mirror of
https://github.com/trapexit/mergerfs.git
synced 2026-10-19 16:16:48 +00:00
Fix readlink implementation, add more tests
This commit is contained in:
Antonio SJ Musumeci
committed by
trapexit
trapexit
parent
3099b15db1
commit
08f9cc6932
+15
-5
@@ -27,6 +27,7 @@
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#include "fuse.h"
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#include <algorithm>
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#include <cstring>
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@@ -39,11 +40,12 @@ _readlink_core_standard(const fs::path &fullpath_,
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{
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int rv;
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rv = fs::readlink(fullpath_,buf_,(bufsize_ - 1));
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rv = fs::readlink(fullpath_,buf_,bufsize_);
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if(rv < 0)
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return rv;
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buf_[rv] = '\0';
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if((size_t)rv < bufsize_)
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buf_[rv] = '\0';
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return 0;
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}
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@@ -56,17 +58,23 @@ _readlink_core_symlinkify(const fs::path &fullpath_,
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const time_t symlinkify_timeout_)
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{
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int rv;
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size_t n;
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std::string fullpath_str;
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struct stat st;
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rv = fs::lstat(fullpath_,&st);
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fullpath_str = fullpath_.string();
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rv = fs::lstat(fullpath_str,&st);
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if(rv < 0)
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return rv;
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if(!symlinkify::can_be_symlink(st,symlinkify_timeout_))
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return ::_readlink_core_standard(fullpath_,buf_,bufsize_);
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strncpy(buf_,fullpath_.c_str(),(bufsize_ - 1));
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buf_[bufsize_ - 1] = '\0';
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n = std::min(fullpath_str.size(),bufsize_);
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memcpy(buf_,fullpath_str.c_str(),n);
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if(n < bufsize_)
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buf_[n] = '\0';
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return 0;
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}
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@@ -106,6 +114,8 @@ _readlink(const Policy::Search &searchFunc_,
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rv = searchFunc_(ibranches_,fusepath_,obranches);
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if(rv < 0)
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return rv;
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if(obranches.empty())
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return -ENOENT;
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return ::_readlink_core(obranches[0]->path,
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fusepath_,
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Executable
+219
@@ -0,0 +1,219 @@
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#!/usr/bin/env python3
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import ctypes
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import errno
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import os
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import sys
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import tempfile
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libc = ctypes.CDLL(None, use_errno=True)
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libc.readlink.argtypes = [ctypes.c_char_p, ctypes.c_char_p, ctypes.c_size_t]
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libc.readlink.restype = ctypes.c_ssize_t
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def readlink_raw(path: str, bufsiz: int):
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buf = ctypes.create_string_buffer(bufsiz)
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ctypes.set_errno(0)
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rv = libc.readlink(path.encode(), buf, bufsiz)
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err = ctypes.get_errno()
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return rv, err, bytes(buf)
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def compare_case(name: str,
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merge_path: str,
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native_path: str,
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bufsiz: int,
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expect_errno: int = None):
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m_rv, m_errno, m_buf = readlink_raw(merge_path, bufsiz)
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n_rv, n_errno, n_buf = readlink_raw(native_path, bufsiz)
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if m_rv != n_rv:
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return f"{name}: return mismatch mergerfs={m_rv} native={n_rv}"
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if m_errno != n_errno:
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return f"{name}: errno mismatch mergerfs={m_errno} native={n_errno}"
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if m_rv >= 0 and m_buf != n_buf:
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return f"{name}: buffer mismatch mergerfs={m_buf!r} native={n_buf!r}"
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if expect_errno is not None and n_errno != expect_errno:
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return f"{name}: expected errno={expect_errno}, got errno={n_errno}"
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return None
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def main():
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if len(sys.argv) != 2:
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print("usage: TEST_readlink_semantics <mountpoint>", file=sys.stderr)
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return 1
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mount = sys.argv[1]
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target = "target-abcdefghijklmnopqrstuvwxyz"
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with tempfile.TemporaryDirectory() as native_dir:
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paths = {
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"merge_link": os.path.join(mount, "readlink-semantics-link"),
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"native_link": os.path.join(native_dir, "readlink-semantics-link"),
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"merge_regular": os.path.join(mount, "readlink-semantics-regular"),
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"native_regular": os.path.join(native_dir, "readlink-semantics-regular"),
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"merge_notdir": os.path.join(mount, "readlink-semantics-notdir"),
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"native_notdir": os.path.join(native_dir, "readlink-semantics-notdir"),
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"merge_loop": os.path.join(mount, "readlink-semantics-loop"),
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"native_loop": os.path.join(native_dir, "readlink-semantics-loop"),
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"merge_private_dir": os.path.join(mount, "readlink-semantics-private"),
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"native_private_dir": os.path.join(native_dir, "readlink-semantics-private"),
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}
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paths["merge_private_link"] = os.path.join(paths["merge_private_dir"], "link")
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paths["native_private_link"] = os.path.join(paths["native_private_dir"], "link")
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for p in (
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paths["merge_private_link"],
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paths["merge_link"],
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paths["merge_regular"],
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paths["merge_notdir"],
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paths["merge_loop"],
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):
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try:
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os.unlink(p)
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except FileNotFoundError:
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pass
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try:
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os.rmdir(paths["merge_private_dir"])
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except FileNotFoundError:
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pass
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except OSError:
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pass
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os.symlink(target, paths["merge_link"])
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os.symlink(target, paths["native_link"])
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with open(paths["merge_regular"], "w", encoding="ascii"):
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pass
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with open(paths["native_regular"], "w", encoding="ascii"):
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pass
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with open(paths["merge_notdir"], "w", encoding="ascii"):
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pass
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with open(paths["native_notdir"], "w", encoding="ascii"):
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pass
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os.symlink("readlink-semantics-loop", paths["merge_loop"])
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os.symlink("readlink-semantics-loop", paths["native_loop"])
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os.makedirs(paths["merge_private_dir"], exist_ok=True)
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os.makedirs(paths["native_private_dir"], exist_ok=True)
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os.symlink(target, paths["merge_private_link"])
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os.symlink(target, paths["native_private_link"])
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try:
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cases = []
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for bufsiz in (0, 1, 2, 5, 8, len(target), len(target) + 1):
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cases.append((
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f"success/truncation bufsiz={bufsiz}",
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paths["merge_link"],
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paths["native_link"],
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bufsiz,
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errno.EINVAL if bufsiz == 0 else None,
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))
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cases.extend([
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(
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"EINVAL non-symlink",
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paths["merge_regular"],
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paths["native_regular"],
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128,
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errno.EINVAL,
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),
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(
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"ENOENT missing path",
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os.path.join(mount, "readlink-semantics-missing"),
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os.path.join(native_dir, "readlink-semantics-missing"),
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128,
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errno.ENOENT,
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),
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(
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"ENOTDIR non-directory prefix",
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os.path.join(paths["merge_notdir"], "child"),
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os.path.join(paths["native_notdir"], "child"),
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128,
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errno.ENOTDIR,
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),
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(
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"ELOOP prefix symlink loop",
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os.path.join(paths["merge_loop"], "child"),
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os.path.join(paths["native_loop"], "child"),
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128,
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errno.ELOOP,
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),
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(
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"ENAMETOOLONG long pathname",
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os.path.join(mount, "a" * 8192),
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os.path.join(native_dir, "a" * 8192),
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128,
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errno.ENAMETOOLONG,
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),
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])
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os.chmod(paths["merge_private_dir"], 0o600)
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os.chmod(paths["native_private_dir"], 0o600)
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cases.append((
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"EACCES unreadable path prefix",
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paths["merge_private_link"],
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paths["native_private_link"],
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128,
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errno.EACCES if os.geteuid() != 0 else None,
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))
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for case in cases:
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err = compare_case(*case)
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if err is not None:
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print(err, end="")
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return 1
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# Explicitly guard the prior regression.
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rv, err, _ = readlink_raw(paths["merge_link"], 1)
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if rv != 1 or err != 0:
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print(f"bufsiz=1 expected rv=1 errno=0, got rv={rv} errno={err}", end="")
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return 1
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return 0
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finally:
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try:
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os.chmod(paths["merge_private_dir"], 0o700)
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except (FileNotFoundError, PermissionError):
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pass
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try:
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os.chmod(paths["native_private_dir"], 0o700)
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except (FileNotFoundError, PermissionError):
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pass
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for p in (
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paths["merge_private_link"],
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paths["native_private_link"],
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paths["merge_link"],
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paths["native_link"],
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paths["merge_regular"],
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paths["native_regular"],
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paths["merge_notdir"],
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paths["native_notdir"],
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paths["merge_loop"],
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paths["native_loop"],
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):
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try:
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os.unlink(p)
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except FileNotFoundError:
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pass
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for p in (paths["merge_private_dir"], paths["native_private_dir"]):
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try:
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os.rmdir(p)
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except FileNotFoundError:
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pass
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except OSError:
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pass
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if __name__ == "__main__":
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raise SystemExit(main())
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