* _GNU_SOURCE doesn't enable cuserid() declaration
@ 2018-11-29 2:22 Tony Cook
2018-11-29 10:28 ` Corinna Vinschen
0 siblings, 1 reply; 2+ messages in thread
From: Tony Cook @ 2018-11-29 2:22 UTC (permalink / raw)
To: cygwin
Linux stdio.h exposes the declaration of cuserid() both with standard
version macros and with _GNU_SOURCE:
tony@mars:~/play$ cat testcuserid.c
#define _GNU_SOURCE
#include <stdio.h>
int main() {
puts(cuserid(NULL));
return 0;
}
tony@mars:~/play$ gcc -otestcuserid -Werror=all testcuserid.c
tony@mars:~/play$ ./testcuserid
tony
tony@mars:~/play$ uname -a
Linux mars 4.9.0-8-amd64 #1 SMP Debian 4.9.110-3+deb9u4 (2018-08-21) x86_64 GNU/Linux
while on Cygwin _GNU_SOURCE doesn't expose cuserid():
tony@phobos /cygdrive/n/play
$ gcc -otestcuserid.exe -Werror=all testcuserid.c
testcuserid.c: In function âmainâ:
testcuserid.c:5:8: error: implicit declaration of function âcuseridâ; did you mean âL_cuseridâ? [-Werror=implicit-function-declaration]
puts(cuserid(NULL));
^~~~~~~
L_cuserid
testcuserid.c:5:8: warning: passing argument 1 of âputsâ makes pointer from integer without a cast [-Wint-conversion]
In file included from testcuserid.c:2:0:
/usr/include/stdio.h:221:5: note: expected âconst char *â but argument is of type âintâ
int puts (const char *);
^~~~
cc1: some warnings being treated as errors
tony@phobos /cygdrive/n/play
$ uname -a
CYGWIN_NT-6.1 phobos 2.11.2(0.329/5/3) 2018-11-08 14:34 x86_64 Cygwin
This seems unintentional, since L_cuserid is exposed with _GNU_SOURCE
on Cygwin:
tony@phobos /cygdrive/n/play
$ cat testlcuserid.c
#define _GNU_SOURCE
#include <stdio.h>
int main() {
printf("%d\n", (int)L_cuserid);
return 0;
}
tony@phobos /cygdrive/n/play
$ gcc -otestlcuserid.exe -Werror=all testlcuserid.c
and on Linux:
tony@mars:~/play$ gcc -otestlcuserid -Werror=all testlcuserid.c
(neither produces a diagnostic)
Tony
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: _GNU_SOURCE doesn't enable cuserid() declaration
2018-11-29 2:22 _GNU_SOURCE doesn't enable cuserid() declaration Tony Cook
@ 2018-11-29 10:28 ` Corinna Vinschen
0 siblings, 0 replies; 2+ messages in thread
From: Corinna Vinschen @ 2018-11-29 10:28 UTC (permalink / raw)
To: cygwin
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On Nov 29 13:22, Tony Cook wrote:
> Linux stdio.h exposes the declaration of cuserid() both with standard
> version macros and with _GNU_SOURCE:
>
> tony@mars:~/play$ cat testcuserid.c
> #define _GNU_SOURCE
> #include <stdio.h>
>
> int main() {
> puts(cuserid(NULL));
> return 0;
> }
> tony@mars:~/play$ gcc -otestcuserid -Werror=all testcuserid.c
> tony@mars:~/play$ ./testcuserid
> tony
> tony@mars:~/play$ uname -a
> Linux mars 4.9.0-8-amd64 #1 SMP Debian 4.9.110-3+deb9u4 (2018-08-21) x86_64 GNU/Linux
>
> while on Cygwin _GNU_SOURCE doesn't expose cuserid():
Thanks, I pushed a patch.
https://sourceware.org/git/?p=newlib-cygwin.git;a=commitdiff;h=09870c6e958c
Of course, that doesn't make cuserid more portable. The rule given in
the Linux man page still applies: "Do not use cuserid()."
Corinna
--
Corinna Vinschen
Cygwin Maintainer
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