Add support for ZSTD compression

Author: mkozlowski

.github/workflows/ci-clang.yml

@@ -14,24 +14,35 @@ jobs:
       run: |
         sudo apt-get update
         sudo apt-get install -y liblz4-dev liblz4-1
+        sudo apt-get install -y libzstd-dev libzstd1
         sudo apt-get install -y libssl-dev libssl3
 
     - name: build
       run: |
         make CC=clang
         make clean
 
-    - name: build lz4
+    - name: build with lz4
       run: |
-        make CC=clang COMPRESS_LZ4=1
+        make COMPRESS_LZ4=1 CC=clang
         make clean
 
-    - name: build md5
+    - name: build with zstd
       run: |
-        make CC=clang CHECKSUM_MD5=1
+        make COMPRESS_ZSTD=1 CC=clang
         make clean
 
-    - name: build lz4 md5 enc
+    - name: build with md5
       run: |
-        make CC=clang COMPRESS_LZ4=1 CHECKSUM_MD5=1 ENCRYPT=1
+        make CHECKSUM_MD5=1 CC=clang
+        make clean
+
+    - name: build with enc
+      run: |
+        make ENCRYPT=1 CC=clang
+        make clean
+
+    - name: build with lz4 zstd md5 enc
+      run: |
+        make COMPRESS_LZ4=1 COMPRESS_ZSTD=1 CHECKSUM_MD5=1 ENCRYPT=1 CC=clang
         make clean

.github/workflows/ci-x86_64.yml

@@ -14,24 +14,35 @@ jobs:
       run: |
         sudo apt-get update
         sudo apt-get install -y liblz4-dev liblz4-1
+        sudo apt-get install -y libzstd-dev libzstd1
         sudo apt-get install -y libssl-dev libssl3
 
     - name: build
       run: |
         make
         make clean
 
-    - name: build lz4
+    - name: build with lz4
       run: |
         make COMPRESS_LZ4=1
         make clean
 
-    - name: build md5
+    - name: build with zstd
+      run: |
+        make COMPRESS_ZSTD=1
+        make clean
+
+    - name: build with md5
       run: |
         make CHECKSUM_MD5=1
         make clean
 
-    - name: build lz4 md5 enc
+    - name: build with enc
+      run: |
+        make ENCRYPT=1
+        make clean
+
+    - name: build with lz4 zstd md5 enc
       run: |
-        make COMPRESS_LZ4=1 CHECKSUM_MD5=1 ENCRYPT=1
+        make COMPRESS_LZ4=1 COMPRESS_ZSTD=1 CHECKSUM_MD5=1 ENCRYPT=1
         make clean

Makefile

@@ -1,5 +1,6 @@
 #
 # Copyright (C) 2022 Liberty Global Service B.V.
+# Copyright (C) 2022-2025 Mariusz Kozłowski
 #
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
@@ -38,6 +39,11 @@ ifeq ($(COMPRESS_LZ4), 1)
     LDFLAGS += -llz4
 endif
 
+ifeq ($(COMPRESS_ZSTD), 1)
+    MCFLAGS += -DCOMPRESS_ZSTD
+    LDFLAGS += -lzstd
+endif
+
 ifeq ($(CHECKSUM_MD5), 1)
     MCFLAGS += -DCHECKSUM_MD5
     LDFLAGS += -lcrypto
@@ -142,10 +148,13 @@ $(B)/enter.o: arch/$(ARCH)/enter.c
 $(B)/cpu.o: arch/$(ARCH)/cpu.c
 	$(CC) $(MCFLAGS) -c $^ -o $@
 
+$(B)/compress.o: compress.c compress.h
+	$(CC) $(MCFLAGS) -c $< -o $@
+
 $(B)/memcr.o: memcr.c $(B)/parasite-blob.h
 	$(CC) $(MCFLAGS) -DGIT_VERSION='"$(GIT_VERSION)"' -DARCH_NAME='"$(ARCH)"' -I$(B) -c $< -o $@
 
-$(B)/memcr: $(B)/memcr.o $(B)/cpu.o $(B)/enter.o
+$(B)/memcr: $(B)/memcr.o $(B)/cpu.o $(B)/enter.o $(B)/compress.o
 	$(CC) $(MCFLAGS) $^ $(LDFLAGS) -o $@
 	@stat -c "-> %n: %s bytes <-" $@
 	@size $@
@@ -193,18 +202,19 @@ clean:
 
 help:
 	@echo 'Build targets:'
-	@echo '  all            - build all targets'
-	@echo '  memcr          - build memcr binary'
+	@echo '  all             - build all targets'
+	@echo '  memcr           - build memcr binary'
 	@echo ''
 	@echo 'Compilation options:'
-	@echo '  COMPRESS_LZ4=1 - compile in support for memory dump LZ4 compression'
-	@echo '  CHECKSUM_MD5=1 - compile in support for memory dump MD5 checksumming'
-	@echo '  ENCRYPT=1      - compile libencrypt.so that can be preloaded for memcr'
+	@echo '  COMPRESS_LZ4=1  - compile in support for memory dump LZ4 compression'
+	@echo '  COMPRESS_ZSTD=1 - compile in support for memory dump ZSTD compression'
+	@echo '  CHECKSUM_MD5=1  - compile in support for memory dump MD5 checksumming'
+	@echo '  ENCRYPT=1       - compile libencrypt.so that can be preloaded for memcr'
 	@echo ''
 	@echo 'Test targets:'
-	@echo '  tests          - build and run memcr tests'
+	@echo '  tests           - build and run memcr tests'
 	@echo ''
 	@echo 'Clean targets:'
-	@echo '  clean          - remove generated files'
+	@echo '  clean           - remove generated files'
 
 .PHONY: all tests clean help

README.md

@@ -18,19 +18,21 @@ make
 ##### compilation options
 You can enable support for compression and checksumming of memory dump file:
  - `COMPRESS_LZ4=1` - requires liblz4
+ - `COMPRESS_ZSTD=1` - requires libzstd
  - `CHECKSUM_MD5=1` - requires libcrypto and openssl headers
 
  There is also `ENCRYPT` option for building `libencrypt.so` that provides sample implementation of encryption layer based on libcrypto API. memcr is not linked with libencrypt.so, but it can be preloaded with `LD_PRELOAD`.
  - `ENCRYPT=1` - requires libcrypto and openssl headers
 
-##### compilation on Ubuntu 22.04:
+##### compilation on Ubuntu 24.04:
 ```
 sudo apt-get install liblz4-dev liblz4-1
+sudo apt-get install libzstd-dev libzstd1
 sudo apt-get install libssl-dev libssl3
 ```
 
 ```
-make COMPRESS_LZ4=1 CHECKSUM_MD5=1 ENCRYPT=1
+make COMPRESS_LZ4=1 COMPRESS_ZSTD=1 CHECKSUM_MD5=1 ENCRYPT=1
 ```
 
 ##### cross compilation
@@ -52,15 +54,15 @@ memcr -p <target pid>
 ```
 For the list of available options, check memcr help:
 ```
-memcr [-h] [-p PID] [-d DIR] [-S DIR] [-l PORT|PATH] [-n] [-m] [-f] [-z] [-c] [-e] [-V]
+memcr [-h] [-p PID] [-d DIR] [-S DIR] [-G gid] [-N] [-l PORT|PATH] [-g gid] [-n] [-m] [-f] [-z lz4|zstd] [-c] [-e] [-t] [-V]
 options:
   -h --help             help
   -p --pid              target process pid
   -d --dir              dir where memory dump is stored (defaults to /tmp)
   -S --parasite-socket-dir      dir where socket to communicate with parasite is created
         (abstract socket will be used if no path specified)
-  -G --parasite-socket-gid     group ID for parasite UNIX domain socket file, valid only for if --parasite-socket-dir provided,
-                               note: the group ID provided need to be common for: the user running memcr daemon and the user running suspended process
+  -G --parasite-socket-gid      group ID for parasite UNIX domain socket file, valid only for if --parasite-socket-dir provided
+                                note: the group ID provided need to be common for: the user running memcr daemon and the user running suspended process
   -N --parasite-socket-netns    use network namespace of parasite when connecting to socket
         (useful if parasite is running in a container with netns)
   -l --listen           work as a service waiting for requests on a socket
@@ -70,12 +72,11 @@ options:
   -n --no-wait          no wait for key press
   -m --proc-mem         get pages from /proc/pid/mem
   -f --rss-file         include file mapped memory
-  -z --compress         compress memory dump
+  -z --compress         compress memory dump with zstd or lz4 (default)
   -c --checksum         enable md5 checksum for memory dump
   -e --encrypt          enable encryption of memory dump
   -t --timeout          timeout in seconds for checkpoint/restore execution in service mode
   -V --version          print version and exit
-
 ```
 memcr also supports client / server scenario where memcr runs as a daemon and listens for commands from a client process. The main reason for supporting this is that memcr needs rather high privileges to hijack target process and it's a good idea to keep it separate from memcr-client that can run in a container with low privileges.