[Libguestfs] [nbdkit PATCH v3 08/14] filters: Add .export_description wrappers

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(a)redhat.com&gt; --- 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