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file_iterator: dynamically allocate zero block #166

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merged 1 commit into from
Nov 20, 2023
Merged

file_iterator: dynamically allocate zero block #166

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25 changes: 25 additions & 0 deletions libsqsh/include/sqsh_archive_private.h
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Original file line number Diff line number Diff line change
Expand Up @@ -225,6 +225,7 @@ struct SqshArchive {
uint8_t initialized;
struct SqshConfig config;
sqsh__mutex_t lock;
uint8_t *zero_block;
};

/**
Expand Down Expand Up @@ -270,6 +271,30 @@ SQSH_NO_EXPORT int sqsh__archive_data_extract_manager(
SQSH_NO_EXPORT struct SqshExtractManager *
sqsh__archive_metablock_extract_manager(struct SqshArchive *archive);

/**
* @internal
* @memberof SqshArchive
* @brief Returns a 16k block of zeros.
*
* @param archive the SqshArchive to retrieve the zero block from
*
* @return the SqshExtractManager.
*/
SQSH_NO_EXPORT const uint8_t *
sqsh__archive_zero_block(const struct SqshArchive *archive);

/**
* @internal
* @memberof SqshArchive
* @brief Returns a 16k block of zeros.
*
* @param archive the SqshArchive to retrieve the zero block from
*
* @return the SqshExtractManager.
*/
SQSH_NO_EXPORT size_t
sqsh__archive_zero_block_size(const struct SqshArchive *archive);

/**
* @internal
* @memberof SqshArchive
Expand Down
20 changes: 20 additions & 0 deletions libsqsh/src/archive/archive.c
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@
#include <string.h>

static const uint64_t NO_SEGMENT = 0xFFFFFFFFFFFFFFFF;
static const size_t ZERO_BLOCK_SIZE = 16384;

enum InitializedBitmap {
INITIALIZED_ID_TABLE = 1 << 0,
Expand Down Expand Up @@ -112,6 +113,12 @@ sqsh__archive_init(
memset(&archive->config, 0, sizeof(struct SqshConfig));
}

archive->zero_block = calloc(ZERO_BLOCK_SIZE, sizeof(uint8_t));
if (archive->zero_block == NULL) {
rv = -SQSH_ERROR_MALLOC_FAILED;
goto out;
}

/* RECURSIVE is needed because: inode_map may access the export_table
* during initialization. */
rv = sqsh__mutex_init_recursive(&archive->lock);
Expand Down Expand Up @@ -346,6 +353,17 @@ sqsh_archive_map_manager(struct SqshArchive *archive) {
return &archive->map_manager;
}

const uint8_t *
sqsh__archive_zero_block(const struct SqshArchive *archive) {
return archive->zero_block;
}

size_t
sqsh__archive_zero_block_size(const struct SqshArchive *archive) {
(void)archive;
return ZERO_BLOCK_SIZE;
}

int
sqsh__archive_cleanup(struct SqshArchive *archive) {
int rv = 0;
Expand Down Expand Up @@ -374,6 +392,8 @@ sqsh__archive_cleanup(struct SqshArchive *archive) {

sqsh__mutex_destroy(&archive->lock);

free(archive->zero_block);

return rv;
}

Expand Down
12 changes: 7 additions & 5 deletions libsqsh/src/file/file_iterator.c
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Original file line number Diff line number Diff line change
Expand Up @@ -40,8 +40,6 @@

#define BLOCK_INDEX_FINISHED UINT32_MAX

static const uint8_t ZERO_BLOCK[16384] = {0};

static bool
is_last_block(const struct SqshFileIterator *iterator) {
const struct SqshFile *file = iterator->file;
Expand Down Expand Up @@ -188,15 +186,19 @@ map_block_uncompressed(

static int
map_zero_block(struct SqshFileIterator *iterator) {
const struct SqshFile *file = iterator->file;
const struct SqshArchive *archive = file->archive;
const size_t zero_block_size = sqsh__archive_zero_block_size(archive);

size_t current_sparse_size = iterator->sparse_size;

if (current_sparse_size > sizeof(ZERO_BLOCK)) {
current_sparse_size = sizeof(ZERO_BLOCK);
if (current_sparse_size > zero_block_size) {
current_sparse_size = zero_block_size;
}
iterator->sparse_size -= current_sparse_size;

iterator->size = current_sparse_size;
iterator->data = ZERO_BLOCK;
iterator->data = sqsh__archive_zero_block(archive);

return current_sparse_size;
}
Expand Down