[Libguestfs] [nbdkit PATCH v3 08/14] filters: Add .export_description wrappers
Eric Blake
eblake at redhat.com
Mon Sep 21 16:23:52 UTC 2020
When extracting an obvious subset of a larger container (ext2, gzip,
partition, tar, xz), it's fairly easy to add a nice updated
description for what the client is seeing, but only if the original
plugin offered a description itself (there's no need to volunteer
something if the plugin did not think it worth doing).
Signed-off-by: Eric Blake <eblake at redhat.com>
---
filters/ext2/ext2.c | 51 ++++++++++++++++++++-----------
filters/gzip/gzip.c | 37 +++++++++++++++--------
filters/partition/partition.c | 56 ++++++++++++++++++++++++-----------
filters/tar/tar.c | 46 ++++++++++++++++++----------
filters/xz/xz.c | 40 +++++++++++++++++--------
5 files changed, 155 insertions(+), 75 deletions(-)
diff --git a/filters/ext2/ext2.c b/filters/ext2/ext2.c
index 75ac2c4c..7e4c0161 100644
--- a/filters/ext2/ext2.c
+++ b/filters/ext2/ext2.c
@@ -294,6 +294,22 @@ static int ext2_thread_model (void)
return NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS;
}
+/* Description. */
+static const char *
+ext2_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ struct handle *h = handle;
+ const char *fname = file ?: h->exportname;
+ const char *slash = fname[0] == '/' ? "" : "/";
+ const char *base = next_ops->export_description (nxdata);
+
+ if (!base)
+ return NULL;
+ return nbdkit_printf_intern ("embedded '%s%s' from within ext2 image: %s",
+ slash, fname, base);
+}
+
/* Get the disk size. */
static int64_t
ext2_get_size (struct nbdkit_next_ops *next_ops, void *nxdata, void *handle)
@@ -412,23 +428,24 @@ ext2_flush (struct nbdkit_next_ops *next_ops, void *nxdata,
*/
static struct nbdkit_filter filter = {
- .name = "ext2",
- .longname = "nbdkit ext2 filter",
- .load = ext2_load,
- .unload = ext2_unload,
- .config = ext2_config,
- .config_complete = ext2_config_complete,
- .config_help = ext2_config_help,
- .thread_model = ext2_thread_model,
- .open = ext2_open,
- .prepare = ext2_prepare,
- .close = ext2_close,
- .can_fua = ext2_can_fua,
- .can_cache = ext2_can_cache,
- .get_size = ext2_get_size,
- .pread = ext2_pread,
- .pwrite = ext2_pwrite,
- .flush = ext2_flush,
+ .name = "ext2",
+ .longname = "nbdkit ext2 filter",
+ .load = ext2_load,
+ .unload = ext2_unload,
+ .config = ext2_config,
+ .config_complete = ext2_config_complete,
+ .config_help = ext2_config_help,
+ .thread_model = ext2_thread_model,
+ .open = ext2_open,
+ .prepare = ext2_prepare,
+ .close = ext2_close,
+ .can_fua = ext2_can_fua,
+ .can_cache = ext2_can_cache,
+ .export_description = ext2_export_description,
+ .get_size = ext2_get_size,
+ .pread = ext2_pread,
+ .pwrite = ext2_pwrite,
+ .flush = ext2_flush,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/gzip/gzip.c b/filters/gzip/gzip.c
index 929260bf..20b533b9 100644
--- a/filters/gzip/gzip.c
+++ b/filters/gzip/gzip.c
@@ -287,6 +287,18 @@ gzip_can_cache (struct nbdkit_next_ops *next_ops, void *nxdata,
return NBDKIT_CACHE_EMULATE;
}
+/* Description. */
+static const char *
+gzip_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ const char *base = next_ops->export_description (nxdata);
+
+ if (!base)
+ return NULL;
+ return nbdkit_printf_intern ("expansion of gzip-compressed image: %s", base);
+}
+
/* Get the file size. */
static int64_t
gzip_get_size (struct nbdkit_next_ops *next_ops, void *nxdata,
@@ -339,18 +351,19 @@ gzip_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
}
static struct nbdkit_filter filter = {
- .name = "gzip",
- .longname = "nbdkit gzip filter",
- .unload = gzip_unload,
- .thread_model = gzip_thread_model,
- .open = gzip_open,
- .prepare = gzip_prepare,
- .can_write = gzip_can_write,
- .can_extents = gzip_can_extents,
- .can_cache = gzip_can_cache,
- .prepare = gzip_prepare,
- .get_size = gzip_get_size,
- .pread = gzip_pread,
+ .name = "gzip",
+ .longname = "nbdkit gzip filter",
+ .unload = gzip_unload,
+ .thread_model = gzip_thread_model,
+ .open = gzip_open,
+ .prepare = gzip_prepare,
+ .can_write = gzip_can_write,
+ .can_extents = gzip_can_extents,
+ .can_cache = gzip_can_cache,
+ .prepare = gzip_prepare,
+ .export_description = gzip_export_description,
+ .get_size = gzip_get_size,
+ .pread = gzip_pread,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/partition/partition.c b/filters/partition/partition.c
index 849f0cc7..d897b374 100644
--- a/filters/partition/partition.c
+++ b/filters/partition/partition.c
@@ -37,6 +37,7 @@
#include <stdint.h>
#include <string.h>
#include <inttypes.h>
+#include <assert.h>
#include <nbdkit-filter.h>
@@ -83,6 +84,7 @@ partition_config_complete (nbdkit_next_config_complete *next, void *nxdata)
struct handle {
int64_t offset;
int64_t range;
+ const char *type;
};
/* Open a connection. */
@@ -139,13 +141,17 @@ partition_prepare (struct nbdkit_next_ops *next_ops, void *nxdata,
/* Is it GPT? */
if (size >= 2 * 34 * SECTOR_SIZE &&
- memcmp (&lba01[SECTOR_SIZE], "EFI PART", 8) == 0)
+ memcmp (&lba01[SECTOR_SIZE], "EFI PART", 8) == 0) {
r = find_gpt_partition (next_ops, nxdata, size, &lba01[SECTOR_SIZE],
&h->offset, &h->range);
+ h->type = "GPT";
+ }
/* Is it MBR? */
- else if (lba01[0x1fe] == 0x55 && lba01[0x1ff] == 0xAA)
+ else if (lba01[0x1fe] == 0x55 && lba01[0x1ff] == 0xAA) {
r = find_mbr_partition (next_ops, nxdata, size, lba01,
&h->offset, &h->range);
+ h->type = "MBR";
+ }
else {
nbdkit_error ("disk does not contain MBR or GPT partition table signature");
r = -1;
@@ -168,6 +174,21 @@ partition_prepare (struct nbdkit_next_ops *next_ops, void *nxdata,
return 0;
}
+/* Description. */
+static const char *
+partition_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ struct handle *h = handle;
+ const char *base = next_ops->export_description (nxdata);
+
+ assert (h->type);
+ if (!base)
+ return NULL;
+ return nbdkit_printf_intern ("partition %d of %s disk: %s", partnum, h->type,
+ base);
+}
+
/* Get the file size. */
static int64_t
partition_get_size (struct nbdkit_next_ops *next_ops, void *nxdata,
@@ -266,21 +287,22 @@ partition_cache (struct nbdkit_next_ops *next_ops, void *nxdata,
}
static struct nbdkit_filter filter = {
- .name = "partition",
- .longname = "nbdkit partition filter",
- .config = partition_config,
- .config_complete = partition_config_complete,
- .config_help = partition_config_help,
- .open = partition_open,
- .prepare = partition_prepare,
- .close = partition_close,
- .get_size = partition_get_size,
- .pread = partition_pread,
- .pwrite = partition_pwrite,
- .trim = partition_trim,
- .zero = partition_zero,
- .extents = partition_extents,
- .cache = partition_cache,
+ .name = "partition",
+ .longname = "nbdkit partition filter",
+ .config = partition_config,
+ .config_complete = partition_config_complete,
+ .config_help = partition_config_help,
+ .open = partition_open,
+ .prepare = partition_prepare,
+ .close = partition_close,
+ .export_description = partition_export_description,
+ .get_size = partition_get_size,
+ .pread = partition_pread,
+ .pwrite = partition_pwrite,
+ .trim = partition_trim,
+ .zero = partition_zero,
+ .extents = partition_extents,
+ .cache = partition_cache,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/tar/tar.c b/filters/tar/tar.c
index cb42b918..fa4b61dc 100644
--- a/filters/tar/tar.c
+++ b/filters/tar/tar.c
@@ -295,6 +295,19 @@ tar_prepare (struct nbdkit_next_ops *next_ops, void *nxdata,
return 0;
}
+/* Description. */
+static const char *
+tar_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ const char *base = next_ops->export_description (nxdata);
+
+ if (!base)
+ return NULL;
+ return nbdkit_printf_intern ("embedded %s from within tar file: %s",
+ entry, base);
+}
+
/* Get the file size. */
static int64_t
tar_get_size (struct nbdkit_next_ops *next_ops, void *nxdata,
@@ -395,22 +408,23 @@ tar_cache (struct nbdkit_next_ops *next_ops, void *nxdata,
}
static struct nbdkit_filter filter = {
- .name = "tar",
- .longname = "nbdkit tar filter",
- .config = tar_config,
- .config_complete = tar_config_complete,
- .config_help = tar_config_help,
- .thread_model = tar_thread_model,
- .open = tar_open,
- .close = tar_close,
- .prepare = tar_prepare,
- .get_size = tar_get_size,
- .pread = tar_pread,
- .pwrite = tar_pwrite,
- .trim = tar_trim,
- .zero = tar_zero,
- .extents = tar_extents,
- .cache = tar_cache,
+ .name = "tar",
+ .longname = "nbdkit tar filter",
+ .config = tar_config,
+ .config_complete = tar_config_complete,
+ .config_help = tar_config_help,
+ .thread_model = tar_thread_model,
+ .open = tar_open,
+ .close = tar_close,
+ .prepare = tar_prepare,
+ .export_description = tar_export_description,
+ .get_size = tar_get_size,
+ .pread = tar_pread,
+ .pwrite = tar_pwrite,
+ .trim = tar_trim,
+ .zero = tar_zero,
+ .extents = tar_extents,
+ .cache = tar_cache,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/xz/xz.c b/filters/xz/xz.c
index 26cfa959..72801536 100644
--- a/filters/xz/xz.c
+++ b/filters/xz/xz.c
@@ -47,6 +47,7 @@
#include "xzfile.h"
#include "blkcache.h"
+#include "cleanup.h"
static uint64_t maxblock = 512 * 1024 * 1024;
static uint32_t maxdepth = 8;
@@ -156,6 +157,18 @@ xz_prepare (struct nbdkit_next_ops *next_ops, void *nxdata, void *handle,
return 0;
}
+/* Description. */
+static const char *
+xz_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ const char *base = next_ops->export_description (nxdata);
+
+ if (!base)
+ return NULL;
+ return nbdkit_printf_intern ("expansion of xz-compressed image: %s", base);
+}
+
/* Get the file size. */
static int64_t
xz_get_size (struct nbdkit_next_ops *next_ops, void *nxdata, void *handle)
@@ -245,19 +258,20 @@ static int xz_thread_model (void)
}
static struct nbdkit_filter filter = {
- .name = "xz",
- .longname = "nbdkit XZ filter",
- .config = xz_config,
- .config_help = xz_config_help,
- .thread_model = xz_thread_model,
- .open = xz_open,
- .close = xz_close,
- .prepare = xz_prepare,
- .get_size = xz_get_size,
- .can_write = xz_can_write,
- .can_extents = xz_can_extents,
- .can_cache = xz_can_cache,
- .pread = xz_pread,
+ .name = "xz",
+ .longname = "nbdkit XZ filter",
+ .config = xz_config,
+ .config_help = xz_config_help,
+ .thread_model = xz_thread_model,
+ .open = xz_open,
+ .close = xz_close,
+ .prepare = xz_prepare,
+ .export_description = xz_export_description,
+ .get_size = xz_get_size,
+ .can_write = xz_can_write,
+ .can_extents = xz_can_extents,
+ .can_cache = xz_can_cache,
+ .pread = xz_pread,
};
NBDKIT_REGISTER_FILTER(filter)
--
2.28.0
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