Support for loading Xz-compressed modules

Makefile.am

@@ -27,6 +27,8 @@ SED_PROCESS = \
 	-e 's,@exec_prefix\@,$(exec_prefix),g' \
 	-e 's,@libdir\@,$(libdir),g' \
 	-e 's,@includedir\@,$(includedir),g' \
+	-e 's,@liblzma_CFLAGS\@,${liblzma_CFLAGS},g' \
+	-e 's,@liblzma_LIBS\@,${liblzma_LIBS},g' \
 	-e 's,@zlib_CFLAGS\@,${zlib_CFLAGS},g' \
 	-e 's,@zlib_LIBS\@,${zlib_LIBS},g' \
 	< $< > $@ || rm $@
@@ -63,7 +65,7 @@ libkmod_libkmod_la_LDFLAGS = $(AM_LDFLAGS) \
 	-version-info $(LIBKMOD_CURRENT):$(LIBKMOD_REVISION):$(LIBKMOD_AGE) \
 	-Wl,--version-script=$(top_srcdir)/libkmod/libkmod.sym
 libkmod_libkmod_la_DEPENDENCIES = ${top_srcdir}/libkmod/libkmod.sym
-libkmod_libkmod_la_LIBADD = ${zlib_LIBS}
+libkmod_libkmod_la_LIBADD = ${liblzma_LIBS} ${zlib_LIBS}
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = libkmod/libkmod.pc

configure.ac

@@ -51,6 +51,16 @@ AS_IF([test "x$enable_logging" = "xyes"], [
 	AC_DEFINE(ENABLE_LOGGING, [1], [System logging.])
 ])
 
+AC_ARG_WITH([xz],
+	AS_HELP_STRING([--with-xz], [handle Xz-compressed modules @<:@default=disabled@:>@]),
+	[], [with_xz=no])
+AS_IF([test "x$with_xz" != "xno"], [
+	PKG_CHECK_MODULES([liblzma], [liblzma >= 4.99])
+	AC_DEFINE([ENABLE_XZ], [1], [Enable Xz for modules.])
+], [
+	AC_MSG_NOTICE([Xz support not requested])
+])
+
 AC_ARG_WITH([zlib],
 	AS_HELP_STRING([--with-zlib], [handle gzipped modules @<:@default=disabled@:>@]),
 	[], [with_zlib=no])
@@ -139,6 +149,6 @@ AC_MSG_RESULT([
 
 	tools:			${enable_tools}
 	logging:		${enable_logging}
-	zlib:			${with_zlib}
+	compression:		xz=${with_xz}  zlib=${with_zlib}
 	debug:			${enable_debug}
 ])

libkmod/libkmod-file.c

@@ -18,6 +18,7 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <errno.h>
@@ -30,11 +31,17 @@
 #include "libkmod.h"
 #include "libkmod-private.h"
 
+#ifdef ENABLE_XZ
+#include <lzma.h>
+#endif
 #ifdef ENABLE_ZLIB
 #include <zlib.h>
 #endif
 
 struct kmod_file {
+#ifdef ENABLE_XZ
+	bool xz_used;
+#endif
 #ifdef ENABLE_ZLIB
 	gzFile gzf;
 #endif
@@ -43,6 +50,120 @@ struct kmod_file {
 	void *memory;
 };
 
+#ifdef ENABLE_XZ
+static bool xz_detect(struct kmod_file *file)
+{
+	ssize_t ret;
+	char buf[6];
+
+	ret = read(file->fd, buf, sizeof(buf));
+	if (ret < 0 || lseek(file->fd, 0, SEEK_SET))
+		return -errno;
+	return ret == sizeof(buf) &&
+	       memcmp(buf, "\xFD""7zXZ\x00", sizeof(buf)) == 0;
+}
+
+static void xz_uncompress_belch(lzma_ret ret)
+{
+	switch (ret) {
+	case LZMA_MEM_ERROR:
+		fprintf(stderr, "xz: %s\n", strerror(ENOMEM));
+		break;
+	case LZMA_FORMAT_ERROR:
+		fprintf(stderr, "xz: File format not recognized\n");
+		break;
+	case LZMA_OPTIONS_ERROR:
+		fprintf(stderr, "xz: Unsupported compression options\n");
+		break;
+	case LZMA_DATA_ERROR:
+		fprintf(stderr, "xz: File is corrupt\n");
+		break;
+	case LZMA_BUF_ERROR:
+		fprintf(stderr, "xz: Unexpected end of input\n");
+		break;
+	default:
+		fprintf(stderr, "xz: Internal error (bug)\n");
+		break;
+	}
+}
+
+static int xz_uncompress(lzma_stream *strm, struct kmod_file *file)
+{
+	uint8_t in_buf[BUFSIZ], out_buf[BUFSIZ];
+	lzma_action action = LZMA_RUN;
+	lzma_ret ret;
+	void *p = NULL;
+	size_t total = 0;
+
+	strm->avail_in  = 0;
+	strm->next_out  = out_buf;
+	strm->avail_out = sizeof(out_buf);
+
+	while (true) {
+		if (strm->avail_in == 0) {
+			ssize_t rdret = read(file->fd, in_buf, sizeof(in_buf));
+			if (rdret < 0) {
+				ret = -errno;
+				goto out;
+			}
+			strm->next_in  = in_buf;
+			strm->avail_in = rdret;
+			if (rdret == 0)
+				action = LZMA_FINISH;
+		}
+		ret = lzma_code(strm, action);
+		if (strm->avail_out == 0 || ret != LZMA_OK) {
+			size_t write_size = BUFSIZ - strm->avail_out;
+			char *tmp = realloc(p, total + write_size);
+			if (tmp == NULL) {
+				ret = -errno;
+				goto out;
+			}
+			memcpy(tmp + total, out_buf, write_size);
+			total += write_size;
+			p = tmp;
+			strm->next_out = out_buf;
+			strm->avail_out = BUFSIZ;
+		}
+		if (ret == LZMA_STREAM_END)
+			break;
+		if (ret != LZMA_OK) {
+			xz_uncompress_belch(ret);
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+	file->memory = p;
+	file->size = total;
+	return 0;
+ out:
+	free(p);
+	close(file->fd);
+	return ret;
+}
+
+static int xz_file_open(struct kmod_file *file)
+{
+	lzma_stream strm = LZMA_STREAM_INIT;
+	lzma_ret lzret;
+	int ret;
+
+	lzret = lzma_stream_decoder(&strm, UINT64_MAX, LZMA_CONCATENATED);
+	if (lzret == LZMA_MEM_ERROR) {
+		fprintf(stderr, "xz: %s\n", strerror(ENOMEM));
+		close(file->fd);
+		return -ENOMEM;
+	} else if (lzret != LZMA_OK) {
+		fprintf(stderr, "xz: Internal error (bug)\n");
+		close(file->fd);
+		return -EINVAL;
+	}
+	ret = xz_uncompress(&strm, file);
+	lzma_end(&strm);
+	return ret;
+}
+#endif
+
 #ifdef ENABLE_ZLIB
 #define READ_STEP (4 * 1024 * 1024)
 
@@ -152,6 +273,11 @@ struct kmod_file *kmod_file_open(const char *filename)
 		goto error;
 	}
 
+#ifdef ENABLE_XZ
+	if (xz_detect(file))
+		err = xz_file_open(file);
+	else
+#endif
 #ifdef ENABLE_ZLIB
 	if (check_zlib(file))
 		err = zlib_file_open(file);
@@ -181,6 +307,12 @@ off_t kmod_file_get_size(const struct kmod_file *file)
 
 void kmod_file_unref(struct kmod_file *file)
 {
+#ifdef ENABLE_XZ
+	if (file->xz_used) {
+		free(file->memory);
+		close(file->fd);
+	} else
+#endif
 #ifdef ENABLE_ZLIB
 	if (file->gzf != NULL) {
 		free(file->memory);

libkmod/libkmod.pc.in

@@ -7,5 +7,5 @@ Name: libkmod
 Description: Library to deal with kernel modules
 Version: @VERSION@
 Libs: -L${libdir} -lkmod
-Libs.private: @zlib_LIBS@
-Cflags: -I${includedir} @zlib_CFLAGS@
+Libs.private: @liblzma_LIBS@ @zlib_LIBS@
+Cflags: -I${includedir} @liblzma_CFLAGS@ @zlib_CFLAGS@