tests: compile some tools/tests as C++

[lttng-tools.git] / tests / utils / testapp / gen-syscall-events / gen-syscall-events.cpp

diff --git a/tests/utils/testapp/gen-syscall-events/gen-syscall-events.cpp b/tests/utils/testapp/gen-syscall-events/gen-syscall-events.cpp
new file mode 100644 (file)
index 0000000..6a24686
--- /dev/null
+++ b/tests/utils/testapp/gen-syscall-events/gen-syscall-events.cpp
@@ -0,0 +1,131 @@
+/*
+ * Copyright (C) 2017 Francis Deslauriers <francis.deslauriers@efficios.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ */
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <common/error.h>
+#include <common/align.h>
+
+#include "utils.h"
+
+#define MAX_LEN 16
+
+/*
+ * The LTTng system call tracing facilities can't handle page faults at the
+ * moment. If a fault would occur while reading a syscall argument, the
+ * tracer will report an empty string (""). Since the proper execution of the
+ * tests which use this generator depends on some syscall string arguments being
+ * present, this util allows us to mitigate the page-fault risk.
+ *
+ * This isn't a proper fix; it is simply the best we can do for now.
+ * See bug #1261 for more context.
+ */
+static
+void prefault_string(const char *p)
+{
+       const char * const end = p + strlen(p) + 1;
+
+       while (p < end) {
+               /*
+                * Trigger a read attempt on *p, faulting-in the pages
+                * for reading.
+                */
+               asm volatile("" : : "m"(*p));
+               p += sysconf(_SC_PAGE_SIZE);
+       }
+}
+
+static
+int open_read_close(const char *path)
+{
+       int fd, ret;
+       char buf[MAX_LEN];
+
+       /*
+        * Start generating syscalls. We use syscall(2) to prevent libc from
+        * changing the underlying syscall (e.g. calling openat(2) instead of
+        * open(2)).
+        */
+       prefault_string(path);
+       fd = syscall(SYS_openat, AT_FDCWD, path, O_RDONLY);
+       if (fd < 0) {
+               PERROR_NO_LOGGER("Failed to open file with openat(): path = '%s'", path);
+               ret = -1;
+               goto error;
+       }
+
+       ret = syscall(SYS_read, fd, buf, MAX_LEN);
+       if (ret < 0) {
+               PERROR_NO_LOGGER("Failed to read file: path = '%s', fd = %d, length = %d",
+                               path, fd, MAX_LEN);
+               ret = -1;
+               goto error;
+       }
+
+       ret = syscall(SYS_close, fd);
+       if (ret == -1) {
+               PERROR_NO_LOGGER("Failed to close file: path = '%s', fd = %d", path, fd);
+               ret = -1;
+               goto error;
+       }
+
+error:
+       return ret;
+}
+
+/*
+ * The process waits for the creation of a file passed as argument from an
+ * external processes to execute a syscall and exiting. This is useful for tests
+ * in combinaison with LTTng's PID tracker feature where we can trace the kernel
+ * events generated by our test process only.
+ */
+int main(int argc, char **argv)
+{
+       int ret;
+       const char *start_file, *path1, *path2;
+
+       if (argc != 4) {
+               fprintf(stderr, "Error: Missing argument\n");
+               fprintf(stderr, "USAGE: %s PATH_WAIT_FILE PATH1_TO_OPEN PATH2_TO_OPEN\n", argv[0]);
+               ret = -1;
+               goto error;
+       }
+
+       start_file = argv[1];
+       path1 = argv[2];
+       path2 = argv[3];
+
+       /*
+        * Wait for the start_file to be created by an external process
+        * (typically the test script) before executing the syscalls.
+        */
+       ret = wait_on_file(start_file);
+       if (ret != 0) {
+               goto error;
+       }
+
+       /*
+        * Start generating syscalls. We use syscall(2) to prevent libc to change
+        * the underlying syscall. e.g. calling openat(2) instead of open(2).
+        */
+       ret = open_read_close(path1);
+       if (ret == -1) {
+               ret = -1;
+               goto error;
+       }
+
+       ret = open_read_close(path2);
+       if (ret == -1) {
+               ret = -1;
+               goto error;
+       }
+
+error:
+       return ret;
+}