Hi Jason,
I think the recommendation to use the current locale for handling
pathnames isn't good.
If I use the C locale (and I do have systems with the C locale), then
programs running on that system would corrupt files that go through that
system. Let's say you send me María.song, and I download it on a system
using the C locale. Programs would fail to copy the file.
Instead, I think a good recommendation would be to behave in one of the
following ways:
- Accept only the POSIX Portable Filename Character Set.
- Assume UTF-8, but reject control characters.
- Assume UTF-8.
- Accept anything, but reject control characters.
- Accept anything, just like the kernel.
The current locale should actively be ignored when handling pathnames.
I've modified the example in the manual page to use a filename that's
non-ASCII, to make it more interesting. See how it fails:
alx@devuan:~/tmp/gcc$ cat path.c
#include <err.h>
#include <iconv.h>
#include <langinfo.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <uchar.h>
#define NELEMS(a) (sizeof(a) / sizeof(a[0]))
int
main(void)
{
char *locale_pathname;
char *in, *out;
FILE *fp;
size_t size;
size_t inbytes, outbytes;
iconv_t cd;
char32_t utf32_pathname[] = U"María";
if (setlocale(LC_ALL, "") == NULL)
err(EXIT_FAILURE, "setlocale");
size = NELEMS(utf32_pathname) * MB_CUR_MAX;
locale_pathname = malloc(size);
if (locale_pathname == NULL)
err(EXIT_FAILURE, "malloc");
cd = iconv_open(nl_langinfo(CODESET), "UTF-32");
if (cd == (iconv_t)-1)
err(EXIT_FAILURE, "iconv_open");
in = (char *) utf32_pathname;
inbytes = sizeof(utf32_pathname);
out = locale_pathname;
outbytes = size;
if (iconv(cd, &in, &inbytes, &out, &outbytes) == (size_t) -1)
err(EXIT_FAILURE, "iconv");
if (iconv_close(cd) == -1)
err(EXIT_FAILURE, "iconv_close");
fp = fopen(locale_pathname, "w");
if (fp == NULL)
err(EXIT_FAILURE, "fopen");
fputs("Hello, world!\n", fp);
if (fclose(fp) == EOF)
err(EXIT_FAILURE, "fclose");
free(locale_pathname);
exit(EXIT_SUCCESS);
}
alx@devuan:~/tmp/gcc$ cc -Wall -Wextra path.c
alx@devuan:~/tmp/gcc$ ls
a.out path.c
alx@devuan:~/tmp/gcc$ ./a.out ; echo $?
0
alx@devuan:~/tmp/gcc$ ls
María a.out path.c
alx@devuan:~/tmp/gcc$ cat María
Hello, world!
alx@devuan:~/tmp/gcc$ LC_ALL=C ./a.out ; echo $?
a.out: iconv: Invalid or incomplete multibyte or wide character
1
What do you think?
Have a lovely day!
Alex
--
<https://www.alejandro-colomar.es/>
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