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Minor but important changes to minivhd's dynamic/diff vhd handling

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1. Changed the first seek_end in create_block to seek_set.
2. Avoid expansion overflow through a check if the block offset is below the total sectors.
This commit is contained in:
TC1995
2024-08-25 23:05:13 +02:00
parent 3e1991390f
commit da5757f802
1 changed files with 36 additions and 29 deletions
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65
src/disk/minivhd/minivhd_io.c
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@@ -37,6 +37,7 @@
#ifndef _FILE_OFFSET_BITS
# define _FILE_OFFSET_BITS 64
#endif
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
@@ -45,6 +46,10 @@
#include <time.h>
#include "minivhd.h"
#include "internal.h"
#define HAVE_STDARG_H
#include "cpu.h"
#include <86box/86box.h>
/*
* The following bit array macros adapted from:
@@ -158,7 +163,7 @@ create_block(MVHDMeta *vhdm, int blk)
uint8_t footer[MVHD_FOOTER_SIZE] = { 0 };
/* Seek to where the footer SHOULD be */
mvhd_fseeko64(vhdm->f, -MVHD_FOOTER_SIZE, SEEK_END);
mvhd_fseeko64(vhdm->f, -MVHD_FOOTER_SIZE, SEEK_SET);
(void) !fread(footer, sizeof footer, 1, vhdm->f);
mvhd_fseeko64(vhdm->f, -MVHD_FOOTER_SIZE, SEEK_END);
@@ -334,36 +339,38 @@ mvhd_sparse_diff_write(MVHDMeta *vhdm, uint32_t offset, int num_sectors, void *i
int sib = 0;
ls = offset + transfer_sectors;
for (s = offset; s < ls; s++) {
blk = s / vhdm->sect_per_block;
sib = s % vhdm->sect_per_block;
if (vhdm->bitmap.curr_block != blk && prev_blk >= 0) {
/* Write the sector bitmap for the previous block, before we replace it. */
write_curr_sect_bitmap(vhdm);
}
if (vhdm->block_offset[blk] == MVHD_SPARSE_BLK) {
/* "read" the sector bitmap first, before creating a new block, as the bitmap will be
zero either way */
read_sect_bitmap(vhdm, blk);
create_block(vhdm, blk);
}
if (blk != prev_blk) {
if (vhdm->bitmap.curr_block != blk) {
read_sect_bitmap(vhdm, blk);
mvhd_fseeko64(vhdm->f, (uint64_t)sib * MVHD_SECTOR_SIZE, SEEK_CUR);
} else {
addr = (((int64_t) vhdm->block_offset[blk]) + vhdm->bitmap.sector_count + sib) *
MVHD_SECTOR_SIZE;
mvhd_fseeko64(vhdm->f, addr, SEEK_SET);
if (offset < total_sectors) {
for (s = offset; s < ls; s++) {
blk = s / vhdm->sect_per_block;
sib = s % vhdm->sect_per_block;
if (vhdm->bitmap.curr_block != blk && prev_blk >= 0) {
/* Write the sector bitmap for the previous block, before we replace it. */
write_curr_sect_bitmap(vhdm);
}
prev_blk = blk;
}
fwrite(buff, MVHD_SECTOR_SIZE, 1, vhdm->f);
VHD_SETBIT(vhdm->bitmap.curr_bitmap, sib);
buff += MVHD_SECTOR_SIZE;
if (vhdm->block_offset[blk] == MVHD_SPARSE_BLK) {
/* "read" the sector bitmap first, before creating a new block, as the bitmap will be
zero either way */
read_sect_bitmap(vhdm, blk);
create_block(vhdm, blk);
}
if (blk != prev_blk) {
if (vhdm->bitmap.curr_block != blk) {
read_sect_bitmap(vhdm, blk);
mvhd_fseeko64(vhdm->f, (uint64_t)sib * MVHD_SECTOR_SIZE, SEEK_CUR);
} else {
addr = (((int64_t) vhdm->block_offset[blk]) + vhdm->bitmap.sector_count + sib) *
MVHD_SECTOR_SIZE;
mvhd_fseeko64(vhdm->f, addr, SEEK_SET);
}
prev_blk = blk;
}
fwrite(buff, MVHD_SECTOR_SIZE, 1, vhdm->f);
VHD_SETBIT(vhdm->bitmap.curr_bitmap, sib);
buff += MVHD_SECTOR_SIZE;
}
}
/* And write the sector bitmap for the last block we visited to disk */