| 1 | /* |
| 2 | * Copyright (C) 2017 Francis Deslauriers <francis.deslauriers@efficios.com> |
| 3 | * |
| 4 | * SPDX-License-Identifier: LGPL-2.1-only |
| 5 | * |
| 6 | */ |
| 7 | |
| 8 | #include <fcntl.h> |
| 9 | #include <stdio.h> |
| 10 | #include <sys/syscall.h> |
| 11 | #include <unistd.h> |
| 12 | |
| 13 | #include "utils.h" |
| 14 | |
| 15 | #define MAX_LEN 16 |
| 16 | /* |
| 17 | * The process waits for the creation of a file passed as argument from an |
| 18 | * external processes to execute a syscall and exiting. This is useful for tests |
| 19 | * in combinaison with LTTng's PID tracker feature where we can trace the kernel |
| 20 | * events generated by our test process only. |
| 21 | */ |
| 22 | int main(int argc, char **argv) |
| 23 | { |
| 24 | int fd, ret; |
| 25 | char buf[MAX_LEN]; |
| 26 | char *start_file; |
| 27 | |
| 28 | if (argc != 2) { |
| 29 | fprintf(stderr, "Error: Missing argument\n"); |
| 30 | fprintf(stderr, "USAGE: %s PATH_WAIT_FILE\n", argv[0]); |
| 31 | ret = -1; |
| 32 | goto error; |
| 33 | } |
| 34 | |
| 35 | start_file = argv[1]; |
| 36 | |
| 37 | /* |
| 38 | * Wait for the start_file to be created by an external process |
| 39 | * (typically the test script) before executing the syscalls. |
| 40 | */ |
| 41 | ret = wait_on_file(start_file); |
| 42 | if (ret != 0) { |
| 43 | goto error; |
| 44 | } |
| 45 | |
| 46 | /* |
| 47 | * Start generating syscalls. We use syscall(2) to prevent libc to change |
| 48 | * the underlying syscall. e.g. calling openat(2) instead of open(2). |
| 49 | */ |
| 50 | fd = syscall(SYS_openat, AT_FDCWD, "/proc/cpuinfo", O_RDONLY); |
| 51 | if (fd < 0) { |
| 52 | perror("open"); |
| 53 | ret = -1; |
| 54 | goto error; |
| 55 | } |
| 56 | |
| 57 | ret = syscall(SYS_read, fd, buf, MAX_LEN); |
| 58 | if (ret < 0) { |
| 59 | perror("read"); |
| 60 | ret = -1; |
| 61 | goto error; |
| 62 | } |
| 63 | |
| 64 | ret = syscall(SYS_close, fd); |
| 65 | if (ret == -1) { |
| 66 | perror("close"); |
| 67 | ret = -1; |
| 68 | goto error; |
| 69 | } |
| 70 | |
| 71 | error: |
| 72 | return ret; |
| 73 | } |