[preservefiles] Introduce the notion of optionally-preserved files

src/modules/preservefiles/Item.cpp

@@ -12,6 +12,7 @@
 #include "utils/CalamaresUtilsSystem.h"
 #include "utils/Logger.h"
 #include "utils/Units.h"
+#include "utils/Variant.h"
 
 #include <QFile>
 
@@ -56,7 +57,7 @@ Item::fromVariant( const QVariant& v, const CalamaresUtils::Permissions& default
         QString filename = v.toString();
         if ( !filename.isEmpty() )
         {
-            return { filename, filename, defaultPermissions, ItemType::Path };
+            return { filename, filename, defaultPermissions, ItemType::Path, false };
         }
         else
         {
@@ -70,6 +71,7 @@ Item::fromVariant( const QVariant& v, const CalamaresUtils::Permissions& default
 
         CalamaresUtils::Permissions perm( defaultPermissions );
         ItemType t = ItemType::None;
+        bool optional = CalamaresUtils::getBool( map, "optional", false );
 
         {
             QString perm_string = map[ "perm" ].toString();
@@ -99,11 +101,11 @@ Item::fromVariant( const QVariant& v, const CalamaresUtils::Permissions& default
         switch ( t )
         {
         case ItemType::Config:
-            return { QString(), dest, perm, t };
+            return { QString(), dest, perm, t, optional };
         case ItemType::Log:
-            return { QString(), dest, perm, t };
+            return { QString(), dest, perm, t, optional };
         case ItemType::Path:
-            return { map[ "src" ].toString(), dest, perm, t };
+            return { map[ "src" ].toString(), dest, perm, t, optional };
         case ItemType::None:
             cWarning() << "Invalid type for preservefiles, item" << v;
             return {};

src/modules/preservefiles/Item.h

@@ -35,14 +35,16 @@ class Item
     QString source;
     QString dest;
     CalamaresUtils::Permissions perm;
-    ItemType m_type;
+    ItemType m_type = ItemType::None;
+    bool m_optional = false;
 
 public:
-    Item( const QString& src, const QString& d, CalamaresUtils::Permissions p, ItemType t )
+    Item( const QString& src, const QString& d, CalamaresUtils::Permissions p, ItemType t, bool optional )
         : source( src )
         , dest( d )
         , perm( std::move( p ) )
         , m_type( t )
+        , m_optional( optional )
     {
     }
 
@@ -53,6 +55,7 @@ public:
 
     operator bool() const { return m_type != ItemType::None; }
     ItemType type() const { return m_type; }
+    bool isOptional() const { return m_optional; }
 
     bool exec( const std::function< QString( QString ) >& replacements ) const;
 

src/modules/preservefiles/PreserveFiles.cpp

@@ -72,7 +72,9 @@ PreserveFiles::exec()
             ++count;
             continue;
         }
-        if ( it.exec( atReplacements ) )
+        // Try to preserve the file. If it's marked as optional, count it
+        // as a success regardless.
+        if ( it.exec( atReplacements ) || it.isOptional() )
         {
             ++count;
         }

src/modules/preservefiles/preservefiles.conf

@@ -7,24 +7,38 @@
 # the list should have one of these forms:
 #
 # - an absolute path (probably within the host system). This will be preserved
-#   as the same path within the target system (chroot). If, globally, dontChroot
-#   is true, then these items are ignored (since the destination is the same
-#   as the source).
+#   as the same path within the target system (chroot). If, globally,
+#   *dontChroot* is true, then these items will be ignored (since the
+#   destination is the same as the source).
 # - a map with a *dest* key. The *dest* value is a path interpreted in the
 #   target system (if the global *dontChroot* is true, then the host is the
-#   target as well). Relative paths are not recommended. There are three
-#   possible other keys in the map:
+#   target as well). Relative paths are not recommended. There are two
+#   ways to select the source data for the file:
 #   - *from*, which must have one of the values, below; it is used to
 #     preserve files whose pathname is known to Calamares internally.
 #   - *src*, to refer to a path interpreted in the host system. Relative
 #     paths are not recommended, and are interpreted relative to where
 #     Calamares is being run.
+#   Exactly one of the two source keys (either *from* or *src*) must be set.
+#
+#   Special values for the key *from* are:
+#     - *log*, for the complete log file (up to the moment the preservefiles
+#       module is run),
+#     - *config*, for a JSON dump of the contents of global storage.
+#       Note that this may contain sensitive information, and should be
+#       given restrictive permissions.
+#
+#  A map with a *dest* key can have these additional fields:
 #   - *perm*, is a colon-separated tuple of <user>:<group>:<mode>
 #     where <mode> is in octal (e.g. 4777 for wide-open, 0400 for read-only
 #     by owner). If set, the file's ownership and permissions are set to
 #     those values within the target system; if not set, no permissions
 #     are changed.
-#   Exactly one of the two source keys (either *from* or *src*) must be set.
+#   - *optional*, is a boolean; if this is set to `true` then failure to
+#     preserve the file will **not** be counted as a failure of the
+#     module, and installation will proceed. Set this for files that might
+#     not exist in the host system (e.g. nvidia configuration files that
+#     are created in some boot scenarios and not in others).
 #
 # The target path (*dest*) is modified as follows:
 #   - `@@ROOT@@` is replaced by the path to the target root (may be /).
@@ -33,12 +47,6 @@
 #   - `@@USER@@` is replaced by the username entered by on the user
 #       page (may be empty, for instance if no user page is enabled)
 #
-# Special values for the key *from* are:
-#   - *log*, for the complete log file (up to the moment the preservefiles
-#     module is run),
-#   - *config*, for a JSON dump of the contents of global storage.
-#     Note that this may contain sensitive information, and should be
-#     given restrictive permissions.
 #
 #
 files:
@@ -48,6 +56,9 @@ files:
   - from: config
     dest: /var/log/Calamares-install.json
     perm: root:wheel:600
+# - src: /var/log/nvidia.conf
+#   dest: /var/log/Calamares-nvidia.conf
+#   optional: true
 
 # The *perm* key contains a default value to apply to all files listed
 # above that do not have a *perm* key of their own. If not set,