Dear ALL,

Return value of ulimit(UL_GETFSIZE) in X32 architecture seems to be wrong.

Here is the implementation of ulimit function in MUSL 1.1.22:

#include <sys/resource.h>

#include <ulimit.h>

#include <stdarg.h>

long ulimit(int cmd, ...)

{

                 struct rlimit rl;

                 getrlimit(RLIMIT_FSIZE, &rl);

                 if (cmd == UL_SETFSIZE) {

                         long val;

                         va_list ap;

                         va_start(ap, cmd);

                         val = va_arg(ap, long);

                         va_end(ap);

                         rl.rlim_cur = 512ULL * val;

                                     if (setrlimit(RLIMIT_FSIZE, &rl)) return -1;

                 }

                 return rl.rlim_cur / 512;

}

Make it simple in case of “cmd = UL_GETFSIZE”, ulimit function becomes to be:

         long ulimit(int cmd, …)

         {

                   struct rlimit rl;

                   getrlimit(RLIMIT_FSIZE, &rl);

                   return rl.rlim_cur / 512;

}

rl.rlim in ulimit function is the type of long long(8 Byte), however the return value in X32 architecture is the type of long(4 Byte).

So in that case, rl.rlim_cur / 512 would be larger than 0x7fffffff and ulimit function returns -1.

I also tried an experiment to improve my opinion as follows.

[benchmark]

$ cat ulimit_test.c

#include <stdio.h>

#include <ulimit.h>

int main()

{

        printf("ret:%d\n", ulimit(UL_GETFSIZE));

        return 0;

}

[testcase]

Environment: Linux 4.4.171 #1 SMP Thu Apr 25 00:39:22 UTC 2019 armv7l GNU/Linux

$ /tmp # ulimit -f

unlimited

$ /tmp # ./ulimit_test

ret:-1

$ /tmp # cp musl/libc.so /usr/lib/                                 // copy a new MUSL libc.so with my [patch]

$ /tmp # ./ulimit_test

ret:2147483647                                                               // 0x7fffffff

[patch]

---

diff --git a/src/legacy/ulimit.c b/src/legacy/ulimit.c

index 1f59e8e..d1620e6 100644

--- a/src/legacy/ulimit.c

+++ b/src/legacy/ulimit.c

@@ -1,6 +1,7 @@

#include <sys/resource.h>

#include <ulimit.h>

#include <stdarg.h>

+#include <limits.h>

 long ulimit(int cmd, ...)

{

@@ -15,5 +16,5 @@ long ulimit(int cmd, ...)

                rl.rlim_cur = 512ULL * val;

                if (setrlimit(RLIMIT_FSIZE, &rl)) return -1;

       }

-        return rl.rlim_cur / 512;

+       return rl.rlim_cur == RLIM_INFINITY ? LONG_MAX : rl.rlim_cur / 512;

}

---

Looking forward to your reply.

Best regards.

Cheng Liu