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

   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 static
  18 int open_read_close(const char *path)
  19 {
  20         int fd, ret;
  21         char buf[MAX_LEN];
  22         /*
  23          * Start generating syscalls. We use syscall(2) to prevent libc to change
  24          * the underlying syscall. e.g. calling openat(2) instead of open(2).
  25          */
  26         fd = syscall(SYS_openat, AT_FDCWD, path, O_RDONLY);
  27         if (fd < 0) {
  28                 perror("open");
  29                 ret = -1;
  30                 goto error;
  31         }
  32
  33         ret = syscall(SYS_read, fd, buf, MAX_LEN);
  34         if (ret < 0) {
  35                 perror("read");
  36                 ret = -1;
  37                 goto error;
  38         }
  39
  40         ret = syscall(SYS_close, fd);
  41         if (ret == -1) {
  42                 perror("close");
  43                 ret = -1;
  44                 goto error;
  45         }
  46
  47 error:
  48         return ret;
  49 }
  50
  51 /*
  52  * The process waits for the creation of a file passed as argument from an
  53  * external processes to execute a syscall and exiting. This is useful for tests
  54  * in combinaison with LTTng's PID tracker feature where we can trace the kernel
  55  * events generated by our test process only.
  56  */
  57 int main(int argc, char **argv)
  58 {
  59         int ret;
  60         char *start_file;
  61
  62         if (argc != 2) {
  63                 fprintf(stderr, "Error: Missing argument\n");
  64                 fprintf(stderr, "USAGE: %s PATH_WAIT_FILE\n", argv[0]);
  65                 ret = -1;
  66                 goto error;
  67         }
  68
  69         start_file = argv[1];
  70
  71         /*
  72          * Wait for the start_file to be created by an external process
  73          * (typically the test script) before executing the syscalls.
  74          */
  75         ret = wait_on_file(start_file);
  76         if (ret != 0) {
  77                 goto error;
  78         }
  79
  80         /*
  81          * Start generating syscalls. We use syscall(2) to prevent libc to change
  82          * the underlying syscall. e.g. calling openat(2) instead of open(2).
  83          */
  84         ret = open_read_close("/proc/cpuinfo");
  85         if (ret == -1) {
  86                 ret = -1;
  87                 goto error;
  88         }
  89
  90         ret = open_read_close("/proc/cmdline");
  91         if (ret == -1) {
  92                 ret = -1;
  93                 goto error;
  94         }
  95
  96 error:
  97         return ret;
  98 }