Hi Jason,
On Fri, Jan 17, 2025 at 07:01:46PM -0500, Jason Yundt wrote:
> On Fri, Jan 17, 2025 at 03:14:55PM +0100, Alejandro Colomar wrote:
> > Curiously, my system is also limited to 255 for tmpfs filesystems but
> > yours is not? I still get longer paths rejected.
>
> That was my mistake. Running your program confirms that tmpfs filenames
> are limited to 255 bytes as well. I had originally assumed that /tmp
> was tmpfs on my system, but it was actually bcachefs which has a
> _PC_NAME_MAX of 512.
>
> > Doesn't iconv(3) terminate its output? I've never used that API, so I
> > don't know.
>
> I thought that at first because I hadn’t ever used iconv(3) either. I
> created a test program in order to make sure that it doesn’t terminate
> its output:
>
> $ cat iconv_termination_test.c
> #include <err.h>
> #include <iconv.h>
> #include <langinfo.h>
> #include <locale.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> #include <uchar.h>
>
> #define NELEMS(a) (sizeof(a) / sizeof(a[0]))
>
>
> void
> display_memory(char *memory_block, size_t len) {
> for (size_t i = 0; i < len; i++) {
> printf("%02hhX ", memory_block[i]);
> }
> printf("\n");
> }
>
> int
> main(void)
> {
> char32_t utf32_pathname[] = U"example";
> size_t pathname_len = NELEMS(utf32_pathname) - 1;
There's no other length. You could just call it len. pathname_ just
adds noise here. See the section on "Variable names" here:
<https://doc.cat-v.org/bell_labs/pikestyle>.
> size_t utf8_pathname_size = pathname_len * 4 + 1;
> char *utf8_pathname = malloc(utf8_pathname_size);
> if (utf8_pathname == NULL) {
> err(EXIT_FAILURE, "calloc");
> }
> memset(utf8_pathname, 0xFF, utf8_pathname_size);
> printf("utf8_pathname before calling iconv: ");
> display_memory(utf8_pathname, utf8_pathname_size);
>
> iconv_t cd = iconv_open("UTF-8", "UTF-32");
> if (cd == (iconv_t) - 1) {
> err(EXIT_FAILURE, "iconv_open");
> }
> char *inbuf = (char *) utf32_pathname;
> size_t inbytesleft = pathname_len * (sizeof *utf32_pathname);
> char *outbuf = utf8_pathname;
> size_t outbytesleft = utf8_pathname_size;
> size_t iconv_result;
> while (inbytesleft > 0) {
I don't think we need a loop. Do you? iconv(3) should convert the
entire string if it is valid and there's enough room.
> iconv_result =
> iconv(cd, &inbuf, &inbytesleft, &outbuf, &outbytesleft);
It seems you're passing a non-terminated string, and thus it's producing
a non-terminated string. Why don't you pass a null-terminated string?
That is, inbytesleft should include be the length + 1.
Have a lovely night!
Alex
> if (iconv_result == -1) {
> err(EXIT_FAILURE, "iconv");
> }
> }
> iconv_result =
> iconv(cd, NULL, &inbytesleft, &outbuf, &outbytesleft);
> if (iconv_result == -1) {
> err(EXIT_FAILURE, "iconv");
> }
> if (iconv_close(cd) == -1) {
> err(EXIT_FAILURE, "iconv_close");
> }
>
> printf("utf8_pathname after calling iconv: ");
> display_memory(utf8_pathname, utf8_pathname_size);
>
> free(utf8_pathname);
> exit(EXIT_SUCCESS);
> }
> $ gcc -Wall iconv_termination_test.c
> $ ./a.out
> utf8_pathname before calling iconv: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
> utf8_pathname after calling iconv: 65 78 61 6D 70 6C 65 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
> $
--
<https://www.alejandro-colomar.es/>
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