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expose phdr, shdr parsing

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This commit is contained in:
Asherah Connor 2021-01-14 15:30:28 +11:00
parent 49ab6bb429
commit 32d69d70cf
3 changed files with 110 additions and 94 deletions
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7
lib/std/build/emit_raw.zig
View File

@ -51,9 +51,10 @@ const BinaryElfOutput = struct {
.segments = ArrayList(*BinaryElfSegment).init(allocator),
.sections = ArrayList(*BinaryElfSection).init(allocator),
};
const elf_hdr = try std.elf.readHeader(elf_file);
const elf_source = std.elf.FileParseSource{ .file = elf_file };
const elf_hdr = try std.elf.Header.read(elf_source);
var section_headers = elf_hdr.section_header_iterator(elf_file);
var section_headers = elf_hdr.section_header_iterator(elf_source);
while (try section_headers.next()) |section| {
if (sectionValidForOutput(section)) {
const newSection = try allocator.create(BinaryElfSection);
@ -67,7 +68,7 @@ const BinaryElfOutput = struct {
}
}
var program_headers = elf_hdr.program_header_iterator(elf_file);
var program_headers = elf_hdr.program_header_iterator(elf_source);
while (try program_headers.next()) |phdr| {
if (phdr.p_type == elf.PT_LOAD) {
const newSegment = try allocator.create(BinaryElfSegment);

192
lib/std/elf.zig
View File

@ -334,6 +334,40 @@ pub const ET = extern enum(u16) {
pub const HIPROC = 0xffff;
};
pub const FileParseSource = struct {
file: std.fs.File,
fn readNoEof(self: FileParseSource, buf: []u8, offset: u64) !void {
var i: usize = 0;
while (i < buf.len) {
const len = self.file.pread(buf[i .. buf.len - i], offset + i) catch |err| switch (err) {
error.SystemResources => return error.SystemResources,
error.IsDir => return error.UnableToReadElfFile,
error.OperationAborted => return error.UnableToReadElfFile,
error.BrokenPipe => return error.UnableToReadElfFile,
error.Unseekable => return error.UnableToReadElfFile,
error.ConnectionResetByPeer => return error.UnableToReadElfFile,
error.ConnectionTimedOut => return error.UnableToReadElfFile,
error.InputOutput => return error.FileSystem,
error.Unexpected => return error.Unexpected,
error.WouldBlock => return error.Unexpected,
error.NotOpenForReading => return error.Unexpected,
error.AccessDenied => return error.Unexpected,
};
if (len == 0) return error.UnexpectedEndOfFile;
i += len;
}
}
};
pub const BufferParseSource = struct {
buffer: []const u8,
fn readNoEof(self: BufferParseSource, buf: []u8, offset: u64) !void {
std.mem.copy(u8, buf, self.buffer[offset .. offset + buf.len]);
}
};
/// All integers are native endian.
pub const Header = struct {
endian: builtin.Endian,
@ -347,20 +381,26 @@ pub const Header = struct {
shnum: u16,
shstrndx: u16,
pub fn program_header_iterator(self: Header, file: File) ProgramHeaderIterator {
return .{
pub fn program_header_iterator(self: Header, parse_source: anytype) ProgramHeaderIterator(@TypeOf(parse_source)) {
return ProgramHeaderIterator(@TypeOf(parse_source)){
.elf_header = self,
.file = file,
.parse_source = parse_source,
};
}
pub fn section_header_iterator(self: Header, file: File) SectionHeaderIterator {
pub fn section_header_iterator(self: Header, parse_source: anytype) SectionHeaderIterator {
return .{
.elf_header = self,
.file = file,
.parse_source = parse_source,
};
}
pub fn read(parse_source: anytype) !Header {
var hdr_buf: [@sizeOf(Elf64_Ehdr)]u8 align(@alignOf(Elf64_Ehdr)) = undefined;
try parse_source.readNoEof(&hdr_buf, 0);
return Header.parse(&hdr_buf);
}
pub fn parse(hdr_buf: *align(@alignOf(Elf64_Ehdr)) const [@sizeOf(Elf64_Ehdr)]u8) !Header {
const hdr32 = @ptrCast(*const Elf32_Ehdr, hdr_buf);
const hdr64 = @ptrCast(*const Elf64_Ehdr, hdr_buf);
@ -395,78 +435,74 @@ pub const Header = struct {
}
};
pub fn readHeader(file: File) !Header {
var hdr_buf: [@sizeOf(Elf64_Ehdr)]u8 align(@alignOf(Elf64_Ehdr)) = undefined;
try preadNoEof(file, &hdr_buf, 0);
return Header.parse(&hdr_buf);
}
pub fn ProgramHeaderIterator(ParseSource: anytype) type {
return struct {
elf_header: Header,
parse_source: ParseSource,
index: usize = 0,
pub const ProgramHeaderIterator = struct {
elf_header: Header,
file: File,
index: usize = 0,
pub fn next(self: *@This()) !?Elf64_Phdr {
if (self.index >= self.elf_header.phnum) return null;
defer self.index += 1;
pub fn next(self: *ProgramHeaderIterator) !?Elf64_Phdr {
if (self.index >= self.elf_header.phnum) return null;
defer self.index += 1;
if (self.elf_header.is_64) {
var phdr: Elf64_Phdr = undefined;
const offset = self.elf_header.phoff + @sizeOf(@TypeOf(phdr)) * self.index;
try self.parse_source.readNoEof(mem.asBytes(&phdr), offset);
if (self.elf_header.is_64) {
var phdr: Elf64_Phdr = undefined;
// ELF endianness matches native endianness.
if (self.elf_header.endian == std.builtin.endian) return phdr;
// Convert fields to native endianness.
return Elf64_Phdr{
.p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
.p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
.p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
.p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
.p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
.p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
.p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
.p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
};
}
var phdr: Elf32_Phdr = undefined;
const offset = self.elf_header.phoff + @sizeOf(@TypeOf(phdr)) * self.index;
try preadNoEof(self.file, mem.asBytes(&phdr), offset);
try self.parse_source.readNoEof(mem.asBytes(&phdr), offset);
// ELF endianness matches native endianness.
if (self.elf_header.endian == std.builtin.endian) return phdr;
// ELF endianness does NOT match native endianness.
if (self.elf_header.endian != std.builtin.endian) {
// Convert fields to native endianness.
phdr = .{
.p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
.p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
.p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
.p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
.p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
.p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
.p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
.p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
};
}
// Convert fields to native endianness.
// Convert 32-bit header to 64-bit.
return Elf64_Phdr{
.p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
.p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
.p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
.p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
.p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
.p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
.p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
.p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
.p_type = phdr.p_type,
.p_offset = phdr.p_offset,
.p_vaddr = phdr.p_vaddr,
.p_paddr = phdr.p_paddr,
.p_filesz = phdr.p_filesz,
.p_memsz = phdr.p_memsz,
.p_flags = phdr.p_flags,
.p_align = phdr.p_align,
};
}
var phdr: Elf32_Phdr = undefined;
const offset = self.elf_header.phoff + @sizeOf(@TypeOf(phdr)) * self.index;
try preadNoEof(self.file, mem.asBytes(&phdr), offset);
// ELF endianness does NOT match native endianness.
if (self.elf_header.endian != std.builtin.endian) {
// Convert fields to native endianness.
phdr = .{
.p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
.p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
.p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
.p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
.p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
.p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
.p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
.p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
};
}
// Convert 32-bit header to 64-bit.
return Elf64_Phdr{
.p_type = phdr.p_type,
.p_offset = phdr.p_offset,
.p_vaddr = phdr.p_vaddr,
.p_paddr = phdr.p_paddr,
.p_filesz = phdr.p_filesz,
.p_memsz = phdr.p_memsz,
.p_flags = phdr.p_flags,
.p_align = phdr.p_align,
};
}
};
};
}
pub const SectionHeaderIterator = struct {
elf_header: Header,
file: File,
parse_source: ParseSource,
index: usize = 0,
pub fn next(self: *SectionHeaderIterator) !?Elf64_Shdr {
@ -476,7 +512,7 @@ pub const SectionHeaderIterator = struct {
if (self.elf_header.is_64) {
var shdr: Elf64_Shdr = undefined;
const offset = self.elf_header.shoff + @sizeOf(@TypeOf(shdr)) * self.index;
try preadNoEof(self.file, mem.asBytes(&shdr), offset);
try self.parse_source.readNoEof(mem.asBytes(&shdr), offset);
// ELF endianness matches native endianness.
if (self.elf_header.endian == std.builtin.endian) return shdr;
@ -498,7 +534,7 @@ pub const SectionHeaderIterator = struct {
var shdr: Elf32_Shdr = undefined;
const offset = self.elf_header.shoff + @sizeOf(@TypeOf(shdr)) * self.index;
try preadNoEof(self.file, mem.asBytes(&shdr), offset);
try self.parse_source.readNoEof(mem.asBytes(&shdr), offset);
// ELF endianness does NOT match native endianness.
if (self.elf_header.endian != std.builtin.endian) {
@ -553,28 +589,6 @@ pub fn int32(need_bswap: bool, int_32: anytype, comptime Int64: anytype) Int64 {
}
}
fn preadNoEof(file: std.fs.File, buf: []u8, offset: u64) !void {
var i: usize = 0;
while (i < buf.len) {
const len = file.pread(buf[i .. buf.len - i], offset + i) catch |err| switch (err) {
error.SystemResources => return error.SystemResources,
error.IsDir => return error.UnableToReadElfFile,
error.OperationAborted => return error.UnableToReadElfFile,
error.BrokenPipe => return error.UnableToReadElfFile,
error.Unseekable => return error.UnableToReadElfFile,
error.ConnectionResetByPeer => return error.UnableToReadElfFile,
error.ConnectionTimedOut => return error.UnableToReadElfFile,
error.InputOutput => return error.FileSystem,
error.Unexpected => return error.Unexpected,
error.WouldBlock => return error.Unexpected,
error.NotOpenForReading => return error.Unexpected,
error.AccessDenied => return error.Unexpected,
};
if (len == 0) return error.UnexpectedEndOfFile;
i += len;
}
}
pub const EI_NIDENT = 16;
pub const EI_CLASS = 4;

5
src/test.zig
View File

@ -989,8 +989,9 @@ pub const TestContext = struct {
var file = try tmp_dir.openFile(bin_name, .{ .read = true });
defer file.close();
const header = try std.elf.readHeader(file);
var iterator = header.program_header_iterator(file);
const elf_source = std.elf.FileParseSource{ .file = file };
const header = try std.elf.Header.read(elf_source);
var iterator = header.program_header_iterator(elf_source);
var none_loaded = true;