On 04/05/2020 20:52, Theodore Y. Ts'o wrote:
On Mon, May 04, 2020 at 08:38:33AM +0100, Jonny Grant wrote:
I noticed that mkdir() returns EEXIST if a directory already exists.
strerror(EEXIST) text is "File exists"
Can ext4_find_dest_de() be amended to return EISDIR if a directory already
exists? This will make the error message clearer.
No; this will confuse potentially a large number of existing programs.
Also, the current behavior is required by POSIx and the Single Unix
Specification standards.
https://pubs.opengroup.org/onlinepubs/009695399/
Is it likely POSIX would introduce this change? It's a shame we're still
constrained by old standards (SVr4, BSD), but it's fine if they can be
updated.
No, because it has the potential to break existing Unix/Linux/Posix-compliant
programs. There may very well be C programs doing the following....
if (mkdir(filename) < 0) {
if (errno != EEXIST) {
perror(filename);
exit(1);
}
}
For example, there may very well be implementations of "mkdir -p" that
do precisely this.
If we change the error returned by the mkdir system call as you
propose, it would break these innocent, unsuspecting programs. That's
not something which will be allowed, because it falls into the
category of a Bad Thing.
Thank you for your reply.
What's an appropriate solution to this problem?
To achieve the desired output. when a directory exists.
$ mkdir test
$ mkdir: cannot create directory ‘test’: Is a directory
Cheers, Jonny
