rob.
Function filepath.Glob returns the names of all files matching the pattern.
The files may be directories, regular files, links, and so forth.
Function os.ReadDir expects the name of a directory. If the name is not a
directory, it returns an error.
Your Glob pattern is "*.txt". It probably returns regular files, not
directories.
A simple example,
package main
import (
"fmt"
"os"
"path/filepath"
)
func GlobFiles(pattern string) ([]os.FileInfo, error) {
var infos []os.FileInfo
filenames, err := filepath.Glob(pattern)
if err != nil {
return nil, err
}
for _, filename := range filenames {
info, err := os.Lstat(filename)
if err != nil {
continue
}
infos = append(infos, info)
}
return infos, nil
}
func main() {
glob := "*.txt"
infos, err := GlobFiles(glob)
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
for _, info := range infos {
fmt.Println(
"From os.Lstat: Name =", info.Name(),
", Size =", info.Size(),
", IsDir =", info.IsDir(),
)
}
}
https://play.golang.org/p/9F7pFSpDhBJ
peter
On Thursday, March 11, 2021 at 7:55:23 AM UTC-5 rob wrote:
> I've been writing some code to learn about the library changes in Go 1.16.
>
> The following code uses filepath.Glob to get a slice of matching
> filenames, then uses os.ReadDir to get more information about these
> files. I found that os.ReadDir reports a file not found error for the
> filenames returned by filepath.Glob. I do not understand why, as when I
> use os.Lstat there are no errors. This code is extracted and simplified
> from a longer program I wrote.
>
> This code has been compiled w/ go1.16.1 and I'm getting the same error
> messages.
>
> I do not understand why. I would have expected that os.ReadDir can find
> the filename just as os.Lstat does.
>
> --rob solomon
>
>
> // rddirpblm to isolate the problem w/ going from filepath.Glob to
> os.ReadDir on Win10.
>
> package main
>
> import (
> "fmt"
> "os"
> "path/filepath"
> "runtime"
> "strconv"
> )
>
> const LastAltered = "11 Mar 2021"
>
> /*
> Revision History
> ----------------
> 11 Mar 21 -- Isolating Glob -> ReadDir issue. Go 1.16 is deprecating
> ioutil functions.
> */
>
> func main() {
> var err error
>
> fmt.Print("rddirpblm LastAltered ", LastAltered, ", compiled using
> ", runtime.Version(), ".")
> fmt.Println()
>
> direntries := make([]os.DirEntry, 0, 500)
>
> sepstring := string(filepath.Separator)
> HomeDirStr, e := os.UserHomeDir() // HomeDir code used for
> processing ~ symbol meaning home directory.
> if e != nil {
> fmt.Fprintln(os.Stderr, e)
> HomeDirStr = ""
> }
> HomeDirStr = HomeDirStr + sepstring
> fmt.Println(" HomeDirStr is", HomeDirStr)
>
> globfor := "*.txt"
>
> filenamesStringSlice, err := filepath.Glob(globfor)
> if err != nil {
> fmt.Fprintln(os.Stderr, err, " Exiting.")
> os.Exit(1)
> }
>
> for i := 0; i < 20; i++ {
> fn := filenamesStringSlice[i]
> direntry, err := os.ReadDir(fn)
> if err != nil {
> fmt.Fprintln(os.Stderr, "fn =", fn, err)
> fmt.Fprintln(os.Stderr, "Will try os.Lstat")
> fi, er := os.Lstat(fn)
> if er != nil {
> fmt.Fprintln(os.Stderr, err)
> }
> fmt.Println("From os.Lstat: Name =", fi.Name(), ", Size =",
> fi.Size(), ", IsDir =", fi.IsDir())
> fmt.Println()
> continue
> }
> if len(direntry) > 1 {
> fmt.Fprintln(os.Stderr, " expecting only 1 direntry, but
> len(direntry) is", len(direntry), ". Don't know what this means yet.")
> }
> direntries = append(direntries, direntry[0])
> }
>
> for _, d := range direntries {
> f, err := d.Info()
> if err != nil {
> fmt.Fprintln(os.Stderr, err, ". No idea why this caused an
> error.")
> }
>
> sizestr := strconv.FormatInt(f.Size(), 10)
> if f.Size() > 100000 {
> sizestr = AddCommas(sizestr)
> }
> fmt.Printf("%17s %s %s\n", sizestr, sizestr, d.Name())
> } // end for range direntries
> } // end main
>
> //--------------------------------------------------------------------
> InsertByteSlice
> func InsertIntoByteSlice(slice, insertion []byte, index int) []byte {
> return append(slice[:index], append(insertion, slice[index:]...)...)
> } // InsertIntoByteSlice
>
> //----------------------------------------------------------------------
> AddCommas
> func AddCommas(instr string) string {
> //var Comma []byte = []byte{','} Getting error that type can be
> omitted
> Comma := []byte{','}
>
> BS := make([]byte, 0, 15)
> BS = append(BS, instr...)
>
> i := len(BS)
>
> for NumberOfCommas := i / 3; (NumberOfCommas > 0) && (i > 3);
> NumberOfCommas-- {
> i -= 3
> BS = InsertIntoByteSlice(BS, Comma, i)
> }
> return string(BS)
> } // AddCommas
>
> // ------------------------------- MyReadDir
> -----------------------------------
> func MyReadDir(dir string) []os.DirEntry {
>
> dirname, err := os.Open(dir)
> if err != nil {
> fmt.Fprintln(os.Stderr, err)
> return nil
> }
> defer dirname.Close()
>
> names, err := dirname.Readdirnames(0) // zero means read all names
> into the returned []string
> if err != nil {
> fmt.Fprintln(os.Stderr, err)
> return nil
> }
>
> direntries := make([]os.DirEntry, 0, len(names))
> for _, name := range names {
> d, err := os.ReadDir(name)
> if err != nil {
> fmt.Fprintln(os.Stderr, " Error from os.ReadDir. ", err)
> continue
> }
> if len(d) > 1 {
> fmt.Fprintln(os.Stderr, " expected len(d) == 1, but it's",
> len(d), ", which I don't yet understand.")
> }
> direntries = append(direntries, d[0])
> }
> return direntries
> } // MyReadDir
>
>
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