Commit af1e196db3bca66c29979c685b1c9c896c275211 | zig

author	Kendall Condon <goon.pri.low@gmail.com> 2025-11-02 09:57:15-05:00
committer	Kendall Condon <goon.pri.low@gmail.com> 2026-02-13 17:58:09-05:00
log	af1e196db3bca66c29979c685b1c9c896c275211
tree	03ab8aa21c4fd56ad91561f8efc48ef6b9a88946
parent	3c9024be08f34d2bb38693df38e5b4b334c74f90

align end of elf archives

The end of the archive needs to also be aligned to a two-byte boundary,
not just the start of records. This was causing lld to reject archives.

Notably, this was happening with compiler_rt when rebuilding in fuzz
mode, which is why this commit is included in this patchset.

2 files changed, 11 insertions(+), 5 deletions(-)

lib
- std
  - Build
    Step
    CheckObject.zig
src
- link
  - Elf
    relocatable.zig

lib/std/Build/Step/CheckObject.zig+5-1

...	...	@@ -1702,6 +1702,10 @@ const ElfDumper = struct {
1702	1702	return error.InvalidArchiveMagicNumber;
1703	1703	}
1704	1704
	1705	if (!mem.isAligned(bytes.len, 2)) {
	1706	return error.InvalidArchivePadding;
	1707	}
	1708
1705	1709	var ctx = ArchiveContext{
1706	1710	.gpa = gpa,
1707	1711	.data = bytes,
...	...	@@ -1715,8 +1719,8 @@ const ElfDumper = struct {
1715	1719	}
1716	1720
1717	1721	while (true) {
1718		if (reader.seek >= ctx.data.len) break;
1719	1722	if (!mem.isAligned(reader.seek, 2)) reader.seek += 1;
	1723	if (reader.seek >= ctx.data.len) break;
1720	1724
1721	1725	const hdr = try reader.takeStruct(elf.ar_hdr, .little);
1722	1726

src/link/Elf/relocatable.zig+6-4

...	...	@@ -95,10 +95,11 @@ pub fn flushStaticLib(elf_file: Elf, comp: Compilation) !void {
95	95	const total_size: usize = blk: {
96	96	var pos: usize = elf.ARMAG.len;
97	97	pos += @sizeOf(elf.ar_hdr) + ar_symtab.size(.p64);
	98	pos = mem.alignForward(usize, pos, 2);
98	99
99	100	if (ar_strtab.size() > 0) {
100		pos = mem.alignForward(usize, pos, 2);
101	101	pos += @sizeOf(elf.ar_hdr) + ar_strtab.size();
	102	pos = mem.alignForward(usize, pos, 2);
102	103	}
103	104
104	105	for (files.items) \|index\| {
...	...	@@ -108,9 +109,9 @@ pub fn flushStaticLib(elf_file: Elf, comp: Compilation) !void {
108	109	.object => \|x\| &x.output_ar_state,
109	110	else => unreachable,
110	111	};
111		pos = mem.alignForward(usize, pos, 2);
112	112	state.file_off = pos;
113	113	pos += @sizeOf(elf.ar_hdr) + (math.cast(usize, state.size) orelse return error.Overflow);
	114	pos = mem.alignForward(usize, pos, 2);
114	115	}
115	116
116	117	break :blk pos;
...	...	@@ -131,17 +132,18 @@ pub fn flushStaticLib(elf_file: Elf, comp: Compilation) !void {
131	132
132	133	// Write symtab
133	134	try ar_symtab.write(.p64, elf_file, &writer);
	135	if (!mem.isAligned(writer.end, 2)) try writer.writeByte(0);
134	136
135	137	// Write strtab
136	138	if (ar_strtab.size() > 0) {
137		if (!mem.isAligned(writer.end, 2)) try writer.writeByte(0);
138	139	try ar_strtab.write(&writer);
	140	if (!mem.isAligned(writer.end, 2)) try writer.writeByte(0);
139	141	}
140	142
141	143	// Write object files
142	144	for (files.items) \|index\| {
143		if (!mem.isAligned(writer.end, 2)) try writer.writeByte(0);
144	145	try elf_file.file(index).?.writeAr(elf_file, &writer);
	146	if (!mem.isAligned(writer.end, 2)) try writer.writeByte(0);
145	147	}
146	148
147	149	assert(writer.buffered().len == total_size);