| 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 | #include <fcntl.h> |
| 19 | #include <stdio.h> |
| 20 | #include <sys/syscall.h> |
| 21 | #include <unistd.h> |
| 22 | |
| 23 | #include "utils.h" |
| 24 | |
| 25 | #define MAX_LEN 16 |
| 26 | /* |
| 27 | * The process waits for the creation of a file passed as argument from an |
| 28 | * external processes to execute a syscall and exiting. This is useful for tests |
| 29 | * in combinaison with LTTng's PID tracker feature where we can trace the kernel |
| 30 | * events generated by our test process only. |
| 31 | */ |
| 32 | int main(int argc, char **argv) |
| 33 | { |
| 34 | int fd, ret; |
| 35 | char buf[MAX_LEN]; |
| 36 | char *start_file; |
| 37 | |
| 38 | if (argc != 2) { |
| 39 | fprintf(stderr, "Error: Missing argument\n"); |
| 40 | fprintf(stderr, "USAGE: %s PATH_WAIT_FILE\n", argv[0]); |
| 41 | ret = -1; |
| 42 | goto error; |
| 43 | } |
| 44 | |
| 45 | start_file = argv[1]; |
| 46 | |
| 47 | /* |
| 48 | * Wait for the start_file to be created by an external process |
| 49 | * (typically the test script) before executing the syscalls. |
| 50 | */ |
| 51 | ret = wait_on_file(start_file); |
| 52 | if (ret != 0) { |
| 53 | goto error; |
| 54 | } |
| 55 | |
| 56 | /* |
| 57 | * Start generating syscalls. We use syscall(2) to prevent libc to change |
| 58 | * the underlying syscall. e.g. calling openat(2) instead of open(2). |
| 59 | */ |
| 60 | fd = syscall(SYS_openat, AT_FDCWD, "/proc/cpuinfo", O_RDONLY); |
| 61 | if (fd < 0) { |
| 62 | perror("open"); |
| 63 | ret = -1; |
| 64 | goto error; |
| 65 | } |
| 66 | |
| 67 | ret = syscall(SYS_read, fd, buf, MAX_LEN); |
| 68 | if (ret < 0) { |
| 69 | perror("read"); |
| 70 | ret = -1; |
| 71 | goto error; |
| 72 | } |
| 73 | |
| 74 | ret = syscall(SYS_close, fd); |
| 75 | if (ret == -1) { |
| 76 | perror("close"); |
| 77 | ret = -1; |
| 78 | goto error; |
| 79 | } |
| 80 | |
| 81 | error: |
| 82 | return ret; |
| 83 | } |