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ziglang
MacOS builds are not reproducible
Zig Version
0.11.0-dev.3395+1e7dcaa3a
Steps to Reproduce and Observed Behavior
Adjust the path to the Zig compiler and invoke the following script twice:
ZIG=# path to zig compiler
cat >main.zig <<EOF
const std = @import("std");
pub fn main() void {
std.io.getStdOut().writeAll(
"Hello World!\n",
) catch unreachable;
}
EOF
test() {
local mode="$1"
local target="$2"
echo "$mode $target (PWD $PWD)"
rm -f main main.old main.o
$ZIG build-exe -target $target -O $mode main.zig
md5sum main
{ llvm-objdump --syms main | grep $PWD; } && echo contains PWD || echo does not contain PWD
mv main main.old
rm -f main main.o
$ZIG build-exe -target $target -O $mode main.zig
md5sum main
diffoscope main main.old || true
echo "----------------------------------------"
}
test Debug x86_64-linux
test Debug x86_64-macos
test ReleaseFast x86_64-macos
test ReleaseSafe x86_64-macos
test ReleaseSmall x86_64-macos
The output I observe on Ubuntu 22.04 is the following:
Debug x86_64-linux (PWD /tmp/zig-reproducible-binary-macos)
d24be1f3e202412214295c85b3c5db81 main
does not contain PWD
d24be1f3e202412214295c85b3c5db81 main
----------------------------------------
Debug x86_64-macos (PWD /tmp/zig-reproducible-binary-macos)
519c273df69d7404ac7bafbf326db2b5 main
0000000000000000 d *UND* /tmp/zig-reproducible-binary-macos
0000000064896444 d *UND* /tmp/zig-reproducible-binary-macos/main.o
contains PWD
c6687a2eae53d2b9d73000752ed4a9fa main
--- main
+++ main.old
├── llvm-readobj --symbols {}
│ @@ -8288,15 +8288,15 @@
│ Symbol {
│ Name: /tmp/zig-reproducible-binary-macos/main.o (51146)
│ Type: SymDebugTable (0x66)
│ Section: (0x0)
│ RefType: ReferenceFlagUndefinedLazy (0x1)
│ Flags [ (0x0)
│ ]
│ - Value: 0x64896445
│ + Value: 0x64896444
│ }
│ Symbol {
│ Name: (0)
│ Type: SymDebugTable (0x2E)
│ Section: (0x1)
│ RefType: UndefinedNonLazy (0x0)
│ Flags [ (0x0)
├── x86_64
│┄ Format-specific differences are supported for this file format but no file-specific differences were detected; falling back to a binary diff. file(1) reports: Mach-O 64-bit x86_64 executable, flags:<NOUNDEFS|DYLDLINK|TWOLEVEL|PIE|HAS_TLV_DESCRIPTORS>
│ @@ -97,15 +97,15 @@
│ 00000600: 0e00 0000 2000 0000 0c00 0000 2f75 7372 .... ......./usr
│ 00000610: 2f6c 6962 2f64 796c 6400 0000 0000 0000 /lib/dyld.......
│ 00000620: 2800 0080 1800 0000 c006 0000 0000 0000 (...............
│ 00000630: 0000 0000 0000 0000 2a00 0000 1000 0000 ........*.......
│ 00000640: 0000 0000 0000 0000 3200 0000 2000 0000 ........2... ...
│ 00000650: 0100 0000 0007 0b00 0007 0b00 0100 0000 ................
│ 00000660: 0500 0000 0000 0000 1b00 0000 1800 0000 ................
│ -00000670: 8266 5768 5140 385a 852d 3470 f4af 39a1 [email protected].
│ +00000670: 9778 c914 8de0 3de6 a58e dc05 c7bd 8c27 .x....=........'
│ 00000680: 0c00 0000 3800 0000 1800 0000 0200 0000 ....8...........
│ 00000690: 0564 0c05 0000 0100 2f75 7372 2f6c 6962 .d....../usr/lib
│ 000006a0: 2f6c 6962 5379 7374 656d 2e42 2e64 796c /libSystem.B.dyl
│ 000006b0: 6962 0000 0000 0000 0000 0000 0000 0000 ib..............
│ 000006c0: 5548 89e5 4881 ec10 0100 0089 bd44 ffff UH..H........D..
│ 000006d0: ff48 89b5 48ff ffff 4889 9550 ffff ff48 .H..H...H..P...H
│ 000006e0: 8b05 1aa9 0800 488b 0048 8945 f889 bd5c ......H..H.E...\
│ @@ -37783,15 +37783,15 @@
│ 00093960: a05e 0700 0100 0000 d7b1 0000 0e01 0000 .^..............
│ 00093970: f0e3 0700 0100 0000 02b2 0000 0e01 0000 ................
│ 00093980: c0f7 0700 0100 0000 16b2 0000 0e01 0000 ................
│ 00093990: 60f8 0700 0100 0000 2bb2 0000 0e0c 0000 `.......+.......
│ 000939a0: 00d2 0800 0100 0000 a2c7 0000 6400 0000 ............d...
│ 000939b0: 0000 0000 0000 0000 c5c7 0000 6400 0000 ............d...
│ 000939c0: 0000 0000 0000 0000 cac7 0000 6600 0100 ............f...
│ -000939d0: 4564 8964 0000 0000 0000 0000 2e01 0000 Ed.d............
│ +000939d0: 4464 8964 0000 0000 0000 0000 2e01 0000 Dd.d............
│ 000939e0: c006 0000 0100 0000 0100 0000 2401 0000 ............$...
│ 000939f0: c006 0000 0100 0000 0000 0000 2400 0000 ............$...
│ 00093a00: 2003 0000 0000 0000 0000 0000 4e01 0000 ...........N...
│ 00093a10: 2003 0000 0000 0000 0000 0000 2e01 0000 ...............
│ 00093a20: e009 0000 0100 0000 2c00 0000 2401 0000 ........,...$...
│ 00093a30: e009 0000 0100 0000 0000 0000 2400 0000 ............$...
│ 00093a40: a000 0000 0000 0000 0000 0000 4e01 0000 ............N...
----------------------------------------
ReleaseFast x86_64-macos (PWD /tmp/zig-reproducible-binary-macos)
949c5ce8bed677ce941dffebf6ffa09f main
0000000000000000 d *UND* /tmp/zig-reproducible-binary-macos
000000006489644c d *UND* /tmp/zig-reproducible-binary-macos/main.o
contains PWD
0bc5cd1419fb02de3cf29b3d607f3f12 main
--- main
+++ main.old
├── llvm-readobj --symbols {}
│ @@ -1040,15 +1040,15 @@
│ Symbol {
│ Name: /tmp/zig-reproducible-binary-macos/main.o (5753)
│ Type: SymDebugTable (0x66)
│ Section: (0x0)
│ RefType: ReferenceFlagUndefinedLazy (0x1)
│ Flags [ (0x0)
│ ]
│ - Value: 0x6489644F
│ + Value: 0x6489644C
│ }
│ Symbol {
│ Name: (0)
│ Type: SymDebugTable (0x2E)
│ Section: (0x1)
│ RefType: UndefinedNonLazy (0x0)
│ Flags [ (0x0)
├── x86_64
│┄ Format-specific differences are supported for this file format but no file-specific differences were detected; falling back to a binary diff. file(1) reports: Mach-O 64-bit x86_64 executable, flags:<NOUNDEFS|DYLDLINK|TWOLEVEL|PIE|HAS_TLV_DESCRIPTORS>
│ @@ -7071,15 +7071,15 @@
│ 0001b9e0: 9914 0000 0e0c 0000 08a1 0100 0100 0000 ................
│ 0001b9f0: b014 0000 0e0c 0000 04a1 0100 0100 0000 ................
│ 0001ba00: c314 0000 0e0c 0000 e0a0 0100 0100 0000 ................
│ 0001ba10: cc14 0000 0e0c 0000 f0a0 0100 0100 0000 ................
│ 0001ba20: d814 0000 0e0c 0000 00a1 0100 0100 0000 ................
│ 0001ba30: 5116 0000 6400 0000 0000 0000 0000 0000 Q...d...........
│ 0001ba40: 7416 0000 6400 0000 0000 0000 0000 0000 t...d...........
│ -0001ba50: 7916 0000 6600 0100 4f64 8964 0000 0000 y...f...Od.d....
│ +0001ba50: 7916 0000 6600 0100 4c64 8964 0000 0000 y...f...Ld.d....
│ 0001ba60: 0000 0000 2e01 0000 c006 0000 0100 0000 ................
│ 0001ba70: 0100 0000 2401 0000 c006 0000 0100 0000 ....$...........
│ 0001ba80: 0000 0000 2400 0000 d000 0000 0000 0000 ....$...........
│ 0001ba90: 0000 0000 4e01 0000 d000 0000 0000 0000 ....N...........
│ 0001baa0: 0000 0000 2e01 0000 9007 0000 0100 0000 ................
│ 0001bab0: 2c00 0000 2401 0000 9007 0000 0100 0000 ,...$...........
│ 0001bac0: 0000 0000 2400 0000 1000 0000 0000 0000 ....$...........
----------------------------------------
ReleaseSafe x86_64-macos (PWD /tmp/zig-reproducible-binary-macos)
9abeea3d229ac296f088c9fa2d2ec45b main
0000000000000000 d *UND* /tmp/zig-reproducible-binary-macos
0000000064896457 d *UND* /tmp/zig-reproducible-binary-macos/main.o
contains PWD
f6ae1efd9d425ddd9b02829fddef3367 main
--- main
+++ main.old
├── llvm-readobj --symbols {}
│ @@ -1311,15 +1311,15 @@
│ Symbol {
│ Name: /tmp/zig-reproducible-binary-macos/main.o (7219)
│ Type: SymDebugTable (0x66)
│ Section: (0x0)
│ RefType: ReferenceFlagUndefinedLazy (0x1)
│ Flags [ (0x0)
│ ]
│ - Value: 0x6489645E
│ + Value: 0x64896457
│ }
│ Symbol {
│ Name: (0)
│ Type: SymDebugTable (0x2E)
│ Section: (0x1)
│ RefType: UndefinedNonLazy (0x0)
│ Flags [ (0x0)
├── x86_64
│┄ Format-specific differences are supported for this file format but no file-specific differences were detected; falling back to a binary diff. file(1) reports: Mach-O 64-bit x86_64 executable, flags:<NOUNDEFS|DYLDLINK|TWOLEVEL|PIE|HAS_TLV_DESCRIPTORS>
│ @@ -10694,15 +10694,15 @@
│ 00029c50: e880 0200 0100 0000 1c1a 0000 0e0c 0000 ................
│ 00029c60: f880 0200 0100 0000 281a 0000 0e0c 0000 ........(.......
│ 00029c70: 0881 0200 0100 0000 391a 0000 0e0c 0000 ........9.......
│ 00029c80: 0c81 0200 0100 0000 4c1a 0000 0e0c 0000 ........L.......
│ 00029c90: 1081 0200 0100 0000 0b1c 0000 6400 0000 ............d...
│ 00029ca0: 0000 0000 0000 0000 2e1c 0000 6400 0000 ............d...
│ 00029cb0: 0000 0000 0000 0000 331c 0000 6600 0100 ........3...f...
│ -00029cc0: 5e64 8964 0000 0000 0000 0000 2e01 0000 ^d.d............
│ +00029cc0: 5764 8964 0000 0000 0000 0000 2e01 0000 Wd.d............
│ 00029cd0: c006 0000 0100 0000 0100 0000 2401 0000 ............$...
│ 00029ce0: c006 0000 0100 0000 0000 0000 2400 0000 ............$...
│ 00029cf0: 4002 0000 0000 0000 0000 0000 4e01 0000 @...........N...
│ 00029d00: 4002 0000 0000 0000 0000 0000 2e01 0000 @...............
│ 00029d10: 0009 0000 0100 0000 2c00 0000 2401 0000 ........,...$...
│ 00029d20: 0009 0000 0100 0000 0000 0000 2400 0000 ............$...
│ 00029d30: 4000 0000 0000 0000 0000 0000 4e01 0000 @...........N...
----------------------------------------
ReleaseSmall x86_64-macos (PWD /tmp/zig-reproducible-binary-macos)
6afd08f5fc26a4c4befd9067c18f6bbb main
does not contain PWD
6afd08f5fc26a4c4befd9067c18f6bbb main
----------------------------------------
This indicates two issues:
- The hashes of the resulting binaries differ between invocations for the Debug, ReleaseFast, and ReleaseSafe build modes on MacOS.
- The path to the current working directory is included in the resulting binary, making the binary non-reproducible in a context where this path is not reproducible (e.g. under build systems that create isolated working directories under non-reproducible prefixes, e.g. Bazel, see https://github.com/aherrmann/rules_zig/issues/79)
(I found https://github.com/ziglang/zig/issues/13919 as a relevant issue. However, it is closed as fixed.)
Expected Behavior
- The produced binaries are reproducible.
- The produced binaries do not contain the absolute path to the current working directory or any other non-reproducible filepath.
(Side note: I see that the Debug build mode has no reproducibility requirement. This is problematic for build systems that use content addressed storage for caching, such as Bazel.)
