tests/utils/testapp/gen-syscall-events/gen-syscall-events.c

   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  */
  34 int main(int argc, char **argv)
  35 {
  36         int fd, ret;
  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
  83 error:
  84         return ret;
  85 }