[PATCH] tests/ioctl_kvm_run.c: handle cpuid at the end of vcpu dentry

[Dmitry V. Levin]

On Tue, May 01, 2018 at 03:36:48AM +0900, Masatake YAMATO wrote:
[...]
> @@ -56,7 +57,7 @@ kvm_ioctl(int fd, unsigned long cmd, const char *cmd_str, void *arg)
>  
>  static const char dev[] = "/dev/kvm";
>  static const char vm_dev[] = "anon_inode:kvm-vm";
> -static const char vcpu_dev[] = "anon_inode:kvm-vcpu";
> +static char vcpu_dev[] = "anon_inode:kvm-vcpu:0";
>  static size_t page_size;
>  
>  extern const char code[];
> @@ -165,6 +166,23 @@ run_kvm(const int vcpu_fd, struct kvm_run *const run, const size_t mmap_size,
>  	}
>  }
>  
> +static int
> +vcpu_dev_should_have_cpuid(int fd)
> +{
> +	int r = 0;
> +	char *filename = NULL;
> +	char buf[sizeof("/proc/4294967296/fd/anon_inode:kvm-vcpu:0") + 1] = {'\0',};

This is quite non-traditional way of initializing strings.

> +	if (asprintf(&filename, "/proc/%d/fd/%d", getpid(), fd) < 0)
> +		error_msg_and_fail("asprintf");
> +
> +	if ((readlink(filename, buf, sizeof(buf) - 1) >= 0)
> +	    && (strcmp(buf, "anon_inode:kvm-vcpu:0") == 0))

This cannot work properly because readlink does not append a null byte
to buf.  I think the following alternative should work better:

	char buf[sizeof(vcpu_dev)];
	if (readlink(filename, buf, sizeof(buf)) == sizeof(buf) - 1
	    && memcmp(buf, vcpu_dev, sizeof(buf) - 1) == 0)


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