fix and document on the fly compressor config

libapt allows to configure compressors to be used by its system via
configuration implemented in 03bef78461c6f443187b60799402624326843396,
but that was never really documented and also only partly working, which
also explains why the tests weren't using it…

1 files changed, 12 insertions, 13 deletions

diff --git a/apt-pkg/aptconfiguration.cc b/apt-pkg/aptconfiguration.cc
index 01ae5a642..32778e273 100644
--- a/apt-pkg/aptconfiguration.cc
+++ b/apt-pkg/aptconfiguration.cc
@@ -35,6 +35,7 @@ namespace APT {
 // setDefaultConfigurationForCompressors				/*{{{*/
 static void setDefaultConfigurationForCompressors() {
 	// Set default application paths to check for optional compression types
+	_config->CndSet("Dir::Bin::gzip", "/bin/gzip");
 	_config->CndSet("Dir::Bin::bzip2", "/bin/bzip2");
 	_config->CndSet("Dir::Bin::xz", "/usr/bin/xz");
 	_config->CndSet("Dir::Bin::lz4", "/usr/bin/lz4");
@@ -60,6 +61,12 @@ static void setDefaultConfigurationForCompressors() {
 			_config->Set("APT::Compressor::lzma::UncompressArg::", "-d");
 		}
 	}
+	// setup the defaults for the compressiontypes => method mapping
+	_config->CndSet("Acquire::CompressionTypes::xz","xz");
+	_config->CndSet("Acquire::CompressionTypes::bz2","bzip2");
+	_config->CndSet("Acquire::CompressionTypes::lzma","lzma");
+	_config->CndSet("Acquire::CompressionTypes::gz","gzip");
+	_config->CndSet("Acquire::CompressionTypes::lz4","lz4");
 }
 									/*}}}*/
 // getCompressionTypes - Return Vector of usable compressiontypes	/*{{{*/
@@ -75,14 +82,6 @@ const Configuration::getCompressionTypes(bool const &Cached) {
 			types.clear();
 	}
 
-	// setup the defaults for the compressiontypes => method mapping
-	_config->CndSet("Acquire::CompressionTypes::xz","xz");
-	_config->CndSet("Acquire::CompressionTypes::bz2","bzip2");
-	_config->CndSet("Acquire::CompressionTypes::lzma","lzma");
-	_config->CndSet("Acquire::CompressionTypes::gz","gzip");
-	_config->CndSet("Acquire::CompressionTypes::lz4","lz4");
-
-	setDefaultConfigurationForCompressors();
 	std::vector<APT::Configuration::Compressor> const compressors = getCompressors();
 
 	// load the order setting into our vector
@@ -398,12 +397,12 @@ const Configuration::getCompressors(bool const Cached) {
 		compressors.push_back(Compressor("lzma",".lzma","false", NULL, NULL, 400));
 #endif
 
-	std::vector<std::string> const comp = _config->FindVector("APT::Compressor");
-	for (std::vector<std::string>::const_iterator c = comp.begin();
-	     c != comp.end(); ++c) {
-		if (c->empty() || *c == "." || *c == "gzip" || *c == "bzip2" || *c == "lzma" || *c == "xz")
+	std::vector<std::string> const comp = _config->FindVector("APT::Compressor", "", true);
+	for (auto const &c: comp)
+	{
+		if (c.empty() || std::any_of(compressors.begin(), compressors.end(), [&c](Compressor const &ac) { return ac.Name == c; }))
 			continue;
-		compressors.push_back(Compressor(c->c_str(), std::string(".").append(*c).c_str(), c->c_str(), "-9", "-d", 100));
+		compressors.push_back(Compressor(c.c_str(), std::string(".").append(c).c_str(), c.c_str(), nullptr, nullptr, 1000));
 	}
 
 	return compressors;