[gparted/ro-mount: 2/5] Add parsing of read-only mount option into mount maps (#10)

[Mike Fleetwood <mfleetwo src gnome org>]

commit 1b7be5fc0275e55e7601b2375f26d54d6e0c7c28
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Mon Sep 17 14:21:50 2018 +0100

    Add parsing of read-only mount option into mount maps (#10)
    
    Parse file system mount options string from file and mount command
    output, extracting the setting for the read-only flag and storing in the
    mount maps.  Read-only flag for swap space gets the struct MountEntry
    constructor default of false.
    
    Closes #10 - Gparted fails to resize btrfs partition that is mounted
                 read-only

 include/Mount_Info.h |  8 +++++---
 src/Mount_Info.cc    | 44 ++++++++++++++++++++++++++++++++++----------
 2 files changed, 39 insertions(+), 13 deletions(-)
---
diff --git a/include/Mount_Info.h b/include/Mount_Info.h
index b37395ae..f3d2ca1b 100644
--- a/include/Mount_Info.h
+++ b/include/Mount_Info.h
@@ -55,9 +55,11 @@ public:
 
 private:
        static void read_mountpoints_from_file( const Glib::ustring & filename, MountMapping & map );
-       static void add_node_and_mountpoint( MountMapping & map,
-                                            Glib::ustring & node,
-                                            Glib::ustring & mountpoint );
+       static void add_mountpoint_entry( MountMapping & map,
+                                         Glib::ustring & node,
+                                         Glib::ustring & mountpoint,
+                                         bool readonly );
+       static bool parse_readonly_flag( const Glib::ustring & str );
        static void read_mountpoints_from_file_swaps( const Glib::ustring & filename,
                                                      MountMapping & map );
        static bool have_rootfs_dev( MountMapping & map );
diff --git a/src/Mount_Info.cc b/src/Mount_Info.cc
index 8196baea..50e6dca6 100644
--- a/src/Mount_Info.cc
+++ b/src/Mount_Info.cc
@@ -31,10 +31,11 @@ namespace GParted
 
 // Associative array mapping currently mounted devices to one or more mount points.
 // E.g.
-//     //                                         readonly, mountpoints
-//     mount_info[BlockSpecial("/dev/sda1")] -> {false   , ["/boot"]}
-//     mount_info[BlockSpecial("/dev/sda2")] -> {false   , [""]     }  // swap
-//     mount_info[BlockSpecial("/dev/sda3")] -> {false   , ["/"]    }
+//     //                                        readonly, mountpoints
+//     mount_info[BlockSpecial("/dev/sda1")] -> {false   , ["/boot"]                       }
+//     mount_info[BlockSpecial("/dev/sda2")] -> {false   , [""]                            }  // swap
+//     mount_info[BlockSpecial("/dev/sda3")] -> {false   , ["/"]                           }
+//     mount_info[BlockSpecial("/dev/sr0")]  -> {true    , ["/run/media/user/GParted-live"]}
 static Mount_Info::MountMapping mount_info;
 
 // Associative array mapping configured devices to one or more mount points read from
@@ -137,20 +138,42 @@ void Mount_Info::read_mountpoints_from_file( const Glib::ustring & filename, Mou
                        node = FS_Info::get_path_by_label( label );
 
                if ( ! node.empty() )
-                       add_node_and_mountpoint( map, node, mountpoint );
+                       add_mountpoint_entry( map, node, mountpoint, parse_readonly_flag( p->mnt_opts ) );
        }
 
        endmntent( fp );
 }
 
-void Mount_Info::add_node_and_mountpoint( MountMapping & map,
-                                          Glib::ustring & node,
-                                          Glib::ustring & mountpoint )
+void Mount_Info::add_mountpoint_entry( MountMapping & map,
+                                       Glib::ustring & node,
+                                       Glib::ustring & mountpoint,
+                                       bool readonly )
 {
        // Only add node path if mount point exists
        if ( file_test( mountpoint, Glib::FILE_TEST_EXISTS ) )
+       {
                // Map::operator[] default constructs MountEntry for new keys (nodes).
-               map[BlockSpecial( node )].mountpoints.push_back( mountpoint );
+               MountEntry & mountentry = map[BlockSpecial( node )];
+               mountentry.readonly = readonly;
+               mountentry.mountpoints.push_back( mountpoint );
+       }
+}
+
+// Parse file system mount options string into read-only boolean
+// E.g. "ro,relatime" -> true
+//      "rw,seclabel,relatime,attr2,inode64,noquota" -> false
+bool Mount_Info::parse_readonly_flag( const Glib::ustring & str )
+{
+       std::vector<Glib::ustring> mntopts;
+       Utils::split( str, mntopts, "," );
+       for ( unsigned int i = 0 ; i < mntopts.size() ; i ++ )
+       {
+               if ( mntopts[i] == "rw" )
+                       return false;
+               else if ( mntopts[i] == "ro" )
+                       return true;
+       }
+       return false;  // Default is read-write mount
 }
 
 void Mount_Info::read_mountpoints_from_file_swaps( const Glib::ustring & filename, MountMapping & map )
@@ -200,8 +223,9 @@ void Mount_Info::read_mountpoints_from_mount_command( MountMapping & map )
                        // Process line like "/dev/sda3 on / type ext4 (rw)"
                        Glib::ustring node = Utils::regexp_label( lines[ i ], "^([^[:blank:]]+) on " );
                        Glib::ustring mountpoint = Utils::regexp_label( lines[ i ], "^[^[:blank:]]+ on 
([^[:blank:]]+) " );
+                       Glib::ustring mntopts = Utils::regexp_label( lines[i], " type [^[:blank:]]+ 
\\(([^\\)]*)\\)" );
                        if ( ! node.empty() )
-                               add_node_and_mountpoint( map, node, mountpoint );
+                               add_mountpoint_entry( map, node, mountpoint, parse_readonly_flag( mntopts ) );
                }
        }
 }