Add /etc/libguestfs-tools.conf configuration file.

This allows the default for --ro or --rw to be controlled for the
three tools guestfish, guestmount and virt-rescue.

6 files changed, 214 insertions, 20 deletions

diff --git a/fish/Makefile.am b/fish/Makefile.am
index 311da896..3eae8e47 100644
--- a/fish/Makefile.am
+++ b/fish/Makefile.am
@@ -1,5 +1,5 @@
 # libguestfs
-# Copyright (C) 2009-2010 Red Hat Inc.
+# Copyright (C) 2009-2011 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
@@ -60,6 +60,7 @@ EXTRA_DIST = \
 # so we know which ones are shared.  These files must not include
 # other guestfish files.
 SHARED_SOURCE_FILES = \
+	config.c \
 	inspect.c \
 	keys.c \
 	options.h \
@@ -118,10 +119,13 @@ guestfish_CFLAGS = \
 	-DGUESTFS_DEFAULT_PATH='"$(libdir)/guestfs"' \
 	-DLOCALEBASEDIR=\""$(datadir)/locale"\" \
 	-I$(srcdir)/../gnulib/lib -I../gnulib/lib \
-	$(WARN_CFLAGS) $(WERROR_CFLAGS)
+	$(WARN_CFLAGS) $(WERROR_CFLAGS) \
+	$(LIBCONFIG_CFLAGS)
 
 guestfish_LDADD = \
-	$(top_builddir)/src/libguestfs.la $(LIBREADLINE) -lm
+	$(LIBCONFIG_LIBS) \
+	$(LIBREADLINE) \
+	$(top_builddir)/src/libguestfs.la -lm
 
 # Make guestfish use the convenience libraries.
 noinst_LTLIBRARIES = libcmds.la librc_protocol.la
@@ -207,6 +211,11 @@ stamp-virt-tar-out.pod: virt-tar-out.pod
 	  $<
 	touch $@
 
+# libguestfs tools config file.
+
+toolsconfdir = $(sysconfdir)
+toolsconf_DATA = libguestfs-tools.conf
+
 # Bash completion script.
 
 bashcompletiondir = $(sysconfdir)/bash_completion.d
diff --git a/fish/config.c b/fish/config.c
new file mode 100644
index 00000000..c92bc4e2
--- /dev/null
+++ b/fish/config.c
@@ -0,0 +1,142 @@
+/* libguestfs - guestfish and guestmount shared option parsing
+ * Copyright (C) 2011 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>
+
+#ifdef HAVE_LIBCONFIG
+#include <libconfig.h>
+#endif
+
+#include "guestfs.h"
+
+#include "options.h"
+
+static const char *home_filename = /* $HOME/ */ ".libguestfs-tools.rc";
+static const char *etc_filename = "/etc/libguestfs-tools.conf";
+
+#ifdef HAVE_LIBCONFIG
+
+/* Note that parse_config is called very early, before command line
+ * parsing and before the verbose flag has been set.
+ */
+
+void
+parse_config (void)
+{
+  const char *home;
+  size_t len;
+  char *path;
+  FILE *fp;
+  config_t conf;
+
+  config_init (&conf);
+
+  /* Try $HOME first. */
+  home = getenv ("HOME");
+  if (home != NULL) {
+    len = strlen (home) + 1 + strlen (home_filename) + 1;
+    path = malloc (len);
+    if (path == NULL) {
+      perror ("malloc");
+      exit (EXIT_FAILURE);
+    }
+    snprintf (path, len, "%s/%s", home, home_filename);
+
+    fp = fopen (path, "r");
+    if (fp != NULL) {
+      /*
+      if (verbose)
+        fprintf (stderr, "%s: reading configuration from %s\n",
+                 program_name, path);
+      */
+
+      if (config_read (&conf, fp) == CONFIG_FALSE) {
+        fprintf (stderr,
+                 _("%s: %s: line %d: error parsing configuration file: %s\n"),
+                 program_name, path, config_error_line (&conf),
+                 config_error_text (&conf));
+        exit (EXIT_FAILURE);
+      }
+
+      if (fclose (fp) == -1) {
+        perror (path);
+        exit (EXIT_FAILURE);
+      }
+
+      /* Notes:
+       *
+       * (1) It's not obvious from the documentation, that config_read
+       * completely resets the 'conf' structure.  This means we cannot
+       * call config_read twice on the two possible configuration
+       * files, but instead have to copy out settings into our
+       * variables between calls.
+       *
+       * (2) If the next call fails then 'read_only' variable is not
+       * updated.  Failure could happen just because the setting is
+       * missing from the configuration file, so we ignore it here.
+       */
+      config_lookup_bool (&conf, "read_only", &read_only);
+    }
+
+    free (path);
+  }
+
+  fp = fopen (etc_filename, "r");
+  if (fp != NULL) {
+    /*
+    if (verbose)
+      fprintf (stderr, "%s: reading configuration from %s\n",
+               program_name, etc_filename);
+    */
+
+    if (config_read (&conf, fp) == CONFIG_FALSE) {
+      fprintf (stderr,
+               _("%s: %s: line %d: error parsing configuration file: %s\n"),
+               program_name, etc_filename, config_error_line (&conf),
+               config_error_text (&conf));
+      exit (EXIT_FAILURE);
+    }
+
+    if (fclose (fp) == -1) {
+      perror (path);
+      exit (EXIT_FAILURE);
+    }
+
+    config_lookup_bool (&conf, "read_only", &read_only);
+  }
+
+  config_destroy (&conf);
+}
+
+#else /* !HAVE_LIBCONFIG */
+
+void
+parse_config (void)
+{
+  /*
+  if (verbose)
+    fprintf (stderr,
+             _("%s: compiled without libconfig, guestfish configuration file ignored\n"),
+             program_name);
+  */
+}
+
+#endif /* !HAVE_LIBCONFIG */
diff --git a/fish/fish.c b/fish/fish.c
index 65a0c1dd..c4fdf799 100644
--- a/fish/fish.c
+++ b/fish/fish.c
@@ -158,6 +158,8 @@ main (int argc, char *argv[])
   bindtextdomain (PACKAGE, LOCALEBASEDIR);
   textdomain (PACKAGE);
 
+  parse_config ();
+
   set_up_terminal ();
 
   enum { HELP_OPTION = CHAR_MAX + 1 };
diff --git a/fish/guestfish.pod b/fish/guestfish.pod
index 98286d18..58f0bd9d 100644
--- a/fish/guestfish.pod
+++ b/fish/guestfish.pod
@@ -402,7 +402,9 @@ Display the guestfish / libguestfs version number and exit.
 
 =item B<--rw>
 
-This option does nothing at the moment.
+This changes the I<-a>, I<-d> and I<-m> options so that disks are
+added and mounts are done read-write.
+
 See L</OPENING DISKS FOR READ AND WRITE> below.
 
 =item B<-x>
@@ -466,27 +468,30 @@ asked for without doing this.
 
 =head1 OPENING DISKS FOR READ AND WRITE
 
-The guestfish (and L<guestmount(1)>) options I<--ro> and I<--rw>
-affect whether the other command line options I<-a>, I<-c>, I<-d>,
-I<-i> and I<-m> open disk images read-only or for writing.
+The guestfish, L<guestmount(1)> and L<virt-rescue(1)> options I<--ro>
+and I<--rw> affect whether the other command line options I<-a>,
+I<-c>, I<-d>, I<-i> and I<-m> open disk images read-only or for
+writing.
 
-In libguestfs E<lt> 1.6.2, guestfish and guestmount defaulted to
-opening disk images supplied on the command line for write.  To open a
-disk image read-only you have to do I<-a image --ro>.
+In libguestfs E<le> 1.8, guestfish, guestmount and virt-rescue
+defaulted to opening disk images supplied on the command line for
+write.  To open a disk image read-only you have to do I<-a image --ro>.
 
 This matters: If you accidentally open a live VM disk image writable
 then you will cause irreversible disk corruption.
 
-By libguestfs 1.10 we intend to change the default the other way.  Disk
-images will be opened read-only.  You will have to either specify
-I<guestfish --rw> or change a configuration file in order to get write
-access for disk images specified by those other command line options.
+By libguestfs 1.10 we intend to change the default the other way.
+Disk images will be opened read-only.  You will have to either specify
+I<guestfish --rw>, I<guestmount --rw>, I<virt-rescue --rw>, or change
+the configuration file C</etc/libguestfs-tools.conf> in order to get
+write access for disk images specified by those other command line
+options.
 
-This version of guestfish has a I<--rw> option which does nothing (it
-is already the default).  However it is highly recommended that you
-use this option to indicate that guestfish needs write access, and to
-prepare your scripts for the day when this option will be required for
-write access.
+This version of guestfish, guestmount and virt-rescue has a I<--rw>
+option which does nothing (it is already the default).  However it is
+highly recommended that you use this option to indicate that you need
+write access, and prepare your scripts for the day when this option
+will be required for write access.
 
 B<Note:> This does I<not> affect commands like L</add> and L</mount>,
 or any other libguestfs program apart from guestfish and guestmount.
@@ -1081,6 +1086,15 @@ enough.
 
 =over 4
 
+=item $HOME/.libguestfs-tools.rc
+
+=item /etc/libguestfs-tools.conf
+
+This configuration file controls the default read-only or read-write
+mode (I<--ro> or I<--rw>).
+
+See L</OPENING DISKS FOR READ AND WRITE>.
+
 =item $HOME/.guestfish
 
 If compiled with GNU readline support, then the command history
@@ -1156,7 +1170,7 @@ Richard W.M. Jones (C<rjones at redhat dot com>)
 
 =head1 COPYRIGHT
 
-Copyright (C) 2009-2010 Red Hat Inc.
+Copyright (C) 2009-2011 Red Hat Inc.
 L<http://libguestfs.org/>
 
 This program is free software; you can redistribute it and/or modify
diff --git a/fish/libguestfs-tools.conf b/fish/libguestfs-tools.conf
new file mode 100644
index 00000000..7e604684
--- /dev/null
+++ b/fish/libguestfs-tools.conf
@@ -0,0 +1,24 @@
+# /etc/libguestfs-tools.conf or .libguestfs-tools.rc
+#
+# This configuration file changes the defaults for the following programs:
+#   * guestfish
+#   * guestmount
+#   * virt-rescue
+# For more information on these programs, read the manual pages
+# (guestfish(1) etc).
+#
+# /etc/libguestfs-tools.conf is the global configuration file for all
+# of the above programs.  Local users can override the global
+# configuration by copying this file into '.libguestfs-tools.rc' in
+# their home directory and modifying it accordingly.
+#
+# This file is parsed by the libconfig library.  For more information
+# about the format, see
+# http://www.hyperrealm.com/libconfig/libconfig_manual.html
+
+# Uncomment the following line to make guestfish, guestmount,
+# virt-rescue be read-only by default (as if the --ro flag was given).
+# If it is commented out then the default is read-write.  Note that
+# the semi-colon (;) is required.
+
+#read_only = true;
diff --git a/fish/options.h b/fish/options.h
index e0cad013..9b9aee5e 100644
--- a/fish/options.h
+++ b/fish/options.h
@@ -112,6 +112,9 @@ struct mp {
   char *options;
 };
 
+/* in config.c */
+extern void parse_config (void);
+
 /* in inspect.c */
 extern void inspect_mount (void);
 extern void print_inspect_prompt (void);