Mon 14 Oct 23:06:38 CEST 2024

kernel/cdromfs.c

@@ -0,0 +1,268 @@
+/*
+Copyright (C) 2016-2019 The University of Notre Dame
+This software is distributed under the GNU General Public License.
+See the file LICENSE for details.
+*/
+
+#include "kmalloc.h"
+#include "kernel/types.h"
+#include "kernel/error.h"
+#include "string.h"
+#include "page.h"
+#include "fs.h"
+#include "fs_internal.h"
+#include "cdromfs.h"
+#include "iso9660.h"
+#include "device.h"
+#include "bcache.h"
+
+static struct fs_dirent *cdrom_dirent_create(struct fs_volume *volume, int sector, int length, int isdir)
+{
+	struct fs_dirent *d = kmalloc(sizeof(*d));
+	if(!d) return 0;
+
+	d->volume = volume;
+	d->refcount = 1;
+	d->size = length;
+	d->isdir = isdir;
+	d->cdrom.sector = sector;
+
+	return d;
+}
+
+static int cdrom_dirent_read_block(struct fs_dirent *d, char *buffer, uint32_t blocknum)
+{
+	int nblocks = bcache_read(d->volume->device, buffer, 1, d->cdrom.sector + blocknum);
+	if(nblocks == 1) {
+		return CDROMFS_BLOCK_SIZE;
+	} else {
+		return -1;
+	}
+}
+
+static void fix_filename(char *name, int length)
+{
+	// Plain files typically end with a semicolon and version, remove it.
+	if(length > 2 && name[length - 2] == ';') {
+		length -= 2;
+	}
+	// Files without a suffix end with a dot, remove it.
+	if(length > 1 && name[length - 1] == '.') {
+		length--;
+	}
+	// In any case, null-terminate the string
+	name[length] = 0;
+
+	// And make it lowercase
+	strtolower(name);
+}
+
+static struct fs_dirent *cdrom_dirent_lookup(struct fs_dirent *dir, const char *name)
+{
+	if(!dir->isdir) return 0;
+
+	char *temp = page_alloc(0);
+	if(!temp) return 0;
+
+	int nsectors = dir->size / CDROMFS_BLOCK_SIZE + (dir->size % CDROMFS_BLOCK_SIZE ? 1 : 0);
+
+	int i;
+	for(i=0;i<nsectors;i++) {
+		cdrom_dirent_read_block(dir,temp,i);
+		// XXX check result here!
+
+		struct iso_9660_directory_entry *d = (struct iso_9660_directory_entry *) temp;
+
+		while(d->descriptor_length > 0) {
+
+			const char *dname;
+			int dname_length;
+
+			if(d->ident[0] == 0) {
+				dname = ".";
+				dname_length = 2;
+			} else if(d->ident[0] == 1) {
+				dname = "..";
+				dname_length = 3;
+			} else {
+				fix_filename(d->ident, d->ident_length);
+				dname = d->ident;
+				dname_length = strlen(dname) + 1;
+			}
+
+			if(!strncmp(name,dname,dname_length)) {
+				struct fs_dirent *r;
+				r = cdrom_dirent_create(
+					dir->volume,
+					d->first_sector_little,
+					d->length_little,
+					d->flags & ISO_9660_EXTENT_FLAG_DIRECTORY);
+				page_free(temp);
+				return r;
+			}
+			d = (struct iso_9660_directory_entry *) ((char *) d + d->descriptor_length);
+		}
+	}
+
+	page_free(temp);
+
+	return 0;
+}
+
+static int cdrom_dirent_close( struct fs_dirent *d )
+{
+	return 0;
+}
+
+static int cdrom_dirent_list(struct fs_dirent *dir, char *buffer, int buffer_length)
+{
+	if(!dir->isdir) return KERROR_NOT_A_DIRECTORY;
+
+	char *temp = page_alloc(0);
+	if(!temp) return KERROR_OUT_OF_MEMORY;
+
+	int nsectors = dir->size / CDROMFS_BLOCK_SIZE + (dir->size % CDROMFS_BLOCK_SIZE ? 1 : 0);
+	int total = 0;
+
+	int i;
+	for(i=0;i<nsectors;i++) {
+		cdrom_dirent_read_block(dir,temp,i);
+
+		struct iso_9660_directory_entry *d = (struct iso_9660_directory_entry *) temp;
+
+		while(d->descriptor_length > 0 && buffer_length > 0) {
+
+			const char *dname;
+			int dname_length;
+
+			if(d->ident[0] == 0) {
+				dname = ".";
+				dname_length = 2;
+			} else if(d->ident[0] == 1) {
+				dname = "..";
+				dname_length = 3;
+			} else {
+				fix_filename(d->ident, d->ident_length);
+				dname = d->ident;
+				dname_length = strlen(dname) + 1;
+			}
+
+			// If there is enough space, keep copying items.
+			// If not, count them up to return the value.
+
+			if (buffer_length > dname_length) {
+				strcpy(buffer,dname);
+				buffer += dname_length;
+				buffer_length -= dname_length;
+			}
+
+			total += dname_length;
+
+			d = (struct iso_9660_directory_entry *) ((char *) d + d->descriptor_length);
+		}
+	}
+
+	page_free(temp);
+
+	return total;
+}
+
+static struct fs_volume *cdrom_volume_create( struct device *device )
+{
+	struct fs_volume *v = kmalloc(sizeof(*v));
+	if(!v) return 0;
+
+	memset(v, 0, sizeof(struct fs_volume));
+	v->device = device;
+	v->refcount = 1;
+	v->block_size = device_block_size(device);
+
+	return v;
+}
+
+static int cdrom_volume_close(struct fs_volume *v)
+{
+	return 0;
+}
+
+static struct fs_volume *cdrom_volume_open( struct device *device )
+{
+	struct fs_volume *v = cdrom_volume_create(device);
+
+	struct iso_9660_volume_descriptor *d = page_alloc(0);
+	if(!d) {
+		kfree(v);
+		return 0;
+	}
+
+	printf("cdromfs: scanning %s unit %d...\n",device_name(device),device_unit(device));
+
+	int j;
+
+	for(j = 0; j < 16; j++) {
+		printf("cdromfs: checking volume %d\n", j);
+
+		bcache_read(device, (char*)d, 1, j + 16);
+		// XXX check reuslt
+
+		if(strncmp(d->magic, "CD001", 5))
+			continue;
+
+		if(d->type == ISO_9660_VOLUME_TYPE_PRIMARY) {
+			v->cdrom.root_sector = d->root.first_sector_little;
+			v->cdrom.root_length = d->root.length_little;
+			v->cdrom.total_sectors = d->nsectors_little;
+			v->device = device;
+
+			printf("cdromfs: mounted filesystem on %s-%d\n", device_name(v->device), device_unit(v->device));
+
+			page_free(d);
+
+			return v;
+
+		} else if(d->type == ISO_9660_VOLUME_TYPE_TERMINATOR) {
+			break;
+		} else {
+			continue;
+		}
+	}
+
+	page_free(d);
+	cdrom_volume_close(v);
+
+	printf("cdromfs: no filesystem found\n");
+	return 0;
+}
+
+static struct fs_dirent *cdrom_volume_root(struct fs_volume *v)
+{
+	return cdrom_dirent_create(v,v->cdrom.root_sector,v->cdrom.root_length, 1);
+}
+
+const static struct fs_ops cdrom_ops = {
+	.volume_open = cdrom_volume_open,
+	.volume_close = cdrom_volume_close,
+	.volume_root = cdrom_volume_root,
+
+	.lookup = cdrom_dirent_lookup,
+	.mkdir = 0,
+	.mkfile = 0,
+	.read_block = cdrom_dirent_read_block,
+	.write_block = 0,
+	.list = cdrom_dirent_list,
+	.remove = 0,
+	.resize = 0,
+	.close = cdrom_dirent_close,
+};
+
+static struct fs cdrom_fs = {
+	"cdromfs",
+	&cdrom_ops,
+	0
+};
+
+int cdrom_init()
+{
+	fs_register(&cdrom_fs);
+	return 0;
+}