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Virtual ISO: Add El Torito boot image loading for both emulation and non-emulation modes

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This commit is contained in:
RichardG867
2022-03-27 13:37:06 -03:00
parent b78c11f789
commit 8e971eaf5a
1 changed files with 132 additions and 8 deletions
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140
src/cdrom/cdrom_image_viso.c
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@@ -90,13 +90,13 @@ typedef struct _viso_entry_ {
} viso_entry_t;
typedef struct {
uint64_t vol_size_offsets[2], pt_meta_offsets[2];
uint64_t vol_size_offsets[2], pt_meta_offsets[2], eltorito_offset;
uint32_t metadata_sectors, all_sectors, entry_map_size;
unsigned int sector_size, file_fifo_pos;
uint8_t *metadata;
track_file_t tf;
viso_entry_t root_dir, **entry_map, *file_fifo[VISO_OPEN_FILES];
viso_entry_t root_dir, *eltorito_entry, **entry_map, *file_fifo[VISO_OPEN_FILES];
} viso_t;
#define ENABLE_CDROM_IMAGE_VISO_LOG 1
@@ -660,6 +660,10 @@ viso_init(const char *dirname, int *error)
viso->entry_map_size++; /* round up to the next sector */
}
/* Detect El Torito boot code file and set it accordingly. */
if (!strnicmp(readdir_entry->d_name, "eltorito.", 9) && (!stricmp(readdir_entry->d_name + 9, "com") || !stricmp(readdir_entry->d_name + 9, "img")))
viso->eltorito_entry = last_entry;
/* Set short filename. */
if (viso_get_short_filename(dir, last_entry->name_short, readdir_entry->d_name))
goto end;
@@ -821,6 +825,29 @@ next_dir:
/* Write volume descriptor. */
fwrite(data, viso->sector_size, 1, viso->tf.file);
/* Write El Torito boot descriptor. This is an awkward spot for
that, but the spec requires it to be the second descriptor. */
if (!i && viso->eltorito_entry) {
p = data;
*p++ = 0; /* type */
memcpy(p, "CD001", 5); /* standard ID */
p += 5;
*p++ = 1; /* version */
memcpy(p, "EL TORITO SPECIFICATION", 24); /* identifier */
p += 24;
VISO_SKIP(p, 40);
/* Save the boot catalog pointer's offset for later. */
viso->eltorito_offset = ftello64(viso->tf.file) + (p - data);
/* Blank the rest of the working sector. */
memset(p, 0x00, viso->sector_size - (p - data));
/* Write boot descriptor. */
fwrite(data, viso->sector_size, 1, viso->tf.file);
}
}
/* Fill terminator. */
@@ -845,6 +872,82 @@ next_dir:
fwrite(data, write, 1, viso->tf.file);
}
/* Handle El Torito boot catalog. */
if (viso->eltorito_entry) {
/* Write a pointer to this boot catalog to the boot descriptor. */
*((uint32_t *) data) = ftello64(viso->tf.file) / viso->sector_size;
viso_pwrite(data, viso->eltorito_offset, 4, 1, viso->tf.file);
/* Fill boot catalog validation entry. */
p = data;
*p++ = 0x01; /* header ID */
*p++ = 0x00; /* platform */
*p++ = 0x00; /* reserved */
*p++ = 0x00;
VISO_SKIP(p, 24);
strncpy((char *) (p - 24), EMU_NAME, 24); /* ID string */
*p++ = 0x00; /* checksum */
*p++ = 0x00;
*p++ = 0x55; /* key bytes */
*p++ = 0xaa;
/* Calculate checksum. */
uint16_t eltorito_checksum = 0;
for (int i = 0; i < (p - data); i += 2)
eltorito_checksum -= *((uint16_t *) &data[i]);
*((uint16_t *) &data[28]) = eltorito_checksum;
/* Now fill the default boot entry. */
*p++ = 0x88; /* bootable flag */
if (viso->eltorito_entry->name_short[9] == 'C') { /* boot media type */
*p++ = 0x00;
} else {
/* This could use with a decoupling of fdd_img's algorithms
for loading non-raw images and detecting raw image sizes. */
switch (viso->eltorito_entry->stats.st_size) {
case 0 ... 1228800: /* 1.2 MB */
*p++ = 0x01;
break;
case 1228801 ... 1474560: /* 1.44 MB */
*p++ = 0x02;
break;
case 1474561 ... 2949120: /* 2.88 MB */
*p++ = 0x03;
break;
default: /* hard drive */
*p++ = 0x04;
break;
}
}
*p++ = 0x00; /* load segment */
*p++ = 0x00;
*p++ = 0x00; /* system type (is this even relevant?) */
*p++ = 0x00; /* reserved */
/* Save offsets to the boot catalog entry's offset and size fields for later. */
viso->eltorito_offset = ftello64(viso->tf.file) + (p - data);
/* Blank the rest of the working sector. This includes the sector count,
ISO sector offset and 20-byte selection criteria fields at the end. */
memset(p, 0x00, viso->sector_size - (p - data));
/* Write boot catalog. */
fwrite(data, viso->sector_size, 1, viso->tf.file);
/* Pad to the next even sector. */
write = ftello64(viso->tf.file) % (viso->sector_size * 2);
if (write) {
write = (viso->sector_size * 2) - write;
memset(data, 0x00, write);
fwrite(data, write, 1, viso->tf.file);
}
}
/* Write each path table. */
for (int i = 0; i < 4; i++) {
cdrom_image_viso_log("VISO: Generating path table #%d:\n", i);
@@ -960,6 +1063,10 @@ next_dir:
viso_entry_t *entry = dir->first_child;
int dir_type = VISO_DIR_CURRENT;
while (entry) {
/* Skip the El Torito boot code entry if present. */
if (entry == viso->eltorito_entry)
goto next_entry;
cdrom_image_viso_log("[%08X] %s => %s\n", entry,
entry->path ? entry->path : ((dir_type == VISO_DIR_PARENT) ? dir->parent->path : dir->path),
i ? entry->name_rr : entry->name_short);
@@ -996,7 +1103,7 @@ next_dir:
/* Write entry. */
fwrite(data, data[0], 1, viso->tf.file);
next_entry:
/* Move on to the next entry, and stop if the end of this directory was reached. */
entry = entry->next;
if (entry && (entry->parent != dir))
@@ -1045,11 +1152,28 @@ next_dir:
continue;
}
/* Write this file's starting sector offset to its directory entries. */
p = data;
VISO_LBE_32(p, viso->all_sectors);
for (int i = 0; i < (sizeof(entry->dr_offsets) / sizeof(entry->dr_offsets[0])); i++)
viso_pwrite(data, entry->dr_offsets[i] + 2, 8, 1, viso->tf.file);
/* Write this file's starting sector offset to its directory
entries, unless this is the El Torito boot code entry,
in which case, write offset and size to the boot entry. */
if (entry == viso->eltorito_entry) {
/* Load the entire file if not emulating, or just the first virtual
sector (which usually contains all the boot code) if emulating. */
if (entry->name_short[9] == 'C') {
uint32_t boot_size = entry->stats.st_size;
if (boot_size % 512) /* round up */
boot_size += 512 - (boot_size % 512);
*((uint16_t *) &data[0]) = boot_size / 512;
} else {
*((uint16_t *) &data[0]) = 1;
}
*((uint32_t *) &data[2]) = viso->all_sectors;
viso_pwrite(data, viso->eltorito_offset, 6, 1, viso->tf.file);
} else {
p = data;
VISO_LBE_32(p, viso->all_sectors);
for (int i = 0; i < (sizeof(entry->dr_offsets) / sizeof(entry->dr_offsets[0])); i++)
viso_pwrite(data, entry->dr_offsets[i] + 2, 8, 1, viso->tf.file);
}
/* Save this file's starting offset. This overwrites dr_offsets in the union. */
entry->data_offset = ((uint64_t) viso->all_sectors) * viso->sector_size;