Move compressors to utility library

- Remove compressor registration interface. Doesn't work in a static
   library, since all the files containing no exported members are
   optimized away at link time.
 - Repack as seperate utility library.

Signed-off-by: David Oberhollenzer <goliath@infraroot.at>

include/comp/compressor.h

@@ -29,16 +29,8 @@ typedef struct compressor_t {
 	compressor_stream_t *(*uncompression_stream)(struct compressor_t *cmp);
 } compressor_t;
 
-void compressor_register(compressor_t *compressor);
-
 compressor_t *compressor_by_name(const char *name);
 
 compressor_t *compressor_by_id(PKG_COMPRESSION id);
 
-#define REGISTER_COMPRESSOR(compressor) \
-	static void __attribute__((constructor)) register_##compressor(void) \
-	{ \
-		compressor_register((compressor_t *)&compressor); \
-	}
-
 #endif /* COMPRESSOR_H */

include/pkgwriter.h

@@ -4,8 +4,8 @@
 
 #include <stdbool.h>
 
+#include "comp/compressor.h"
 #include "pkgformat.h"
-#include "compressor.h"
 
 typedef struct pkg_writer_t pkg_writer_t;
 

lib/Makemodule.am

@@ -9,4 +9,23 @@ libfilelist_a_SOURCES = lib/filelist/dump_toc.c lib/filelist/image_entry.c
 libfilelist_a_SOURCES += lib/filelist/image_entry_sort.c
 libfilelist_a_SOURCES += include/filelist/image_entry.h
 
-noinst_LIBRARIES += libutil.a libfilelist.a
+libcomp_a_SOURCES = lib/comp/compressor.c lib/comp/none.c
+libcomp_a_SOURCES += include/comp/compressor.h lib/comp/internal.h
+libcomp_a_CFLAGS = $(AM_CFLAGS)
+libcomp_a_CPPFLAGS = $(AM_CPPFLAGS)
+
+if WITH_ZLIB
+libcomp_a_SOURCES += lib/comp/zlib.c
+
+libcomp_a_CFLAGS += $(ZLIB_CFLAGS)
+libcomp_a_CPPFLAGS += -DWITH_ZLIB
+endif
+
+if WITH_LZMA
+libcomp_a_SOURCES += lib/comp/lzma.c
+
+libcomp_a_CFLAGS += $(XZ_CFLAGS)
+libcomp_a_CPPFLAGS += -DWITH_LZMA
+endif
+
+noinst_LIBRARIES += libutil.a libfilelist.a libcomp.a

lib/comp/compressor.c

@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: ISC */
+#include <string.h>
+
+#include "internal.h"
+
+static compressor_t *compressors[] = {
+	[PKG_COMPRESSION_NONE] = &comp_none,
+#ifdef WITH_ZLIB
+	[PKG_COMPRESSION_ZLIB] = &comp_zlib,
+#endif
+#ifdef WITH_LZMA
+	[PKG_COMPRESSION_LZMA] = &comp_lzma,
+#endif
+};
+
+compressor_t *compressor_by_name(const char *name)
+{
+	size_t i;
+
+	for (i = 0; i < sizeof(compressors) / sizeof(compressors[0]); ++i) {
+		if (compressors[i] == NULL)
+			continue;
+		if (strcmp(compressors[i]->name, name) == 0)
+			return compressors[i];
+	}
+
+	return NULL;
+}
+
+compressor_t *compressor_by_id(PKG_COMPRESSION id)
+{
+	if ((int)id < 0)
+		return NULL;
+
+	if ((size_t)id >= sizeof(compressors) / sizeof(compressors[0]))
+		return NULL;
+
+	return compressors[id];
+}

lib/comp/internal.h

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: ISC */
+#ifndef INTERNAL_H
+#define INTERNAL_H
+
+#include "comp/compressor.h"
+
+extern compressor_t comp_lzma;
+extern compressor_t comp_none;
+extern compressor_t comp_zlib;
+
+#endif /* INTERNAL_H */

lib/comp/lzma.c

@@ -5,7 +5,7 @@
 #include <stdio.h>
 #include <lzma.h>
 
-#include "compressor.h"
+#include "internal.h"
 
 #define CHUNK_SIZE 16384
 
@@ -160,11 +160,9 @@ static compressor_stream_t *lzma_uncompress(compressor_t *cmp)
 	return create_stream(false);
 }
 
-static compressor_t lzma = {
+compressor_t comp_lzma = {
 	.name = "lzma",
 	.id = PKG_COMPRESSION_LZMA,
 	.compression_stream = lzma_compress,
 	.uncompression_stream = lzma_uncompress,
 };
-
-REGISTER_COMPRESSOR(lzma)

lib/comp/none.c

@@ -4,7 +4,7 @@
 #include <stdio.h>
 #include <zlib.h>
 
-#include "compressor.h"
+#include "internal.h"
 
 #define CHUNK_SIZE 16384
 
@@ -81,11 +81,9 @@ static compressor_stream_t *create_dummy_stream(compressor_t *cmp)
 	return base;
 }
 
-static compressor_t none = {
+compressor_t comp_none = {
 	.name = "none",
 	.id = PKG_COMPRESSION_NONE,
 	.compression_stream = create_dummy_stream,
 	.uncompression_stream = create_dummy_stream,
 };
-
-REGISTER_COMPRESSOR(none)

lib/comp/zlib.c

@@ -5,7 +5,7 @@
 #include <stdio.h>
 #include <zlib.h>
 
-#include "compressor.h"
+#include "internal.h"
 
 #define CHUNK_SIZE 16384
 
@@ -159,11 +159,9 @@ static compressor_stream_t *zlib_uncompress(compressor_t *cmp)
 	return create_stream(false);
 }
 
-static compressor_t zlib = {
+compressor_t comp_zlib = {
 	.name = "zlib",
 	.id = PKG_COMPRESSION_ZLIB,
 	.compression_stream = zlib_compress,
 	.uncompression_stream = zlib_uncompress,
 };
-
-REGISTER_COMPRESSOR(zlib)

main/Makemodule.am

@@ -1,13 +1,12 @@
 pkg_SOURCES = include/pkgformat.h include/pkgreader.h include/pkgio.h
-pkg_SOURCES += include/compressor.h include/command.h include/pkgwriter.h
+pkg_SOURCES += include/command.h include/pkgwriter.h include/depgraph.h
-pkg_SOURCES += include/depgraph.h
+pkg_SOURCES += main/pkg.c main/command.c main/pkgreader.c
-pkg_SOURCES += main/pkg.c main/compressor.c main/command.c main/pkgreader.c
 pkg_SOURCES += main/pkgwriter.c main/pkgio_rd_image_entry.c main/pkg_unpack.c
 pkg_SOURCES += main/depgraph/collect.c main/depgraph/pkglist.c
 pkg_SOURCES += main/depgraph/tsort.c
 
 pkg_CFLAGS = $(AM_CFLAGS)
-pkg_LDADD = libutil.a libfilelist.a
+pkg_LDADD = libutil.a libfilelist.a libcomp.a
 
 ##### commands #####
 
@@ -40,24 +39,12 @@ pkg_SOURCES += main/cmd/unpack.c
 pkg_SOURCES += main/cmd/help.c
 
 ##### compressors #####
-
-# dummy compressor
-pkg_SOURCES += main/compressors/none.c
-
-# zlib compressor
-if WITH_ZLIB
-pkg_SOURCES += main/compressors/zlib.c
-
-pkg_CFLAGS += $(ZLIB_CFLAGS)
-pkg_LDADD += $(ZLIB_LIBS)
-endif
-
-# lzma compressor
 if WITH_LZMA
-pkg_SOURCES += main/compressors/lzma.c
-
-pkg_CFLAGS += $(XZ_CFLAGS)
 pkg_LDADD += $(XZ_LIBS)
 endif
 
+if WITH_ZLIB
+pkg_LDADD += $(ZLIB_LIBS)
+endif
+
 bin_PROGRAMS += pkg

main/cmd/pack/pack.h

@@ -21,7 +21,7 @@
 
 #include "filelist/image_entry.h"
 
-#include "compressor.h"
+#include "comp/compressor.h"
 #include "pkgformat.h"
 #include "pkgwriter.h"
 #include "command.h"

main/compressor.c

@@ -1,32 +0,0 @@
-/* SPDX-License-Identifier: ISC */
-#include <string.h>
-
-#include "compressor.h"
-
-static compressor_t *list = NULL;
-
-void compressor_register(compressor_t *compressor)
-{
-	compressor->next = list;
-	list = compressor;
-}
-
-compressor_t *compressor_by_name(const char *name)
-{
-	compressor_t *it = list;
-
-	while (it != NULL && strcmp(it->name, name) != 0)
-		it = it->next;
-
-	return it;
-}
-
-compressor_t *compressor_by_id(PKG_COMPRESSION id)
-{
-	compressor_t *it = list;
-
-	while (it != NULL && it->id != id)
-		it = it->next;
-
-	return it;
-}

main/pkgreader.c

@@ -8,9 +8,9 @@
 #include <errno.h>
 #include <ctype.h>
 
+#include "comp/compressor.h"
 #include "util/util.h"
 #include "pkgreader.h"
-#include "compressor.h"
 
 struct pkg_reader_t {
 	int fd;