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#include <stdbool.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <signal.h>
#define _SDT_HAS_SEMAPHORES 1
#include "sdt.h"
#define SEC(name) __attribute__((section(name), used))
#define BUF_SIZE 256
/* defined in urandom_read_aux.c */
void urand_read_without_sema(int iter_num, int iter_cnt, int read_sz);
/* these are coming from urandom_read_lib{1,2}.c */
void urandlib_read_with_sema(int iter_num, int iter_cnt, int read_sz);
void urandlib_read_without_sema(int iter_num, int iter_cnt, int read_sz);
unsigned short urand_read_with_sema_semaphore SEC(".probes");
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);
/* trigger USDTs defined in executable itself */
urand_read_without_sema(i, count, BUF_SIZE);
STAP_PROBE3(urand, read_with_sema, i, count, BUF_SIZE);
/* trigger USDTs defined in shared lib */
urandlib_read_without_sema(i, count, BUF_SIZE);
urandlib_read_with_sema(i, count, BUF_SIZE);
}
}
static volatile bool parent_ready;
static void handle_sigpipe(int sig)
{
parent_ready = true;
}
int main(int argc, char *argv[])
{
int fd = open("/dev/urandom", O_RDONLY);
int count = 4;
bool report_pid = false;
if (fd < 0)
return 1;
if (argc >= 2)
count = atoi(argv[1]);
if (argc >= 3) {
report_pid = true;
/* install SIGPIPE handler to catch when parent closes their
* end of the pipe (on the other side of our stdout)
*/
signal(SIGPIPE, handle_sigpipe);
}
/* report PID and wait for parent process to send us "signal" by
* closing stdout
*/
if (report_pid) {
while (!parent_ready) {
fprintf(stdout, "%d\n", getpid());
fflush(stdout);
}
/* at this point stdout is closed, parent process knows our
* PID and is ready to trace us
*/
}
urandom_read(fd, count);
close(fd);
return 0;
}
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