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Reworked VHD creation to avoid large stack allocation

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This commit is contained in:
shermp
2018-11-26 16:56:49 +13:00
parent 5bf86bff03
commit 8747019ef3
2 changed files with 18 additions and 13 deletions
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29
minivhd.c
View File

@@ -159,31 +159,36 @@ void vhd_create_file(FILE *f, VHDMeta *vhdm, int cyl, int heads, int spt, VHDTyp
if (vhdm->curr_size % vhdm->sparse_block_sz != 0)
{vhdm->sparse_max_bat += 1;}
vhd_new_raw(vhdm);
uint8_t zero_buff[VHD_SECTOR_SZ];
memset(zero_buff, 0, sizeof zero_buff);
if (type == VHD_DYNAMIC)
{
uint8_t zero_padding[VHD_BLK_PADDING];
uint8_t bat_buff[VHD_MAX_BAT_SIZE_BYTES];
memset(bat_buff, 255, sizeof(bat_buff));
memset(zero_padding, 0, sizeof(zero_padding));
size_t s;
uint8_t zero_byte = 0U;
uint8_t max_byte = 255U;
fseeko64(f, 0, SEEK_SET);
fwrite(&vhdm->raw_footer, VHD_FOOTER_SZ, 1, f);
fseeko64(f, vhdm->sparse_header_offset, SEEK_SET);
fwrite(&vhdm->raw_sparse_header, VHD_SPARSE_HEAD_SZ, 1, f);
fseeko64(f, vhdm->sparse_bat_offset, SEEK_SET);
fwrite(bat_buff, sizeof(bat_buff), 1, f);
fwrite(zero_padding, sizeof(zero_padding), 1, f);
for (s = 0; s < VHD_MAX_BAT_SIZE_BYTES; s++)
{
fwrite(&max_byte, sizeof max_byte, 1, f);
}
for (s = 0; s < VHD_BLK_PADDING_SECT; s++)
{
fwrite(zero_buff, sizeof zero_buff, 1, f);
}
fwrite(&vhdm->raw_footer, VHD_FOOTER_SZ, 1, f);
}
else
{
uint8_t zero_buff[VHD_SECTOR_SZ];
memset(zero_buff, 0, sizeof(zero_buff));
uint32_t vhd_sect_sz = vhdm->curr_size / VHD_SECTOR_SZ;
uint32_t i;
fseeko64(f, 0, SEEK_SET);
for (i = 0; i < vhd_sect_sz; i++)
{
fwrite(zero_buff, sizeof(zero_buff), 1, f);
fwrite(zero_buff, sizeof zero_buff, 1, f);
}
fwrite(&vhdm->raw_footer, VHD_FOOTER_SZ, 1, f);
}
@@ -371,10 +376,8 @@ static void vhd_create_blk(VHDMeta *vhdm, FILE *f, int blk_num)
uint8_t ftr[VHD_SECTOR_SZ];
uint8_t zero_sect[VHD_SECTOR_SZ];
uint8_t full_sect[VHD_SECTOR_SZ];
uint8_t zero_padding[VHD_BLK_PADDING];
memset(zero_sect, 0, VHD_SECTOR_SZ);
memset(full_sect, 255, VHD_SECTOR_SZ);
memset(zero_padding, 0, sizeof(zero_padding));
uint32_t new_blk_offset;
fseeko64(f, -512, SEEK_END);
new_blk_offset = (uint64_t)ftello64(f) / VHD_SECTOR_SZ;
@@ -393,7 +396,9 @@ static void vhd_create_blk(VHDMeta *vhdm, FILE *f, int blk_num)
else
{fwrite(zero_sect, VHD_SECTOR_SZ, 1, f);}
}
fwrite(zero_padding, sizeof(zero_padding), 1, f);
for (s = 0; s < VHD_BLK_PADDING_SECT; s++) {
fwrite(zero_sect, sizeof zero_sect, 1, f);
}
fwrite(ftr, VHD_FOOTER_SZ, 1, f);
vhdm->sparse_bat_arr[blk_num] = new_blk_offset;
vhd_update_bat(vhdm, f, blk_num);

2
minivhd.h
View File

@@ -56,7 +56,7 @@
#define VHD_MAX_CYL 65535 /* VHD stores the cylinders as a 16-bit unsigned int */
#define VHD_MAX_SZ_MB 130559 /* Using max (65535 * 16 * 255) geom */
/* Win 10 appears to add 7 sectors of zero padding between blocks, and before the footer. */
#define VHD_BLK_PADDING 3584
#define VHD_BLK_PADDING_SECT 7
typedef enum VHDError
{