ARM readdir returning overflow

[Paulo Matos]

Hi,

I was preparing an example of using qemu with an arm binary and got an
unexpected result. With a cross-compiler from crosstool-ng for armv7:

$ armv7-rpi2-linux-gnueabihf-gcc --version
armv7-rpi2-linux-gnueabihf-gcc (crosstool-NG 1.24.0) 8.3.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.

With this example (listdir.c):

$ cat > listdir.c<<EOF
#include <stdio.h>
#include <sys/types.h>
#include <dirent.h>

int main(void)
{
    struct dirent *de;
    DIR *dr = opendir("/");
    while ((de = readdir(dr)) != NULL)
            printf("%s\n", de->d_name);
    closedir(dr);
    return 0;
}
EOF

After statically compiling, when I run qemu 4.1.0:
$ armv7-rpi2-linux-gnueabihf-gcc -static -o listdir listdir.c
$ qemu-arm ./listdir
$

Nothing happens, if you do a perror("") on the readdir call (which is
returning NULL), you get the error:
Value too large for defined data type

Could this be a bug in the arm backend for qemu or a misunderstanding on
my part?

Regards,

Paulo Matos