Check for g_read_data(9) errors properly:

o The only indication of error condition is NULL value returned by
  the function;

o value pointed to by error argument is undefined in the case when
  operation completes successfully.

Discussed with: phk

17 files changed, 26 insertions, 26 deletions

diff --git a/sys/geom/eli/g_eli.c b/sys/geom/eli/g_eli.c
index 230156a..f00a6e2 100644
--- a/sys/geom/eli/g_eli.c
+++ b/sys/geom/eli/g_eli.c
@@ -576,7 +576,7 @@ g_eli_read_metadata(struct g_class *mp, struct g_provider *pp,
 	buf = g_read_data(cp, pp->mediasize - pp->sectorsize, pp->sectorsize,
 	    &error);
 	g_topology_lock();
-	if (error != 0)
+	if (buf == NULL)
 		goto end;
 	eli_metadata_decode(buf, md);
 end:
diff --git a/sys/geom/geom_aes.c b/sys/geom/geom_aes.c
index de7e1c6..e0b414b 100644
--- a/sys/geom/geom_aes.c
+++ b/sys/geom/geom_aes.c
@@ -300,7 +300,7 @@ g_aes_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
 		sectorsize = cp->provider->sectorsize;
 		mediasize = cp->provider->mediasize;
 		buf = g_read_data(cp, 0, sectorsize, &error);
-		if (buf == NULL || error != 0) {
+		if (buf == NULL) {
 			break;
 		}
 		sc = g_malloc(sizeof(struct g_aes_softc), M_WAITOK | M_ZERO);
diff --git a/sys/geom/geom_apple.c b/sys/geom/geom_apple.c
index 04f5cac..883fe70 100644
--- a/sys/geom/geom_apple.c
+++ b/sys/geom/geom_apple.c
@@ -166,7 +166,7 @@ g_apple_taste(struct g_class *mp, struct g_provider *pp, int insist)
 			break;
 
 		buf = g_read_data(cp, 0, sectorsize, &error);
-		if (buf == NULL || error != 0)
+		if (buf == NULL)
 			break;
 
 		/*
@@ -188,7 +188,7 @@ g_apple_taste(struct g_class *mp, struct g_provider *pp, int insist)
 		 * Read in the first partition map
 		 */
 		buf = g_read_data(cp, sectorsize, sectorsize,  &error);
-		if (buf == NULL || error != 0)
+		if (buf == NULL)
 			break;
 
 		/*
@@ -206,7 +206,7 @@ g_apple_taste(struct g_class *mp, struct g_provider *pp, int insist)
 	       
 		buf = g_read_data(cp, 2 * sectorsize, 
 		    (NAPMPART - 1) * sectorsize,  &error);
-		if (buf == NULL || error != 0)
+		if (buf == NULL)
 			break;
 
 		for (i = 1; i < NAPMPART; i++) {
diff --git a/sys/geom/geom_bsd.c b/sys/geom/geom_bsd.c
index 6b2220d..d715ded 100644
--- a/sys/geom/geom_bsd.c
+++ b/sys/geom/geom_bsd.c
@@ -207,7 +207,7 @@ g_bsd_try(struct g_geom *gp, struct g_slicer *gsp, struct g_consumer *cp, int se
 	error = 0;
 	secoff = offset % secsize;
 	buf = g_read_data(cp, offset - secoff, secsize, &error);
-	if (buf == NULL || error != 0)
+	if (buf == NULL)
 		return (ENOENT);
 
 	/* Decode into our native format. */
@@ -248,7 +248,7 @@ g_bsd_writelabel(struct g_geom *gp, u_char *bootcode)
 	secoff = ms->labeloffset % secsize;
 	if (bootcode == NULL) {
 		buf = g_read_data(cp, ms->labeloffset - secoff, secsize, &error);
-		if (buf == NULL || error != 0)
+		if (buf == NULL)
 			return (error);
 		bcopy(ms->label, buf + secoff, sizeof(ms->label));
 	} else {
diff --git a/sys/geom/geom_fox.c b/sys/geom/geom_fox.c
index 2eef7cd..89f444b 100644
--- a/sys/geom/geom_fox.c
+++ b/sys/geom/geom_fox.c
@@ -373,7 +373,7 @@ g_fox_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
 		g_topology_unlock();
 		buf = g_read_data(cp, 0, sectorsize, &error);
 		g_topology_lock();
-		if (buf == NULL || error != 0)
+		if (buf == NULL)
 			break;
 		if (memcmp(buf, FOX_MAGIC, strlen(FOX_MAGIC)))
 			break;
diff --git a/sys/geom/geom_gpt.c b/sys/geom/geom_gpt.c
index 5f07a81..89a91ab 100644
--- a/sys/geom/geom_gpt.c
+++ b/sys/geom/geom_gpt.c
@@ -300,7 +300,7 @@ g_gpt_has_pmbr(struct g_consumer *cp, int *error)
 	uint16_t magic;
 
 	buf = g_read_data(cp, 0L, cp->provider->sectorsize, error);
-	if (*error != 0)
+	if (buf == NULL)
 		return (0);
 
 	pmbr = 0;
@@ -826,14 +826,14 @@ g_gpt_taste(struct g_class *mp, struct g_provider *pp, int insist __unused)
 	 * there's a GPT, including whether recovery is appropriate.
 	 */
 	buf = g_read_data(cp, pp->sectorsize, pp->sectorsize, &error);
-	if (error != 0)
+	if (buf == NULL)
 		goto fail;
 	g_gpt_load_hdr(softc, pp, GPT_HDR_PRIMARY, buf);
 	g_free(buf);
 
 	buf = g_read_data(cp, pp->mediasize - pp->sectorsize, pp->sectorsize,
 	    &error);
-	if (error != 0)
+	if (buf == NULL)
 		goto fail;
 	g_gpt_load_hdr(softc, pp, GPT_HDR_SECONDARY, buf);
 	g_free(buf);
@@ -915,7 +915,7 @@ g_gpt_taste(struct g_class *mp, struct g_provider *pp, int insist __unused)
 
 	ofs = hdr->hdr_lba_table * pp->sectorsize;
 	buf = g_read_data(cp, ofs, nbytes, &error);
-	if (error != 0)
+	if (buf == NULL)
 		goto fail;
 
 	/*
@@ -934,7 +934,7 @@ g_gpt_taste(struct g_class *mp, struct g_provider *pp, int insist __unused)
 		hdr = softc->hdr + GPT_HDR_SECONDARY;
 		ofs = hdr->hdr_lba_table * pp->sectorsize;
 		buf = g_read_data(cp, ofs, nbytes, &error);
-		if (error != 0)
+		if (buf == NULL)
 			goto fail;
 
 		if (!g_gpt_tbl_ok(hdr, buf)) {
diff --git a/sys/geom/geom_mbr.c b/sys/geom/geom_mbr.c
index 9fbb3c7..218517e 100644
--- a/sys/geom/geom_mbr.c
+++ b/sys/geom/geom_mbr.c
@@ -284,7 +284,7 @@ g_mbr_taste(struct g_class *mp, struct g_provider *pp, int insist)
 			break;
 		ms->sectorsize = sectorsize;
 		buf = g_read_data(cp, 0, sectorsize, &error);
-		if (buf == NULL || error != 0)
+		if (buf == NULL)
 			break;
 
 		/*
@@ -454,7 +454,7 @@ g_mbrext_taste(struct g_class *mp, struct g_provider *pp, int insist __unused)
 			break;
 		for (;;) {
 			buf = g_read_data(cp, off, sectorsize, &error);
-			if (buf == NULL || error != 0)
+			if (buf == NULL)
 				break;
 			if (buf[0x1fe] != 0x55 && buf[0x1ff] != 0xaa) {
 				g_free(buf);
diff --git a/sys/geom/geom_pc98.c b/sys/geom/geom_pc98.c
index 77c4ac2..a380f0d 100644
--- a/sys/geom/geom_pc98.c
+++ b/sys/geom/geom_pc98.c
@@ -289,7 +289,7 @@ g_pc98_taste(struct g_class *mp, struct g_provider *pp, int flags)
 		if (sectorsize % 512 != 0)
 			break;
 		buf = g_read_data(cp, 0, 8192, &error);
-		if (buf == NULL || error != 0)
+		if (buf == NULL)
 			break;
 		ms->fwsectors = fwsectors;
 		ms->fwheads = fwheads;
diff --git a/sys/geom/geom_sunlabel.c b/sys/geom/geom_sunlabel.c
index 4c453cd..06e3bbd7 100644
--- a/sys/geom/geom_sunlabel.c
+++ b/sys/geom/geom_sunlabel.c
@@ -278,7 +278,7 @@ g_sunlabel_taste(struct g_class *mp, struct g_provider *pp, int flags)
 		g_topology_unlock();
 		buf = g_read_data(cp, 0, ms->sectorsize, &error);
 		g_topology_lock();
-		if (buf == NULL || error != 0)
+		if (buf == NULL)
 			break;
 
 		/*
diff --git a/sys/geom/geom_vol_ffs.c b/sys/geom/geom_vol_ffs.c
index d90222f..f6fd88e 100644
--- a/sys/geom/geom_vol_ffs.c
+++ b/sys/geom/geom_vol_ffs.c
@@ -100,7 +100,7 @@ g_vol_ffs_taste(struct g_class *mp, struct g_provider *pp, int flags)
 
 		fs = (struct fs *) g_read_data(cp, superblock,
 			SBLOCKSIZE, &error);
-		if (fs == NULL || error != 0)
+		if (fs == NULL)
 			continue;
 		/* Check for magic and make sure things are the right size */
 		if (fs->fs_magic == FS_UFS1_MAGIC) {
diff --git a/sys/geom/label/g_label_iso9660.c b/sys/geom/label/g_label_iso9660.c
index 0a2fa8e..21078e1 100644
--- a/sys/geom/label/g_label_iso9660.c
+++ b/sys/geom/label/g_label_iso9660.c
@@ -57,7 +57,7 @@ g_label_iso9660_taste(struct g_consumer *cp, char *label, size_t size)
 		return;
 	sector = (char *)g_read_data(cp, ISO9660_OFFSET, pp->sectorsize,
 	    &error);
-	if (sector == NULL || error != 0)
+	if (sector == NULL)
 		return;
 	if (bcmp(sector, ISO9660_MAGIC, sizeof(ISO9660_MAGIC) - 1) != 0) {
 		g_free(sector);
diff --git a/sys/geom/label/g_label_msdosfs.c b/sys/geom/label/g_label_msdosfs.c
index ff0d7c3..670b52a 100644
--- a/sys/geom/label/g_label_msdosfs.c
+++ b/sys/geom/label/g_label_msdosfs.c
@@ -56,7 +56,7 @@ g_label_msdosfs_taste(struct g_consumer *cp, char *label, size_t size)
 	label[0] = '\0';
 
 	sector = (char *)g_read_data(cp, 0, pp->sectorsize, &error);
-	if (sector == NULL || error != 0)
+	if (sector == NULL)
 		return;
 	if (strncmp(sector + 0x36, FAT12, strlen(FAT12)) == 0) {
 		G_LABEL_DEBUG(1, "MSDOS (FAT12) file system detected on %s.",
diff --git a/sys/geom/label/g_label_ufs.c b/sys/geom/label/g_label_ufs.c
index 1be6b85..890669b 100644
--- a/sys/geom/label/g_label_ufs.c
+++ b/sys/geom/label/g_label_ufs.c
@@ -72,7 +72,7 @@ g_label_ufs_taste(struct g_consumer *cp, char *label, size_t size)
 
 		fs = (struct fs *)g_read_data(cp, superblock, SBLOCKSIZE,
 		    &error);
-		if (fs == NULL || error != 0)
+		if (fs == NULL)
 			continue;
 		/* Check for magic and make sure things are the right size */
 		if (fs->fs_magic == FS_UFS1_MAGIC) {
diff --git a/sys/geom/mirror/g_mirror.c b/sys/geom/mirror/g_mirror.c
index b6b0040..e627c60 100644
--- a/sys/geom/mirror/g_mirror.c
+++ b/sys/geom/mirror/g_mirror.c
@@ -2346,7 +2346,7 @@ g_mirror_read_metadata(struct g_consumer *cp, struct g_mirror_metadata *md)
 	    &error);
 	g_topology_lock();
 	g_access(cp, -1, 0, 0);
-	if (error != 0) {
+	if (buf == NULL) {
 		G_MIRROR_DEBUG(1, "Cannot read metadata from %s (error=%d).",
 		    cp->provider->name, error);
 		if (buf != NULL)
diff --git a/sys/geom/raid3/g_raid3.c b/sys/geom/raid3/g_raid3.c
index a16817d..0d109df 100644
--- a/sys/geom/raid3/g_raid3.c
+++ b/sys/geom/raid3/g_raid3.c
@@ -2571,7 +2571,7 @@ g_raid3_read_metadata(struct g_consumer *cp, struct g_raid3_metadata *md)
 	    &error);
 	g_topology_lock();
 	g_access(cp, -1, 0, 0);
-	if (error != 0) {
+	if (buf == NULL) {
 		G_RAID3_DEBUG(1, "Cannot read metadata from %s (error=%d).",
 		    cp->provider->name, error);
 		if (buf != NULL)
diff --git a/sys/geom/uzip/g_uzip.c b/sys/geom/uzip/g_uzip.c
index 7fb5614..4fcb137 100644
--- a/sys/geom/uzip/g_uzip.c
+++ b/sys/geom/uzip/g_uzip.c
@@ -380,7 +380,7 @@ g_uzip_taste(struct g_class *mp, struct g_provider *pp, int flags)
 	DPRINTF(("%s: media sectorsize %u, mediasize %lld\n",
 	    gp->name, pp->sectorsize, pp->mediasize));
 	buf = g_read_data(cp, 0, pp->sectorsize, &error);
-	if (buf == NULL || error != 0)
+	if (buf == NULL)
 		goto err;
 	header = (struct cloop_header *) buf;
 	if (strncmp(header->magic, CLOOP_MAGIC_START,
@@ -430,7 +430,7 @@ g_uzip_taste(struct g_class *mp, struct g_provider *pp, int flags)
 		free(buf, M_GEOM);
 		buf = g_read_data(
 		    cp, blk * pp->sectorsize, pp->sectorsize, &error);
-		if (buf == NULL || error != 0)
+		if (buf == NULL)
 			goto err;
 		nread = MIN(total_offsets - offsets_read,
 		     pp->sectorsize / sizeof(uint64_t));
diff --git a/sys/geom/vinum/geom_vinum_drive.c b/sys/geom/vinum/geom_vinum_drive.c
index 2cdeb08..519c9f1 100644
--- a/sys/geom/vinum/geom_vinum_drive.c
+++ b/sys/geom/vinum/geom_vinum_drive.c
@@ -453,7 +453,7 @@ gv_drive_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
 	/* Now check if the provided slice is a valid vinum drive. */
 	do {
 		vhdr = g_read_data(cp, GV_HDR_OFFSET, pp->sectorsize, &error);
-		if (vhdr == NULL || error != 0)
+		if (vhdr == NULL)
 			break;
 		if (vhdr->magic != GV_MAGIC) {
 			g_free(vhdr);