MFC r285735:

  lseek() allows an offset to be set beyond the end of file. Using
  it to check that partition has enough space to write bootcode doesn't
  work. Use the known size of provider instead.

  PR:		201504

1 files changed, 4 insertions, 7 deletions

diff --git a/sbin/geom/class/part/geom_part.c b/sbin/geom/class/part/geom_part.c
index 83e0b11..521ac23 100644
--- a/sbin/geom/class/part/geom_part.c
+++ b/sbin/geom/class/part/geom_part.c
@@ -1095,14 +1095,11 @@ gpart_write_partcode(struct ggeom *gp, int idx, void *code, ssize_t size)
 
 	if (pp != NULL) {
 		snprintf(dsf, sizeof(dsf), "/dev/%s", pp->lg_name);
+		if (pp->lg_mediasize < size)
+			errx(EXIT_FAILURE, "%s: not enough space", dsf);
 		fd = open(dsf, O_WRONLY);
 		if (fd == -1)
 			err(EXIT_FAILURE, "%s", dsf);
-		if (lseek(fd, size, SEEK_SET) != size)
-			errx(EXIT_FAILURE, "%s: not enough space", dsf);
-		if (lseek(fd, 0, SEEK_SET) != 0)
-			err(EXIT_FAILURE, "%s", dsf);
-
 		/*
 		 * When writing to a disk device, the write must be
 		 * sector aligned and not write to any partial sectors,
@@ -1141,11 +1138,11 @@ gpart_write_partcode_vtoc8(struct ggeom *gp, int idx, void *code)
 		if (pp->lg_sectorsize != sizeof(struct vtoc8))
 			errx(EXIT_FAILURE, "%s: unexpected sector "
 			    "size (%d)\n", dsf, pp->lg_sectorsize);
+		if (pp->lg_mediasize < VTOC_BOOTSIZE)
+			continue;
 		fd = open(dsf, O_WRONLY);
 		if (fd == -1)
 			err(EXIT_FAILURE, "%s", dsf);
-		if (lseek(fd, VTOC_BOOTSIZE, SEEK_SET) != VTOC_BOOTSIZE)
-			continue;
 		/*
 		 * We ignore the first VTOC_BOOTSIZE bytes of boot code in
 		 * order to avoid overwriting the label.