block.c

/* $Id: block.c,v 1.1 2008/12/11 12:18:17 ecd Exp $
 */

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/stat.h>

#include "qemu-common.h"
#include <block.h>
#include "block_int.h"

#define SECTOR_BITS	9
#define SECTOR_SIZE	(1 << SECTOR_BITS)

static BlockDriverState *bdrv_first;
static BlockDriver *first_drv;

#ifndef ENOMEDIUM
#define ENOMEDIUM	ENODEV
#endif

static void bdrv_close(BlockDriverState *bs);

static int
path_is_absolute(const char *path)
{
	const char *p;
#ifdef _WIN32
	/* specific case for names like: "\\.\d:" */
	if (*path == '/' || *path == '\\')
		return 1;
#endif
	p = strchr(path, ':');
	if (p)
		p++;
	else
		p = path;
#ifdef _WIN32
	return (*p == '/' || *p == '\\');
#else
	return (*p == '/');
#endif
}

/* if filename is absolute, just copy it to dest. Otherwise, build a
   path to it by considering it is relative to base_path. URL are
   supported. */
static void
path_combine(char *dest, int dest_size,
	     const char *base_path,
	     const char *filename)
{
	const char *p, *p1;
	int len;

	if (dest_size <= 0)
		return;
	if (path_is_absolute(filename)) {
		pstrcpy(dest, dest_size, filename);
	} else {
		p = strchr(base_path, ':');
		if (p)
			p++;
		else
			p = base_path;
		p1 = strrchr(base_path, '/');
#ifdef _WIN32
		{
			const char *p2;
			p2 = strrchr(base_path, '\\');
			if (!p1 || p2 > p1)
				p1 = p2;
		}
#endif
		if (p1)
			p1++;
		else
			p1 = base_path;
		if (p1 > p)
			p = p1;
		len = p - base_path;
		if (len > dest_size - 1)
			len = dest_size - 1;
		memcpy(dest, base_path, len);
		dest[len] = '\0';
		pstrcat(dest, dest_size, filename);
	}
}

#ifdef _WIN32
void get_tmp_filename(char *filename, int size)
{
	char temp_dir[MAX_PATH];

	GetTempPath(MAX_PATH, temp_dir);
	GetTempFileName(temp_dir, "x49", 0, filename);
}
#else
void get_tmp_filename(char *filename, int size)
{
	int fd;

	/* XXX: race condition possible */
	pstrcpy(filename, size, "/tmp/x49gp.XXXXXX");
	fd = mkstemp(filename);
	close(fd);
}
#endif

#ifdef _WIN32
static int is_windows_drive_prefix(const char *filename)
{
	return (((filename[0] >= 'a' && filename[0] <= 'z') ||
		 (filename[0] >= 'A' && filename[0] <= 'Z')) &&
		  filename[1] == ':');
}
    
static int is_windows_drive(const char *filename)
{
	if (is_windows_drive_prefix(filename) && 
	    filename[2] == '\0')
		return 1;
	if (strstart(filename, "\\\\.\\", NULL) ||
	    strstart(filename, "//./", NULL))
		return 1;
	return 0;
}
#endif

static BlockDriver *
find_protocol(const char *filename)
{
	BlockDriver *drv1;
	char protocol[128];
	int len;
	const char *p;

#ifdef _WIN32
	if (is_windows_drive(filename) ||
	    is_windows_drive_prefix(filename))
		return &bdrv_raw;
#endif
	p = strchr(filename, ':');
	if (!p)
		return &bdrv_raw;
	len = p - filename;
	if (len > sizeof(protocol) - 1)
		len = sizeof(protocol) - 1;
	memcpy(protocol, filename, len);
	protocol[len] = '\0';
	for(drv1 = first_drv; drv1 != NULL; drv1 = drv1->next) {
#ifdef DEBUG_X49GP_BLOCK
		fprintf(stderr,
			"%s:%u: protocol '%s', drv->protocol_name '%s'\n",
			__FUNCTION__, __LINE__, protocol, drv1->protocol_name);
#endif
		if (drv1->protocol_name && 
		    !strcmp(drv1->protocol_name, protocol)) {
#ifdef DEBUG_X49GP_BLOCK
			fprintf(stderr, "%s:%u: protocol '%s', drv %p\n",
				__FUNCTION__, __LINE__, protocol, drv1);
#endif
			return drv1;
		}
	}
#ifdef DEBUG_X49GP_BLOCK
	fprintf(stderr, "%s:%u: protocol '%s', NULL\n",
		__FUNCTION__, __LINE__, protocol);
#endif
	return NULL;
}

/* XXX: force raw format if block or character device ? It would
   simplify the BSD case */
static BlockDriver *
find_image_format(const char *filename)
{
	int ret, score, score_max;
	BlockDriver *drv1, *drv;
	uint8_t buf[2048];
	BlockDriverState *bs;
    
	drv = find_protocol(filename);
	/* no need to test disk image formats for vvfat */
	if (drv == &bdrv_vvfat)
		return drv;

	ret = bdrv_file_open(&bs, filename, BDRV_O_RDONLY);
	if (ret < 0)
		return NULL;
	ret = bdrv_pread(bs, 0, buf, sizeof(buf));
	bdrv_delete(bs);
	if (ret < 0) {
		return NULL;
	}

	score_max = 0;
	for(drv1 = first_drv; drv1 != NULL; drv1 = drv1->next) {
		if (drv1->bdrv_probe) {
			score = drv1->bdrv_probe(buf, ret, filename);
			if (score > score_max) {
				score_max = score;
				drv = drv1;
			}
		}
	}
	return drv;
}

int
bdrv_create(BlockDriver *drv,
	    const char *filename, int64_t size_in_sectors,
	    const char *backing_file, int flags)
{
	if (!drv->bdrv_create)
		return -ENOTSUP;
	return drv->bdrv_create(filename, size_in_sectors, backing_file, flags);
}

static void
bdrv_register(BlockDriver *bdrv)
{
	bdrv->next = first_drv;
	first_drv = bdrv;
}
		
/* create a new block device (by default it is empty) */
BlockDriverState *
bdrv_new(const char *device_name)
{
	BlockDriverState **pbs, *bs;

	bs = qemu_mallocz(sizeof(BlockDriverState));
	if(!bs)
		return NULL;
	pstrcpy(bs->device_name, sizeof(bs->device_name), device_name);
	if (device_name[0] != '\0') {
		/* insert at the end */
		pbs = &bdrv_first;
		while (*pbs != NULL)
			pbs = &(*pbs)->next;
		*pbs = bs;
	}
	return bs;
}

/** 
 * Truncate file to 'offset' bytes (needed only for file protocols)
 */
int
bdrv_truncate(BlockDriverState *bs, int64_t offset)
{   
	BlockDriver *drv = bs->drv;
	if (!drv)
		return -ENOMEDIUM;
	if (!drv->bdrv_truncate)
		return -ENOTSUP;
	return drv->bdrv_truncate(bs, offset);
}

/**
 * Length of a file in bytes. Return < 0 if error or unknown.
 */
int64_t
bdrv_getlength(BlockDriverState *bs)
{
	BlockDriver *drv = bs->drv;
	if (!drv)
		return -ENOMEDIUM;
	if (!drv->bdrv_getlength) {
		/* legacy mode */
		return bs->total_sectors * SECTOR_SIZE;
	}
	return drv->bdrv_getlength(bs);
}

int
bdrv_file_open(BlockDriverState **pbs, const char *filename, int flags)
{
	BlockDriverState *bs;
	int ret;
#ifdef DEBUG_X49GP_BLOCK
	fprintf(stderr, "%s:%u: filename '%s'\n",
		__FUNCTION__, __LINE__, filename);
#endif

	bs = bdrv_new("");
	if (!bs)
		return -ENOMEM;
	ret = bdrv_open(bs, filename, flags | BDRV_O_FILE);
	if (ret < 0) {
		bdrv_delete(bs);
#ifdef DEBUG_X49GP_BLOCK
		fprintf(stderr, "%s:%u: '%s': %d\n",
			__FUNCTION__, __LINE__, filename, ret);
#endif
		return ret;
	}
	*pbs = bs;
#ifdef DEBUG_X49GP_BLOCK
	fprintf(stderr, "%s:%u: return 0\n", __FUNCTION__, __LINE__);
#endif
	return 0;
}

int
bdrv_open(BlockDriverState *bs, const char *filename, int flags)
{
	int ret, open_flags;
	char backing_filename[1024];
	BlockDriver *drv = NULL;

#ifdef DEBUG_X49GP_BLOCK
	fprintf(stderr, "%s:%u: filename '%s'\n",
		__FUNCTION__, __LINE__, filename);
#endif

	bs->read_only = 0;
	bs->is_temporary = 0;
	bs->encrypted = 0;

	pstrcpy(bs->filename, sizeof(bs->filename), filename);
	if (flags & BDRV_O_FILE) {
		drv = find_protocol(filename);
		if (!drv) {
#ifdef DEBUG_X49GP_BLOCK
f			printf(stderr, "%s:%u: drv: %p\n",
			       __FUNCTION__, __LINE__, drv);
#endif
			return -ENOENT;
		}
	} else {
		if (!drv) {
			drv = find_image_format(filename);
			if (!drv) {
#ifdef DEBUG_X49GP_BLOCK
				fprintf(stderr, "%s:%u: drv: %p\n",
					__FUNCTION__, __LINE__, drv);
#endif
				return -1;
			}
		}
	}

#ifdef DEBUG_X49GP_BLOCK
	fprintf(stderr, "%s:%u: drv: %p\n", __FUNCTION__, __LINE__, drv);
#endif
	bs->drv = drv;
	bs->opaque = qemu_mallocz(drv->instance_size);
	if (bs->opaque == NULL && drv->instance_size > 0) {
#ifdef DEBUG_X49GP_BLOCK
		fprintf(stderr, "%s:%u: no opaque\n", __FUNCTION__, __LINE__);
#endif
		return -1;
	}
	/* Note: for compatibility, we open disk image files as RDWR, and
	   RDONLY as fallback */
	if (!(flags & BDRV_O_FILE))
		open_flags = BDRV_O_RDWR;
	else
		open_flags = flags & ~(BDRV_O_FILE);
	ret = drv->bdrv_open(bs, filename, open_flags);
#ifdef DEBUG_X49GP_BLOCK
	fprintf(stderr, "%s:%u: drv->bdrv_open: %d\n",
		__FUNCTION__, __LINE__, ret);
#endif
	if (ret == -EACCES && !(flags & BDRV_O_FILE)) {
		ret = drv->bdrv_open(bs, filename, BDRV_O_RDONLY);
		bs->read_only = 1;
	}
	if (ret < 0) {
		qemu_free(bs->opaque);
		bs->opaque = NULL;
		bs->drv = NULL;
#ifdef DEBUG_X49GP_BLOCK
		fprintf(stderr, "%s:%u: return %d\n",
			__FUNCTION__, __LINE__, ret);
#endif
		return ret;
	}
	if (drv->bdrv_getlength) {
		bs->total_sectors = bdrv_getlength(bs) >> SECTOR_BITS;
	}
#ifndef _WIN32
	if (bs->is_temporary) {
		unlink(filename);
	}
#endif
	if (bs->backing_file[0] != '\0') {
		/* if there is a backing file, use it */
		bs->backing_hd = bdrv_new("");
		if (!bs->backing_hd) {
	fail:
			bdrv_close(bs);
#ifdef DEBUG_X49GP_BLOCK
			fprintf(stderr, "%s:%u: return -ENOMEM\n",
				__FUNCTION__, __LINE__);
#endif
			return -ENOMEM;
		}
#ifdef DEBUG_X49GP_BLOCK
		fprintf(stderr, "%s:%u: combine '%s' '%s'\n",
			__FUNCTION__, __LINE__, filename, bs->backing_file);
#endif
		path_combine(backing_filename, sizeof(backing_filename),
			     filename, bs->backing_file);
#ifdef DEBUG_X49GP_BLOCK
		fprintf(stderr, "%s:%u: combine: '%s'\n",
			__FUNCTION__, __LINE__, backing_filename);
#endif
		if (bdrv_open(bs->backing_hd, backing_filename, 0) < 0) {
#ifdef DEBUG_X49GP_BLOCK
			fprintf(stderr, "%s:%u: backing fail\n",
				__FUNCTION__, __LINE__);
#endif
			goto fail;
		}
	}

	/* call the change callback */
	bs->media_changed = 1;
	if (bs->change_cb)
		bs->change_cb(bs->change_opaque);

#ifdef DEBUG_X49GP_BLOCK
	fprintf(stderr, "%s:%u: return 0\n", __FUNCTION__, __LINE__);
#endif
	return 0;
}

static void
bdrv_close(BlockDriverState *bs)
{
	if (NULL == bs->drv)
		return;

	/* call the change callback */
	bs->media_changed = 1;
	if (bs->change_cb)
		bs->change_cb(bs->change_opaque);

	if (bs->backing_hd)
		bdrv_delete(bs->backing_hd);

	bs->drv->bdrv_close(bs);

#ifdef _WIN32
	if (bs->is_temporary) {
		unlink(bs->filename);
	}
#endif

	qemu_free(bs->opaque);
	bs->opaque = NULL;
	bs->drv = NULL;
}

void
bdrv_delete(BlockDriverState *bs)
{
	/* XXX: remove the driver list */
	bdrv_close(bs);
	qemu_free(bs);
}

/* return < 0 if error. See bdrv_write() for the return codes */
int
bdrv_read(BlockDriverState * bs, int64_t sector_num,
	  uint8_t * buf, int nb_sectors)
{
	BlockDriver *drv = bs->drv;

	if (!drv)
		return -ENOMEDIUM;

	if (sector_num == 0 && bs->boot_sector_enabled && nb_sectors > 0) {
		memcpy(buf, bs->boot_sector_data, 512);
		sector_num++;
		nb_sectors--;
		buf += 512;
		if (nb_sectors == 0)
			return 0;
	}
	if (drv->bdrv_pread) {
		int ret, len;

		len = nb_sectors * 512;
		ret = drv->bdrv_pread(bs, sector_num * 512, buf, len);
		if (ret < 0)
			return ret;
		else if (ret != len)
			return -EINVAL;
		else
			return 0;
	} else {
		return drv->bdrv_read(bs, sector_num, buf, nb_sectors);
	}
}

/* Return < 0 if error. Important errors are: 
  -EIO         generic I/O error (may happen for all errors)
  -ENOMEDIUM   No media inserted.
  -EINVAL      Invalid sector number or nb_sectors
  -EACCES      Trying to write a read-only device
*/
static int
bdrv_write(BlockDriverState * bs, int64_t sector_num,
	   const uint8_t * buf, int nb_sectors)
{
	BlockDriver *drv = bs->drv;

	if (!bs->drv)
		return -ENOMEDIUM;
	if (bs->read_only)
		return -EACCES;
	if (sector_num == 0 && bs->boot_sector_enabled && nb_sectors > 0) {
		memcpy(bs->boot_sector_data, buf, 512);
	}
	if (drv->bdrv_pwrite) {
		int ret, len;

		len = nb_sectors * 512;
		ret = drv->bdrv_pwrite(bs, sector_num * 512, buf, len);
		if (ret < 0)
			return ret;
		else if (ret != len)
			return -EIO;
		else
			return 0;
	} else {
		return drv->bdrv_write(bs, sector_num, buf, nb_sectors);
	}
}

static int
bdrv_pread_em(BlockDriverState * bs, int64_t offset, uint8_t * buf, int count1)
{
	uint8_t tmp_buf[SECTOR_SIZE];
	int len, nb_sectors, count;
	int64_t sector_num;

	count = count1;
	/* first read to align to sector start */
	len = (SECTOR_SIZE - offset) & (SECTOR_SIZE - 1);
	if (len > count)
		len = count;
	sector_num = offset >> SECTOR_BITS;
	if (len > 0) {
		if (bdrv_read(bs, sector_num, tmp_buf, 1) < 0)
			return -EIO;
		memcpy(buf, tmp_buf + (offset & (SECTOR_SIZE - 1)), len);
		count -= len;
		if (count == 0)
			return count1;
		sector_num++;
		buf += len;
	}

	/* read the sectors "in place" */
	nb_sectors = count >> SECTOR_BITS;
	if (nb_sectors > 0) {
		if (bdrv_read(bs, sector_num, buf, nb_sectors) < 0)
			return -EIO;
		sector_num += nb_sectors;
		len = nb_sectors << SECTOR_BITS;
		buf += len;
		count -= len;
	}

	/* add data from the last sector */
	if (count > 0) {
		if (bdrv_read(bs, sector_num, tmp_buf, 1) < 0)
			return -EIO;
		memcpy(buf, tmp_buf, count);
	}
	return count1;
}

static int
bdrv_pwrite_em(BlockDriverState * bs, int64_t offset,
	       const uint8_t * buf, int count1)
{
	uint8_t tmp_buf[SECTOR_SIZE];
	int len, nb_sectors, count;
	int64_t sector_num;

	count = count1;
	/* first write to align to sector start */
	len = (SECTOR_SIZE - offset) & (SECTOR_SIZE - 1);
	if (len > count)
		len = count;
	sector_num = offset >> SECTOR_BITS;
	if (len > 0) {
		if (bdrv_read(bs, sector_num, tmp_buf, 1) < 0)
			return -EIO;
		memcpy(tmp_buf + (offset & (SECTOR_SIZE - 1)), buf, len);
		if (bdrv_write(bs, sector_num, tmp_buf, 1) < 0)
			return -EIO;
		count -= len;
		if (count == 0)
			return count1;
		sector_num++;
		buf += len;
	}

	/* write the sectors "in place" */
	nb_sectors = count >> SECTOR_BITS;
	if (nb_sectors > 0) {
		if (bdrv_write(bs, sector_num, buf, nb_sectors) < 0)
			return -EIO;
		sector_num += nb_sectors;
		len = nb_sectors << SECTOR_BITS;
		buf += len;
		count -= len;
	}

	/* add data from the last sector */
	if (count > 0) {
		if (bdrv_read(bs, sector_num, tmp_buf, 1) < 0)
			return -EIO;
		memcpy(tmp_buf, buf, count);
		if (bdrv_write(bs, sector_num, tmp_buf, 1) < 0)
			return -EIO;
	}
	return count1;
}

/**
 * Read with byte offsets (needed only for file protocols) 
 */
int
bdrv_pread(BlockDriverState * bs, int64_t offset, void *buf1, int count1)
{
	BlockDriver *drv = bs->drv;

	if (!drv)
		return -ENOMEDIUM;
	if (!drv->bdrv_pread)
		return bdrv_pread_em(bs, offset, buf1, count1);
	return drv->bdrv_pread(bs, offset, buf1, count1);
}

/** 
 * Write with byte offsets (needed only for file protocols) 
 */
int
bdrv_pwrite(BlockDriverState * bs, int64_t offset, const void *buf1, int count1)
{
	BlockDriver *drv = bs->drv;

	if (!drv)
		return -ENOMEDIUM;
	if (!drv->bdrv_pwrite)
		return bdrv_pwrite_em(bs, offset, buf1, count1);
	return drv->bdrv_pwrite(bs, offset, buf1, count1);
}

void
bdrv_flush(BlockDriverState *bs)
{
	if (bs->drv->bdrv_flush)
		bs->drv->bdrv_flush(bs);
	if (bs->backing_hd)
		bdrv_flush(bs->backing_hd);
}

void
bdrv_init(void)
{
	/* bdrv_register(&bdrv_raw); */
	/* bdrv_register(&bdrv_host_device); */
	bdrv_register(&bdrv_qcow);
	bdrv_register(&bdrv_vvfat);
}