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package disk
import (
"errors"
"fmt"
"io/fs"
"os"
"syscall"
"codeberg.org/gruf/go-fastpath/v2"
"codeberg.org/gruf/go-storage/internal"
)
// NOTE:
// These functions are for opening storage files,
// not necessarily for e.g. initial setup (OpenFile)
// walkDir traverses the dir tree of the supplied path, performing the supplied walkFn on each entry
func walkDir(pb *fastpath.Builder, path string, args OpenArgs, walkFn func(string, fs.DirEntry) error) error {
// Read directory entries at path.
entries, err := readDir(path, args)
if err != nil {
return err
}
// frame represents a directory entry
// walk-loop snapshot, taken when a sub
// directory requiring iteration is found
type frame struct {
path string
entries []fs.DirEntry
}
// stack contains a list of held snapshot
// frames, representing unfinished upper
// layers of a directory structure yet to
// be traversed.
var stack []frame
outer:
for {
if len(entries) == 0 {
if len(stack) == 0 {
// Reached end
break outer
}
// Pop frame from stack
frame := stack[len(stack)-1]
stack = stack[:len(stack)-1]
// Update loop vars
entries = frame.entries
path = frame.path
}
for len(entries) > 0 {
// Pop next entry from queue
entry := entries[0]
entries = entries[1:]
// Pass to provided walk function
if err := walkFn(path, entry); err != nil {
return err
}
if entry.IsDir() {
// Push current frame to stack
stack = append(stack, frame{
path: path,
entries: entries,
})
// Update current directory path
path = pb.Join(path, entry.Name())
// Read next directory entries
next, err := readDir(path, args)
if err != nil {
return err
}
// Set next entries
entries = next
continue outer
}
}
}
return nil
}
// cleanDirs traverses the dir tree of the supplied path, removing any folders with zero children
func cleanDirs(path string, args OpenArgs) error {
pb := internal.GetPathBuilder()
err := cleanDir(pb, path, args, true)
internal.PutPathBuilder(pb)
return err
}
// cleanDir performs the actual dir cleaning logic for the above top-level version.
func cleanDir(pb *fastpath.Builder, path string, args OpenArgs, top bool) error {
// Get directory entries at path.
entries, err := readDir(path, args)
if err != nil {
return err
}
// If no entries, delete dir.
if !top && len(entries) == 0 {
return rmdir(path)
}
var errs []error
// Iterate all directory entries.
for _, entry := range entries {
if entry.IsDir() {
// Calculate directory path.
dir := pb.Join(path, entry.Name())
// Recursively clean sub-directory entries, adding errs.
if err := cleanDir(pb, dir, args, false); err != nil {
err = fmt.Errorf("error(s) cleaning subdir %s: %w", dir, err)
errs = append(errs, err)
}
}
}
// Return combined errors.
return errors.Join(errs...)
}
// readDir will open file at path, read the unsorted list of entries, then close.
func readDir(path string, args OpenArgs) ([]fs.DirEntry, error) {
// Open directory at path.
file, err := open(path, args)
if err != nil {
return nil, err
}
// Read ALL directory entries.
entries, err := file.ReadDir(-1)
// Done with file
_ = file.Close()
return entries, err
}
// open is a simple wrapper around syscall.Open().
func open(path string, args OpenArgs) (*os.File, error) {
var fd int
err := retryOnEINTR(func() (err error) {
fd, err = syscall.Open(path, args.Flags, args.Perms)
return
})
if err != nil {
return nil, err
}
return os.NewFile(uintptr(fd), path), nil
}
// stat is a simple wrapper around syscall.Stat().
func stat(path string) (*syscall.Stat_t, error) {
var stat syscall.Stat_t
err := retryOnEINTR(func() error {
return syscall.Stat(path, &stat)
})
if err != nil {
if err == syscall.ENOENT {
// not-found is no error
err = nil
}
return nil, err
}
return &stat, nil
}
// unlink is a simple wrapper around syscall.Unlink().
func unlink(path string) error {
return retryOnEINTR(func() error {
return syscall.Unlink(path)
})
}
// rmdir is a simple wrapper around syscall.Rmdir().
func rmdir(path string) error {
return retryOnEINTR(func() error {
return syscall.Rmdir(path)
})
}
// retryOnEINTR is a low-level filesystem function
// for retrying syscalls on O_EINTR received.
func retryOnEINTR(do func() error) error {
for {
err := do()
if err == syscall.EINTR {
continue
}
return err
}
}
|
