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Make Readdirnames work properly on Linux.

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Refactor so Readdir is portable code.

R=rsc
DELTA=192  (50 added, 130 deleted, 12 changed)
OCL=24770
CL=24772
This commit is contained in:
Rob Pike 2009-02-10 11:55:48 -08:00
parent 651972b31f
commit 00b3d48f13
3 changed files with 62 additions and 142 deletions
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60
src/lib/os/dir_amd64_darwin.go
View File

@ -64,63 +64,3 @@ func Readdirnames(fd *FD, count int) (names []string, err *os.Error) {
}
return names, nil
}
// TODO(r): see comment in dir_amd64_linux.go
// Negative count means read until EOF.
func Readdir(fd *FD, count int) (dirs []Dir, err *os.Error) {
dirname := fd.name;
if dirname == "" {
dirname = ".";
}
dirname += "/";
// Getdirentries needs the file offset - it's too hard for the kernel to remember
// a number it already has written down.
base, err1 := syscall.Seek(fd.fd, 0, 1);
if err1 != 0 {
return nil, os.ErrnoToError(err1)
}
// The buffer must be at least a block long.
// TODO(r): use fstatfs to find fs block size.
var buf = make([]byte, blockSize);
dirs = make([]Dir, 0, 100); // TODO: could be smarter about size
for {
if count == 0 {
break
}
ret, err2 := syscall.Getdirentries(fd.fd, &buf[0], int64(len(buf)), &base);
if ret < 0 || err2 != 0 {
return dirs, os.ErrnoToError(err2)
}
if ret == 0 {
break
}
for w, i := uintptr(0),uintptr(0); i < uintptr(ret); i += w {
if count == 0 {
break
}
dirent := unsafe.Pointer((uintptr(unsafe.Pointer(&buf[0])) + i)).(*syscall.Dirent);
w = uintptr(dirent.Reclen);
if dirent.Ino == 0 {
continue
}
count--;
if len(dirs) == cap(dirs) {
ndirs := make([]Dir, len(dirs), 2*len(dirs));
for i := 0; i < len(dirs); i++ {
ndirs[i] = dirs[i]
}
dirs = ndirs;
}
dirs = dirs[0:len(dirs)+1];
filename := string(dirent.Name[0:dirent.Namlen]);
dirp, err := Lstat(dirname + filename);
if dirp == nil || err != nil {
dirs[len(dirs)-1].Name = filename; // rest will be zeroed out
} else {
dirs[len(dirs)-1] = *dirp;
}
}
}
return dirs, nil;
}

109
src/lib/os/dir_amd64_linux.go
View File

@ -10,6 +10,10 @@ import (
"unsafe";
)
const (
blockSize = 4096 // TODO(r): use statfs
)
func clen(n []byte) int {
for i := 0; i < len(n); i++ {
if n[i] == 0 {
@ -21,28 +25,38 @@ func clen(n []byte) int {
// Negative count means read until EOF.
func Readdirnames(fd *FD, count int) (names []string, err *os.Error) {
// The buffer should be at least a block long.
// If this fd has no dirinfo, create one.
if fd.dirinfo == nil {
fd.dirinfo = new(DirInfo);
// The buffer must be at least a block long.
// TODO(r): use fstatfs to find fs block size.
var buf = make([]syscall.Dirent, 8192/unsafe.Sizeof(*new(syscall.Dirent)));
names = make([]string, 0, 100); // TODO: could be smarter about size
for {
if count == 0 {
break
fd.dirinfo.buf = make([]byte, blockSize);
}
ret, err2 := syscall.Getdents(fd.fd, &buf[0], int64(len(buf) * unsafe.Sizeof(buf[0])));
if ret < 0 || err2 != 0 {
return names, os.ErrnoToError(err2)
d := fd.dirinfo;
size := count;
if size < 0 {
size = 100
}
if ret == 0 {
break
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 int64;
dbuf := unsafe.Pointer(&d.buf[0]).(*syscall.Dirent);
d.nbuf, errno = syscall.Getdents(fd.fd, dbuf, int64(len(d.buf)));
if d.nbuf < 0 {
return names, os.ErrnoToError(errno)
}
for w, i := uintptr(0),uintptr(0); i < uintptr(ret); i += w {
if count == 0 {
break
if d.nbuf == 0 {
break // EOF
}
dirent := unsafe.Pointer((uintptr(unsafe.Pointer(&buf[0])) + i)).(*syscall.Dirent);
w = uintptr(dirent.Reclen);
if dirent.Ino == 0 {
d.bufp = 0;
}
// Drain the buffer
for count != 0 && d.bufp < d.nbuf {
dirent := unsafe.Pointer(&d.buf[d.bufp]).(*syscall.Dirent);
d.bufp += int64(dirent.Reclen);
if dirent.Ino == 0 { // File absent in directory.
continue
}
count--;
@ -59,64 +73,3 @@ func Readdirnames(fd *FD, count int) (names []string, err *os.Error) {
}
return names, nil;
}
// TODO(r): Readdir duplicates a lot of Readdirnames. The other way would
// be to have Readdir (which could then be portable) call Readdirnames and
// then do the Stats. The existing design was chosen to avoid allocating a
// throwaway names array, but the issue should be revisited once we have
// a better handle on what that overhead is with a strong garbage collector.
// Also, it's possible given the nature of the Unix kernel that interleaving
// reads of the directory with stats (as done here) would work better than
// one big read of the directory followed by a long run of Stat calls.
// Negative count means read until EOF.
func Readdir(fd *FD, count int) (dirs []Dir, err *os.Error) {
dirname := fd.name;
if dirname == "" {
dirname = ".";
}
dirname += "/";
// The buffer must be at least a block long.
// TODO(r): use fstatfs to find fs block size.
var buf = make([]syscall.Dirent, 8192/unsafe.Sizeof(*new(syscall.Dirent)));
dirs = make([]Dir, 0, 100); // TODO: could be smarter about size
for {
if count == 0 {
break
}
ret, err2 := syscall.Getdents(fd.fd, &buf[0], int64(len(buf) * unsafe.Sizeof(buf[0])));
if ret < 0 || err2 != 0 {
return dirs, os.ErrnoToError(err2)
}
if ret == 0 {
break
}
for w, i := uintptr(0),uintptr(0); i < uintptr(ret); i += w {
if count == 0 {
break
}
dirent := unsafe.Pointer((uintptr(unsafe.Pointer(&buf[0])) + i)).(*syscall.Dirent);
w = uintptr(dirent.Reclen);
if dirent.Ino == 0 {
continue
}
count--;
if len(dirs) == cap(dirs) {
ndirs := make([]Dir, len(dirs), 2*len(dirs));
for i := 0; i < len(dirs); i++ {
ndirs[i] = dirs[i]
}
dirs = ndirs;
}
dirs = dirs[0:len(dirs)+1];
filename := string(dirent.Name[0:clen(dirent.Name)]);
dirp, err := Stat(dirname + filename);
if dirp == nil || err != nil {
dirs[len(dirs)-1].Name = filename; // rest will be zeroed out
} else {
dirs[len(dirs)-1] = *dirp;
}
}
}
return dirs, nil;
}

27
src/lib/os/os_file.go
View File

@ -160,3 +160,30 @@ func Lstat(name string) (dir *Dir, err *Error) {
}
return dirFromStat(name, new(Dir), stat), nil
}
// Non-portable function defined in operating-system-dependent file.
func Readdirnames(fd *FD, count int) (names []string, err *os.Error)
// Negative count means read until EOF.
func Readdir(fd *FD, count int) (dirs []Dir, err *os.Error) {
dirname := fd.name;
if dirname == "" {
dirname = ".";
}
dirname += "/";
names, err1 := Readdirnames(fd, count);
if err1 != nil {
return nil, err1
}
dirs = make([]Dir, len(names));
for i, filename := range names {
dirp, err := Stat(dirname + filename);
if dirp == nil || err != nil {
dirs[i].Name = filename // rest is already zeroed out
} else {
dirs[i] = *dirp
}
}
return
}