Tests: Add test app to generate syscalls
[lttng-tools.git] / tests / utils / testapp / gen-syscall-events / gen-syscall-events.c
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1/*
2 * Copyright (C) - 2017 Francis Deslauriers <francis.deslauriers@efficios.com>
3 *
4 * This library is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU Lesser General Public License as published by the
6 * Free Software Foundation; version 2.1 of the License.
7 *
8 * This library is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
11 * for more details.
12 *
13 * You should have received a copy of the GNU Lesser General Public License
14 * along with this library; if not, write to the Free Software Foundation,
15 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
16 */
17
18#define _LGPL_SOURCE
19
20#include <fcntl.h>
21#include <stdio.h>
22#include <sys/syscall.h>
23#include <unistd.h>
24
25#include "utils.h"
26
27#define MAX_LEN 16
28/*
29 * The process waits for the creation of a file passed as argument from an
30 * external processes to execute a syscall and exiting. This is useful for tests
31 * in combinaison with LTTng's PID tracker feature where we can trace the kernel
32 * events generated by our test process only.
33 */
34int main(int argc, char **argv)
35{
36 int fd, ret = 0;
37 char buf[MAX_LEN];
38 char *start_file;
39
40 if (argc != 2) {
41 fprintf(stderr, "Error: Missing argument\n");
42 fprintf(stderr, "USAGE: %s PATH_WAIT_FILE\n", argv[0]);
43 ret = -1;
44 goto error;
45 }
46
47 start_file = argv[1];
48
49 /*
50 * Wait for the start_file to be created by an external process
51 * (typically the test script) before executing the syscalls.
52 */
53 ret = wait_on_file(start_file);
54 if (ret != 0) {
55 goto error;
56 }
57
58 /*
59 * Start generating syscalls. We use syscall(2) to prevent libc to change
60 * the underlying syscall. e.g. calling openat(2) instead of open(2).
61 */
62 fd = syscall(SYS_open, "/proc/cpuinfo", O_RDONLY);
63 if (fd < 0) {
64 perror("open");
65 ret = -1;
66 goto error;
67 }
68
69 ret = syscall(SYS_read, fd, buf, MAX_LEN);
70 if (ret < 0) {
71 perror("read");
72 ret = -1;
73 goto error;
74 }
75
76 ret = syscall(SYS_close, fd);
77 if (ret == -1) {
78 perror("close");
79 ret = -1;
80 goto error;
81 }
82
83error:
84 return ret;
85}
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