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;
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) {
iconv_result =
iconv(cd, &inbuf, &inbytesleft, &outbuf, &outbytesleft);
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
$
