From 910e6b5fae7cbf84e4a3fcfa6739e20239080bcd Mon Sep 17 00:00:00 2001
From: Damien Neil <dneil@google.com>
Date: Wed, 24 Jul 2024 10:29:13 -0700
Subject: [PATCH] os: document CopyFS behavior for symlinks in destination
Also clarify the permissions of created files,
and note that CopyFS will not overwrite files.
Update a few places in documentation to use 0oXXX for octal consts.
For #62484
Change-Id: I208ed2bde250304bc7fac2b93963ba57037e791e
Reviewed-on: https://go-review.googlesource.com/c/go/+/600775
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---
src/os/dir.go | 18 ++++++++++--------
src/os/example_test.go | 2 +-
src/os/file.go | 8 ++++----
3 files changed, 15 insertions(+), 13 deletions(-)
diff --git a/src/os/dir.go b/src/os/dir.go
index 471a2913458..dab75b5d436 100644
--- a/src/os/dir.go
+++ b/src/os/dir.go
@@ -132,15 +132,17 @@ func ReadDir(name string) ([]DirEntry, error) {
// CopyFS copies the file system fsys into the directory dir,
// creating dir if necessary.
//
-// Newly created directories and files have their default modes
-// where any bits from the file in fsys that are not part of the
-// standard read, write, and execute permissions will be zeroed
-// out, and standard read and write permissions are set for owner,
-// group, and others while retaining any existing execute bits from
-// the file in fsys.
+// Files are created with mode 0o666 plus any execute permissions
+// from the source, and directories are created with mode 0o777
+// (before umask).
//
-// Symbolic links in fsys are not supported, a *PathError with Err set
-// to ErrInvalid is returned on symlink.
+// CopyFS will not overwrite existing files, and returns an error
+// if a file name in fsys already exists in the destination.
+//
+// Symbolic links in fsys are not supported. A *PathError with Err set
+// to ErrInvalid is returned when copying from a symbolic link.
+//
+// Symbolic links in dir are followed.
//
// Copying stops at and returns the first error encountered.
func CopyFS(dir string, fsys fs.FS) error {
diff --git a/src/os/example_test.go b/src/os/example_test.go
index 7437a74cd0c..c507d46c463 100644
--- a/src/os/example_test.go
+++ b/src/os/example_test.go
@@ -61,7 +61,7 @@ func ExampleFileMode() {
log.Fatal(err)
}
- fmt.Printf("permissions: %#o\n", fi.Mode().Perm()) // 0400, 0777, etc.
+ fmt.Printf("permissions: %#o\n", fi.Mode().Perm()) // 0o400, 0o777, etc.
switch mode := fi.Mode(); {
case mode.IsRegular():
fmt.Println("regular file")
diff --git a/src/os/file.go b/src/os/file.go
index b2fb328e13d..541b4320819 100644
--- a/src/os/file.go
+++ b/src/os/file.go
@@ -366,7 +366,7 @@ func Open(name string) (*File, error) {
}
// Create creates or truncates the named file. If the file already exists,
-// it is truncated. If the file does not exist, it is created with mode 0666
+// it is truncated. If the file does not exist, it is created with mode 0o666
// (before umask). If successful, methods on the returned File can
// be used for I/O; the associated file descriptor has mode O_RDWR.
// If there is an error, it will be of type *PathError.
@@ -606,11 +606,11 @@ func UserHomeDir() (string, error) {
// On Unix, the mode's permission bits, ModeSetuid, ModeSetgid, and
// ModeSticky are used.
//
-// On Windows, only the 0200 bit (owner writable) of mode is used; it
+// On Windows, only the 0o200 bit (owner writable) of mode is used; it
// controls whether the file's read-only attribute is set or cleared.
// The other bits are currently unused. For compatibility with Go 1.12
-// and earlier, use a non-zero mode. Use mode 0400 for a read-only
-// file and 0600 for a readable+writable file.
+// and earlier, use a non-zero mode. Use mode 0o400 for a read-only
+// file and 0o600 for a readable+writable file.
//
// On Plan 9, the mode's permission bits, ModeAppend, ModeExclusive,
// and ModeTemporary are used.
--
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