use set_error instead of printf in library to report errors.

From: Ludwig Nussel <ludwig.nussel@suse.de>

Signed-off-by: Ludwig Nussel <ludwig.nussel@suse.de>
---

 lib/utils.c          |    2 +-
 luks/keyencryption.c |    5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/utils.c b/lib/utils.c
index fbf34bc..b9fc006 100644
--- a/lib/utils.c
+++ b/lib/utils.c
@@ -227,7 +227,7 @@ ssize_t read_blockwise(int fd, void *orig_buf, size_t count) {
 	while(count) {
 		r = read(fd,padbuf,bsize);
 		if(r < 0 || r != bsize) {
-			fprintf(stderr, "read failed in read_blockwise.\n");
+			set_error("read failed in read_blockwise()");
 			goto out;
 		}
 		step = count<bsize?count:bsize;
diff --git a/luks/keyencryption.c b/luks/keyencryption.c
index f154a01..de02f50 100644
--- a/luks/keyencryption.c
+++ b/luks/keyencryption.c
@@ -58,7 +58,7 @@ static int setup_mapping(const char *cipher, const char *name,
 	 * device's sector size, otherwise the mapping will be refused.
 	 */
 	if(device_sector_size < 0) {
-		fprintf(stderr,_("Unable to obtain sector size for %s"),device);
+		set_error(_("Unable to obtain sector size for %s"),device);
 		return -EINVAL;
 	}
 	options->size = round_up_modulo(srcLength,device_sector_size)/SECTOR_SIZE;
@@ -138,7 +138,8 @@ static int LUKS_endec_template(char *src, size_t srcLength,
 
 	r = setup_mapping(dmCipherSpec,name,device,hdr->payloadOffset,key,keyLength,sector,srcLength,backend,mode);
 	if(r < 0) {
-		fprintf(stderr,"Failed to setup dm-crypt key mapping.\nCheck kernel for support for the %s cipher spec and verify that %s contains at least %d sectors.\n",
+		if(!get_error())
+			set_error("Failed to setup dm-crypt key mapping.\nCheck kernel for support for the %s cipher spec and verify that %s contains at least %d sectors",
 			dmCipherSpec, 
 			device, 
 			sector + div_round_up(srcLength,SECTOR_SIZE));