code review 152142: FreeBSD-specific porting work.

src/pkg/os/dir_freebsd.go

+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package os
+
+import (
+        "syscall";
+        "unsafe";
+)
+
+const (
+        blockSize = 4096;       // TODO(r): use statfs
+)
+
+// Readdirnames reads the contents of the directory associated with file and

[rsc, 2009/11/16 21:26:54]

drop comment; already one on dir_darwin and godoc
gets confused when there are two.

+// returns an array of up to count names, in directory order.  Subsequent
+// calls on the same file will yield further names.
+// A negative count means to read until EOF.
+// Readdirnames returns the array and an Error, if any.
+func (file *File) Readdirnames(count int) (names []string, err Error) {
+        // If this file has no dirinfo, create one.
+        if file.dirinfo == nil {
+                file.dirinfo = new(dirInfo);
+                // The buffer must be at least a block long.
+                // TODO(r): use fstatfs to find fs block size.
+                file.dirinfo.buf = make([]byte, blockSize);
+        }
+        d := file.dirinfo;
+        size := count;
+        if size < 0 {
+                size = 100
+        }
+        names = make([]string, 0, size);        // Empty with room to grow.
+        for count != 0 {
+                // Refill the buffer if necessary
+                if d.bufp >= d.nbuf {
+                        var errno int;
+                        d.bufp = 0;
+                        // Final argument is (basep *uintptr) and the syscall doesn't take nil.
+                        d.nbuf, errno = syscall.Getdirentries(file.fd, d.buf, new(uintptr));
+                        if errno != 0 {
+                                d.nbuf = 0;
+                                return names, NewSyscallError("getdirentries", errno);
+                        }
+                        if d.nbuf <= 0 {
+                                break   // EOF
+                        }
+                }
+                // Drain the buffer
+                for count != 0 && d.bufp < d.nbuf {
+                        dirent := (*syscall.Dirent)(unsafe.Pointer(&d.buf[d.bufp]));
+                        if dirent.Reclen == 0 {
+                                d.bufp = d.nbuf;
+                                break;
+                        }
+                        d.bufp += int(dirent.Reclen);
+                        if dirent.Fileno == 0 { // File absent in directory.
+                                continue
+                        }
+                        bytes := (*[len(dirent.Name)]byte)(unsafe.Pointer(&dirent.Name[0]));
+                        var name = string(bytes[0:dirent.Namlen]);
+                        if name == "." || name == ".." {        // Useless names
+                                continue
+                        }
+                        count--;
+                        if len(names) == cap(names) {
+                                nnames := make([]string, len(names), 2*len(names));
+                                for i := 0; i < len(names); i++ {
+                                        nnames[i] = names[i]
+                                }
+                                names = nnames;
+                        }
+                        names = names[0 : len(names)+1];
+                        names[len(names)-1] = name;
+                }
+        }
+        return names, nil;
+}