fix: pam locale error

[liaohanqin]

pam message with error language env.

[github-actions]

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Please head over to https://ubuntu.com/legal/contributors to read more about it.

[robert-ancell]

What problem is this PR solving? Should the PAM conversation not inherit the system locale?

[thiagoneo]

Wow, I applied this patch and it really solved the problem of lightdm not showing the PAM messages in the correct locale. Canonical should merge this ...

[lo1ol]

What problem is this PR solving? Should the PAM conversation not inherit the system locale?

Pam modules not inherit system locale. Pam application should set it explicitly. Actually applications don't use system locale on startup. If you don't call setlocale(LC_ALL, "") the default locale will be "C":

On startup of the main program, the portable "C" locale is
selected as default. A program may be made portable to all
locales by calling:
setlocale(LC_ALL, "");

System and parent's process locale don't matter

cat > main.c << EOF
#include <stdio.h>
#include <libintl.h>
#include <locale.h>
#include <stdlib.h>

int main() {
   printf("%s\n", dgettext("Linux-PAM", "Password: "));
   setlocale(LC_ALL, "");
   printf("%s\n", dgettext("Linux-PAM", "Password: "));
   system("./main2");
}
EOF

cat > main2.c << EOF
#include <stdio.h>
#include <libintl.h>
#include <locale.h>

int main() {
   printf("%s\n", dgettext("Linux-PAM", "Password: "));
}
EOF

gcc main.c -o main
gcc main2.c -o main2

LANG=ru_RU.UTF-8 ./main

My output is:

Password: 
Пароль: 
Password: 

So, this change really helps.

I think PR's author abandoned it. If you have no time to support it, I could