diff options
Diffstat (limited to 'device.c')
-rw-r--r-- | device.c | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/device.c b/device.c new file mode 100644 index 0000000..4bbf7b8 --- /dev/null +++ b/device.c @@ -0,0 +1,72 @@ +/* Copyright 2021 Alain Knaff. + * This file is part of mtools. + * + * Mtools is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * Mtools is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with Mtools. If not, see <http://www.gnu.org/licenses/>. + */ + +#include "sysincludes.h" +#include "llong.h" +#include "device.h" + +int check_if_sectors_fit(uint32_t tot_sectors, + mt_off_t maxBytes, + uint32_t sectorSize, + char *errmsg) +{ + if(!maxBytes) + return 0; /* Maxbytes = 0 => no checking */ + if(tot_sectors > (smt_off_t) maxBytes / (smt_off_t) sectorSize) { + sprintf(errmsg, + "%d sectors too large for this platform\n", + tot_sectors); + return -1; + } + return 0; +} + +/* + * Calculate number of total sectors on device if needed, and check that + * they fit into + */ +int chs_to_totsectors(struct device *dev, char *errmsg) +{ + uint32_t sect_per_track, tot_sectors; + + if(dev->tot_sectors) + return 0; + + if(!dev->heads || !dev->sectors || !dev->tracks) + return 0; /* not fully specified => we cannot do + anything anyways */ + + /* Cannot overflow as both dev->heads and dev->sectors are 16 + * bit quantities, whose product will be put into a 32 bit + * field */ + sect_per_track = dev->heads * dev->sectors; + + if(dev->tracks > UINT32_MAX / sect_per_track) { + /* Would not fit in 32 bits */ + + if(errmsg) + sprintf(errmsg, + "Number of sectors larger than 2^32\n"); + return -1; + } + + tot_sectors = dev->tracks * sect_per_track; + if(tot_sectors > dev->hidden % sect_per_track) + tot_sectors -= dev->hidden % sect_per_track; + dev->tot_sectors = tot_sectors; + return 0; +} |