daemon: Deduplicate some utility functions.

The following functions were previously reimplemented in OCaml.  This
commit replaces them with calls to the C functions:

 - is_root_device
 - prog_exists
 - udev_settle

plus the internal get_verbose_flag function.

However note that we cannot do this for every utility function.  In
particular the C function must not call any reply* functions.

daemon/Makefile.am

@@ -174,6 +174,7 @@ guestfsd_SOURCES = \
 	umask.c \
 	upload.c \
 	utils.c \
+	utils-c.c \
 	utimens.c \
 	utsname.c \
 	uuids.c \
@@ -297,7 +298,8 @@ OCAMLPACKAGES = \
 	-I $(top_srcdir)/common/mlutils \
 	-I $(top_builddir)/common/utils/.libs \
 	-I $(top_srcdir)/common/mlpcre \
-	-I $(top_builddir)/common/mlpcre/.libs
+	-I $(top_builddir)/common/mlpcre/.libs \
+	-I $(top_builddir)/gnulib/lib/.libs
 
 OCAMLFLAGS = $(OCAML_FLAGS) $(OCAML_WARN_FLAGS)
 
@@ -350,12 +352,25 @@ TESTS = \
 check-valgrind:
 	$(MAKE) VG="@VG@" check
 
-daemon_utils_tests_SOURCES = dummy.c
+daemon_utils_tests_SOURCES = \
+	command.c \
+	daemon-utils-tests-stubs.c \
+	utils.c \
+	utils-c.c
 daemon_utils_tests_CPPFLAGS = \
 	-I. \
 	-I$(top_builddir) \
 	-I$(shell $(OCAMLC) -where) \
-	-I$(top_srcdir)/lib
+	-I$(top_srcdir)/gnulib/lib \
+	-I$(top_builddir)/gnulib/lib \
+	-I$(top_srcdir)/common/errnostring \
+	-I$(top_builddir)/common/errnostring \
+	-I$(top_srcdir)/common/protocol \
+	-I$(top_builddir)/common/protocol \
+	-I$(top_srcdir)/common/utils \
+	-I$(top_builddir)/common/utils \
+	-I$(top_srcdir)/lib \
+	-I$(top_builddir)/lib
 daemon_utils_tests_BOBJECTS = \
 	utils.cmo \
 	daemon_utils_tests.cmo
@@ -377,7 +392,9 @@ daemon_utils_tests_DEPENDENCIES = \
 	$(daemon_utils_tests_THEOBJECTS) \
 	$(top_srcdir)/ocaml-link.sh
 daemon_utils_tests_LINK = \
-	$(top_srcdir)/ocaml-link.sh -- \
+	$(top_srcdir)/ocaml-link.sh \
+	  -cclib '-lutils -lgnu' \
+	  -- \
 	  $(OCAMLFIND) $(BEST) $(OCAMLFLAGS) $(OCAMLLINKFLAGS) \
 	  $(OCAMLPACKAGES) \
 	  $(daemon_utils_tests_THEOBJECTS) -o $@

daemon/daemon-c.c

@@ -76,13 +76,6 @@ guestfs_int_daemon_exn_to_reply_with_error (const char *func, value exn)
                       func, exn_name);
 }
 
-/* NB: This is a "noalloc" call. */
-value
-guestfs_int_daemon_get_verbose_flag (value unitv)
-{
-  return Val_bool (verbose);
-}
-
 /* Implement String (Mountable, _) parameter. */
 value
 guestfs_int_daemon_copy_mountable (const mountable_t *mountable)

daemon/daemon-c.h

@@ -27,7 +27,6 @@
 
 #include <caml/mlvalues.h>
 
-extern value guestfs_int_daemon_get_verbose_flag (value unitv);
 extern void guestfs_int_daemon_exn_to_reply_with_error (const char *func, value exn);
 extern value guestfs_int_daemon_copy_mountable (const mountable_t *mountable);
 extern char **guestfs_int_daemon_return_string_list (value retv);

daemon/daemon-utils-tests-stubs.c

@@ -0,0 +1,32 @@
+/* guestfsd
+ * Copyright (C) 2017 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "daemon.h"
+
+/* This stubs out some functions that we want to link to the unit
+ * tests, but don't want to actually pull in plus dependencies.
+ */
+
+char *device_name_translation (const char *device) { abort (); }
+void reply_with_error_errno (int err, const char *fs, ...) { abort (); }
+void reply_with_perror_errno (int err, const char *fs, ...) { abort (); }

daemon/daemon.ml

@@ -18,9 +18,6 @@
 
 open Printf
 
-external get_verbose_flag : unit -> bool =
-  "guestfs_int_daemon_get_verbose_flag" "noalloc"
-
 (* When guestfsd starts up, early on (after parsing the command line
  * but not much else), it calls 'caml_startup' which runs all
  * initialization code in the OCaml modules, including this one.
@@ -32,7 +29,7 @@ let () =
   (* Connect the guestfsd [-v] (verbose) flag into 'verbose ()'
    * used in OCaml code to print debugging messages.
    *)
-  if get_verbose_flag () then (
+  if Utils.get_verbose_flag () then (
     Std_utils.set_verbose ();
     eprintf "OCaml daemon loaded\n%!"
   );

daemon/dummy.c

@@ -1,2 +0,0 @@
-/* Dummy source, to be used for OCaml-based tools with no C sources. */
-enum { foo = 1 };

daemon/utils-c.c

@@ -0,0 +1,75 @@
+/* guestfsd
+ * Copyright (C) 2017 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * Bindings for utility functions.
+ *
+ * Note that functions called from OCaml code B<must never> call
+ * any of the C<reply*> functions.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <caml/alloc.h>
+#include <caml/mlvalues.h>
+#include <caml/memory.h>
+#include <caml/unixsupport.h>
+
+#include "daemon.h"
+
+#pragma GCC diagnostic ignored "-Wmissing-prototypes"
+
+/* NB: This is a "noalloc" call. */
+value
+guestfs_int_daemon_get_verbose_flag (value unitv)
+{
+  return Val_bool (verbose);
+}
+
+/* NB: This is a "noalloc" call. */
+value
+guestfs_int_daemon_is_root_device (value device)
+{
+  return Val_bool (is_root_device (String_val (device)));
+}
+
+/* NB: This is a "noalloc" call. */
+value
+guestfs_int_daemon_prog_exists (value prog)
+{
+  return Val_bool (prog_exists (String_val (prog)));
+}
+
+/* NB: This is a "noalloc" call. */
+value
+guestfs_int_daemon_udev_settle (value optfilenamev, value unitv)
+{
+  const char *file;
+
+  if (optfilenamev == Val_int (0))
+    file = NULL;
+  else
+    file = String_val (Field (optfilenamev, 0));
+
+  udev_settle_file (file);
+
+  return Val_unit;
+}

daemon/utils.ml

@@ -21,9 +21,10 @@ open Printf
 
 open Std_utils
 
-let prog_exists prog =
-  try ignore (which prog); true
-  with Executable_not_found _ -> false
+external get_verbose_flag : unit -> bool = "guestfs_int_daemon_get_verbose_flag" "noalloc"
+external is_root_device : string -> bool = "guestfs_int_daemon_is_root_device" "noalloc"
+external prog_exists : string -> bool = "guestfs_int_daemon_prog_exists" "noalloc"
+external udev_settle : ?filename:string -> unit -> unit = "guestfs_int_daemon_udev_settle" "noalloc"
 
 let commandr ?(fold_stdout_on_stderr = false) prog args =
   if verbose () then
@@ -101,38 +102,6 @@ let command ?fold_stdout_on_stderr prog args =
     failwithf "%s exited with status %d: %s" prog r stderr;
   stdout
 
-let udev_settle ?filename () =
-  let args = ref [] in
-  if verbose () then
-    push_back args "--debug";
-  push_back args "settle";
-  (match filename with
-   | None -> ()
-   | Some filename ->
-      push_back args "-E";
-      push_back args filename
-  );
-  let args = !args in
-  let r, _, err = commandr "udevadm" args in
-  if r <> 0 then
-    eprintf "udevadm settle: %s\n" err
-
-let root_device = lazy ((stat "/").st_dev)
-
-let is_root_device_stat statbuf =
-  statbuf.st_rdev = Lazy.force root_device
-
-let is_root_device device =
-  udev_settle ~filename:device ();
-  try
-    let statbuf = stat device in
-    is_root_device_stat statbuf
-  with
-    Unix_error (err, func, arg) ->
-      eprintf "is_root_device: %s: %s: %s: %s\n"
-              device func arg (error_message err);
-      false
-
 (* XXX This function is copied from C, but is misconceived.  It
  * cannot by design work for devices like /dev/md0.  It would be
  * better if it checked for the existence of devices and partitions

daemon/utils.mli

@@ -37,10 +37,6 @@ val udev_settle : ?filename:string -> unit -> unit
 val is_root_device : string -> bool
 (** Return true if this is the root (appliance) device. *)
 
-val is_root_device_stat : Unix.stats -> bool
-(** As for {!is_root_device} but operates on a statbuf instead of
-    a device name. *)
-
 val split_device_partition : string -> string * int
 (** Split a device name like [/dev/sda1] into a device name and
     partition number, eg. ["sda", 1].
@@ -85,3 +81,6 @@ val commandr : ?fold_stdout_on_stderr:bool -> string -> string list -> (int * st
 
 val is_small_file : string -> bool
 (** Return true if the path is a small regular file. *)
+
+(**/**)
+val get_verbose_flag : unit -> bool

docs/C_SOURCE_FILES

@@ -87,6 +87,7 @@ daemon/cpio.c
 daemon/cpmv.c
 daemon/daemon-c.c
 daemon/daemon-c.h
+daemon/daemon-utils-tests-stubs.c
 daemon/daemon.h
 daemon/dd.c
 daemon/debug-bmap.c
@@ -99,7 +100,6 @@ daemon/dispatch.c
 daemon/dmesg.c
 daemon/dropcaches.c
 daemon/du.c
-daemon/dummy.c
 daemon/echo-daemon.c
 daemon/ext2.c
 daemon/fallocate.c
@@ -182,6 +182,8 @@ daemon/truncate.c
 daemon/tsk.c
 daemon/umask.c
 daemon/upload.c
+daemon/utils-c.c
+daemon/utils.c
 daemon/utimens.c
 daemon/utsname.c
 daemon/uuids.c