From 52571bc9602e3dd41626876ffc6c2e65b0e098bc Mon Sep 17 00:00:00 2001
From: TapTap <taptap.programming@gmail.com>
Date: Thu, 16 Jul 2026 12:29:31 +0200
Subject: [PATCH] streaming zstd: switch to ZSTD_compressStream2 /
 ZSTD_decompressStream

Replaced one-shot ZSTD_compress / ZSTD_decompress with streaming
API (ZSTD_compressStream2 + ZSTD_decompressStream) in both
data_compress and data_decompress. Interface unchanged.

Prepares for true streaming transfer where compression can be
interleaved with transmission.
---
 src/shared/compression.c | 68 +++++++++++++++++++++++++++++-----------
 1 file changed, 49 insertions(+), 19 deletions(-)

diff --git a/src/shared/compression.c b/src/shared/compression.c
index 627659c..cc605e8 100644
--- a/src/shared/compression.c
+++ b/src/shared/compression.c
@@ -6,18 +6,31 @@
 
 Data *data_compress(Data *data_to_compress, int compression_level) {
   log_message(LOG_LEVEL_DEBUG, "Starting to compress data");
-  Data *compressed_data =
-      data_create_empty(ZSTD_compressBound(data_to_compress->size));
+  size_t dst_size = ZSTD_compressBound(data_to_compress->size);
+  Data *compressed_data = data_create_empty(dst_size);
 
-  compressed_data->size = ZSTD_compress(
-      compressed_data->data, compressed_data->size, data_to_compress->data,
-      data_to_compress->size, compression_level);
-  if (ZSTD_isError(compressed_data->size)) {
-    log_message(LOG_LEVEL_ERROR, "Compression failed: %s",
-                ZSTD_getErrorName(compressed_data->size));
+  ZSTD_CCtx *cctx = ZSTD_createCCtx();
+  if (!cctx) {
+    log_message(LOG_LEVEL_ERROR, "Failed to create ZSTD compression context");
     exit(EXIT_FAILURE);
   }
 
+  ZSTD_inBuffer input = {data_to_compress->data, data_to_compress->size, 0};
+  ZSTD_outBuffer output = {compressed_data->data, dst_size, 0};
+
+  size_t ret;
+  do {
+    ret = ZSTD_compressStream2(cctx, &output, &input, ZSTD_e_end);
+    if (ZSTD_isError(ret)) {
+      log_message(LOG_LEVEL_ERROR, "Compression failed: %s",
+                  ZSTD_getErrorName(ret));
+      exit(EXIT_FAILURE);
+    }
+  } while (ret > 0);
+
+  compressed_data->size = output.pos;
+  ZSTD_freeCCtx(cctx);
+
   log_message(LOG_LEVEL_DEBUG, "Data succesfully compressed from %zu to %zu",
               data_to_compress->size, compressed_data->size);
   return compressed_data;
@@ -25,22 +38,39 @@ Data *data_compress(Data *data_to_compress, int compression_level) {
 
 Data *data_decompress(Data *compressed_data) {
   log_message(LOG_LEVEL_DEBUG, "Start to decompress data");
-  Data *uncompressed_data = data_create_empty(
-      ZSTD_getFrameContentSize(compressed_data->data, compressed_data->size));
-  if (ZSTD_isError(uncompressed_data->size)) {
-    log_message(LOG_LEVEL_ERROR, "Decompression failed: %s",
-                ZSTD_getErrorName(uncompressed_data->size));
+  unsigned long long dst_size = ZSTD_getFrameContentSize(
+      compressed_data->data, compressed_data->size);
+  if (ZSTD_isError(dst_size)) {
+    log_message(LOG_LEVEL_ERROR, "Failed to get decompressed size: %s",
+                ZSTD_getErrorName(dst_size));
     exit(EXIT_FAILURE);
   }
 
-  uncompressed_data->size =
-      ZSTD_decompress(uncompressed_data->data, uncompressed_data->size,
-                      compressed_data->data, compressed_data->size);
-  if (ZSTD_isError(uncompressed_data->size)) {
-    log_message(LOG_LEVEL_ERROR, "Decompression failed: %s",
-                ZSTD_getErrorName(uncompressed_data->size));
+  Data *uncompressed_data = data_create_empty((size_t)dst_size);
+
+  ZSTD_DCtx *dctx = ZSTD_createDCtx();
+  if (!dctx) {
+    log_message(LOG_LEVEL_ERROR,
+                "Failed to create ZSTD decompression context");
     exit(EXIT_FAILURE);
   }
+
+  ZSTD_inBuffer input = {compressed_data->data, compressed_data->size, 0};
+  ZSTD_outBuffer output = {uncompressed_data->data, (size_t)dst_size, 0};
+
+  size_t ret;
+  do {
+    ret = ZSTD_decompressStream(dctx, &output, &input);
+    if (ZSTD_isError(ret)) {
+      log_message(LOG_LEVEL_ERROR, "Decompression failed: %s",
+                  ZSTD_getErrorName(ret));
+      exit(EXIT_FAILURE);
+    }
+  } while (ret > 0);
+
+  uncompressed_data->size = output.pos;
+  ZSTD_freeDCtx(dctx);
+
   log_message(LOG_LEVEL_DEBUG, "Decompressed data successfully");
   return uncompressed_data;
 }