On Thu, Nov 12, 2015 at 10:10:51AM +0100, Florian Margaine wrote:
> New patch is attached.
Applied with some modifications, thanks.
> +/*
> + * Takes a loop device path (e.g. /dev/loop0) and returns
> + * the associated file (e.g. /images/my_btrfs.img) using
> + * loopdev API
> + */
> +static int resolve_loop_device_with_loopdev(const char* loop_dev, char* loop_file)
> +{
> + int fd;
> + struct loop_info64 lo64;
> +
> + if (!(fd = open(loop_dev, O_RDONLY | O_NONBLOCK)))
fd = ... moved before if
> + return -errno;
> + if (ioctl(fd, LOOP_GET_STATUS64, &lo64) != 0)
open and ioctl return < 0 in case of error
> + return -errno;
> +
> + memcpy(loop_file, lo64.lo_file_name, strlen(lo64.lo_file_name) + 1);
> + if (close(fd) != 0)
> + return -errno;
> +
> + return 0;
> +}
>
> /* Takes a loop device path (e.g. /dev/loop0) and returns
> * the associated file (e.g. /images/my_btrfs.img) */
> @@ -1185,5 +1206,10 @@ static int resolve_loop_device(const char* loop_dev, char* loop_file,
> if (!realpath(loop_dev, real_loop_dev))
> return -errno;
> snprintf(p, PATH_MAX, "/sys/block/%s/loop/backing_file", strrchr(real_loop_dev, '/'));
> - if (!(f = fopen(p, "r")))
> + if (!(f = fopen(p, "r"))) {
> + if (errno == ENOENT)
> + /* It's possibly a partitioned loop device, which
> + is resolvable with loopdev API. */
comment style fixed
> + return resolve_loop_device_with_loopdev(loop_dev, loop_file);
> return -errno;
> + }
>
> snprintf(fmt, 20, "%%%i[^\n]", max_len-1);
> ret = fscanf(f, fmt, loop_file);
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