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  * SPDX-License-Identifier: LGPL-2.1-only
   6  *
   7  */
   8
   9 #include <fcntl.h>
  10 #include <stdio.h>
  11 #include <string.h>
  12 #include <sys/stat.h>
  13 #include <sys/types.h>
  14 #include <unistd.h>
  15
  16 #include "utils.h"
  17
  18 #define LTTNG_MODULES_FILE "/proc/lttng-test-filter-event"
  19
  20 /*
  21  * The process waits for the creation of a file passed as argument from an
  22  * external processes to execute a syscall and exiting. This is useful for tests
  23  * in combinaison with LTTng's PID tracker feature where we can trace the kernel
  24  * events generated by our test process only.
  25  */
  26 int main(int argc, char **argv)
  27 {
  28         int fd = -1, ret;
  29         char *start_file, *nr_events_str;
  30         ssize_t len;
  31
  32         if (argc != 3) {
  33                 fprintf(stderr, "Error: Missing argument\n");
  34                 fprintf(stderr, "USAGE: %s PATH_WAIT_FILE NR_EVENTS\n",
  35                                 argv[0]);
  36                 ret = -1;
  37                 goto end;
  38         }
  39
  40         start_file = argv[1];
  41         nr_events_str = argv[2];
  42
  43         /*
  44          * Wait for the start_file to be created by an external process
  45          * (typically the test script) before executing the syscalls.
  46          */
  47         ret = wait_on_file(start_file);
  48         if (ret != 0) {
  49                 goto end;
  50         }
  51
  52         /*
  53          * Start generating events.
  54          */
  55         fd = open(LTTNG_MODULES_FILE, O_RDWR);
  56         if (fd < 0) {
  57                 perror("open");
  58                 ret = -1;
  59                 goto end;
  60         }
  61
  62         len = write(fd, nr_events_str, strlen(nr_events_str) + 1);
  63         if (len != strlen(nr_events_str) + 1) {
  64                 perror("write");
  65                 ret = -1;
  66         } else {
  67                 ret = 0;
  68         }
  69
  70 end:
  71         if (fd >= 0) {
  72                 int closeret = close(fd);
  73                 if (closeret) {
  74                         perror("close");
  75                 }
  76         }
  77         return ret;
  78 }