# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1641336236 -3600
# Node ID 9cfd2fb90c331d63c10e799500c6620fdba8e327
# Parent  ded81f25f1aae24d7f01f88f83b2d0e10a8ea1f4
Added initial support for file removal.

diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsclient/include/fsclient/client.h
--- a/libfsclient/include/fsclient/client.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsclient/include/fsclient/client.h	Tue Jan 04 23:43:56 2022 +0100
@@ -47,6 +47,11 @@
 long client_pipe(file_t **reader, file_t **writer, flags_t flags);
 long client_pipe_using(file_t **reader, file_t **writer, flags_t flags, l4_cap_idx_t server);
 
+/* Other file operations. */
+
+long client_remove(const char *name);
+long client_remove_using(const char *name, l4_cap_idx_t server);
+
 /* File and region operations. */
 
 long client_flush(file_t *file);
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsclient/include/fsclient/file.h
--- a/libfsclient/include/fsclient/file.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsclient/include/fsclient/file.h	Tue Jan 04 23:43:56 2022 +0100
@@ -84,11 +84,13 @@
 
 void file_close(file_t *file);
 long file_open(file_t *file, const char *filename, flags_t flags, l4_cap_idx_t server);
+long file_remove(const char *filename, l4_cap_idx_t server);
 
 /* File lifecycle operations. */
 
 long file_context(file_t *file, l4_cap_idx_t server);
 long file_context_open(file_t *file, flags_t flags, file_t *context);
+long file_context_remove(file_t *context);
 void file_init(file_t *file);
 
 /* File and region operations. */
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsclient/lib/src/client.cc
--- a/libfsclient/lib/src/client.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsclient/lib/src/client.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -359,6 +359,24 @@
 
 
 
+/* Remove a file from the filesystem. */
+
+long client_remove(const char *name)
+{
+  l4_cap_idx_t server = l4re_env_get_cap("server");
+
+  return client_remove_using(name, server);
+}
+
+/* Remove a file from the filesystem via a named capability. */
+
+long client_remove_using(const char *name, l4_cap_idx_t server)
+{
+  return file_remove(name, server);
+}
+
+
+
 /* Obtain the current region of a pipe. */
 
 long client_current_region(file_t *file)
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsclient/lib/src/file.cc
--- a/libfsclient/lib/src/file.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsclient/lib/src/file.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -137,6 +137,30 @@
   return err;
 }
 
+/* Remove a file from the filesystem. This is a convenience function invoking
+   file_context and file_context_remove. */
+
+long file_remove(const char *filename, l4_cap_idx_t server)
+{
+  file_t context;
+  long err;
+
+  err = file_context(&context, server);
+  if (err)
+    return err;
+
+  if (!file_string_set(&context, filename, 0, NULL))
+    return -L4_ENOMEM;
+
+  err = file_context_remove(&context);
+
+  /* Close the context, although a separate mechanism could permit contexts to
+     open several files. */
+
+  file_close(&context);
+  return err;
+}
+
 
 
 /* Initialise a file structure for a context obtained from the given server
@@ -179,6 +203,14 @@
   return openercontext.open(flags, &file->size, &file->ref, &file->object_flags);
 }
 
+/* Remove a file using the given context. */
+
+long file_context_remove(file_t *context)
+{
+  client_OpenerContext openercontext(context->ref);
+  return openercontext.remove();
+}
+
 
 
 /* Flush populated data and obtain an updated file size and populated data
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/accessor.h
--- a/libfsserver/include/fsserver/accessor.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/accessor.h	Tue Jan 04 23:43:56 2022 +0100
@@ -57,6 +57,10 @@
     virtual void fill(Flexpage *flexpage);
 
     virtual void flush(Flexpage *flexpage);
+
+    /* Lifecycle methods. */
+
+    virtual void remove();
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/ext2_file_accessor.h
--- a/libfsserver/include/fsserver/ext2_file_accessor.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/ext2_file_accessor.h	Tue Jan 04 23:43:56 2022 +0100
@@ -51,6 +51,8 @@
     virtual offset_t get_size();
 
     virtual void set_size(offset_t size);
+
+    virtual void remove();
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/ext2_file_opener.h
--- a/libfsserver/include/fsserver/ext2_file_opener.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/ext2_file_opener.h	Tue Jan 04 23:43:56 2022 +0100
@@ -62,6 +62,10 @@
     virtual long make_directory_accessor(const char *path, flags_t flags,
                                          fileid_t fileid,
                                          DirectoryAccessor **accessor);
+
+    virtual long remove_object(const char *path, fileid_t fileid);
+
+    virtual long unlink_object(const char *path, fileid_t fileid);
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/ext2_file_operations.h
--- a/libfsserver/include/fsserver/ext2_file_operations.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/ext2_file_operations.h	Tue Jan 04 23:43:56 2022 +0100
@@ -61,23 +61,33 @@
 
     bool is_file(ext2_ino_t ino_file);
 
+    void close_file(ext2_file_t file);
+
     long create_file(ext2_ino_t ino_parent, const char *filename, user_t user,
                      ext2_ino_t *ino);
 
     long find_file(const char *path, ext2_ino_t *ino, const char **remaining);
 
-    void close_file(ext2_file_t file);
+    long open_file(ext2_ino_t ino, ext2_file_t *file);
+
+    long remove(ext2_ino_t ino);
 
-    long open_file(ext2_ino_t ino, ext2_file_t *file);
+    long unlink(ext2_ino_t ino_parent, ext2_ino_t ino);
+
+    /* File property methods. */
 
     offset_t get_size(ext2_file_t file);
 
     void set_size(ext2_file_t file, offset_t size);
 
+    /* File access methods. */
+
     offset_t read_file(ext2_file_t file, offset_t filepos, void *addr, offset_t size);
 
     void write_file(ext2_file_t file, offset_t filepos, const void *addr, offset_t size);
 
+    /* Directory access. */
+
     long directory_iterate(ext2_ino_t dir,
                            int func(struct ext2_dir_entry *, int, int, char *, void *),
                            void *priv_data);
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/file_opening.h
--- a/libfsserver/include/fsserver/file_opening.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/file_opening.h	Tue Jan 04 23:43:56 2022 +0100
@@ -43,6 +43,10 @@
     virtual long make_directory_accessor(const char *path, flags_t flags,
                                          fileid_t fileid,
                                          DirectoryAccessor **accessor) = 0;
+
+    virtual long remove_object(const char *path, fileid_t fileid) = 0;
+
+    virtual long unlink_object(const char *path, fileid_t fileid) = 0;
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/file_provider.h
--- a/libfsserver/include/fsserver/file_provider.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/file_provider.h	Tue Jan 04 23:43:56 2022 +0100
@@ -44,6 +44,8 @@
 
     virtual long make_resource(offset_t *size, object_flags_t *object_flags,
                                Resource **resource);
+
+    virtual void remove();
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/host_file_opener.h
--- a/libfsserver/include/fsserver/host_file_opener.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/host_file_opener.h	Tue Jan 04 23:43:56 2022 +0100
@@ -72,6 +72,10 @@
     virtual long make_directory_accessor(const char *path, flags_t flags,
                                          fileid_t fileid,
                                          DirectoryAccessor **accessor);
+
+    virtual long remove_object(const char *path, fileid_t fileid);
+
+    virtual long unlink_object(const char *path, fileid_t fileid);
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/opener_context_resource.h
--- a/libfsserver/include/fsserver/opener_context_resource.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/opener_context_resource.h	Tue Jan 04 23:43:56 2022 +0100
@@ -60,6 +60,8 @@
     long open(flags_t flags, offset_t *size, l4_cap_idx_t *file,
               object_flags_t *object_flags);
 
+    long remove();
+
     /* Pager/dataspace methods. */
 
     long map(unsigned long offset, address_t hot_spot, map_flags_t flags,
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/opener_resource.h
--- a/libfsserver/include/fsserver/opener_resource.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/opener_resource.h	Tue Jan 04 23:43:56 2022 +0100
@@ -63,6 +63,8 @@
     long open(const char *path, flags_t flags, offset_t *size,
               l4_cap_idx_t *cap, object_flags_t *object_flags);
 
+    long remove(const char *path);
+
     /* Opener interface methods. */
 
     long context(l4_cap_idx_t *context);
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/provider.h
--- a/libfsserver/include/fsserver/provider.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/provider.h	Tue Jan 04 23:43:56 2022 +0100
@@ -35,6 +35,7 @@
 protected:
     fileid_t _fileid;
     ProviderRegistry *_registry;
+    bool _remove = false;
 
 public:
     explicit Provider(fileid_t fileid, ProviderRegistry *registry);
@@ -45,6 +46,14 @@
 
     virtual long make_resource(offset_t *size, object_flags_t *object_flags,
                                Resource **resource) = 0;
+
+    /* Lifecycle methods. */
+
+    virtual bool removal_pending();
+
+    virtual void remove();
+
+    virtual void remove_pending(bool remove);
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/provider_registry.h
--- a/libfsserver/include/fsserver/provider_registry.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/provider_registry.h	Tue Jan 04 23:43:56 2022 +0100
@@ -49,6 +49,7 @@
     ProviderMapping _providers;
     std::mutex _lock;
 
+public:
     /* Filesystem object access. */
 
     Provider *get(fileid_t fileid);
@@ -57,7 +58,6 @@
 
     void set(fileid_t fileid, Provider *obj);
 
-public:
     /* Methods for resources. */
 
     void detach(fileid_t fileid, Provider *mapper);
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/resource_registry.h
--- a/libfsserver/include/fsserver/resource_registry.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/resource_registry.h	Tue Jan 04 23:43:56 2022 +0100
@@ -56,7 +56,8 @@
 public:
     explicit ResourceRegistry(Pages *pages);
 
-    /* Resource discovery methods. */
+    /* Provider discovery methods.
+       NOTE: To be protected, potentially. */
 
     long find_provider(fileid_t fileid, Provider **provider);
 
@@ -65,6 +66,10 @@
     long get_resource(FileOpening *opening, const char *path, flags_t flags,
                       offset_t *size, object_flags_t *object_flags,
                       Resource **resource);
+
+    /* Provider manipulation methods. */
+
+    long remove_provider(FileOpening *opening, const char *path);
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/include/fsserver/test_file_opener.h
--- a/libfsserver/include/fsserver/test_file_opener.h	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/include/fsserver/test_file_opener.h	Tue Jan 04 23:43:56 2022 +0100
@@ -53,6 +53,10 @@
     virtual long make_directory_accessor(const char *path, flags_t flags,
                                          fileid_t fileid,
                                          DirectoryAccessor **accessor);
+
+    virtual long remove_object(const char *path, fileid_t fileid);
+
+    virtual long unlink_object(const char *path, fileid_t fileid);
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/files/ext2_file_accessor.cc
--- a/libfsserver/lib/files/ext2_file_accessor.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/files/ext2_file_accessor.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -100,4 +100,15 @@
     _ops->write_file(_file, filepos, (const void *) addr, populated_size);
 }
 
+
+
+/* Lifecycle methods. */
+
+/* Remove the underlying filesystem object. */
+
+void Ext2FileAccessor::remove()
+{
+    _ops->remove(fileid);
+}
+
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/files/ext2_file_opener.cc
--- a/libfsserver/lib/files/ext2_file_opener.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/files/ext2_file_opener.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -120,4 +120,26 @@
     return L4_EOK;
 }
 
+/* Remove a filesystem object. */
+
+long Ext2FileOpener::remove_object(const char *path, fileid_t fileid)
+{
+    (void) path;
+
+    return _ops->remove((ext2_ino_t) fileid);
+}
+
+/* Unlink a filesystem object. */
+
+long Ext2FileOpener::unlink_object(const char *path, fileid_t fileid)
+{
+    fileid_t parent;
+    long err = get_parent(path, &parent);
+
+    if (err)
+        return err;
+
+    return _ops->unlink((ext2_ino_t) parent, (ext2_ino_t) fileid);
+}
+
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/files/ext2_file_operations.cc
--- a/libfsserver/lib/files/ext2_file_operations.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/files/ext2_file_operations.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -113,6 +113,38 @@
     return L4_EOK;
 }
 
+/* Remove an object from a directory. */
+
+long Ext2FileOperations::remove(ext2_ino_t ino)
+{
+    std::lock_guard<std::mutex> guard(_lock);
+
+    errcode_t retval = image_remove_by_inode(_fs, ino);
+
+    // NOTE: Map error conditions.
+
+    if (retval)
+        return -L4_EIO;
+
+    return L4_EOK;
+}
+
+/* Unlink an object from a directory. */
+
+long Ext2FileOperations::unlink(ext2_ino_t ino_parent, ext2_ino_t ino)
+{
+    std::lock_guard<std::mutex> guard(_lock);
+
+    errcode_t retval = image_unlink_by_inode(_fs, ino_parent, ino);
+
+    // NOTE: Map error conditions.
+
+    if (retval)
+        return -L4_EIO;
+
+    return L4_EOK;
+}
+
 /* Obtain the size of a file. */
 
 offset_t Ext2FileOperations::get_size(ext2_file_t file)
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/files/file_provider.cc
--- a/libfsserver/lib/files/file_provider.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/files/file_provider.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -73,4 +73,13 @@
     return L4_EOK;
 }
 
+/* Lifecycle methods. */
+
+/* Remove the file using the accessor. */
+
+void FileProvider::remove()
+{
+    _mapper->accessor()->remove();
+}
+
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/files/host_file_opener.cc
--- a/libfsserver/lib/files/host_file_opener.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/files/host_file_opener.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -20,6 +20,7 @@
  */
 
 #include <sys/stat.h>
+#include <unistd.h>
 
 #include <fsclient/client.h>
 
@@ -131,4 +132,39 @@
     return L4_EOK;
 }
 
+/* Remove a filesystem object. */
+
+long HostFileOpener::remove_object(const char *path, fileid_t fileid)
+{
+    (void) path; (void) fileid;
+    return L4_EOK;
+}
+
+/* Unlink a filesystem object. */
+
+long HostFileOpener::unlink_object(const char *path, fileid_t fileid)
+{
+    /* Ignore the fileid and always use the path. */
+
+    (void) fileid;
+
+    // NOTE: Return code may need converting.
+
+    int err = unlink(path);
+
+    if (err)
+        return err;
+
+    /* Remove the file identifier mapping. */
+
+    std::string s(path);
+
+    HostFileIdentifiers::iterator it = _fileids.find(s);
+
+    if (it != _fileids.end())
+        _fileids.erase(it);
+
+    return L4_EOK;
+}
+
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/files/opener_context_resource.cc
--- a/libfsserver/lib/files/opener_context_resource.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/files/opener_context_resource.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -78,4 +78,14 @@
     return _opener->open(path, flags, size, file, object_flags);
 }
 
+long OpenerContextResource::remove()
+{
+    char *path = get_path();
+
+    if (path == NULL)
+        return -L4_EINVAL;
+
+    return _opener->remove(path);
+}
+
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/files/opener_resource.cc
--- a/libfsserver/lib/files/opener_resource.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/files/opener_resource.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -74,7 +74,8 @@
 }
 
 /* Obtain any active parent directory for a path, notifying its subscribers of
-   the file opening event. */
+   the file opening event.
+   NOTE: This might need to happen in the registry due to concurrency issues. */
 
 long OpenerResource::notify_parent(const char *path)
 {
@@ -124,6 +125,13 @@
     return ResourceServer(resource).start_thread(cap);
 }
 
+/* Request the removal of the named filesystem object. */
+
+long OpenerResource::remove(const char *path)
+{
+    return _registry->remove_provider(this, path);
+}
+
 
 
 /* Opener interface methods. */
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/files/test_file_opener.cc
--- a/libfsserver/lib/files/test_file_opener.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/files/test_file_opener.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -79,4 +79,20 @@
     return -L4_EIO;
 }
 
+/* Remove a filesystem object. */
+
+long TestFileOpener::remove_object(const char *path, fileid_t fileid)
+{
+    (void) path; (void) fileid;
+    return L4_EOK;
+}
+
+/* Unlink a filesystem object. */
+
+long TestFileOpener::unlink_object(const char *path, fileid_t fileid)
+{
+    (void) path; (void) fileid;
+    return -L4_EIO;
+}
+
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/generic/accessor.cc
--- a/libfsserver/lib/generic/accessor.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/generic/accessor.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -76,4 +76,12 @@
     (void) flexpage;
 }
 
+/* Lifecycle methods. */
+
+/* Remove a filesystem object. */
+
+void Accessor::remove()
+{
+}
+
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/generic/provider.cc
--- a/libfsserver/lib/generic/provider.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/generic/provider.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -37,4 +37,18 @@
     return _registry;
 }
 
+bool Provider::removal_pending()
+{
+    return _remove;
+}
+
+void Provider::remove()
+{
+}
+
+void Provider::remove_pending(bool remove)
+{
+    _remove = remove;
+}
+
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/generic/provider_registry.cc
--- a/libfsserver/lib/generic/provider_registry.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/generic/provider_registry.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -74,7 +74,16 @@
     std::lock_guard<std::mutex> guard(_lock);
 
     if (!provider->detach())
+    {
+        /* Remove any underlying object if pending. */
+
+        if (provider->removal_pending())
+            provider->remove();
+
+        /* Remove from the registry. */
+
         remove(fileid, provider);
+    }
 }
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libfsserver/lib/generic/resource_registry.cc
--- a/libfsserver/lib/generic/resource_registry.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/libfsserver/lib/generic/resource_registry.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -169,4 +169,44 @@
     return provider->make_resource(size, object_flags, resource);
 }
 
+/* Request the removal of a filesystem object through any active provider. */
+
+long ResourceRegistry::remove_provider(FileOpening *opening, const char *path)
+{
+    std::lock_guard<std::mutex> guard(_lock);
+
+    /* Obtain an identifier for any recognised object. */
+
+    fileid_t fileid;
+    long err = opening->get_fileid(path, 0, &fileid);
+
+    if (err)
+        return err;
+
+    /* Obtain a provider for the object. */
+
+    Provider *provider;
+    err = find_provider(fileid, &provider);
+
+    if (err && (err != -L4_ENOENT))
+        return err;
+
+    /* Unlink the object regardless of whether it can be removed. */
+
+    err = opening->unlink_object(path, fileid);
+
+    if (err)
+        return err;
+
+    /* Without a provider being active, remove the object directly. */
+
+    if (err)
+        return opening->remove_object(path, fileid);
+
+    /* With a provider active, request the object's removal upon closure. */
+
+    provider->remove_pending(true);
+    return L4_EOK;
+}
+
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r ded81f25f1aa -r 9cfd2fb90c33 libsystypes/idl/opener_context.idl
--- a/libsystypes/idl/opener_context.idl	Tue Jan 04 23:27:53 2022 +0100
+++ b/libsystypes/idl/opener_context.idl	Tue Jan 04 23:43:56 2022 +0100
@@ -1,7 +1,8 @@
 #include <systypes/base.h>  /* flags_t, object_flags_t, offset_t */
 
-/* An interface providing a way of opening filesystem objects relying on a
-   dataspace to transfer filesystem paths. */
+/* An interface providing a way of opening or manipulating filesystem objects
+   relying on a dataspace to transfer filesystem paths specifying the objects
+   involved. */
 
 interface OpenerContext
 {
@@ -18,6 +19,10 @@
 
   [opcode(12)] void open(in flags_t flags, out offset_t size, out cap file,
                          out object_flags_t object_flags);
+
+  /* Remove a file using a path written to the context's dataspace. */
+
+  [opcode(14)] void remove();
 };
 
 /* vim: tabstop=2 expandtab shiftwidth=2
diff -r ded81f25f1aa -r 9cfd2fb90c33 tests/dstest_file_readdir_concurrent.cc
--- a/tests/dstest_file_readdir_concurrent.cc	Tue Jan 04 23:27:53 2022 +0100
+++ b/tests/dstest_file_readdir_concurrent.cc	Tue Jan 04 23:43:56 2022 +0100
@@ -79,6 +79,30 @@
   }
 }
 
+static long remove_file(char *filename, bool have_uid, sys_uid_t uid)
+{
+  /* With a user, open a user-specific file opener. */
+
+  if (have_uid)
+  {
+    l4_cap_idx_t opener = client_open_for_user((user_t) {uid, uid, 0022});
+
+    if (l4_is_invalid_cap(opener))
+    {
+      printf("Could not obtain opener for file.\n");
+      return -L4_EIO;
+    }
+
+    /* Invoke the remove method to remove the file. */
+
+    return client_remove_using(filename, opener);
+  }
+  else
+  {
+    return client_remove(filename);
+  }
+}
+
 
 
 int main(int argc, char *argv[])
@@ -108,7 +132,9 @@
   struct dirent *dirent;
   int filenum = 1000, remaining = 100;
   char buffer[strlen(filename) + strlen("/file-XXXX.txt") + 10];
+  char data[256];
   int found = 0;
+  file_t *files[100];
 
   while ((dirent = client_readdir(reader)) != NULL)
   {
@@ -129,6 +155,15 @@
         return 1;
       }
 
+      /* Write something to each file. */
+
+      sprintf(data, "Data in file-%d.txt", filenum - 1);
+      client_write(file, data, strlen(data));
+
+      /* Remember the file for later. */
+
+      files[remaining - 1] = file;
+
       remaining--;
     }
   }
@@ -155,6 +190,54 @@
 
   printf("Files found: %d\n", found);
 
+  /* Remove some files. */
+
+  for (filenum = 1000, remaining = 100; remaining > 0; remaining--)
+  {
+    sprintf(buffer, "%s/file-%d.txt", filename, filenum++);
+
+    long err = remove_file(buffer, have_uid, uid);
+
+    if (err)
+    {
+      printf("Could not remove file: %s\n", buffer);
+      return 1;
+    }
+  }
+
+  /* Re-read, counting files. */
+
+  reader = open_directory(filename, have_uid, uid);
+
+  if (reader == NULL)
+  {
+    printf("Could not read from directory.\n");
+    return 1;
+  }
+
+  found = 0;
+
+  while ((dirent = client_readdir(reader)) != NULL)
+  {
+    free(dirent);
+    found++;
+  }
+
+  printf("Files found: %d\n", found);
+
+  /* Read from the still-open but now removed files. */
+
+  for (remaining = 0; remaining < 100; remaining++)
+  {
+    file_t *file = files[remaining];
+
+    client_seek(file, SEEK_SET, 0);
+    offset_t nread = client_read(file, data, 256);
+
+    data[nread] = '\0';
+    printf("Read: %s\n", data);
+  }
+
   return 0;
 }