fstyp(8): fix exfat detection

In the presence of high-level errors (spec violations, bad boot blocks
checksum), report non-detection instead of detection.

PR:	252787 (related, but does not fully address)
This commit is contained in:
Conrad Meyer 2021-01-17 11:55:06 -08:00
parent f3ea417f96
commit ddf6115613

View File

@ -330,14 +330,15 @@ fstyp_exfat(FILE *fp, char *label, size_t size)
uint32_t chksum;
int error;
error = 1;
cksect = NULL;
ev = (struct exfat_vbr *)read_buf(fp, 0, 512);
if (ev == NULL || strncmp(ev->ev_fsname, "EXFAT ", 8) != 0)
goto fail;
goto out;
if (ev->ev_log_bytes_per_sect < 9 || ev->ev_log_bytes_per_sect > 12) {
warnx("exfat: Invalid BytesPerSectorShift");
goto done;
goto out;
}
bytespersec = (1u << ev->ev_log_bytes_per_sect);
@ -345,7 +346,7 @@ fstyp_exfat(FILE *fp, char *label, size_t size)
error = exfat_compute_boot_chksum(fp, MAIN_BOOT_REGION_SECT,
bytespersec, &chksum);
if (error != 0)
goto done;
goto out;
cksect = read_sect(fp, MAIN_BOOT_REGION_SECT + SUBREGION_CHKSUM_SECT,
bytespersec);
@ -357,7 +358,8 @@ fstyp_exfat(FILE *fp, char *label, size_t size)
if (chksum != le32toh(cksect[0])) {
warnx("exfat: Found checksum 0x%08x != computed 0x%08x",
le32toh(cksect[0]), chksum);
goto done;
error = 1;
goto out;
}
#ifdef WITH_ICONV
@ -365,12 +367,8 @@ fstyp_exfat(FILE *fp, char *label, size_t size)
exfat_find_label(fp, ev, bytespersec, label, size);
#endif
done:
out:
free(cksect);
free(ev);
return (0);
fail:
free(ev);
return (1);
return (error != 0);
}