relayd: track directory handles through the fd-tracker

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

diff --git a/src/common/fd-tracker/utils.c b/src/common/fd-tracker/utils.c
index 1f71fd49623eda113386fc1dd8ed7471cf318234..fe2cdcc4ed4f84f1c629e27c630964d25d10f377 100644 (file)
--- a/src/common/fd-tracker/utils.c
+++ b/src/common/fd-tracker/utils.c
@@ -5,29 +5,35 @@
  *
  */
 
+#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)
+static
+int open_pipe_cloexec(void *data, int *fds)
 {
        return utils_create_pipe_cloexec(fds);
 }
 
-static int close_pipe(void *data, int *pipe)
+static
+int close_pipe(void *data, int *pipe)
 {
        utils_close_pipe(pipe);
        pipe[0] = pipe[1] = -1;
        return 0;
 }
 
+LTTNG_HIDDEN
 int fd_tracker_util_close_fd(void *unused, int *fd)
 {
        return close(*fd);
 }
 
+LTTNG_HIDDEN
 int fd_tracker_util_pipe_open_cloexec(
                struct fd_tracker *tracker, const char *name, int *pipe)
 {
@@ -53,8 +59,134 @@ end:
        return ret;
 }
 
+LTTNG_HIDDEN
 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 = _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 COMPAT_DIRFD
+               *out_fds = new_handle->dirfd;
+#else
+               abort();
+#endif
+
+       }
+end:
+       return ret;
+}
+
+#ifdef COMPAT_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 = 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
+
+LTTNG_HIDDEN
+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);
+}
+
+LTTNG_HIDDEN
+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;
+       struct open_directory_handle_args open_args = {
+               .in_handle = in_handle,
+               .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 COMPAT_DIRFD
+       new_handle->destroy_cb = directory_handle_destroy;
+       new_handle->destroy_cb_data = tracker;
+#endif
+end:
+       free(handle_name);
+       return new_handle;
+}