python shutil.copy fails on fat file systems (ubuntu)

>>>
import os
   >>>
   print hasattr(os, 'chmod')
True
   >>>
   foo = os.chmod >>>
   del os.chmod >>>
   print hasattr(os, 'chmod')
False

>>> setattr(os, 'chmod', foo) >>>
   print hasattr(os, 'chmod')
True

$ mkdir folder
$ touch folder / a
$ python2 .7 - c 'import shutil; shutil.copyfile("folder/a","folder/b")'
$ ls - rthla folder /
   total 0
drwxr - xr - x + Apr 17 12: 49. . /
   -rw - r--r--Apr 17 12: 49 a -
   rw - r--r--Apr 17 12: 50 b
drwxr - xr - x + Apr 17 12: 50 . /

def copy(src, dst):
   ""
"Copy data and mode bits ("
cp src dst ").

The destination may be a directory.

""
"
if os.path.isdir(dst):
   dst = os.path.join(dst, os.path.basename(src))
copyfile(src, dst)
copymode(src, dst)

When calling `shutil.copy('file.txt', 'not_here/')`,
   if directory `not_here/`
does not exist,
the raised error is:

   IsADirectoryError: [Errno 21] Is a directory: 'not_here/'

If the intent of the user was to copy a file in a directory
but the user forgot to create the destination directory,
this can be very misleading,
as the error tends to indicate that the directory exists.

It happened to me and I was thinking
   "yes it's a directory, then what?
that 's exactly what I want,copy to this directory!"
when the problem was that I forgot to create the destination directory.

I would suggest to
catch the `IsADirectoryError` in shutil.copyfile()(at `open(dst, 'wb')`)
and raise instead an error saying something like
   "destination is a directory AND this directory does not exists".

Agreed this is confusing. Is this a Linux specific error? Trying this on Mac gives me a different error code and exception.

# Mac

$ ./python.exe
Python 3.8.0a0 (heads/master:cd449806fa, Nov 12 2018, 09:51:24)
[Clang 7.0.2 (clang-700.1.81)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import shutil
>>> shutil.copy('/tmp/a.py', 'Lib12/')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
      File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/shutil.py", line 385, in copy
      copyfile(src, dst, follow_symlinks=follow_symlinks)
      File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/shutil.py", line 240, in copyfile
      with open(src, 'rb') as fsrc, open(dst, 'wb') as fdst:
      FileNotFoundError: [Errno 2] No such file or directory: 'Lib12/'

      # Ubuntu

      ./python
      Python 3.8.0a0 (heads/master:dce345c51a, Nov 12 2018, 13:01:05)
      [GCC 5.4.0 20160609] on linux
      Type "help", "copyright", "credits" or "license" for more information.
      >>> import shutil
      >>> shutil.copy('/tmp/a.py', 'Lib12/')
      Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
            File "/home/karthi/cpython/Lib/shutil.py", line 386, in copy
            copyfile(src, dst, follow_symlinks=follow_symlinks)
            File "/home/karthi/cpython/Lib/shutil.py", line 241, in copyfile
            with open(src, 'rb') as fsrc, open(dst, 'wb') as fdst:
            IsADirectoryError: [Errno 21] Is a directory: 'Lib12/'

You have the issue with the built - in 'open'
function.

This error is specific to the C-API and not to Python,

here is an example.

#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>

int main(int argc, char **argv, char **environ) {
    int fd;
    fd = open("/tmp/toto/", O_CREAT);
    printf("file descriptor: %d\n", fd);
    printf(strerror(errno));
    close(fd);
    return 0;
}



./a.out
file descriptor: -1
Is a directory

@vstinner & @serhiy

What do you think about this issue ?

   For the same POSIX syscall(open) we get 2 different values
for
the error, 2 on macOS and EISDIR with Linux.

Is a bug in Python or with the compliance of the operating system and the POSIX norm ?

   Thank you

Using `cp`
on Debian Buster I 'm having a better error message:

$ touch foo
$ cp foo bar /
   cp: failed to access 'bar/': Not a directory

From copy.c(from Debian coreutils):

   /* Improve quality of diagnostic when a nonexistent dst_name
      ends in a slash and open fails with errno == EISDIR.  */
   if (dest_desc < 0 && dest_errno == EISDIR &&
      * dst_name && dst_name[strlen(dst_name) - 1] == '/')
      dest_errno = ENOTDIR;

for fd in range(fd_low, fd_high):
   try:
   os.close(fd)
except OSError:
   pass

if os.access("myfile", os.R_OK):
   with open("myfile") as fp:
   return fp.read()
return "some default data"

try:
fp = open("myfile")
except PermissionError:
   return "some default data"
else:
   with fp:
   return fp.read()

with os.scandir(path) as it:
   for entry in it:
   if not entry.name.startswith('.') and entry.is_file():
   print(entry.name)

>>>
import os
   >>>
   statinfo = os.stat('somefile.txt') >>>
   statinfo
os.stat_result(st_mode = 33188, st_ino = 7876932, st_dev = 234881026,
      st_nlink = 1, st_uid = 501, st_gid = 501, st_size = 264, st_atime = 1297230295,
      st_mtime = 1297230027, st_ctime = 1297230027) >>>
   statinfo.st_size
264

os.stat in os.supports_dir_fd