linux/tools/testing/selftests/bpf/urandom_read.c
Ivan Vecera f682752627 selftests: bpf: modify urandom_read and link it non-statically
After some experiences I found that urandom_read does not need to be
linked statically. When the 'read' syscall call is moved to separate
non-inlined function then bpf_get_stackid() is able to find
the executable in stack trace and extract its build_id from it.

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-03-21 19:37:30 -07:00

36 lines
552 B
C

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#define BUF_SIZE 256
static __attribute__((noinline))
void urandom_read(int fd, int count)
{
char buf[BUF_SIZE];
int i;
for (i = 0; i < count; ++i)
read(fd, buf, BUF_SIZE);
}
int main(int argc, char *argv[])
{
int fd = open("/dev/urandom", O_RDONLY);
int count = 4;
if (fd < 0)
return 1;
if (argc == 2)
count = atoi(argv[1]);
urandom_read(fd, count);
close(fd);
return 0;
}