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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
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')
-rw-r--r--lib/sqfs/data_reader.c36
-rw-r--r--lib/sqfs/data_writer.c18
-rw-r--r--lib/sqfs/tree_node_from_inode.c1
-rw-r--r--lib/sqfs/write_inode.c12
4 files changed, 53 insertions, 14 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);
diff --git a/lib/sqfs/data_writer.c b/lib/sqfs/data_writer.c
index 753e5d4..70fe884 100644
--- a/lib/sqfs/data_writer.c
+++ b/lib/sqfs/data_writer.c
@@ -78,6 +78,11 @@ static int grow_fragment_table(data_writer_t *data)
return 0;
}
+static bool is_zero_block(unsigned char *ptr, size_t size)
+{
+ return ptr[0] == 0 && memcmp(ptr, ptr + 1, size - 1) == 0;
+}
+
int data_writer_flush_fragments(data_writer_t *data)
{
uint64_t offset;
@@ -115,6 +120,7 @@ int write_data_from_fd(data_writer_t *data, file_info_t *fi, int infd)
size_t diff;
fi->startblock = data->super->bytes_used;
+ fi->sparse = 0;
while (count != 0) {
diff = count > (uint64_t)data->super->block_size ?
@@ -126,6 +132,18 @@ int write_data_from_fd(data_writer_t *data, file_info_t *fi, int infd)
if ((size_t)ret < diff)
goto fail_trunc;
+ if (is_zero_block(data->block, diff)) {
+ if (diff < data->super->block_size) {
+ fi->fragment_offset = 0xFFFFFFFF;
+ fi->fragment = 0xFFFFFFFF;
+ } else {
+ fi->blocksizes[blk_idx++] = 0;
+ }
+ fi->sparse += diff;
+ count -= diff;
+ continue;
+ }
+
if (diff < data->super->block_size) {
if (data->frag_offset + diff > data->super->block_size) {
if (data_writer_flush_fragments(data))
diff --git a/lib/sqfs/tree_node_from_inode.c b/lib/sqfs/tree_node_from_inode.c
index f9a6599..9c96701 100644
--- a/lib/sqfs/tree_node_from_inode.c
+++ b/lib/sqfs/tree_node_from_inode.c
@@ -113,6 +113,7 @@ tree_node_t *tree_node_from_inode(sqfs_inode_generic_t *inode,
out->name += sizeof(file_info_t);
out->data.file->size = inode->data.file_ext.file_size;
+ out->data.file->sparse = inode->data.file_ext.sparse;
out->data.file->startblock = inode->data.file_ext.blocks_start;
out->data.file->fragment = inode->data.file_ext.fragment_idx;
out->data.file->fragment_offset =
diff --git a/lib/sqfs/write_inode.c b/lib/sqfs/write_inode.c
index fd14913..82663e7 100644
--- a/lib/sqfs/write_inode.c
+++ b/lib/sqfs/write_inode.c
@@ -86,7 +86,7 @@ int meta_writer_write_inode(fstree_t *fs, id_table_t *idtbl, meta_writer_t *im,
fi = node->data.file;
if (fi->startblock > 0xFFFFFFFFUL || fi->size > 0xFFFFFFFFUL ||
- hard_link_count(node) > 1) {
+ hard_link_count(node) > 1 || fi->sparse > 0) {
type = SQFS_INODE_EXT_FILE;
}
}
@@ -185,7 +185,7 @@ int meta_writer_write_inode(fstree_t *fs, id_table_t *idtbl, meta_writer_t *im,
sqfs_inode_file_ext_t ext = {
.blocks_start = htole64(fi->startblock),
.file_size = htole64(fi->size),
- .sparse = htole64(0),
+ .sparse = htole64(fi->sparse),
.nlink = htole32(hard_link_count(node)),
.fragment_idx = htole32(0xFFFFFFFF),
.fragment_offset = htole32(0xFFFFFFFF),
@@ -298,5 +298,13 @@ out_file_blocks:
if (meta_writer_append(im, &bs, sizeof(bs)))
return -1;
}
+
+ if ((fi->size % fs->block_size) != 0 &&
+ (fi->fragment == 0xFFFFFFFF || fi->fragment_offset == 0xFFFFFFFF)) {
+ bs = htole32(0);
+
+ if (meta_writer_append(im, &bs, sizeof(bs)))
+ return -1;
+ }
return 0;
}