pkg/rootless: Implement rootless.IsFdInherited on FreeBSD

This is needed to support --preserve-fds in create and exec.

[NO NEW TESTS NEEDED]

Signed-off-by: Doug Rabson <dfr@rabson.org>

pkg/rootless/rootless_freebsd.c

@@ -0,0 +1,63 @@
+#include <dirent.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/select.h>
+
+static int open_files_max_fd;
+static fd_set *open_files_set;
+
+int
+is_fd_inherited(int fd)
+{
+  if (open_files_set == NULL || fd > open_files_max_fd || fd < 0)
+    return 0;
+
+  return FD_ISSET(fd % FD_SETSIZE, &(open_files_set[fd / FD_SETSIZE])) ? 1 : 0;
+}
+
+static void __attribute__((constructor)) init()
+{
+  /* Store how many FDs were open before the Go runtime kicked in.  */
+  DIR* d = opendir ("/dev/fd");
+  if (d)
+    {
+      struct dirent *ent;
+      size_t size = 0;
+
+      for (ent = readdir (d); ent; ent = readdir (d))
+        {
+          int fd;
+
+          if (ent->d_name[0] == '.')
+            continue;
+
+          fd = atoi (ent->d_name);
+          if (fd == dirfd (d)) {
+            continue;
+          }
+
+          if (fd >= size * FD_SETSIZE)
+            {
+              int i;
+              size_t new_size;
+
+              new_size = (fd / FD_SETSIZE) + 1;
+              open_files_set = realloc (open_files_set, new_size * sizeof (fd_set));
+              if (open_files_set == NULL)
+                _exit (EXIT_FAILURE);
+
+              for (i = size; i < new_size; i++)
+                FD_ZERO (&(open_files_set[i]));
+
+              size = new_size;
+            }
+
+          if (fd > open_files_max_fd) {
+            open_files_max_fd = fd;
+          }
+
+          FD_SET (fd % FD_SETSIZE, &(open_files_set[fd / FD_SETSIZE]));
+        }
+    }
+}

pkg/rootless/rootless_freebsd.go

@@ -0,0 +1,69 @@
+//go:build freebsd && cgo
+// +build freebsd,cgo
+
+package rootless
+
+import (
+	"errors"
+
+	"github.com/containers/storage/pkg/idtools"
+)
+
+// extern int is_fd_inherited(int fd);
+import "C"
+
+// IsRootless returns whether the user is rootless
+func IsRootless() bool {
+	return false
+}
+
+// BecomeRootInUserNS re-exec podman in a new userNS.  It returns whether podman was re-executed
+// into a new user namespace and the return code from the re-executed podman process.
+// If podman was re-executed the caller needs to propagate the error code returned by the child
+// process.  It is a convenience function for BecomeRootInUserNSWithOpts with a default configuration.
+func BecomeRootInUserNS(pausePid string) (bool, int, error) {
+	return false, -1, errors.New("this function is not supported on this os")
+}
+
+// GetRootlessUID returns the UID of the user in the parent userNS
+func GetRootlessUID() int {
+	return -1
+}
+
+// GetRootlessGID returns the GID of the user in the parent userNS
+func GetRootlessGID() int {
+	return -1
+}
+
+// TryJoinFromFilePaths attempts to join the namespaces of the pid files in paths.
+// This is useful when there are already running containers and we
+// don't have a pause process yet.  We can use the paths to the conmon
+// processes to attempt joining their namespaces.
+// If needNewNamespace is set, the file is read from a temporary user
+// namespace, this is useful for containers that are running with a
+// different uidmap and the unprivileged user has no way to read the
+// file owned by the root in the container.
+func TryJoinFromFilePaths(pausePidPath string, needNewNamespace bool, paths []string) (bool, int, error) {
+	return false, -1, errors.New("this function is not supported on this os")
+}
+
+// ConfigurationMatches checks whether the additional uids/gids configured for the user
+// match the current user namespace.
+func ConfigurationMatches() (bool, error) {
+	return true, nil
+}
+
+// GetConfiguredMappings returns the additional IDs configured for the current user.
+func GetConfiguredMappings(quiet bool) ([]idtools.IDMap, []idtools.IDMap, error) {
+	return nil, nil, errors.New("this function is not supported on this os")
+}
+
+// ReadMappingsProc returns the uid_map and gid_map
+func ReadMappingsProc(path string) ([]idtools.IDMap, error) {
+	return nil, nil
+}
+
+// IsFdInherited checks whether the fd is opened and valid to use
+func IsFdInherited(fd int) bool {
+	return int(C.is_fd_inherited(C.int(fd))) > 0
+}

pkg/rootless/rootless_unsupported.go

@@ -1,5 +1,5 @@
-//go:build !linux || !cgo
-// +build !linux !cgo
+//go:build !(linux || freebsd) || !cgo
+// +build !linux,!freebsd !cgo
 
 package rootless