common: compile libfd-tracker as C++

[lttng-tools.git] / src / common / fd-tracker / utils.cpp

diff --git a/src/common/fd-tracker/utils.cpp b/src/common/fd-tracker/utils.cpp
new file mode 100644 (file)
index 0000000..be6c65d
--- /dev/null
+++ b/src/common/fd-tracker/utils.cpp
@@ -0,0 +1,187 @@
+/*
+ * Copyright (C) 2018 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#include <common/error.h>
+#include <common/fd-tracker/utils.h>
+#include <common/utils.h>
+#include <lttng/constant.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static
+int open_pipe_cloexec(void *data, int *fds)
+{
+       return utils_create_pipe_cloexec(fds);
+}
+
+static
+int close_pipe(void *data, int *pipe)
+{
+       utils_close_pipe(pipe);
+       pipe[0] = pipe[1] = -1;
+       return 0;
+}
+
+int fd_tracker_util_close_fd(void *unused, int *fd)
+{
+       return close(*fd);
+}
+
+int fd_tracker_util_pipe_open_cloexec(
+               struct fd_tracker *tracker, const char *name, int *pipe)
+{
+       int ret;
+       const char *name_prefix;
+       char *names[2];
+
+       name_prefix = name ? name : "Unknown pipe";
+       ret = asprintf(&names[0], "%s (read end)", name_prefix);
+       if (ret < 0) {
+               goto end;
+       }
+       ret = asprintf(&names[1], "%s (write end)", name_prefix);
+       if (ret < 0) {
+               goto end;
+       }
+
+       ret = fd_tracker_open_unsuspendable_fd(tracker, pipe,
+                       (const char **) names, 2, open_pipe_cloexec, NULL);
+       free(names[0]);
+       free(names[1]);
+end:
+       return ret;
+}
+
+int fd_tracker_util_pipe_close(struct fd_tracker *tracker, int *pipe)
+{
+       return fd_tracker_close_unsuspendable_fd(
+                       tracker, pipe, 2, close_pipe, NULL);
+}
+
+struct open_directory_handle_args {
+       const struct lttng_directory_handle *in_handle;
+       struct lttng_directory_handle *ret_handle;
+       const char *path;
+};
+
+static
+int open_directory_handle(void *_args, int *out_fds)
+{
+       int ret = 0;
+       struct open_directory_handle_args *args = (open_directory_handle_args *) _args;
+       struct lttng_directory_handle *new_handle = NULL;
+
+       new_handle = args->in_handle ?
+                       lttng_directory_handle_create_from_handle(
+                               args->path, args->in_handle) :
+                       lttng_directory_handle_create(args->path);
+       if (!new_handle) {
+               ret = -errno;
+               goto end;
+       }
+
+       args->ret_handle = new_handle;
+
+       /*
+        * Reserved to indicate that the handle does not use a handle; there is
+        * nothing to track. We want to indicate an error to the fd-tracker so
+        * that it doesn't attempt to track the file descriptor, but also want
+        * the caller to retrieve the newly-created handle.
+        *
+        * Calling this a hack is a fair assessment.
+        */
+       if (!lttng_directory_handle_uses_fd(new_handle)) {
+               ret = ENOTSUP;
+       } else {
+#ifdef HAVE_DIRFD
+               *out_fds = new_handle->dirfd;
+#else
+               abort();
+#endif
+
+       }
+end:
+       return ret;
+}
+
+#ifdef HAVE_DIRFD
+static
+int fd_close(void *unused, int *in_fds)
+{
+       const int ret = close(in_fds[0]);
+
+       in_fds[0] = -1;
+       return ret;
+}
+
+static
+void directory_handle_destroy(
+               struct lttng_directory_handle *handle, void *data)
+{
+       struct fd_tracker *tracker = (fd_tracker *) data;
+       const int ret = fd_tracker_close_unsuspendable_fd(
+                       tracker, &handle->dirfd, 1, fd_close, NULL);
+
+       if (ret) {
+               ERR("Failed to untrack directory handle file descriptor");
+       }
+}
+#endif
+
+struct lttng_directory_handle *fd_tracker_create_directory_handle(
+               struct fd_tracker *tracker, const char *path)
+{
+       return fd_tracker_create_directory_handle_from_handle(
+                       tracker, NULL, path);
+}
+
+struct lttng_directory_handle *fd_tracker_create_directory_handle_from_handle(
+               struct fd_tracker *tracker,
+               struct lttng_directory_handle *in_handle,
+               const char *path)
+{
+       int ret;
+       int dirfd = -1;
+       char *handle_name = NULL;
+       char cwd_path[LTTNG_PATH_MAX] = "working directory";
+       struct lttng_directory_handle *new_handle = NULL;
+       open_directory_handle_args open_args {};
+
+       open_args.in_handle = in_handle;
+       open_args.path = path;
+
+       if (!path) {
+               if (!getcwd(cwd_path, sizeof(cwd_path))) {
+                       PERROR("Failed to get current working directory to name directory handle");
+                       goto end;
+               }
+       }
+
+       ret = asprintf(&handle_name, "Directory handle to %s",
+                       path ? path : cwd_path);
+       if (ret < 0) {
+               PERROR("Failed to format directory handle name");
+               goto end;
+       }
+
+       ret = fd_tracker_open_unsuspendable_fd(tracker, &dirfd,
+                       (const char **) &handle_name, 1, open_directory_handle,
+                       &open_args);
+       if (ret && ret != ENOTSUP) {
+               ERR("Failed to open directory handle to %s through the fd tracker", path ? path : cwd_path);
+       }
+       new_handle = open_args.ret_handle;
+
+#ifdef HAVE_DIRFD
+       new_handle->destroy_cb = directory_handle_destroy;
+       new_handle->destroy_cb_data = tracker;
+#endif
+end:
+       free(handle_name);
+       return new_handle;
+}