WIP: ddrescue mapfile filter

configure.ac

@@ -895,6 +895,7 @@ filters="\
         cache \
         cacheextents \
         cow \
+        ddrescue \
         delay \
         error \
         fua \
@@ -981,6 +982,7 @@ AC_CONFIG_FILES([Makefile
                  filters/cache/Makefile
                  filters/cacheextents/Makefile
                  filters/cow/Makefile
+                 filters/ddrescue/Makefile
                  filters/delay/Makefile
                  filters/error/Makefile
                  filters/fua/Makefile

filters/ddrescue/Makefile.am

@@ -0,0 +1,75 @@
+# nbdkit
+# Copyright (C) 2018 Red Hat Inc.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#
+# * Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# * Neither the name of Red Hat nor the names of its contributors may be
+# used to endorse or promote products derived from this software without
+# specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+
+include $(top_srcdir)/common-rules.mk
+
+EXTRA_DIST = \
+	nbdkit-ddrescue-filter.pod \
+	$(NULL)
+
+filter_LTLIBRARIES = nbdkit-ddrescue-filter.la
+
+nbdkit_ddrescue_filter_la_SOURCES = \
+	ddrescue.c \
+	$(top_srcdir)/include/nbdkit-filter.h \
+	$(NULL)
+
+nbdkit_ddrescue_filter_la_CPPFLAGS = \
+	-I$(top_srcdir)/include \
+	-I$(top_srcdir)/common/include \
+	-I$(top_srcdir)/common/sparse \
+	-I$(top_srcdir)/common/utils \
+	$(NULL)
+nbdkit_ddrescue_filter_la_CFLAGS = \
+	$(WARNINGS_CFLAGS) \
+	$(GNUTLS_CFLAGS) \
+	$(NULL)
+nbdkit_ddrescue_filter_la_LDFLAGS = \
+	-module -avoid-version -shared \
+	-Wl,--version-script=$(top_srcdir)/filters/filters.syms \
+	$(NULL)
+nbdkit_ddrescue_filter_la_LIBADD = \
+	$(top_builddir)/common/sparse/libsparse.la \
+	$(top_builddir)/common/utils/libutils.la \
+	$(GNUTLS_LIBS) \
+	$(NULL)
+
+if HAVE_POD
+
+man_MANS = nbdkit-ddrescue-filter.1
+CLEANFILES += $(man_MANS)
+
+nbdkit-ddrescue-filter.1: nbdkit-ddrescue-filter.pod
+	$(PODWRAPPER) --section=1 --man $@ \
+	    --html $(top_builddir)/html/[email protected] \
+	    $<
+
+endif HAVE_POD

filters/ddrescue/ddrescue.c

@@ -0,0 +1,218 @@
+/* nbdkit
+ * Copyright (C) 2018-2019 Red Hat Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include <string.h>
+
+#include <pthread.h>
+
+#include <nbdkit-filter.h>
+
+#include "cleanup.h"
+
+struct range {
+  int64_t start;
+  int64_t end;
+  int64_t size;
+  char status;
+};
+
+struct mapfile {
+  int ranges_count;
+  struct range *ranges;
+};
+
+static struct mapfile map = { 0, NULL };
+
+static int
+parse_mapfile (const char *filename)
+{
+  FILE *fp = NULL;
+  CLEANUP_FREE char *line = NULL;
+  size_t linelen = 0;
+  ssize_t len;
+  int ret = -1;
+  int status_seen = 0;
+
+  fp = fopen (filename, "r");
+  if (!fp) {
+    nbdkit_error ("%s: ddrescue: fopen: %m", filename);
+    goto out;
+  }
+
+  while ((len = getline (&line, &linelen, fp)) != -1) {
+    const char *delim = " \t";
+    char *sp, *p;
+    int64_t offset, length;
+    char status;
+
+    if (len > 0 && line[len-1] == '\n') {
+      line[len-1] = '\0';
+      len--;
+    }
+
+    if (len > 0 && line[0] == '#')
+      continue;
+
+    if (len > 0 && !status_seen) {
+      /* status line, ignore it for now */
+      status_seen = 1;
+      nbdkit_debug ("%s: skipping status line: '%s'", filename, line);
+      continue;
+    }
+
+    if (sscanf (line, "%" SCNi64 "\t%" SCNi64 "\t%c", &offset, &length, &status) == 3) {
+      if (offset < 0) {
+        nbdkit_error ("block offset must not be negative");
+        return -1;
+      }
+      if (length < 0) {
+        nbdkit_error ("block length must not be negative");
+        return -1;
+      }
+      if (status == '+') {
+        int i = map.ranges_count++;
+        map.ranges = realloc(map.ranges, map.ranges_count * sizeof(struct range));
+        if (map.ranges == NULL) {
+          nbdkit_error ("%s: ddrescue: realloc: %m", filename);
+          goto out;
+        }
+        map.ranges[i].start = offset;
+        map.ranges[i].end = offset + length - 1;
+        map.ranges[i].size = length;
+        map.ranges[i].status = status;
+      }
+
+      nbdkit_debug ("%s: range: 0x%" PRIx64 " 0x%" PRIx64 " '%c'", filename, offset, length, status);
+    }
+  }
+
+  ret = 0;
+
+ out:
+  if (fp)
+    fclose (fp);
+  return ret;
+}
+
+
+static void
+ddrescue_load (void)
+{
+}
+
+/* On unload, free the sparse array. */
+static void
+ddrescue_unload (void)
+{
+  free (map.ranges);
+  map.ranges = NULL;
+  map.ranges_count = 0;
+}
+
+static int
+ddrescue_config (nbdkit_next_config *next, void *nxdata,
+                 const char *key, const char *value)
+{
+  if (strcmp (key, "ddrescue-mapfile") == 0) {
+    if (parse_mapfile (value) == -1)
+      return -1;
+    return 0;
+  }
+
+  else
+    return next (nxdata, key, value);
+}
+
+#define ddrescue_config_help \
+  "ddrescue-mapfile=...     Specify ddrescue mapfile to use"
+
+/* We need this because otherwise the layer below can_write is called
+ * and that might return true (eg. if the plugin has a pwrite method
+ * at all), resulting in writes being passed through to the layer
+ * below.  This is possibly a bug in nbdkit.
+ */
+static int
+ddrescue_can_write (struct nbdkit_next_ops *next_ops, void *nxdata,
+                    void *handle)
+{
+  return 0;
+}
+
+static int
+ddrescue_can_cache (struct nbdkit_next_ops *next_ops, void *nxdata,
+                    void *handle)
+{
+  return 0;
+}
+
+/* Read data. */
+static int
+ddrescue_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
+                void *handle, void *buf, uint32_t count, uint64_t offset,
+                uint32_t flags, int *err)
+{
+  int i;
+
+  for (i = 0; i < map.ranges_count; i++) {
+    if (map.ranges[i].status != '+')
+      continue;
+    if (offset >= map.ranges[i].start && offset <= map.ranges[i].end) {
+      if (offset + count - 1 <= map.ranges[i].end) {
+        /* entirely contained within this range */
+        return next_ops->pread (nxdata, buf, count, offset, flags, err);
+      }
+    }
+  }
+  /* read was not fully covered */
+  *err = EIO;
+  return -1;
+}
+
+static struct nbdkit_filter filter = {
+  .name              = "ddrescue",
+  .longname          = "nbdkit ddrescue mapfile filter",
+  .load              = ddrescue_load,
+  .unload            = ddrescue_unload,
+  .config            = ddrescue_config,
+  .config_help       = ddrescue_config_help,
+  .can_write         = ddrescue_can_write,
+  .can_cache         = ddrescue_can_cache,
+  .pread             = ddrescue_pread,
+};
+
+NBDKIT_REGISTER_FILTER(filter)