diff options
| -rw-r--r-- | sys/geom/geom_gpt.c | 53 |
1 files changed, 35 insertions, 18 deletions
diff --git a/sys/geom/geom_gpt.c b/sys/geom/geom_gpt.c index 92b8371..06ab0b8 100644 --- a/sys/geom/geom_gpt.c +++ b/sys/geom/geom_gpt.c @@ -360,16 +360,17 @@ g_gpt_has_pmbr(struct g_consumer *cp, int *error) { char *buf; uint8_t *typ; - int i, pmbr, vmbr; - uint16_t magic; + uint64_t mediasize; + int i, pmbr, parts; uint32_t dp_start, dp_size; + uint16_t magic; buf = g_read_data(cp, 0L, cp->provider->sectorsize, error); if (buf == NULL) return (0); pmbr = 0; - vmbr = 0; + *error = 0; magic = le16toh(*(uint16_t *)(uintptr_t)(buf + DOSMAGICOFFSET)); if (magic != DOSMAGIC) @@ -379,31 +380,45 @@ g_gpt_has_pmbr(struct g_consumer *cp, int *error) * Check that there are at least one partition of type * DOSPTYP_PMBR that covers the whole unit. */ + parts = 0; + mediasize = cp->provider->mediasize / cp->provider->sectorsize; for (i = 0; i < 4; i++) { typ = buf + DOSPARTOFF + i * sizeof(struct dos_partition) + offsetof(struct dos_partition, dp_typ); + if (*typ != 0) + parts++; + if (*typ != DOSPTYP_PMBR) + continue; + bcopy(buf + DOSPARTOFF + i * sizeof(struct dos_partition) + - offsetof(struct dos_partition, dp_start), &dp_start, sizeof(dp_start)); + offsetof(struct dos_partition, dp_start), &dp_start, + sizeof(dp_start)); + if (le32toh(dp_start) != 1) + break; + bcopy(buf + DOSPARTOFF + i * sizeof(struct dos_partition) + - offsetof(struct dos_partition, dp_size), &dp_size, sizeof(dp_size)); - if ((*typ == DOSPTYP_PMBR) && - (le32toh(dp_start) == 1) && - (cp->provider->mediasize == - (le32toh(dp_size) * 512ULL))) { - pmbr = 1; + offsetof(struct dos_partition, dp_size), &dp_size, + sizeof(dp_size)); + if (le32toh(dp_size) != ~0U && + le32toh(dp_size) != mediasize - 1 && + /* Catch old FreeBSD bug for backward compatibility. */ + le32toh(dp_size) != mediasize) break; - } - if (*typ != 0 && *typ != DOSPTYP_PMBR) - vmbr = 1; + + pmbr = 1; } -out: - g_free(buf); /* - * Return true if protective MBR is detected or if MBR has - * no valid entries at all. + * Treat empty MBRs as PMBRs for increased flexibility. Note that an + * invalid entry of type DOSPTYP_PMBR counts towards the number of + * partitions and will prevent the MBR from being treated as a PMBR. */ - return (pmbr || !vmbr); + if (!pmbr && parts == 0) + pmbr = 1; + +out: + g_free(buf); + return (pmbr); } static void @@ -1013,6 +1028,8 @@ g_gpt_taste(struct g_class *mp, struct g_provider *pp, int insist __unused) * is none and fail. */ if (!g_gpt_has_pmbr(cp, &error)) { + if (error != 0) + goto fail; printf("GEOM: %s: GPT detected, but no protective MBR.\n", pp->name); error = ENXIO; |
