CPack/DEB: Add CPACK_DEBIAN_COMPRESSION_LEVEL variable

Add a new variable `CPACK_DEBIAN_COMPRESSION_LEVEL` to control the compression
level used when generating Debian packages. This complements the existing
`CPACK_DEBIAN_COMPRESSION_TYPE` variable and allows finer control over the
compression performance vs. size trade-off. Supported values correspond to
the compression level accepted by the underlying compressor (e.g. gzip, xz,
zstd, etc.).

Help/cpack_gen/deb.rst

@@ -306,6 +306,37 @@ List of CPack DEB generator specific variables:
 
     Zstandard compression
 
+.. variable:: CPACK_DEBIAN_COMPRESSION_LEVEL
+
+ .. versionadded:: 4.3
+
+ The compression level used for creating the Debian package.
+
+ :Mandatory: No
+ :Default: Automatically determined by the compression tool.
+
+ This variable allows fine-tuning of the compression ratio and speed for the
+ Debian package archive. It controls the numeric compression level passed to
+ the compressor defined by :variable:`CPACK_DEBIAN_COMPRESSION_TYPE`.
+ If ``CPACK_DEBIAN_COMPRESSION_LEVEL`` is not set, or is set to ``0``,
+ the default value will be used.
+
+ The valid range and interpretation depend on the selected compression type:
+
+  - ``gzip``  – level 1–9 (default 6)
+  - ``bzip2`` – level 1–9 (default 9)
+  - ``xz``    – level 1–9 (default 6)
+  - ``lzma``  – level 1–9 (default 6)
+  - ``zstd``  – level 1–19 (default 3)
+
+ Example usage:
+
+ .. code-block:: cmake
+
+   set(CPACK_DEBIAN_COMPRESSION_TYPE "xz")
+   set(CPACK_DEBIAN_COMPRESSION_LEVEL 9)
+
+   include(CPack)
 
 .. variable:: CPACK_DEBIAN_PACKAGE_PRIORITY
               CPACK_DEBIAN_<COMPONENT>_PACKAGE_PRIORITY

Help/release/dev/cpack-deb-compression-level.rst

@@ -0,0 +1,6 @@
+cpack-deb-compression-level
+---------------------------
+
+* The :cpack_gen:`CPack DEB Generator` gained a new variable
+  :variable:`CPACK_DEBIAN_COMPRESSION_LEVEL` to control the
+  compression level used when creating Debian packages.

Modules/Internal/CPack/CPackDeb.cmake

@@ -808,6 +808,10 @@ function(cpack_deb_prepare_package_vars)
     string(REGEX REPLACE "\.deb$" "-dbgsym.ddeb" CPACK_DBGSYM_OUTPUT_FILE_NAME "${CPACK_OUTPUT_FILE_NAME}")
   endif()
 
+  if(NOT DEFINED CPACK_DEBIAN_COMPRESSION_LEVEL)
+    set(CPACK_DEBIAN_COMPRESSION_LEVEL "0")
+  endif()
+
   # Print out some debug information if we were asked for that
   if(CPACK_DEBIAN_PACKAGE_DEBUG)
      message("CPackDeb:Debug: CPACK_TOPLEVEL_DIRECTORY          = '${CPACK_TOPLEVEL_DIRECTORY}'")
@@ -820,6 +824,7 @@ function(cpack_deb_prepare_package_vars)
      message("CPackDeb:Debug: CPACK_TEMPORARY_PACKAGE_FILE_NAME = '${CPACK_TEMPORARY_PACKAGE_FILE_NAME}'")
      message("CPackDeb:Debug: CPACK_DEBIAN_PACKAGE_CONTROL_STRICT_PERMISSION = '${CPACK_DEBIAN_PACKAGE_CONTROL_STRICT_PERMISSION}'")
      message("CPackDeb:Debug: CPACK_DEBIAN_PACKAGE_SOURCE       = '${CPACK_DEBIAN_PACKAGE_SOURCE}'")
+     message("CPackDeb:Debug: CPACK_DEBIAN_COMPRESSION_LEVEL       = '${CPACK_DEBIAN_COMPRESSION_LEVEL}'")
   endif()
 
   # For debian source packages:
@@ -849,6 +854,7 @@ function(cpack_deb_prepare_package_vars)
   set(GEN_CPACK_DEBIAN_PACKAGE_DEPENDS "${CPACK_DEBIAN_PACKAGE_DEPENDS}" PARENT_SCOPE)
   set(GEN_CPACK_DEBIAN_ARCHIVE_TYPE "${CPACK_DEBIAN_ARCHIVE_TYPE}" PARENT_SCOPE)
   set(GEN_CPACK_DEBIAN_COMPRESSION_TYPE "${CPACK_DEBIAN_COMPRESSION_TYPE}" PARENT_SCOPE)
+  set(GEN_CPACK_DEBIAN_COMPRESSION_LEVEL "${CPACK_DEBIAN_COMPRESSION_LEVEL}" PARENT_SCOPE)
   set(GEN_CPACK_DEBIAN_PACKAGE_RECOMMENDS "${CPACK_DEBIAN_PACKAGE_RECOMMENDS}" PARENT_SCOPE)
   set(GEN_CPACK_DEBIAN_PACKAGE_SUGGESTS "${CPACK_DEBIAN_PACKAGE_SUGGESTS}" PARENT_SCOPE)
   set(GEN_CPACK_DEBIAN_PACKAGE_HOMEPAGE "${CPACK_DEBIAN_PACKAGE_HOMEPAGE}" PARENT_SCOPE)

Source/CPack/cmCPackDebGenerator.cxx

@@ -32,8 +32,8 @@ class DebGenerator
 public:
   DebGenerator(cmCPackLog* logger, std::string outputName, std::string workDir,
                std::string topLevelDir, std::string temporaryDir,
-               cmValue debianCompressionType, cmValue numThreads,
-               cmValue debianArchiveType,
+               cmValue debianCompressionType, cmValue debianCompressionLevel,
+               cmValue numThreads, cmValue debianArchiveType,
                std::map<std::string, std::string> controlValues,
                bool genShLibs, std::string shLibsFilename, bool genPostInst,
                std::string postInst, bool genPostRm, std::string postRm,
@@ -69,16 +69,18 @@ private:
   bool const PermissionStrictPolicy;
   std::vector<std::string> const PackageFiles;
   cmArchiveWrite::Compress TarCompressionType;
+  int CompressionLevel = 0;
 };
 
 DebGenerator::DebGenerator(
   cmCPackLog* logger, std::string outputName, std::string workDir,
   std::string topLevelDir, std::string temporaryDir,
-  cmValue debCompressionType, cmValue numThreads, cmValue debianArchiveType,
-  std::map<std::string, std::string> controlValues, bool genShLibs,
-  std::string shLibsFilename, bool genPostInst, std::string postInst,
-  bool genPostRm, std::string postRm, cmValue controlExtra,
-  bool permissionStrictPolicy, std::vector<std::string> packageFiles)
+  cmValue debCompressionType, cmValue debCompressionLevel, cmValue numThreads,
+  cmValue debianArchiveType, std::map<std::string, std::string> controlValues,
+  bool genShLibs, std::string shLibsFilename, bool genPostInst,
+  std::string postInst, bool genPostRm, std::string postRm,
+  cmValue controlExtra, bool permissionStrictPolicy,
+  std::vector<std::string> packageFiles)
   : Logger(logger)
   , OutputName(std::move(outputName))
   , WorkDir(std::move(workDir))
@@ -135,6 +137,19 @@ DebGenerator::DebGenerator(
   } else {
     this->NumThreads = 1;
   }
+
+  if (debCompressionLevel) {
+    long compressionLevel;
+    if (!cmStrToLong(*debCompressionLevel, &compressionLevel)) {
+      compressionLevel = 0;
+      cmCPackLogger(cmCPackLog::LOG_ERROR,
+                    "Unrecognized compression level: " << debCompressionLevel
+                                                       << std::endl);
+    }
+    this->CompressionLevel = static_cast<int>(compressionLevel);
+  } else {
+    this->CompressionLevel = 0;
+  }
 }
 
 bool DebGenerator::generate() const
@@ -192,7 +207,7 @@ bool DebGenerator::generateDataTar() const
     return false;
   }
   cmArchiveWrite data_tar(fileStream_data_tar, this->TarCompressionType,
-                          this->DebianArchiveType, 0,
+                          this->DebianArchiveType, this->CompressionLevel,
                           static_cast<int>(this->NumThreads));
   if (!data_tar.Open()) {
     cmCPackLogger(cmCPackLog::LOG_ERROR,
@@ -324,7 +339,7 @@ bool DebGenerator::generateControlTar(std::string const& md5Filename) const
     return false;
   }
   cmArchiveWrite control_tar(fileStream_control_tar, this->TarCompressionType,
-                             this->DebianArchiveType);
+                             this->DebianArchiveType, this->CompressionLevel);
   if (!control_tar.Open()) {
     cmCPackLogger(cmCPackLog::LOG_ERROR,
                   "Error opening the archive \""
@@ -846,6 +861,7 @@ bool cmCPackDebGenerator::createDeb()
     this->GetOption("CPACK_TOPLEVEL_DIRECTORY"),
     this->GetOption("CPACK_TEMPORARY_DIRECTORY"),
     this->GetOption("GEN_CPACK_DEBIAN_COMPRESSION_TYPE"),
+    this->GetOption("GEN_CPACK_DEBIAN_COMPRESSION_LEVEL"),
     this->GetOption("CPACK_THREADS"),
     this->GetOption("GEN_CPACK_DEBIAN_ARCHIVE_TYPE"), controlValues, gen_shibs,
     shlibsfilename, this->IsOn("GEN_CPACK_DEBIAN_GENERATE_POSTINST"), postinst,
@@ -901,6 +917,7 @@ bool cmCPackDebGenerator::createDbgsymDDeb()
     this->GetOption("CPACK_TOPLEVEL_DIRECTORY"),
     this->GetOption("CPACK_TEMPORARY_DIRECTORY"),
     this->GetOption("GEN_CPACK_DEBIAN_COMPRESSION_TYPE"),
+    this->GetOption("GEN_CPACK_DEBIAN_COMPRESSION_LEVEL"),
     this->GetOption("CPACK_THREADS"),
     this->GetOption("GEN_CPACK_DEBIAN_ARCHIVE_TYPE"), controlValues, false, "",
     false, "", false, "", nullptr,

Tests/RunCMake/CPack_DEB/Basic-verify-stdout.txt

@@ -11,4 +11,8 @@ d[rwx-]+ root/root         0 [0-9-]+ [0-9:]+ \./usr/share/
 d[rwx-]+ root/root         0 [0-9-]+ [0-9:]+ \./usr/share/doc/
 d[rwx-]+ root/root         0 [0-9-]+ [0-9:]+ \./usr/share/doc/basic/
 -[rwx-]+ root/root         0 [0-9-]+ [0-9:]+ \./usr/share/doc/basic/basic\.txt
+-- ar t
+debian-binary
+control\.tar\.xz
+data\.tar\.xz
 --

Tests/RunCMake/CPack_DEB/verify.cmake

@@ -2,3 +2,5 @@ message(STATUS "dpkg-deb --info")
 execute_process(COMMAND dpkg-deb --info ${CMAKE_ARGV4})
 message(STATUS "dpkg-deb --contents")
 execute_process(COMMAND dpkg-deb --contents ${CMAKE_ARGV4})
+message(STATUS "ar t")
+execute_process(COMMAND ar t ${CMAKE_ARGV4})

Tests/RunCMake/RunCPack/Basic/CMakeLists.txt

@@ -3,5 +3,8 @@ project(Basic LANGUAGES NONE VERSION "1.2.3")
 
 install(FILES basic.txt DESTINATION share/doc/basic)
 
+set(CPACK_DEBIAN_COMPRESSION_TYPE "xz")
+set(CPACK_DEBIAN_COMPRESSION_LEVEL "4")
+
 set(CPACK_PACKAGE_CONTACT "[email protected]")
 include(CPack)