From: Nick Terrell <terrelln@fb.com>
Date: Mon, 12 Oct 2020 21:09:12 +0000 (-0700)
Subject: [lib] Take the shortcut when ZSTD_c_stableOutBuffer is set
X-Git-Tag: v1.4.7~38^2~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=987cb4ca6a526923918d40ad65d21e5ef3c724c3;p=thirdparty%2Fzstd.git

[lib] Take the shortcut when ZSTD_c_stableOutBuffer is set

When we have a stable output buffer take the single-pass shortcut.
It is okay to return `dstSizeTooSmall` if the output buffer isn't
big enough, because we know it will never grow.
---

diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index a7ab4dea3..acd150b9d 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -4064,7 +4064,8 @@ static size_t ZSTD_compressStream_generic(ZSTD_CStream* zcs,
 
         case zcss_load:
             if ( (flushMode == ZSTD_e_end)
-              && ((size_t)(oend-op) >= ZSTD_compressBound(iend-ip))  /* enough dstCapacity */
+              && ( (size_t)(oend-op) >= ZSTD_compressBound(iend-ip)     /* Enough output space */
+                || zcs->appliedParams.outBufferMode == ZSTD_bm_stable)  /* OR we are allowed to return dstSizeTooSmall */
               && (zcs->inBuffPos == 0) ) {
                 /* shortcut to compression pass directly into output buffer */
                 size_t const cSize = ZSTD_compressEnd(zcs,