From: nobu@...
Date: 2017-05-22T08:17:30+00:00
Subject: [ruby-core:81329] [Ruby trunk Feature#13568] File#path for	O_TMPFILE fds are unmeaning

Issue #13568 has been updated by nobu (Nobuyoshi Nakada).


```sh
$ ./x86_64-linux/bin/ruby -e 'f = open(File.expand_path("/tmp"), File::RDWR|File::TMPFILE); p open(f).read'
Traceback (most recent call last):
	2: from -e:1:in `<main>'
	1: from -e:1:in `open'
-e:1:in `to_path': unnamed temporary file at /tmp (IOError)
```

```diff
diff --git a/file.c b/file.c
index b234910d5d..261997ecb2 100644
--- a/file.c
+++ b/file.c
@@ -367,7 +367,6 @@ apply2files(void (*func)(const char *, VALUE, void *), int argc, VALUE *argv, vo
 /*
  *  call-seq:
  *     file.path  ->  filename
- *     file.to_path  ->  filename
  *
  *  Returns the pathname used to create <i>file</i> as a string. Does
  *  not normalize the name.
@@ -391,6 +390,38 @@ rb_file_path(VALUE obj)
     return rb_obj_taint(rb_str_dup(fptr->pathv));
 }
 
+#ifdef O_TMPFILE
+/*
+ *  call-seq:
+ *     file.to_path  ->  filename
+ *
+ *  Returns the pathname to open the <i>file</i> as a string.
+ *
+ *  The pathname may not point the file corresponding to <i>file</i>.
+ *  e.g. file has been moved, deleted, or created with <code>File::TMPFILE</code> option.
+ */
+
+static VALUE
+rb_file_to_path(VALUE obj)
+{
+    rb_io_t *fptr;
+    int flags;
+
+    fptr = RFILE(rb_io_taint_check(obj))->fptr;
+    rb_io_check_initialized(fptr);
+    flags = fcntl(fptr->fd, F_GETFL);
+    if (flags == -1) rb_sys_fail_path(fptr->pathv);
+    if ((flags & O_TMPFILE) == O_TMPFILE) {
+	rb_raise(rb_eIOError, "unnamed temporary file at %"PRIsVALUE,
+		 fptr->pathv);
+    }
+    if (NIL_P(fptr->pathv)) return Qnil;
+    return rb_obj_taint(rb_str_dup(fptr->pathv));
+}
+#else
+# define rb_file_to_path rb_file_path
+#endif
+
 static size_t
 stat_memsize(const void *p)
 {
@@ -6140,7 +6171,7 @@ Init_File(void)
     rb_define_const(rb_mFConst, "NULL", rb_fstring_cstr(null_device));
 
     rb_define_method(rb_cFile, "path",  rb_file_path, 0);
-    rb_define_method(rb_cFile, "to_path",  rb_file_path, 0);
+    rb_define_method(rb_cFile, "to_path",  rb_file_to_path, 0);
     rb_define_global_function("test", rb_f_test, -1);
 
     rb_cStat = rb_define_class_under(rb_cFile, "Stat", rb_cObject);
```


----------------------------------------
Feature #13568: File#path for O_TMPFILE fds are unmeaning
https://bugs.ruby-lang.org/issues/13568#change-65019

* Author: sorah (Sorah Fukumori)
* Status: Assigned
* Priority: Normal
* Assignee: sorah (Sorah Fukumori)
* Target version: 
----------------------------------------
By using File::TMPFILE (O_TMPFILE) allows us to create a file without directory entries.

While open(2) with O_TMPFILE don't create a file without directory entries, it still requires a directory name to determine a file system to create a file.

Current Ruby implementation holds such directory names in fptr->pathv and retrievable via File#path.
But such paths are useless and may raise errors. For example, some code [1] checks File#path availability then when available, it attempts to use the path to open a file in different fd, finally raises Errno::EISDIR.

This patch changes File#path (fptr->pathv) not to return String if a fd is opened with O_TMPFILE.

[1]: https://github.com/aws/aws-sdk-ruby/blob/v2.9.17/aws-sdk-core/lib/aws-sdk-core/checksums.rb#L15

---Files--------------------------------
tmpfile-path.patch (1.96 KB)


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