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19009: zig objcopy: add --add-section support

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This commit is contained in:
Patrick Wickenhaeuser 2024-10-04 12:38:34 +02:00
parent b23a5b56c2
commit 172e7161a4
1 changed files with 113 additions and 1 deletions
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114
lib/compiler/objcopy.zig
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@ -40,6 +40,7 @@ fn cmdObjCopy(
var only_keep_debug: bool = false;
var compress_debug_sections: bool = false;
var listen = false;
var add_section: ?AddSectionOptions = null;
while (i < args.len) : (i += 1) {
const arg = args[i];
if (!mem.startsWith(u8, arg, "-")) {
@ -104,6 +105,15 @@ fn cmdObjCopy(
i += 1;
if (i >= args.len) fatal("expected another argument after '{s}'", .{arg});
opt_extract = args[i];
} else if (mem.eql(u8, arg, "--add-section")) {
i += 1;
if (i >= args.len) fatal("expected name and filename arguments after '{s}'", .{arg});
if (splitOption(args[i])) |split| {
add_section = .{ .section_name = split.first, .file = split.second };
} else {
fatal("unrecognized argument: '{s}', expecting <name>=<file>", .{args[i]});
}
} else {
fatal("unrecognized argument: '{s}'", .{arg});
}
@ -156,6 +166,7 @@ fn cmdObjCopy(
.ofmt = out_fmt,
.only_section = only_section,
.pad_to = pad_to,
.add_section = add_section,
});
},
.elf => {
@ -175,6 +186,7 @@ fn cmdObjCopy(
.add_debuglink = opt_add_debuglink,
.extract_to = opt_extract,
.compress_debug = compress_debug_sections,
.add_section = add_section,
});
return std.process.cleanExit();
},
@ -229,6 +241,7 @@ const usage =
\\ --add-gnu-debuglink=<file> Creates a .gnu_debuglink section which contains a reference to <file> and adds it to the output file.
\\ --extract-to <file> Extract the removed sections into <file>, and add a .gnu-debuglink section.
\\ --compress-debug-sections Compress DWARF debug sections with zlib
\\ --add-section <name>=<file> Add file content from <file> with the section name <name>.
\\
;
@ -236,6 +249,12 @@ pub const EmitRawElfOptions = struct {
ofmt: std.Target.ObjectFormat,
only_section: ?[]const u8 = null,
pad_to: ?u64 = null,
add_section: ?AddSectionOptions,
};
const AddSectionOptions = struct {
section_name: []const u8,
file: []const u8,
};
fn emitElf(
@ -678,6 +697,7 @@ const StripElfOptions = struct {
strip_debug: bool = false,
only_keep_debug: bool = false,
compress_debug: bool = false,
add_section: ?AddSectionOptions,
};
fn stripElf(
@ -721,6 +741,14 @@ fn stripElf(
var elf_file = try ElfFile(is_64).parse(allocator, in_file, elf_hdr);
defer elf_file.deinit();
if (options.add_section) |user_section| {
for (elf_file.sections) |section| {
if (std.mem.eql(u8, section.name, user_section.section_name)) {
fatal("zig objcopy: unable to add section '{s}'. Section already exists in input", .{user_section.section_name});
}
}
}
if (filter_complement) |flt| {
// write the .dbg file and close it, so it can be read back to compute the debuglink checksum.
const path = options.extract_to.?;
@ -733,7 +761,7 @@ fn stripElf(
}
const debuglink: ?DebugLink = if (debuglink_path) |path| ElfFileHelper.createDebugLink(path) else null;
try elf_file.emit(allocator, out_file, in_file, .{ .section_filter = filter, .debuglink = debuglink, .compress_debug = options.compress_debug });
try elf_file.emit(allocator, out_file, in_file, .{ .section_filter = filter, .debuglink = debuglink, .compress_debug = options.compress_debug, .add_section = options.add_section });
},
}
}
@ -896,6 +924,7 @@ fn ElfFile(comptime is_64: bool) type {
section_filter: Filter = .all,
debuglink: ?DebugLink = null,
compress_debug: bool = false,
add_section: ?AddSectionOptions = null,
};
fn emit(self: *const Self, gpa: Allocator, out_file: File, in_file: File, options: EmitElfOptions) !void {
var arena = std.heap.ArenaAllocator.init(gpa);
@ -934,6 +963,10 @@ fn ElfFile(comptime is_64: bool) type {
if (options.debuglink != null)
next_idx += 1;
if (options.add_section != null) {
next_idx += 1;
}
break :blk next_idx;
};
@ -959,6 +992,28 @@ fn ElfFile(comptime is_64: bool) type {
break :blk new_offset;
};
// add user section to the string table if needed
const user_section_name: u32 = blk: {
if (options.add_section == null) break :blk elf.SHN_UNDEF;
if (self.raw_elf_header.e_shstrndx == elf.SHN_UNDEF)
fatal("zig objcopy: no strtab, cannot add the user section", .{}); // TODO add the section if needed?
const strtab = &self.sections[self.raw_elf_header.e_shstrndx];
const update = &sections_update[self.raw_elf_header.e_shstrndx];
const name = options.add_section.?.section_name;
const new_offset: u32 = @intCast(strtab.payload.?.len);
const buf = try allocator.alignedAlloc(u8, section_memory_align, new_offset + name.len + 1);
@memcpy(buf[0..new_offset], strtab.payload.?);
@memcpy(buf[new_offset..][0..name.len], name);
buf[new_offset + name.len] = 0;
assert(update.action == .keep);
update.payload = buf;
break :blk new_offset;
};
// maybe compress .debug sections
if (options.compress_debug) {
for (self.sections[1..], sections_update[1..]) |section, *update| {
@ -1134,6 +1189,35 @@ fn ElfFile(comptime is_64: bool) type {
eof_offset += @as(Elf_OffSize, @intCast(payload.len));
}
// add user section
if (options.add_section) |add_section| {
var section_file = fs.cwd().openFile(add_section.file, .{}) catch |err|
fatal("unable to open '{s}': {s}", .{ add_section.file, @errorName(err) });
defer section_file.close();
const max_size = std.math.maxInt(usize);
const payload = try section_file.readToEndAlloc(arena.allocator(), max_size);
const flags = 0; // TODO: 19009: support --set-section-flags
const alignment = 4; // TODO: 19009: support --set-section-alignment
dest_sections[dest_section_idx] = Elf_Shdr{
.sh_name = user_section_name,
.sh_type = elf.SHT_PROGBITS,
.sh_flags = flags,
.sh_addr = 0,
.sh_offset = eof_offset,
.sh_size = @intCast(payload.len),
.sh_link = elf.SHN_UNDEF,
.sh_info = elf.SHN_UNDEF,
.sh_addralign = alignment,
.sh_entsize = 0,
};
dest_section_idx += 1;
cmdbuf.appendAssumeCapacity(.{ .write_data = .{ .data = payload, .out_offset = eof_offset } });
eof_offset += @as(Elf_OffSize, @intCast(payload.len));
}
assert(dest_section_idx == new_shnum);
break :blk dest_sections;
};
@ -1361,3 +1445,31 @@ const ElfFileHelper = struct {
return hasher.final();
}
};
const SplitResult = struct { first: []const u8, second: []const u8 };
fn splitOption(option: []const u8) ?SplitResult {
const separator = '=';
if (option.len < 3) return null; // minimum "a=b"
for (1..option.len - 1) |i| {
if (option[i] == separator) return .{
.first = option[0..i],
.second = option[i + 1 ..],
};
}
return null;
}
test "Split option" {
{
const split = splitOption("a=123");
try std.testing.expect(split != null);
try std.testing.expectEqualStrings("a", split.?.first);
try std.testing.expectEqualStrings("123", split.?.second);
}
try std.testing.expectEqual(null, splitOption(""));
try std.testing.expectEqual(null, splitOption("=abc"));
try std.testing.expectEqual(null, splitOption("abc="));
try std.testing.expectEqual(null, splitOption("abc"));
}