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Merge pull request #7763 from kivikakk/zig-elf-parse

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std.elf: expose parsing decoupled from std.fs.File
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Andrew Kelley 2021-03-04 11:56:31 -08:00 committed by GitHub
commit ffb2568a9f
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3 changed files with 176 additions and 185 deletions
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6
lib/std/build/emit_raw.zig
View File

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

85
lib/std/elf.zig
View File

@ -335,7 +335,7 @@ pub const ET = extern enum(u16) {
};
/// All integers are native endian.
const Header = struct {
pub const Header = struct {
endian: builtin.Endian,
is_64: bool,
entry: u64,
@ -347,26 +347,30 @@ 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 {
return .{
pub fn section_header_iterator(self: Header, parse_source: anytype) SectionHeaderIterator(@TypeOf(parse_source)) {
return SectionHeaderIterator(@TypeOf(parse_source)){
.elf_header = self,
.file = file,
.parse_source = parse_source,
};
}
};
pub fn readHeader(file: File) !Header {
pub fn read(parse_source: anytype) !Header {
var hdr_buf: [@sizeOf(Elf64_Ehdr)]u8 align(@alignOf(Elf64_Ehdr)) = undefined;
try preadNoEof(file, &hdr_buf, 0);
const hdr32 = @ptrCast(*Elf32_Ehdr, &hdr_buf);
const hdr64 = @ptrCast(*Elf64_Ehdr, &hdr_buf);
try parse_source.seekableStream().seekTo(0);
try parse_source.reader().readNoEof(&hdr_buf);
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);
if (!mem.eql(u8, hdr32.e_ident[0..4], "\x7fELF")) return error.InvalidElfMagic;
if (hdr32.e_ident[EI_VERSION] != 1) return error.InvalidElfVersion;
@ -395,21 +399,24 @@ pub fn readHeader(file: File) !Header {
.shnum = int(is_64, need_bswap, hdr32.e_shnum, hdr64.e_shnum),
.shstrndx = int(is_64, need_bswap, hdr32.e_shstrndx, hdr64.e_shstrndx),
});
}
}
};
pub const ProgramHeaderIterator = struct {
pub fn ProgramHeaderIterator(ParseSource: anytype) type {
return struct {
elf_header: Header,
file: File,
parse_source: ParseSource,
index: usize = 0,
pub fn next(self: *ProgramHeaderIterator) !?Elf64_Phdr {
pub fn next(self: *@This()) !?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 preadNoEof(self.file, mem.asBytes(&phdr), offset);
try self.parse_source.seekableStream().seekTo(offset);
try self.parse_source.reader().readNoEof(mem.asBytes(&phdr));
// ELF endianness matches native endianness.
if (self.elf_header.endian == std.builtin.endian) return phdr;
@ -429,7 +436,8 @@ pub const ProgramHeaderIterator = struct {
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.seekableStream().seekTo(offset);
try self.parse_source.reader().readNoEof(mem.asBytes(&phdr));
// ELF endianness does NOT match native endianness.
if (self.elf_header.endian != std.builtin.endian) {
@ -458,21 +466,24 @@ pub const ProgramHeaderIterator = struct {
.p_align = phdr.p_align,
};
}
};
};
}
pub const SectionHeaderIterator = struct {
pub fn SectionHeaderIterator(ParseSource: anytype) type {
return struct {
elf_header: Header,
file: File,
parse_source: ParseSource,
index: usize = 0,
pub fn next(self: *SectionHeaderIterator) !?Elf64_Shdr {
pub fn next(self: *@This()) !?Elf64_Shdr {
if (self.index >= self.elf_header.shnum) return null;
defer self.index += 1;
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.seekableStream().seekTo(offset);
try self.parse_source.reader().readNoEof(mem.asBytes(&shdr));
// ELF endianness matches native endianness.
if (self.elf_header.endian == std.builtin.endian) return shdr;
@ -494,7 +505,8 @@ 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.seekableStream().seekTo(offset);
try self.parse_source.reader().readNoEof(mem.asBytes(&shdr));
// ELF endianness does NOT match native endianness.
if (self.elf_header.endian != std.builtin.endian) {
@ -527,7 +539,8 @@ pub const SectionHeaderIterator = struct {
.sh_entsize = shdr.sh_entsize,
};
}
};
};
}
pub fn int(is_64: bool, need_bswap: bool, int_32: anytype, int_64: anytype) @TypeOf(int_64) {
if (is_64) {
@ -549,28 +562,6 @@ 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;

4
src/test.zig
View File

@ -1030,8 +1030,8 @@ 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 header = try std.elf.Header.read(&file);
var iterator = header.program_header_iterator(&file);
var none_loaded = true;