[PATCH 8/9] lib: unzstd: Switch to the zstd-1.4.6 API

Nick Terrell
2020-09-16T03:44:29Z

From: Nick Terrell <terrelln@fb.com>

Move away from the compatibility wrapper to the zstd-1.4.6 API. This
code is functionally equivalent.

Signed-off-by: Nick Terrell <terrelln@fb.com>
---
lib/decompress_unzstd.c | 40 ++++++++++++++--------------------------
1 file changed, 14 insertions(+), 26 deletions(-)

diff --git a/lib/decompress_unzstd.c b/lib/decompress_unzstd.c
index a79f705f236d..d4685df0e120 100644
--- a/lib/decompress_unzstd.c
+++ b/lib/decompress_unzstd.c
@@ -73,7 +73,8 @@

#include <linux/decompress/mm.h>
#include <linux/kernel.h>
-#include <linux/zstd_compat.h>
+#include <linux/zstd.h>
+#include <linux/zstd_errors.h>

/* 128MB is the maximum window size supported by zstd. */
#define ZSTD_WINDOWSIZE_MAX (1 << ZSTD_WINDOWLOG_MAX)
@@ -120,9 +121,9 @@ static int INIT decompress_single(const u8 *in_buf, long in_len, u8 *out_buf,
long out_len, long *in_pos,
void (*error)(char *x))
{
- const size_t wksp_size = ZSTD_DCtxWorkspaceBound();
+ const size_t wksp_size = ZSTD_estimateDCtxSize();
void *wksp = large_malloc(wksp_size);
- ZSTD_DCtx *dctx = ZSTD_initDCtx(wksp, wksp_size);
+ ZSTD_DCtx *dctx = ZSTD_initStaticDCtx(wksp, wksp_size);
int err;
size_t ret;

@@ -165,7 +166,6 @@ static int INIT __unzstd(unsigned char *in_buf, long in_len,
{
ZSTD_inBuffer in;
ZSTD_outBuffer out;
- ZSTD_frameParams params;
void *in_allocated = NULL;
void *out_allocated = NULL;
void *wksp = NULL;
@@ -229,36 +229,24 @@ static int INIT __unzstd(unsigned char *in_buf, long in_len,
out.size = out_len;

/*
- * We need to know the window size to allocate the ZSTD_DStream.
- * Since we are streaming, we need to allocate a buffer for the sliding
- * window. The window size varies from 1 KB to ZSTD_WINDOWSIZE_MAX
- * (8 MB), so it is important to use the actual value so as not to
- * waste memory when it is smaller.
+ * Zstd determines the workspace size from the window size written
+ * into the frame header. This ensures that we use the minimum value
+ * possible, since the window size varies from 1 KB to ZSTD_WINDOWSIZE_MAX
+ * (1 GB), so it is very important to use the actual value.
*/
- ret = ZSTD_getFrameParams(&params, in.src, in.size);
+ wksp_size = ZSTD_estimateDStreamSize_fromFrame(in.src, in.size);
err = handle_zstd_error(ret, error);
if (err)
goto out;
- if (ret != 0) {
- error("ZSTD-compressed data has an incomplete frame header");
- err = -1;
- goto out;
- }
- if (params.windowSize > ZSTD_WINDOWSIZE_MAX) {
- error("ZSTD-compressed data has too large a window size");
+ wksp = large_malloc(wksp_size);
+ if (wksp == NULL) {
+ error("Out of memory while allocating ZSTD_DStream");
err = -1;
goto out;
}
-
- /*
- * Allocate the ZSTD_DStream now that we know how much memory is
- * required.
- */
- wksp_size = ZSTD_DStreamWorkspaceBound(params.windowSize);
- wksp = large_malloc(wksp_size);
- dstream = ZSTD_initDStream(params.windowSize, wksp, wksp_size);
+ dstream = ZSTD_initStaticDStream(wksp, wksp_size);
if (dstream == NULL) {
- error("Out of memory while allocating ZSTD_DStream");
+ error("ZSTD_initStaticDStream failed");
err = -1;
goto out;
}
--
2.28.0