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// SPDX-License-Identifier: GPL-2.0+ OR Apache-2.0
#include "erofs/internal.h"
#include "erofs/print.h"
#include "erofs/config.h"
#include <zstd.h>
#include <zstd_errors.h>
#include <stdlib.h>
#include "compressor.h"
#include "erofs/atomic.h"
struct erofs_libzstd_context {
ZSTD_CCtx *cctx;
u8 *fitblk_buffer;
unsigned int fitblk_bufsiz;
};
static int libzstd_compress_destsize(const struct erofs_compress *c,
const void *src, unsigned int *srcsize,
void *dst, unsigned int dstsize)
{
struct erofs_libzstd_context *ctx = c->private_data;
size_t l = 0; /* largest input that fits so far */
size_t l_csize = 0;
size_t r = *srcsize + 1; /* smallest input that doesn't fit so far */
size_t m;
if (dstsize + 32 > ctx->fitblk_bufsiz) {
u8 *buf = realloc(ctx->fitblk_buffer, dstsize + 32);
if (!buf)
return -ENOMEM;
ctx->fitblk_bufsiz = dstsize + 32;
ctx->fitblk_buffer = buf;
}
m = dstsize * 4;
for (;;) {
size_t csize;
m = max(m, l + 1);
m = min(m, r - 1);
csize = ZSTD_compress2(ctx->cctx, ctx->fitblk_buffer,
dstsize + 32, src, m);
if (ZSTD_isError(csize)) {
if (ZSTD_getErrorCode(csize) == ZSTD_error_dstSize_tooSmall)
goto doesnt_fit;
return -EFAULT;
}
if (csize > 0 && csize <= dstsize) {
/* Fits */
memcpy(dst, ctx->fitblk_buffer, csize);
l = m;
l_csize = csize;
if (r <= l + 1 || csize + 1 >= dstsize)
break;
/*
* Estimate needed input prefix size based on current
* compression ratio.
*/
m = (dstsize * m) / csize;
} else {
doesnt_fit:
/* Doesn't fit */
r = m;
if (r <= l + 1)
break;
m = (l + r) / 2;
}
}
*srcsize = l;
return l_csize;
}
static int compressor_libzstd_exit(struct erofs_compress *c)
{
struct erofs_libzstd_context *ctx = c->private_data;
if (!ctx)
return -EINVAL;
free(ctx->fitblk_buffer);
ZSTD_freeCCtx(ctx->cctx);
free(ctx);
return 0;
}
static int erofs_compressor_libzstd_setlevel(struct erofs_compress *c,
int compression_level)
{
if (compression_level > erofs_compressor_libzstd.best_level) {
erofs_err("invalid compression level %d", compression_level);
return -EINVAL;
}
c->compression_level = compression_level;
return 0;
}
static int erofs_compressor_libzstd_setdictsize(struct erofs_compress *c,
u32 dict_size)
{
if (!dict_size) {
if (erofs_compressor_libzstd.default_dictsize) {
dict_size = erofs_compressor_libzstd.default_dictsize;
} else {
dict_size = min_t(u32, Z_EROFS_ZSTD_MAX_DICT_SIZE,
cfg.c_mkfs_pclustersize_max << 3);
dict_size = 1 << ilog2(dict_size);
}
}
if (dict_size != 1 << ilog2(dict_size) ||
dict_size > Z_EROFS_ZSTD_MAX_DICT_SIZE) {
erofs_err("invalid dictionary size %u", dict_size);
return -EINVAL;
}
c->dict_size = dict_size;
return 0;
}
static int compressor_libzstd_init(struct erofs_compress *c)
{
struct erofs_libzstd_context *ctx = c->private_data;
static erofs_atomic_bool_t __warnonce;
ZSTD_CCtx *cctx;
size_t errcode;
int err;
if (ctx) {
ZSTD_freeCCtx(ctx->cctx);
ctx->cctx = NULL;
c->private_data = NULL;
} else {
ctx = calloc(1, sizeof(*ctx));
if (!ctx)
return -ENOMEM;
}
cctx = ZSTD_createCCtx();
if (!cctx) {
err = -ENOMEM;
goto out_err;
}
err = -EINVAL;
errcode = ZSTD_CCtx_setParameter(cctx, ZSTD_c_compressionLevel, c->compression_level);
if (ZSTD_isError(errcode)) {
erofs_err("failed to set compression level: %s",
ZSTD_getErrorName(errcode));
goto out_err;
}
errcode = ZSTD_CCtx_setParameter(cctx, ZSTD_c_windowLog, ilog2(c->dict_size));
if (ZSTD_isError(errcode)) {
erofs_err("failed to set window log: %s", ZSTD_getErrorName(errcode));
goto out_err;
}
ctx->cctx = cctx;
c->private_data = ctx;
if (!erofs_atomic_test_and_set(&__warnonce)) {
erofs_warn("EXPERIMENTAL libzstd compressor in use. Note that `fitblk` isn't supported by upstream zstd for now.");
erofs_warn("Therefore it will takes more time in order to get the optimal result.");
erofs_info("You could clarify further needs in zstd repository <https://github.com/facebook/zstd/issues> for reference too.");
}
return 0;
out_err:
ZSTD_freeCCtx(cctx);
free(ctx);
return err;
}
const struct erofs_compressor erofs_compressor_libzstd = {
.default_level = ZSTD_CLEVEL_DEFAULT,
.best_level = 22,
.max_dictsize = Z_EROFS_ZSTD_MAX_DICT_SIZE,
.init = compressor_libzstd_init,
.exit = compressor_libzstd_exit,
.setlevel = erofs_compressor_libzstd_setlevel,
.setdictsize = erofs_compressor_libzstd_setdictsize,
.compress_destsize = libzstd_compress_destsize,
};
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