
451
452 const shdr_buf = std.mem.sliceAsBytes(shdrs_32);
453 const phdr_buf = std.mem.sliceAsBytes(phdrs_32);
454 try preadNoEof(file, shdr_buf, hdrs.header.shoff);
455 try preadNoEof(file, phdr_buf, hdrs.header.phoff);
456
457 if (need_bswap) {
458 for (hdrs.section_headers) |*shdr, i| {
459 const o = shdrs_32[i];
460 shdr.* = .{
461 .sh_name = @byteSwap(@TypeOf(o.sh_name), o.sh_name),
462 .sh_type = @byteSwap(@TypeOf(o.sh_type), o.sh_type),
463 .sh_flags = @byteSwap(@TypeOf(o.sh_flags), o.sh_flags),
464 .sh_addr = @byteSwap(@TypeOf(o.sh_addr), o.sh_addr),
465 .sh_offset = @byteSwap(@TypeOf(o.sh_offset), o.sh_offset),
466 .sh_size = @byteSwap(@TypeOf(o.sh_size), o.sh_size),
467 .sh_link = @byteSwap(@TypeOf(o.sh_link), o.sh_link),
468 .sh_info = @byteSwap(@TypeOf(o.sh_info), o.sh_info),
469 .sh_addralign = @byteSwap(@TypeOf(o.sh_addralign), o.sh_addralign),
470 .sh_entsize = @byteSwap(@TypeOf(o.sh_entsize), o.sh_entsize),
471 };
472 }
473 for (hdrs.program_headers) |*phdr, i| {
474 const o = phdrs_32[i];
475 phdr.* = .{
476 .p_type = @byteSwap(@TypeOf(o.p_type), o.p_type),
477 .p_offset = @byteSwap(@TypeOf(o.p_offset), o.p_offset),
478 .p_vaddr = @byteSwap(@TypeOf(o.p_vaddr), o.p_vaddr),
479 .p_paddr = @byteSwap(@TypeOf(o.p_paddr), o.p_paddr),
480 .p_filesz = @byteSwap(@TypeOf(o.p_filesz), o.p_filesz),
481 .p_memsz = @byteSwap(@TypeOf(o.p_memsz), o.p_memsz),
482 .p_flags = @byteSwap(@TypeOf(o.p_flags), o.p_flags),
483 .p_align = @byteSwap(@TypeOf(o.p_align), o.p_align),
458pub const SectionHeaderIterator = struct {
459 elf_header: Header,
460 file: File,
461 index: usize = 0,
462
463 pub fn next(self: *SectionHeaderIterator) !?Elf64_Shdr {
464 if (self.index >= self.elf_header.shnum) return null;
465 defer self.index += 1;
466
467 if (self.elf_header.is_64) {
468 var shdr: Elf64_Shdr = undefined;
469 const offset = self.elf_header.phoff + @sizeOf(@TypeOf(shdr)) * self.index;
470 try preadNoEof(self.file, mem.asBytes(&shdr), offset);
471
472 // ELF endianness matches native endianness.
473 if (self.elf_header.endian == std.builtin.endian) return shdr;
474
475 // Convert fields to native endianness.
476 return Elf64_Shdr{
477 .sh_name = @byteSwap(@TypeOf(shdr.sh_name), shdr.sh_name),
478 .sh_type = @byteSwap(@TypeOf(shdr.sh_type), shdr.sh_type),
479 .sh_flags = @byteSwap(@TypeOf(shdr.sh_flags), shdr.sh_flags),
480 .sh_addr = @byteSwap(@TypeOf(shdr.sh_addr), shdr.sh_addr),
481 .sh_offset = @byteSwap(@TypeOf(shdr.sh_offset), shdr.sh_offset),
482 .sh_size = @byteSwap(@TypeOf(shdr.sh_size), shdr.sh_size),
483 .sh_link = @byteSwap(@TypeOf(shdr.sh_link), shdr.sh_link),
484 .sh_info = @byteSwap(@TypeOf(shdr.sh_info), shdr.sh_info),
485 .sh_addralign = @byteSwap(@TypeOf(shdr.sh_addralign), shdr.sh_addralign),
486 .sh_entsize = @byteSwap(@TypeOf(shdr.sh_entsize), shdr.sh_entsize),
484487 };
485488 }
486 } else {
487 for (hdrs.section_headers) |*shdr, i| {
488 const o = shdrs_32[i];
489 shdr.* = .{
490 .sh_name = o.sh_name,
491 .sh_type = o.sh_type,
492 .sh_flags = o.sh_flags,
493 .sh_addr = o.sh_addr,
494 .sh_offset = o.sh_offset,
495 .sh_size = o.sh_size,
496 .sh_link = o.sh_link,
497 .sh_info = o.sh_info,
498 .sh_addralign = o.sh_addralign,
499 .sh_entsize = o.sh_entsize,
500 };
501 }
502 for (hdrs.program_headers) |*phdr, i| {
503 const o = phdrs_32[i];
504 phdr.* = .{
505 .p_type = o.p_type,
506 .p_offset = o.p_offset,
507 .p_vaddr = o.p_vaddr,
508 .p_paddr = o.p_paddr,
509 .p_filesz = o.p_filesz,
510 .p_memsz = o.p_memsz,
511 .p_flags = o.p_flags,
512 .p_align = o.p_align,
489
490 var shdr: Elf32_Shdr = undefined;
491 const offset = self.elf_header.shoff + @sizeOf(@TypeOf(shdr)) * self.index;
492 try preadNoEof(self.file, mem.asBytes(&shdr), offset);
493
494 // ELF endianness does NOT match native endianness.
495 if (self.elf_header.endian != std.builtin.endian) {
496 // Convert fields to native endianness.
497 shdr = .{
498 .sh_name = @byteSwap(@TypeOf(shdr.sh_name), shdr.sh_name),
499 .sh_type = @byteSwap(@TypeOf(shdr.sh_type), shdr.sh_type),
500 .sh_flags = @byteSwap(@TypeOf(shdr.sh_flags), shdr.sh_flags),
501 .sh_addr = @byteSwap(@TypeOf(shdr.sh_addr), shdr.sh_addr),
502 .sh_offset = @byteSwap(@TypeOf(shdr.sh_offset), shdr.sh_offset),
503 .sh_size = @byteSwap(@TypeOf(shdr.sh_size), shdr.sh_size),
504 .sh_link = @byteSwap(@TypeOf(shdr.sh_link), shdr.sh_link),
505 .sh_info = @byteSwap(@TypeOf(shdr.sh_info), shdr.sh_info),
506 .sh_addralign = @byteSwap(@TypeOf(shdr.sh_addralign), shdr.sh_addralign),
507 .sh_entsize = @byteSwap(@TypeOf(shdr.sh_entsize), shdr.sh_entsize),
513508 };
514509 }
515 }
516510
517 return hdrs;
518}
511 // Convert 32-bit header to 64-bit.
512 return Elf64_Shdr{
513 .sh_name = shdr.sh_name,
514 .sh_type = shdr.sh_type,
515 .sh_flags = shdr.sh_flags,
516 .sh_addr = shdr.sh_addr,
517 .sh_offset = shdr.sh_offset,
518 .sh_size = shdr.sh_size,
519 .sh_link = shdr.sh_link,
520 .sh_info = shdr.sh_info,
521 .sh_addralign = shdr.sh_addralign,
522 .sh_entsize = shdr.sh_entsize,
523 };
524 }
525};
519526
520527pub fn int(is_64: bool, need_bswap: bool, int_32: anytype, int_64: anytype) @TypeOf(int_64) {
521528 if (is_64) {