unit: introduce ConditionPathIsReadWrite

man/systemd.unit.xml

@@ -684,6 +684,7 @@
                                 <term><varname>ConditionPathIsDirectory=</varname></term>
                                 <term><varname>ConditionPathIsSymbolicLink=</varname></term>
                                 <term><varname>ConditionPathIsMountPoint=</varname></term>
+                                <term><varname>ConditionPathIsReadWrite=</varname></term>
                                 <term><varname>ConditionDirectoryNotEmpty=</varname></term>
                                 <term><varname>ConditionFileIsExecutable=</varname></term>
                                 <term><varname>ConditionKernelCommandLine=</varname></term>
@@ -731,7 +732,13 @@
                                 <varname>ConditionPathExists=</varname>
                                 but verifies whether a certain path
                                 exists and is a mount
-                                point. <varname>ConditionFileIsExecutable=</varname>
+                                point. <varname>ConditionPathIsReadWrite=</varname>
+                                is similar to
+                                <varname>ConditionPathExists=</varname>
+                                but verifies whether the underlying
+                                file system is read and writable
+                                (i.e. not mounted
+                                read-only). <varname>ConditionFileIsExecutable=</varname>
                                 is similar to
                                 <varname>ConditionPathExists=</varname>
                                 but verifies whether a certain path
@@ -780,12 +787,13 @@
                                 <varname>openvz</varname>,
                                 <varname>lxc</varname>,
                                 <varname>lxc-libvirt</varname>,
-                                <varname>systemd-nspawn</varname> to test
+                                <varname>systemd-nspawn</varname> to
-                                against a specific implementation. If
+                                test against a specific
-                                multiple virtualization technologies
+                                implementation. If multiple
-                                are nested only the innermost is
+                                virtualization technologies are nested
-                                considered. The test may be negated by
+                                only the innermost is considered. The
-                                prepending an exclamation mark.
+                                test may be negated by prepending an
+                                exclamation mark.
                                 <varname>ConditionSecurity=</varname>
                                 may be used to check whether the given
                                 security module is enabled on the

src/core/condition.c

@@ -24,6 +24,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <sys/capability.h>
+#include <sys/statvfs.h>
 
 #ifdef HAVE_SELINUX
 #include <selinux/selinux.h>
@@ -222,6 +223,15 @@ bool condition_test(Condition *c) {
         case CONDITION_PATH_IS_MOUNT_POINT:
                 return (path_is_mount_point(c->parameter, true) > 0) == !c->negate;
 
+        case CONDITION_PATH_IS_READ_WRITE: {
+                struct statvfs st;
+
+                if (statvfs(c->parameter, &st) < 0)
+                        return c->negate;
+
+                return !(st.f_flag & ST_RDONLY) == !c->negate;
+        }
+
         case CONDITION_DIRECTORY_NOT_EMPTY: {
                 int k;
 
@@ -313,6 +323,7 @@ static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
         [CONDITION_PATH_IS_DIRECTORY] = "ConditionPathIsDirectory",
         [CONDITION_PATH_IS_SYMBOLIC_LINK] = "ConditionPathIsSymbolicLink",
         [CONDITION_PATH_IS_MOUNT_POINT] = "ConditionPathIsMountPoint",
+        [CONDITION_PATH_IS_READ_WRITE] = "ConditionPathIsReadWrite",
         [CONDITION_DIRECTORY_NOT_EMPTY] = "ConditionDirectoryNotEmpty",
         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
         [CONDITION_VIRTUALIZATION] = "ConditionVirtualization",

src/core/condition.h

@@ -32,6 +32,7 @@ typedef enum ConditionType {
         CONDITION_PATH_IS_DIRECTORY,
         CONDITION_PATH_IS_SYMBOLIC_LINK,
         CONDITION_PATH_IS_MOUNT_POINT,
+        CONDITION_PATH_IS_READ_WRITE,
         CONDITION_DIRECTORY_NOT_EMPTY,
         CONDITION_FILE_IS_EXECUTABLE,
         CONDITION_KERNEL_COMMAND_LINE,

src/load-fragment-gperf.gperf.m4

@@ -118,6 +118,7 @@ Unit.ConditionPathExistsGlob,    config_parse_unit_condition_path,   CONDITION_P
 Unit.ConditionPathIsDirectory,   config_parse_unit_condition_path,   CONDITION_PATH_IS_DIRECTORY,   0
 Unit.ConditionPathIsSymbolicLink,config_parse_unit_condition_path,   CONDITION_PATH_IS_SYMBOLIC_LINK,0
 Unit.ConditionPathIsMountPoint,  config_parse_unit_condition_path,   CONDITION_PATH_IS_MOUNT_POINT, 0
+Unit.ConditionPathIsReadWrite,   config_parse_unit_condition_path,   CONDITION_PATH_IS_READ_WRITE,  0
 Unit.ConditionDirectoryNotEmpty, config_parse_unit_condition_path,   CONDITION_DIRECTORY_NOT_EMPTY, 0
 Unit.ConditionFileIsExecutable,  config_parse_unit_condition_path,   CONDITION_FILE_IS_EXECUTABLE,  0
 Unit.ConditionKernelCommandLine, config_parse_unit_condition_string, CONDITION_KERNEL_COMMAND_LINE, 0