# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1715266004 -7200
# Node ID 21004e509ba51102d7de5326ec01e7c1bcdf746e
# Parent  5b77aef76beac37486d5337021df112dae5dcd6b
Introduced a metadata channel for accessing directory listing content, along
with a directory rewinding operation that makes use of this channel.

diff -r 5b77aef76bea -r 21004e509ba5 libfsclient/include/fsclient/client.h
--- a/libfsclient/include/fsclient/client.h	Mon May 06 01:14:09 2024 +0200
+++ b/libfsclient/include/fsclient/client.h	Thu May 09 16:46:44 2024 +0200
@@ -46,7 +46,7 @@
 file_t *client_opendir(const char *name);
 file_t *client_opendir_using(const char *name, l4_cap_idx_t server);
 
-file_t *client_opendir_at(file_t *file);
+file_t *client_opendir_reader(file_t *file);
 file_t *client_reopen(file_t *file, flags_t flags);
 
 long client_pipe(file_t **reader, file_t **writer, flags_t flags);
@@ -96,6 +96,7 @@
 /* Directory reading operations. */
 
 struct dirent *client_readdir(file_t *file);
+void client_rewinddir(file_t *file);
 
 /* Notification operations. */
 
diff -r 5b77aef76bea -r 21004e509ba5 libfsclient/include/fsclient/file.h
--- a/libfsclient/include/fsclient/file.h	Mon May 06 01:14:09 2024 +0200
+++ b/libfsclient/include/fsclient/file.h	Thu May 09 16:46:44 2024 +0200
@@ -35,9 +35,11 @@
 
 EXTERN_C_BEGIN
 
+struct file_t;
+
 /* File access abstraction compatible with notifiable_base_t. */
 
-typedef struct
+typedef struct file_t
 {
   /* File object reference. */
 
@@ -77,6 +79,10 @@
 
   long error;
 
+  /* Metadata file object reference. */
+
+  struct file_t *metadata;
+
 } file_t;
 
 
diff -r 5b77aef76bea -r 21004e509ba5 libfsclient/lib/src/client.cc
--- a/libfsclient/lib/src/client.cc	Mon May 06 01:14:09 2024 +0200
+++ b/libfsclient/lib/src/client.cc	Thu May 09 16:46:44 2024 +0200
@@ -257,6 +257,9 @@
   if (file == NULL)
     return;
 
+  if (file->metadata != NULL)
+    client_close(file->metadata);
+
   file_flush(file);
   file_close(file);
   free(file);
@@ -348,33 +351,30 @@
 }
 
 /* Open a directory listing stream via the given named directory and a named
-   capability. */
+   capability, returning the directory object with a metadata file object
+   reference to the directory listing stream. */
 
 file_t *client_opendir_using(const char *name, l4_cap_idx_t server)
 {
   file_t *file = client_open_using(name, O_DIRECTORY, server);
 
-  if (file == NULL)
-    return NULL;
-
   /* Return the directory structure itself for error handling. */
 
   if (!client_opened(file))
     return file;
 
-  file_t *reader = client_opendir_at(file);
+  file->metadata = client_opendir_reader(file);
 
-  /* Release the directory and return the reader even if an error occurs. */
+  /* Return the directory even if an error occurs. */
 
-  client_close(file);
-  return reader;
+  return file;
 }
 
 
 
 /* Open a directory listing stream via the given directory. */
 
-file_t *client_opendir_at(file_t *file)
+file_t *client_opendir_reader(file_t *file)
 {
   file_t *reader = (file_t *) malloc(sizeof(file_t));
 
@@ -640,8 +640,11 @@
 
 struct dirent *client_readdir(file_t *file)
 {
+  if ((file == NULL) || (file->metadata == NULL))
+    return NULL;
+
   char buffer[DIRENT_CORE_SIZE];
-  offset_t nread = client_read(file, buffer, DIRENT_CORE_SIZE);
+  offset_t nread = client_read(file->metadata, buffer, DIRENT_CORE_SIZE);
 
   /* Stop if no new structure can be successfully read. */
 
@@ -666,7 +669,7 @@
 
   char *current = entry + DIRENT_CORE_SIZE;
 
-  nread = client_read(file, current, remaining);
+  nread = client_read(file->metadata, current, remaining);
 
   /* Stop if no complete structure can be successfully read. */
 
@@ -679,6 +682,18 @@
   return (struct dirent *) entry;
 }
 
+/* Rewind directory reading. */
+
+void client_rewinddir(file_t *file)
+{
+  if ((file == NULL) || (file->metadata == NULL))
+    return;
+
+  client_close(file->metadata);
+
+  file->metadata = client_opendir_reader(file);
+}
+
 
 
 /* Read from the filesystem object into the buffer provided. */
diff -r 5b77aef76bea -r 21004e509ba5 libfsclient/lib/src/file.cc
--- a/libfsclient/lib/src/file.cc	Mon May 06 01:14:09 2024 +0200
+++ b/libfsclient/lib/src/file.cc	Thu May 09 16:46:44 2024 +0200
@@ -91,6 +91,7 @@
   file->can_block = 0;
   file->flags = 0;
   file->error = 0;
+  file->metadata = NULL;
 
   /* Initialise the notifiable section of the structure. */
 
diff -r 5b77aef76bea -r 21004e509ba5 tests/dstest_file_readdir.cc
--- a/tests/dstest_file_readdir.cc	Mon May 06 01:14:09 2024 +0200
+++ b/tests/dstest_file_readdir.cc	Thu May 09 16:46:44 2024 +0200
@@ -1,7 +1,7 @@
 /*
  * Test directory reading operations.
  *
- * Copyright (C) 2020, 2021, 2022 Paul Boddie <paul@boddie.org.uk>
+ * Copyright (C) 2020, 2021, 2022, 2024 Paul Boddie <paul@boddie.org.uk>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
@@ -122,16 +122,36 @@
     return 1;
   }
 
+  char *name = NULL;
+
   dirent = client_readdir(reader);
 
   if (dirent != NULL)
   {
+    name = strdup(dirent->d_name);
     printf("> %s\n", dirent->d_name);
     free(dirent);
   }
 
   printf("Entry shown.\n");
 
+  /* Rewind to show the same entry. */
+
+  char *name2 = NULL;
+
+  client_rewinddir(reader);
+
+  dirent = client_readdir(reader);
+
+  if (dirent != NULL)
+  {
+    name2 = strdup(dirent->d_name);
+    printf("> %s\n", dirent->d_name);
+    free(dirent);
+  }
+
+  printf("Entry shown and identical: %s\n", (name != NULL) && (name2 != NULL) && !strcmp(name, name2) ? "True" : "False");
+
   printf("End of test.\n");
   return 0;
 }