1#include <stdbool.h>
2#include <stdio.h>
3#include <unistd.h>
4#include <errno.h>
5#include <sys/types.h>
6#include <sys/stat.h>
7#include <fcntl.h>
8#include <stdlib.h>
9#include <signal.h>
10
11#define _SDT_HAS_SEMAPHORES 1
12#include "sdt.h"
13
14#define SHARED 1
15#include "bpf/libbpf_internal.h"
16
17#define SEC(name) __attribute__((section(name), used))
18
19#define BUF_SIZE 256
20
21/* defined in urandom_read_aux.c */
22void urand_read_without_sema(int iter_num, int iter_cnt, int read_sz);
23/* these are coming from urandom_read_lib{1,2}.c */
24void urandlib_read_with_sema(int iter_num, int iter_cnt, int read_sz);
25void urandlib_read_without_sema(int iter_num, int iter_cnt, int read_sz);
26
27int urandlib_api(void);
28COMPAT_VERSION(urandlib_api_old, urandlib_api, LIBURANDOM_READ_1.0.0)
29int urandlib_api_old(void);
30int urandlib_api_sameoffset(void);
31
32unsigned short urand_read_with_sema_semaphore SEC(".probes");
33
34static noinline void urandom_read(int fd, int count)
35{
36	char buf[BUF_SIZE];
37	int i;
38
39	for (i = 0; i < count; ++i) {
40		read(fd, buf, BUF_SIZE);
41
42		/* trigger USDTs defined in executable itself */
43		urand_read_without_sema(i, count, BUF_SIZE);
44		STAP_PROBE3(urand, read_with_sema, i, count, BUF_SIZE);
45
46		/* trigger USDTs defined in shared lib */
47		urandlib_read_without_sema(i, count, BUF_SIZE);
48		urandlib_read_with_sema(i, count, BUF_SIZE);
49	}
50}
51
52static volatile bool parent_ready;
53
54static void handle_sigpipe(int sig)
55{
56	parent_ready = true;
57}
58
59int main(int argc, char *argv[])
60{
61	int fd = open("/dev/urandom", O_RDONLY);
62	int count = 4;
63	bool report_pid = false;
64
65	if (fd < 0)
66		return 1;
67
68	if (argc >= 2)
69		count = atoi(argv[1]);
70	if (argc >= 3) {
71		report_pid = true;
72		/* install SIGPIPE handler to catch when parent closes their
73		 * end of the pipe (on the other side of our stdout)
74		 */
75		signal(SIGPIPE, handle_sigpipe);
76	}
77
78	/* report PID and wait for parent process to send us "signal" by
79	 * closing stdout
80	 */
81	if (report_pid) {
82		while (!parent_ready) {
83			fprintf(stdout, "%d\n", getpid());
84			fflush(stdout);
85		}
86		/* at this point stdout is closed, parent process knows our
87		 * PID and is ready to trace us
88		 */
89	}
90
91	urandom_read(fd, count);
92
93	urandlib_api();
94	urandlib_api_old();
95	urandlib_api_sameoffset();
96
97	close(fd);
98	return 0;
99}
100