golang.org/x/tools/gopls@v0.15.3/internal/cache/os_darwin.go (about)

     1  // Copyright 2020 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package cache
     6  
     7  import (
     8  	"bytes"
     9  	"fmt"
    10  	"os"
    11  	"path/filepath"
    12  	"strings"
    13  	"syscall"
    14  	"unsafe"
    15  )
    16  
    17  func init() {
    18  	checkPathValid = darwinCheckPathValid
    19  }
    20  
    21  func darwinCheckPathValid(path string) error {
    22  	// Darwin provides fcntl(F_GETPATH) to get a path for an arbitrary FD.
    23  	// Conveniently for our purposes, it gives the canonical case back. But
    24  	// there's no guarantee that it will follow the same route through the
    25  	// filesystem that the original path did.
    26  
    27  	path, err := filepath.Abs(path)
    28  	if err != nil {
    29  		return err
    30  	}
    31  	fd, err := syscall.Open(path, os.O_RDONLY, 0)
    32  	if err != nil {
    33  		return err
    34  	}
    35  	defer syscall.Close(fd)
    36  	buf := make([]byte, 4096) // No MAXPATHLEN in syscall, I think it's 1024, this is bigger.
    37  
    38  	// Wheeee! syscall doesn't expose a way to call Fcntl except FcntlFlock.
    39  	// As of writing, it just passes the pointer through, so we can just lie.
    40  	if err := syscall.FcntlFlock(uintptr(fd), syscall.F_GETPATH, (*syscall.Flock_t)(unsafe.Pointer(&buf[0]))); err != nil {
    41  		return err
    42  	}
    43  	buf = buf[:bytes.IndexByte(buf, 0)]
    44  
    45  	isRoot := func(p string) bool {
    46  		return p[len(p)-1] == filepath.Separator
    47  	}
    48  	// Darwin seems to like having multiple names for the same folder. Match as much of the suffix as we can.
    49  	for got, want := path, string(buf); !isRoot(got) && !isRoot(want); got, want = filepath.Dir(got), filepath.Dir(want) {
    50  		g, w := filepath.Base(got), filepath.Base(want)
    51  		if !strings.EqualFold(g, w) {
    52  			break
    53  		}
    54  		if g != w {
    55  			return fmt.Errorf("invalid path %q: component %q is listed by macOS as %q", path, g, w)
    56  		}
    57  	}
    58  	return nil
    59  }