tests/utils/testapp/gen-kernel-test-events/gen-kernel-test-events.c

   1 /*
   2  * Copyright (C) - 2017 Francis Deslauriers <francis.deslauriers@efficios.com>
   3  * Copyright (C) - 2018 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This library is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU Lesser General Public License as published by the
   7  * Free Software Foundation; version 2.1 of the License.
   8  *
   9  * This library is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
  12  * for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public License
  15  * along with this library; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  17  */
  18
  19 #include <fcntl.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <sys/stat.h>
  23 #include <sys/types.h>
  24 #include <unistd.h>
  25
  26 #include "utils.h"
  27
  28 #define LTTNG_MODULES_FILE "/proc/lttng-test-filter-event"
  29
  30 /*
  31  * The process waits for the creation of a file passed as argument from an
  32  * external processes to execute a syscall and exiting. This is useful for tests
  33  * in combinaison with LTTng's PID tracker feature where we can trace the kernel
  34  * events generated by our test process only.
  35  */
  36 int main(int argc, char **argv)
  37 {
  38         int fd = -1, ret;
  39         char *start_file, *nr_events_str;
  40         ssize_t len;
  41
  42         if (argc != 3) {
  43                 fprintf(stderr, "Error: Missing argument\n");
  44                 fprintf(stderr, "USAGE: %s PATH_WAIT_FILE NR_EVENTS\n",
  45                                 argv[0]);
  46                 ret = -1;
  47                 goto end;
  48         }
  49
  50         start_file = argv[1];
  51         nr_events_str = argv[2];
  52
  53         /*
  54          * Wait for the start_file to be created by an external process
  55          * (typically the test script) before executing the syscalls.
  56          */
  57         ret = wait_on_file(start_file);
  58         if (ret != 0) {
  59                 goto end;
  60         }
  61
  62         /*
  63          * Start generating events.
  64          */
  65         fd = open(LTTNG_MODULES_FILE, O_RDWR);
  66         if (fd < 0) {
  67                 perror("open");
  68                 ret = -1;
  69                 goto end;
  70         }
  71
  72         len = write(fd, nr_events_str, strlen(nr_events_str) + 1);
  73         if (len != strlen(nr_events_str) + 1) {
  74                 perror("write");
  75                 ret = -1;
  76         } else {
  77                 ret = 0;
  78         }
  79
  80 end:
  81         if (fd >= 0) {
  82                 int closeret = close(fd);
  83                 if (closeret) {
  84                         perror("close");
  85                 }
  86         }
  87         return ret;
  88 }