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authorDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2019-06-28 12:41:26 +0200
committerDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2019-06-28 15:07:34 +0200
commit4e017928c7b5b590d2c7e04e42cb497eb3a4f8cf (patch)
tree28f649af1074ab74576a9a715991c610b210f1c0 /lib/sqfs/data_reader.c
parentd89d7e3d7f5b21fe53ea0cbf65134bdc3df30950 (diff)
Add support for packing sparse files
This commit adds support for packing sparse files into squashfs images as follows: - In the data writer: simply detect zero blocks and write a zero to the block size field and don't emit any data. Record the number of bytes saved this way. For fragments, set the fragment offset to invalid. - In the inode writer: write out the number of bytes saved for sparse files. If there should be a fragment but there is none, append a block count of 0. - In the data reader: if the block size is 0, read nothing from disk and emit an empty block. Do the same if the fragment is missing. - In the inode reader: restore the number of bytes saved for sparse files. The sparse files can be packed and unpacked, but the unpacking will not create sparse files for now. Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Diffstat (limited to 'lib/sqfs/data_reader.c')
-rw-r--r--lib/sqfs/data_reader.c36
1 files changed, 24 insertions, 12 deletions
diff --git a/lib/sqfs/data_reader.c b/lib/sqfs/data_reader.c
index 22413f2..421d914 100644
--- a/lib/sqfs/data_reader.c
+++ b/lib/sqfs/data_reader.c
@@ -5,6 +5,7 @@
#include <stdlib.h>
#include <unistd.h>
+#include <string.h>
#include <stdio.h>
struct data_reader_t {
@@ -81,12 +82,18 @@ int data_reader_dump_file(data_reader_t *data, file_info_t *fi, int outfd)
if (bs > data->block_size)
goto fail_bs;
- ret = read_retry(data->sqfsfd, data->buffer, bs);
- if (ret < 0)
- goto fail_rd;
+ if (bs == 0) {
+ bs = data->block_size;
+ memset(data->buffer, 0, bs);
+ compressed = false;
+ } else {
+ ret = read_retry(data->sqfsfd, data->buffer, bs);
+ if (ret < 0)
+ goto fail_rd;
- if ((size_t)ret < bs)
- goto fail_trunc;
+ if ((size_t)ret < bs)
+ goto fail_trunc;
+ }
if (compressed) {
ret = data->cmp->do_block(data->cmp,
@@ -114,13 +121,18 @@ int data_reader_dump_file(data_reader_t *data, file_info_t *fi, int outfd)
fragsz = fi->size % data->block_size;
if (fragsz > 0) {
- if (data->frag == NULL)
- goto fail_frag;
-
- if (frag_reader_read(data->frag, fi->fragment,
- fi->fragment_offset, data->buffer,
- fragsz)) {
- return -1;
+ if (fi->fragment == 0xFFFFFFFF ||
+ fi->fragment_offset == 0xFFFFFFFF) {
+ memset(data->buffer, 0, fragsz);
+ } else {
+ if (data->frag == NULL)
+ goto fail_frag;
+
+ if (frag_reader_read(data->frag, fi->fragment,
+ fi->fragment_offset, data->buffer,
+ fragsz)) {
+ return -1;
+ }
}
ret = write_retry(outfd, data->buffer, fragsz);