File.tmpfile requires administrator rights on Windows

[dlangBugzillaToGithub]

verylonglogin.reg (@denis-sh) reported this on 2012-02-18T00:42:44Z

Transfered from https://issues.dlang.org/show_bug.cgi?id=7537

CC List

• bugzilla (@WalterBright)
• bugzilla (@WalterBright)
• dlang-bugzilla (@CyberShadow)
• lovelydear

Description

---
import std.stdio;

void main() {
    File.tmpfile();
}
---
dmd 2.058 compiled version running from non-administrator fails with: std.exception.ErrnoException Could not create temporary file with tmpfile() (Permission denied) at std\stdio.d(875)

[dlangBugzillaToGithub]

dlang-bugzilla (@CyberShadow) commented on 2012-04-05T19:23:30Z

File.tmpfile is just a simple wrapper around core.stdc.stdio.tmpfile, so the issue is with the DMC's C standard library.

[dlangBugzillaToGithub]

lovelydear commented on 2012-04-19T09:01:44Z

This is not a bug. It works as intended. Should close.

[dlangBugzillaToGithub]

dlang-bugzilla (@CyberShadow) commented on 2012-04-19T09:03:04Z

What?? How is this not a bug?

[dlangBugzillaToGithub]

lovelydear commented on 2012-04-19T09:09:13Z

(In reply to comment #3)
> What?? How is this not a bug?

The OS prevents to create the file, so tmpfile() throws an exception. I don't see how this can be considered a bug.

[dlangBugzillaToGithub]

dlang-bugzilla (@CyberShadow) commented on 2012-04-19T09:10:28Z

The filename is chosen by the C runtime, not the operating system. It is a bug in the DigitalMars C runtime. It probably tries to use the hard-coded %WINDIR%\Temp directory, instead of the user profile directory or %TEMP%.

[dlangBugzillaToGithub]

lovelydear commented on 2012-04-19T09:19:52Z

Oh, I just saw the author of the issue. It's not "random Denis".
Anyway, has a bug report been done in DMC C bugzilla ?
Else this one will stay open forever, I'm affraid.

[dlangBugzillaToGithub]

bugzilla (@WalterBright) commented on 2012-04-19T11:23:55Z

(In reply to comment #5)
> The filename is chosen by the C runtime, not the operating system. It is a bug
> in the DigitalMars C runtime. It probably tries to use the hard-coded
> %WINDIR%\Temp directory, instead of the user profile directory or %TEMP%.

Actually, it uses stdio.h's _P_tmpdir, which on Windows is "\\". Did I say that implementation is rather old? I also noticed that Windows 7 does not allow writing to the root directory. XP allowed it.

[dlangBugzillaToGithub]

dlang-bugzilla (@CyberShadow) commented on 2012-04-19T11:32:02Z

(In reply to comment #7)
> XP allowed it.

You mean, to administrator users? I don't think regular users can create files in the drive root on XP either:
http://dump.thecybershadow.net/2d089ee536e35b4a8244f26f36be491c/00000814.png

[dlangBugzillaToGithub]

bugzilla (@WalterBright) commented on 2012-04-19T12:15:09Z

I have it fixed in snn.lib now. You can pick it up here:

ftp://ftp.digitalmars.com/dmc.zip

[dlangBugzillaToGithub]

dlang-bugzilla (@CyberShadow) commented on 2014-01-28T01:52:42Z

(In reply to comment #3)
> What?? How is this not a bug?

I may have been wrong here. The problem is not present on Win32, but on Win64 the MS runtime does what the DMC runtime used to do - attempt to create the file in the drive root. And it's not a bug, it's working according to the documentation:

> The tmpfile function creates a temporary file and returns a pointer to that 
> stream. The temporary file is created in the root directory. To create a 
> temporary file in a directory other than the root, use tmpnam or tempnam in 
> conjunction with fopen.

Conclusion: this function is horrible and needs to be replaced with something better.

Some relevant discussion here:
https://github.com/D-Programming-Language/phobos/pull/691

[dlangBugzillaToGithub]

bugzilla (@WalterBright) commented on 2019-12-12T16:58:52Z

Is this still not fixed?