allow to change system release filename with configure option

configure.ac

@@ -116,6 +116,11 @@ AM_CONDITIONAL(ADD_DEFAULT_PLUGIN_LINK,
                   -o "$default_plugin_name" = "details"])
 AC_SUBST(default_plugin_name)
 
+AC_ARG_WITH(release-file, AC_HELP_STRING([--with-release-file=<path_to_release_file>], [Release File to use to detect distribution (by default /etc/system-reelase)]),RELEASE_FILE=${withval},RELEASE_FILE=/etc/system-release)
+
+AC_SUBST(RELEASE_FILE)
+AC_DEFINE_UNQUOTED(RELEASE_FILE, "$RELEASE_FILE", [Release file path])
+
 # Turn on the additional warnings last, so -Werror doesn't affect other tests.
 
 AC_DEFUN([PLYMOUTH_CC_TRY_FLAG], [

scripts/Makefile.am

@@ -10,6 +10,7 @@ plymouth-populate-initrd: $(srcdir)/plymouth-populate-initrd.in
 	sed -e 's,[@]logofile[@],$(logofile),g'                                \
 	    -e 's,[@]plymouthclientdir[@],$(plymouthclientdir),g'              \
 	    -e 's,[@]plymouthdaemondir[@],$(plymouthdaemondir),g'              \
+	    -e 's,[@]RELEASE_FILE[@],$(RELEASE_FILE),g'              \
 	    $(srcdir)/plymouth-populate-initrd.in > plymouth-populate-initrd
 
 plymouth-set-default-theme: $(srcdir)/plymouth-set-default-theme.in

scripts/plymouth-populate-initrd.in

@@ -70,7 +70,7 @@ inst ${LIBDIR}/plymouth/text.so $INITRDDIR
 inst ${DATADIR}/plymouth/themes/details/details.plymouth $INITRDDIR
 inst ${LIBDIR}/plymouth/details.so $INITRDDIR
 inst ${PLYMOUTH_LOGO_FILE} $INITRDDIR
-inst /etc/system-release $INITRDDIR
+inst @RELEASE_FILE@ $INITRDDIR
 
 if [ -z "$PLYMOUTH_THEME_NAME" ]; then
     echo "No default plymouth plugin is set" > /dev/stderr

src/libplybootsplash/ply-text-progress-bar.c

@@ -102,7 +102,7 @@ get_os_string (void)
    char *buf, *pos, *pos2;
    struct stat sbuf;
    
-   fd = open("/etc/system-release", O_RDONLY);
+   fd = open(RELEASE_FILE, O_RDONLY);
    if (fd == -1) return;
    if (fstat(fd, &sbuf) == -1) return;
    buf = calloc(sbuf.st_size + 1, sizeof(char));