Cleanup dependency handling

Always try to gather all compressor libraries available, but only
complain about missing a one if it has been *explicitly* selected.

If a compressor has been explicityl disabled, we can still turn it
off after checking.

Also, rework gensquashfs to set the default compressor based on
what's available.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

4 files changed, 110 insertions, 89 deletions

diff --git a/configure.ac b/configure.ac
index 4971e11..84a94f4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -42,118 +42,117 @@ AC_SUBST([WARN_CFLAGS])
 ##### config options #####
 
 AC_ARG_WITH([gzip],
-	[AS_HELP_STRING([--without-gzip],
-			[Build without gzip compression support])],
-	[case "${withval}" in
-	yes) AM_CONDITIONAL([WITH_GZIP], [true]) ;;
-	no)  AM_CONDITIONAL([WITH_GZIP], [false]) ;;
-	*) AC_MSG_ERROR([bad value ${withval} for --without-gzip]) ;;
-	esac],
-	[AM_CONDITIONAL([WITH_GZIP], [true])])
+	[AS_HELP_STRING([--with-gzip], [Build with gzip compression support])],
+	[want_gzip="${withval}"], [want_gzip="maybe"])
 
 AC_ARG_WITH([xz],
-	[AS_HELP_STRING([--without-xz],
-			[Build without xz compression support])],
-	[case "${withval}" in
-	yes) AM_CONDITIONAL([WITH_XZ], [true]) ;;
-	no)  AM_CONDITIONAL([WITH_XZ], [false]) ;;
-	*) AC_MSG_ERROR([bad value ${withval} for --without-xz]) ;;
-	esac],
-	[AM_CONDITIONAL([WITH_XZ], [true])])
+	[AS_HELP_STRING([--with-xz], [Build with xz compression support])],
+	[want_xz="${withval}"], [want_xz="maybe"])
 
 AC_ARG_WITH([lzo],
-	[AS_HELP_STRING([--without-lzo],
-			[Build without lzo compression support])],
-	[case "${withval}" in
-	yes) AM_CONDITIONAL([WITH_LZO], [true]) ;;
-	no)  AM_CONDITIONAL([WITH_LZO], [false]) ;;
-	*) AC_MSG_ERROR([bad value ${withval} for --without-lzo]) ;;
-	esac],
-	[AM_CONDITIONAL([WITH_LZO], [true])])
+	[AS_HELP_STRING([--with-lzo], [Build with lzo compression support])],
+	[want_lzo="${withval}"], [want_lzo="maybe"])
 
 AC_ARG_WITH([lz4],
-	[AS_HELP_STRING([--without-lz4],
-			[Build without lz4 compression support])],
-	[case "${withval}" in
-	yes) AM_CONDITIONAL([WITH_LZ4], [true]) ;;
-	no)  AM_CONDITIONAL([WITH_LZ4], [false]) ;;
-	*) AC_MSG_ERROR([bad value ${withval} for --without-lz4]) ;;
-	esac],
-	[AM_CONDITIONAL([WITH_LZ4], [true])])
+	[AS_HELP_STRING([--without-lz4], [Build with lz4 compression support])],
+	[want_lz4="${withval}"], [want_lz4="maybe"])
 
 AC_ARG_WITH([zstd],
-	[AS_HELP_STRING([--without-zstd],
-			[Build without zstd compression support])],
-	[case "${withval}" in
-	yes) AM_CONDITIONAL([WITH_ZSTD], [true]) ;;
-	no)  AM_CONDITIONAL([WITH_ZSTD], [false]) ;;
-	*) AC_MSG_ERROR([bad value ${withval} for --without-zstd]) ;;
-	esac],
-	[AM_CONDITIONAL([WITH_ZSTD], [true])])
+	[AS_HELP_STRING([--with-zstd], [Build with zstd compression support])],
+	[want_zstd="${withval}"], [want_zstd="maybe"])
 
 AC_ARG_WITH([selinux],
-	[AS_HELP_STRING([--without-selinux],
-			[Build without SELinux label file support])],
-	[case "${withval}" in
-	yes) AM_CONDITIONAL([WITH_SELINUX], [true]) ;;
-	no)  AM_CONDITIONAL([WITH_SELINUX], [false]) ;;
-	*) AC_MSG_ERROR([bad value ${withval} for --without-selinux]) ;;
-	esac],
-	[AM_CONDITIONAL([WITH_SELINUX], [true])])
+	[AS_HELP_STRING([--with-selinux],
+			[Build with SELinux label file support])],
+	[want_selinux="${withval}"], [want_selinux="maybe"])
 
 ##### search for dependencies #####
 
-need_zlib="no"
-need_xz="no"
-need_lzo="no"
-need_lz4="no"
-need_zstd="no"
-need_selinux="no"
-
-AM_COND_IF([WITH_GZIP], [need_zlib="yes"])
-AM_COND_IF([WITH_XZ], [need_xz="yes"])
-AM_COND_IF([WITH_LZO], [need_lzo="yes"])
-AM_COND_IF([WITH_LZ4], [need_lz4="yes"])
-AM_COND_IF([WITH_ZSTD], [need_zstd="yes"])
-AM_COND_IF([WITH_SELINUX], [need_selinux="yes"])
-
-if test "x$need_zlib" = "xyes"; then
-	PKG_CHECK_MODULES(ZLIB, [zlib], [], [AC_MSG_ERROR([cannot find zlib])])
-fi
+PKG_CHECK_MODULES(ZLIB, [zlib],
+			[AM_CONDITIONAL([WITH_GZIP], [true])],
+			[AM_CONDITIONAL([WITH_GZIP], [false])])
 
-if test "x$need_xz" = "xyes"; then
-	PKG_CHECK_MODULES(XZ, [liblzma >= 5.0.0], [],
-			      [AC_MSG_ERROR([cannot find xz sdk])])
-fi
+PKG_CHECK_MODULES(XZ, [liblzma >= 5.0.0],
+		      [AM_CONDITIONAL([WITH_XZ], [true])],
+		      [AM_CONDITIONAL([WITH_XZ], [false])])
+
+PKG_CHECK_MODULES(LZ4, [liblz4],
+		       [AM_CONDITIONAL([WITH_LZ4], [true])],
+		       [AM_CONDITIONAL([WITH_LZ4], [false])])
 
-if test "x$need_lzo" = "xyes"; then
+PKG_CHECK_MODULES(ZSTD, [libzstd],
+			[AM_CONDITIONAL([WITH_ZSTD], [true])],
+			[AM_CONDITIONAL([WITH_ZSTD], [false])])
+
+AM_CONDITIONAL([WITH_LZO], [false])
+
+if test "x$want_lzo" != "xno"; then
 	AC_ARG_VAR([LZO_CFLAGS], [C compiler flags for lzo])
 	AC_ARG_VAR([LZO_LIBS], [linker flags for lzo])
+	AM_CONDITIONAL([WITH_LZO], [true])
+
 	AC_CHECK_LIB([lzo2], [lzo1x_1_15_compress], [LZO_LIBS="-llzo2"],
-		[AC_CHECK_LIB([lzo],[lzo1x_1_15_compress],[LZO_LIBS="-llzo"],
-			[AC_MSG_ERROR([cannot find lzo library])]
-		)]
-	)
+			     [AC_CHECK_LIB([lzo],[lzo1x_1_15_compress],
+				[ZO_LIBS="-llzo"],
+			     	[AM_CONDITIONAL([WITH_LZO], [false])]
+			     )]
+		    )
 fi
 
-if test "x$need_lz4" = "xyes"; then
-	PKG_CHECK_MODULES(LZ4, [liblz4], [],
-			       [AC_MSG_ERROR([cannot lz4 library])])
-fi
+AM_CONDITIONAL([WITH_SELINUX], [false])
 
-if test "x$need_zstd" = "xyes"; then
-	PKG_CHECK_MODULES(ZSTD, [libzstd], [],
-			      	[AC_MSG_ERROR([cannot zstd library])])
-fi
+if test "x$want_selinux" != "xno"; then
+	AM_CONDITIONAL([WITH_SELINUX], [true])
 
-if test "x$need_selinux" = "xyes"; then
 	PKG_CHECK_MODULES(LIBSELINUX, [libselinux], [],
-				      [AC_MSG_ERROR([cannot find libselinux])])
-
+			  [AM_CONDITIONAL([WITH_SELINUX], [false])])
 	AC_CHECK_HEADERS([selinux/selinux.h], [],
-			 [AC_MSG_ERROR([cannot find SELinux system headers])])
+			 [AM_CONDITIONAL([WITH_SELINUX], [false])])
 	AC_CHECK_HEADERS([selinux/label.h], [],
-			 [AC_MSG_ERROR([cannot find SELinux system headers])])
+			 [AM_CONDITIONAL([WITH_SELINUX], [false])])
+fi
+
+case "$want_gzip" in
+yes) AM_COND_IF([WITH_GZIP], [], [AC_MSG_ERROR([cannot find zlib])]) ;;
+no)  AM_CONDITIONAL([WITH_GZIP], [false]) ;;
+esac
+
+case "$want_xz" in
+yes) AM_COND_IF([WITH_XZ], [], [AC_MSG_ERROR([cannot find xz sdk])]) ;;
+no)  AM_CONDITIONAL([WITH_XZ], [false]) ;;
+esac
+
+case "$want_lzo" in
+yes) AM_COND_IF([WITH_LZO], [], [AC_MSG_ERROR([cannot find lzo library])]) ;;
+no)  AM_CONDITIONAL([WITH_LZO], [false]) ;;
+esac
+
+case "$want_lz4" in
+yes) AM_COND_IF([WITH_LZ4], [], [AC_MSG_ERROR([cannot find lz4 library])]) ;;
+no)  AM_CONDITIONAL([WITH_LZ4], [false]) ;;
+esac
+
+case "$want_zstd" in
+yes) AM_COND_IF([WITH_ZSTD], [], [AC_MSG_ERROR([cannot find zstd library])]) ;;
+no)  AM_CONDITIONAL([WITH_ZSTD], [false]) ;;
+esac
+
+case "$want_selinux" in
+yes) AM_COND_IF([WITH_SELINUX], [], [AC_MSG_ERROR([cannot find selinux])]) ;;
+no)  AM_CONDITIONAL([WITH_SELINUX], [false]) ;;
+esac
+
+##### sanity check #####
+
+have_compressor="no"
+AM_COND_IF([WITH_GZIP], [have_compressor="yes"])
+AM_COND_IF([WITH_XZ], [have_compressor="yes"])
+AM_COND_IF([WITH_LZO], [have_compressor="yes"])
+AM_COND_IF([WITH_LZ4], [have_compressor="yes"])
+AM_COND_IF([WITH_ZSTD], [have_compressor="yes"])
+
+if test "x$have_compressor" != "xyes"; then
+	AC_MSG_ERROR([no compressor available. At lest one is required])
 fi
 
 ##### generate output #####
diff --git a/include/compress.h b/include/compress.h
index 5f13bc6..c9a4e08 100644
--- a/include/compress.h
+++ b/include/compress.h
@@ -49,4 +49,6 @@ compressor_t *compressor_create(E_SQFS_COMPRESSOR id, bool compress,
 
 void compressor_print_help(E_SQFS_COMPRESSOR id);
 
+E_SQFS_COMPRESSOR compressor_get_default(void);
+
 #endif /* COMPRESS_H */
diff --git a/lib/comp/compressor.c b/lib/comp/compressor.c
index 44b3643..6dff416 100644
--- a/lib/comp/compressor.c
+++ b/lib/comp/compressor.c
@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: GPL-3.0-or-later */
 #include <string.h>
+#include <stdlib.h>
 #include <stdio.h>
 
 #include "internal.h"
@@ -127,3 +128,21 @@ void compressor_print_help(E_SQFS_COMPRESSOR id)
 
 	helpfuns[id]();
 }
+
+E_SQFS_COMPRESSOR compressor_get_default(void)
+{
+#if defined(WITH_XZ)
+	return SQFS_COMP_XZ;
+#elif defined(WITH_ZSTD)
+	return SQFS_COMP_ZSTD;
+#elif defined(WITH_GZIP)
+	return SQFS_COMP_GZIP;
+#elif defined(WITH_LZO)
+	return SQFS_COMP_LZO;
+#elif defined(WITH_LZ4)
+	return SQFS_COMP_LZ4;
+#else
+	fputs("No compressor implementation available!\n", stderr);
+	exit(EXIT_FAILURE);
+#endif
+}
diff --git a/mkfs/options.c b/mkfs/options.c
index e1223ad..69e66f4 100644
--- a/mkfs/options.c
+++ b/mkfs/options.c
@@ -61,7 +61,7 @@ static const char *help_string =
 "\n"
 "  --compressor, -c <name>     Select the compressor to use.\n"
 "                              A list of available compressors is below.\n"
-"                              Defaults to 'xz'.\n"
+"                              Defaults to '%s'.\n"
 "  --comp-extra, -X <options>  A comma seperated list of extra options for\n"
 "                              the selected compressor. Specify 'help' to\n"
 "                              get a list of available options.\n"
@@ -240,7 +240,7 @@ void process_command_line(options_t *opt, int argc, char **argv)
 	opt->def_mode = 0755;
 	opt->def_mtime = 0;
 	opt->outmode = O_WRONLY | O_CREAT | O_EXCL;
-	opt->compressor = SQFS_COMP_XZ;
+	opt->compressor = compressor_get_default();
 	opt->blksz = SQFS_DEFAULT_BLOCK_SIZE;
 	opt->devblksz = SQFS_DEVBLK_SIZE;
 	opt->quiet = false;
@@ -308,6 +308,7 @@ void process_command_line(options_t *opt, int argc, char **argv)
 #endif
 		case 'h':
 			printf(help_string, __progname,
+			       compressors[compressor_get_default()],
 			       SQFS_DEFAULT_BLOCK_SIZE, SQFS_DEVBLK_SIZE);
 
 			fputs("Available compressors:\n", stdout);