Due to a bug in macOS, sparse copies are corrupted on virtual disks formatted with APFS. HFS is not affected. Affected are coreutils install, and gcp when compiled with SEEK_HOLE, as well as macOS Finder.
While reading the entire file returns valid data, scanning for allocated segments may return holes where valid data is present. In this case a sparse copy does not contain these segments and returns zeroes instead. Once the virtual disk is dismounted and then mounted again, a sparse copy produces correct results. This breaks OpenWRT build on macOS. Details: https://github.com/openwrt/openwrt/pull/11960 https://github.com/openwrt/openwrt/pull/11960#issuecomment-1423185579 Signed-off-by: Georgi Valkov <gval...@gmail.com> --- src/copy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/copy.c b/src/copy.c index e16fedb28..4f56138a6 100644 --- a/src/copy.c +++ b/src/copy.c @@ -1065,7 +1065,7 @@ infer_scantype (int fd, struct stat const *sb, return PLAIN_SCANTYPE; } -#ifdef SEEK_HOLE +#if defined(SEEK_HOLE) && !defined(__APPLE__) scan_inference->ext_start = lseek (fd, 0, SEEK_DATA); if (0 <= scan_inference->ext_start || errno == ENXIO) return LSEEK_SCANTYPE; -- 2.39.1 The issue is most likely within APFS, So we need to bring it to Apple's attention. Since it is triggered by building `gcc`, it would be helpful if they can shine some light how their tools are build and what trigger this, in order to create PoC code. **steps to reproduce** _Create a sparse disk image with APFS_ - open Disk Utility - press Command-N to create a new virtual disk - Image Format: sparse disk image - save as: ~/vhd/test - Name: test - Size: 50 GB - Format: APFS (Case-sensitive) - Encryption: none - Partitions: Single partition - GUID Partition Map - Save - the image is mounted under `/Volumes/test` _clone and build coreutils_ ``` bash cd /Volumes/test # patched with sparse support disabled on macOS git clone https://github.com/httpstorm/coreutils.git mv coreutils coreutils-no-sparse cd coreutils-no-sparse git checkout macos_disable-sparse-copy git submodule foreach git pull origin master ./bootstrap make -j 16 cd .. # original code git clone https://github.com/coreutils/coreutils.git cd coreutils git submodule foreach git pull origin master ./bootstrap make -j 16 ``` _download OpenWRT and build gcc_ ``` bash cd /Volumes/test git clone https://github.com/openwrt/openwrt.git cd openwrt ./scripts/feeds update -a ./scripts/feeds install -a make defconfig make menuconfig # Target System (Marvell EBU Armada) # Target Profile (Linksys WRT3200ACM) # Save, Exit make tools/compile -j 16 make toolchain/gcc/initial/compile -j 16 ``` proof of concept ``` bash cd /Volumes/test/openwrt cd build_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-12.2.0_musl_eabi/gcc-12.2.0-initial/gcc /Volumes/test/coreutils/src/cp cc1 cc1-ori ./cc1-ori --help -bash: ./cc1-ori: cannot execute binary file: Exec format error /Volumes/test/coreutils-no-sparse/src/cp cc1 cc1-fix ./cc1-fix --help # works correctly sha1sum cc1 # fcf5d9458f54d5588efc5a76a89388925ca04eda cc1 sha1sum cc1-fix # fcf5d9458f54d5588efc5a76a89388925ca04eda cc1-fix sha1sum cc1-ori # 7b447132f56f3b549ef62a4780945e82d26f7d2c cc1-ori ``` Kind regards, Georgi Valkov httpstorm.com nano RTOS
