[lib] Compress directly into output when ZSTD_c_stableOutBuffer is set

When we have a stable output buffer always compress directly into the
`ZSTD_outBuffer`. We are allowed to return `dstSizeTooSmall`.

diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index acd150b9d1b1ab1a4964e4b57d534bdc1a0768b2..1c8fb2fc2fe45f88d6e77d3e2cc84633eeb5c275 100644 (file)
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -4104,7 +4104,7 @@ static size_t ZSTD_compressStream_generic(ZSTD_CStream* zcs,
                 size_t const iSize = zcs->inBuffPos - zcs->inToCompress;
                 size_t oSize = oend-op;
                 unsigned const lastBlock = (flushMode == ZSTD_e_end) && (ip==iend);
-                if (oSize >= ZSTD_compressBound(iSize))
+                if (oSize >= ZSTD_compressBound(iSize) || zcs->appliedParams.outBufferMode == ZSTD_bm_stable)
                     cDst = op;   /* compress into output buffer, to skip flush stage */
                 else
                     cDst = zcs->outBuff, oSize = zcs->outBuffSize;
@@ -4140,6 +4140,7 @@ static size_t ZSTD_compressStream_generic(ZSTD_CStream* zcs,
            /* fall-through */
         case zcss_flush:
             DEBUGLOG(5, "flush stage");
+            assert(zcs->appliedParams.outBufferMode == ZSTD_bm_buffered);
             {   size_t const toFlush = zcs->outBuffContentSize - zcs->outBuffFlushedSize;
                 size_t const flushed = ZSTD_limitCopy(op, (size_t)(oend-op),
                             zcs->outBuff + zcs->outBuffFlushedSize, toFlush);