Wine server directory name mismatch

[Greelan]

I freely admit to having Claude.ai's help in tracking down this issue and explaining the cause, but nevertheless think it has merit, since the workaround does sidestep it. Hopefully this gives enough information to track down where the box64 emulation is mangling the directory name.

Environment

• Box64 v0.4.3, ARM64 Dynarec
• Wine 11.0 stable (x86-64)
• Neoverse-N1, 4K pagesize
• Docker container on ARM64 host

Problem

Wine fails on startup with:

wine: chdir to /tmp/.wine-1001/server-38-53f7100000000 : No such file or directory

The directory that actually gets created is server-38-53f71. The trailing 00000000 is not present on the created directory, but Wine expects it when it tries to chdir into it.

The values 38 and 53f71 are the st_dev and st_ino of the WINEPREFIX directory.

Cause

Both wineserver and ntdll build the server directory name from the same stat values using the same format string.

server/request.c — create_server_dir() (creates the directory):

asprintf(&server_dir, "%s/server-%llx-%llx", base_dir,
         (unsigned long long)st.st_dev, (unsigned long long)st.st_ino);

dlls/ntdll/unix/server.c — server_dir_init() (looks up the directory):

asprintf(&dir, "/tmp/.wine-%u/server-%llx-%llx", getuid(),
         (unsigned long long)dev, (unsigned long long)ino);

On native x86_64 they always match.

Under Box64, wineserver calls asprintf through the native-wrapped libc path (Using native(wrapped) libc.so.6) and produces the correct short result server-38-53f71. The asprintf call inside ntdll.so runs from emulated x86_64 code (Using emulated .../ntdll.so) and produces server-38-53f7100000000 — as if the upper 32 bits of the unsigned long long variadic argument contain garbage or the argument layout is wrong.

Reproduction

1. Install Wine 11.0 stable x86-64 on ARM64 with Box64
2. Set a WINEPREFIX and run wine wineboot
3. Compare ls /tmp/.wine-$(id -u)/ against the path in the error message

The created directory is always shorter than the one Wine tries to chdir into.

Workaround

Create a dangling symlink before launching Wine. It resolves once Wine creates the short-named directory:

WINEPREFIX="${WINEPREFIX:-$HOME/.wine}"
WINE_TMP="/tmp/.wine-$(id -u)"
mkdir -p "$WINEPREFIX" "$WINE_TMP"
DEV_HEX=$(printf '%x' "$(stat -c '%d' "$WINEPREFIX")")
INO_HEX=$(printf '%x' "$(stat -c '%i' "$WINEPREFIX")")
ln -sf "$WINE_TMP/server-${DEV_HEX}-${INO_HEX}" \
       "$WINE_TMP/server-${DEV_HEX}-${INO_HEX}00000000"

[ptitSeb]

So, it's strange I don't reproduce the issue on my side, on any of my Arm64 system.
I guess the issue is not the asprintf but the stat that comes before, as if the ino field was 4 bytes farther then expected. Again, this is a bit strange as this function stat is wrapped and the stat structure is already converted. So not sure what can cause the issue you are seeing on your side.

[Greelan]

Happy to do some testing if there is something you believe may shed further light?

[Greelan]

Based on some logging, it seems:

• wineserver calls __fstat64 through Box64's native-wrapped libc, getting the correct directory name (31 chars)
• ntdll does a raw syscall (no libc wrapper), getting a broken directory name (40 chars)

[ptitSeb]

Ah ok. I'll work on that: the syscall might need fixing.