Add recoding implementation for the xattr writer

This commit implements the part of the API responsible for recoding
and deduplicating xattr key-value blocks.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

3 files changed, 310 insertions, 1 deletions

diff --git a/lib/sqfs/Makemodule.am b/lib/sqfs/Makemodule.am
index c44a85c..ad5c8af 100644
--- a/lib/sqfs/Makemodule.am
+++ b/lib/sqfs/Makemodule.am
@@ -16,7 +16,7 @@ libsquashfs_la_SOURCES += lib/sqfs/read_super.c lib/sqfs/meta_reader.c
 libsquashfs_la_SOURCES += lib/sqfs/read_inode.c lib/sqfs/write_inode.c
 libsquashfs_la_SOURCES += lib/sqfs/dir_writer.c lib/sqfs/xattr_reader.c
 libsquashfs_la_SOURCES += lib/sqfs/read_table.c lib/sqfs/comp/compressor.c
-libsquashfs_la_SOURCES += lib/sqfs/comp/internal.h
+libsquashfs_la_SOURCES += lib/sqfs/comp/internal.h lib/sqfs/xattr_writer.c
 libsquashfs_la_SOURCES += lib/sqfs/dir_reader.c lib/sqfs/read_tree.c
 libsquashfs_la_SOURCES += lib/sqfs/inode.c lib/sqfs/data_writer/fragment.c
 libsquashfs_la_SOURCES += lib/sqfs/data_writer/block.c
diff --git a/lib/sqfs/xattr_writer.c b/lib/sqfs/xattr_writer.c
new file mode 100644
index 0000000..7643d49
--- /dev/null
+++ b/lib/sqfs/xattr_writer.c
@@ -0,0 +1,301 @@
+/* SPDX-License-Identifier: LGPL-3.0-or-later */
+/*
+ * xattr_writer.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#define SQFS_BUILDING_DLL
+#include "config.h"
+
+#include "sqfs/xattr_writer.h"
+#include "sqfs/meta_writer.h"
+#include "sqfs/super.h"
+#include "sqfs/xattr.h"
+#include "sqfs/error.h"
+#include "sqfs/block.h"
+#include "sqfs/io.h"
+
+#include "str_table.h"
+#include "util.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+
+#define XATTR_KEY_BUCKETS 31
+#define XATTR_VALUE_BUCKETS 511
+#define XATTR_INITIAL_PAIR_CAP 128
+
+#define MK_PAIR(key, value) (((sqfs_u64)(key) << 32UL) | (sqfs_u64)(value))
+#define GET_KEY(pair) ((pair >> 32UL) & 0x0FFFFFFFFUL)
+#define GET_VALUE(pair) (pair & 0x0FFFFFFFFUL)
+
+
+static const char *hexmap = "0123456789ABCDEF";
+
+static char *to_base32(const void *input, size_t size)
+{
+	const uint8_t *in = input;
+	char *out, *ptr;
+	size_t i;
+
+	out = malloc(2 * size + 1);
+	if (out == NULL)
+		return NULL;
+
+	ptr = out;
+
+	for (i = 0; i < size; ++i) {
+		*(ptr++) = hexmap[ in[i]       & 0x0F];
+		*(ptr++) = hexmap[(in[i] >> 4) & 0x0F];
+	}
+
+	*ptr = '\0';
+	return out;
+}
+
+static void *from_base32(const char *input, size_t *size_out)
+{
+	uint8_t lo, hi, *out, *ptr;
+	size_t len;
+
+	len = strlen(input);
+	*size_out = len / 2;
+
+	out = malloc(*size_out);
+	if (out == NULL)
+		return NULL;
+
+	ptr = out;
+
+	while (*input != '\0') {
+		lo = strchr(hexmap, *(input++)) - hexmap;
+		hi = strchr(hexmap, *(input++)) - hexmap;
+
+		*(ptr++) = lo | (hi << 4);
+	}
+
+	return out;
+}
+
+static int compare_u64(const void *a, const void *b)
+{
+	sqfs_u64 lhs = *((const sqfs_u64 *)a);
+	sqfs_u64 rhs = *((const sqfs_u64 *)b);
+
+	return (lhs < rhs ? -1 : (lhs > rhs ? 1 : 0));
+}
+
+
+
+typedef struct kv_block_desc_t {
+	struct kv_block_desc_t *next;
+	size_t start;
+	size_t count;
+} kv_block_desc_t;
+
+struct sqfs_xattr_writer_t {
+	str_table_t keys;
+	str_table_t values;
+
+	sqfs_u64 *kv_pairs;
+	size_t max_pairs;
+	size_t num_pairs;
+
+	size_t kv_start;
+
+	kv_block_desc_t *kv_blocks;
+	size_t num_blocks;
+};
+
+
+sqfs_xattr_writer_t *sqfs_xattr_writer_create(void)
+{
+	sqfs_xattr_writer_t *xwr = calloc(1, sizeof(*xwr));
+
+	if (str_table_init(&xwr->keys, XATTR_KEY_BUCKETS))
+		goto fail_keys;
+
+	if (str_table_init(&xwr->values, XATTR_VALUE_BUCKETS))
+		goto fail_values;
+
+	xwr->max_pairs = XATTR_INITIAL_PAIR_CAP;
+	xwr->kv_pairs = alloc_array(sizeof(xwr->kv_pairs[0]), xwr->max_pairs);
+
+	if (xwr->kv_pairs == NULL)
+		goto fail_pairs;
+
+	return xwr;
+fail_pairs:
+	str_table_cleanup(&xwr->values);
+fail_values:
+	str_table_cleanup(&xwr->keys);
+fail_keys:
+	free(xwr);
+	return NULL;
+}
+
+void sqfs_xattr_writer_destroy(sqfs_xattr_writer_t *xwr)
+{
+	kv_block_desc_t *blk;
+
+	while (xwr->kv_blocks != NULL) {
+		blk = xwr->kv_blocks;
+		xwr->kv_blocks = xwr->kv_blocks->next;
+		free(blk);
+	}
+
+	free(xwr->kv_pairs);
+	str_table_cleanup(&xwr->values);
+	str_table_cleanup(&xwr->keys);
+	free(xwr);
+}
+
+int sqfs_xattr_writer_begin(sqfs_xattr_writer_t *xwr)
+{
+	xwr->kv_start = xwr->num_pairs;
+	return 0;
+}
+
+int sqfs_xattr_writer_add(sqfs_xattr_writer_t *xwr, const char *key,
+			  const void *value, size_t size)
+{
+	size_t i, key_index, old_value_index, value_index, new_count;
+	sqfs_u64 kv_pair, *new;
+	char *value_str;
+	int err;
+
+	if (!sqfs_has_xattr(key))
+		return SQFS_ERROR_UNSUPPORTED;
+
+	/* resolve key and value into unique, incremental IDs */
+	err = str_table_get_index(&xwr->keys, key, &key_index);
+	if (err)
+		return err;
+
+	value_str = to_base32(value, size);
+	if (value_str == NULL)
+		return SQFS_ERROR_ALLOC;
+
+	err = str_table_get_index(&xwr->values, value_str, &value_index);
+	free(value_str);
+	if (err)
+		return err;
+
+	str_table_add_ref(&xwr->values, value_index);
+
+	if (sizeof(size_t) > sizeof(sqfs_u32)) {
+		if (key_index > 0x0FFFFFFFFUL || value_index > 0x0FFFFFFFFUL)
+			return SQFS_ERROR_OVERFLOW;
+	}
+
+	/* bail if already have the pair, overwrite if we have the key */
+	kv_pair = MK_PAIR(key_index, value_index);
+
+	for (i = xwr->kv_start; i < xwr->num_pairs; ++i) {
+		if (xwr->kv_pairs[i] == kv_pair)
+			return 0;
+
+		if (GET_KEY(xwr->kv_pairs[i]) == key_index) {
+			old_value_index = GET_VALUE(xwr->kv_pairs[i]);
+
+			str_table_del_ref(&xwr->values, old_value_index);
+
+			xwr->kv_pairs[i] = kv_pair;
+			return 0;
+		}
+	}
+
+	/* append it to the list */
+	if (xwr->max_pairs == xwr->num_pairs) {
+		new_count = xwr->max_pairs * 2;
+		new = realloc(xwr->kv_pairs,
+			      sizeof(xwr->kv_pairs[0]) * new_count);
+
+		if (new == NULL)
+			return SQFS_ERROR_ALLOC;
+
+		xwr->kv_pairs = new;
+		xwr->max_pairs = new_count;
+	}
+
+	xwr->kv_pairs[xwr->num_pairs++] = kv_pair;
+	return 0;
+}
+
+int sqfs_xattr_writer_end(sqfs_xattr_writer_t *xwr, sqfs_u32 *out)
+{
+	kv_block_desc_t *blk, *blk_prev;
+	size_t i, count, value_idx;
+	sqfs_u32 index;
+	int ret;
+
+	count = xwr->num_pairs - xwr->kv_start;
+
+	qsort(xwr->kv_pairs + xwr->kv_start, count,
+	      sizeof(xwr->kv_pairs[0]), compare_u64);
+
+	blk_prev = NULL;
+	blk = xwr->kv_blocks;
+	index = 0;
+
+	while (blk != NULL) {
+		if (blk->count == count) {
+			ret = memcmp(xwr->kv_pairs + blk->start,
+				     xwr->kv_pairs + xwr->kv_start,
+				     sizeof(xwr->kv_pairs[0]) * count);
+
+			if (ret == 0)
+				break;
+		}
+
+		if (index == 0xFFFFFFFF)
+			return SQFS_ERROR_OVERFLOW;
+
+		++index;
+		blk_prev = blk;
+		blk = blk->next;
+	}
+
+	if (blk != NULL) {
+		for (i = 0; i < count; ++i) {
+			value_idx = GET_VALUE(xwr->kv_pairs[xwr->kv_start + i]);
+			str_table_del_ref(&xwr->values, value_idx);
+
+			value_idx = GET_VALUE(xwr->kv_pairs[blk->start + i]);
+			str_table_add_ref(&xwr->values, value_idx);
+		}
+
+		xwr->num_pairs = xwr->kv_start;
+	} else {
+		blk = calloc(1, sizeof(*blk));
+		if (blk == NULL)
+			return SQFS_ERROR_ALLOC;
+
+		blk->start = xwr->kv_start;
+		blk->count = count;
+
+		if (blk_prev == NULL) {
+			xwr->kv_blocks = blk;
+		} else {
+			blk_prev->next = blk;
+		}
+
+		xwr->num_blocks += 1;
+	}
+
+	*out = index;
+	return 0;
+}
+
+/*****************************************************************************/
+
+int sqfs_xattr_writer_flush(sqfs_xattr_writer_t *xwr, sqfs_file_t *file,
+			    sqfs_super_t *super, sqfs_compressor_t *cmp)
+{
+	(void)xwr;
+	(void)file;
+	(void)super;
+	(void)cmp;
+	return 0;
+}
diff --git a/lib/util/str_table.c b/lib/util/str_table.c
index dba61fe..34aa70e 100644
--- a/lib/util/str_table.c
+++ b/lib/util/str_table.c
@@ -176,6 +176,14 @@ void str_table_add_ref(str_table_t *table, size_t index)
 		bucket->refcount += 1;
 }
 
+void str_table_del_ref(str_table_t *table, size_t index)
+{
+	str_bucket_t *bucket = bucket_by_index(table, index);
+
+	if (bucket != NULL && bucket->refcount > 0)
+		bucket->refcount -= 1;
+}
+
 size_t str_table_get_ref_count(str_table_t *table, size_t index)
 {
 	str_bucket_t *bucket = bucket_by_index(table, index);