[Devel] [PATCH VZ10 v4 8/9] selftests/ve: Add more helpers

[Pavel Tikhomirov]

On 7/29/26 18:46, Vladimir Riabchun wrote:
> Some more read/write helpers may be useful.
> 
> Also, add a helper to execute functions in child process with
> switched namespaces and cgroup.
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-135520
> 
> Feature: per-ve failcounters
> Signed-off-by: Vladimir Riabchun <vladimir.riabchun at virtuozzo.com>
> ---
>  tools/testing/selftests/ve/ve_selftest.h | 79 ++++++++++++++++++++++--
>  1 file changed, 73 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/testing/selftests/ve/ve_selftest.h b/tools/testing/selftests/ve/ve_selftest.h
> index 69c0a52dd7ef..ecd0024e888c 100644
> --- a/tools/testing/selftests/ve/ve_selftest.h
> +++ b/tools/testing/selftests/ve/ve_selftest.h
> @@ -43,6 +43,14 @@ static inline int write_file_at(int dirfd, const char *path, const char *val)
>  	return (ret == (int)len) ? 0 : -1;
>  }
>  
> +static inline int write_u64_at(int dirfd, const char *path, unsigned long long val)
> +{
> +	char s[20];
> +
> +	snprintf(s, sizeof(s), "%llu", val);
> +	return write_file_at(dirfd, path, s);
> +}
> +
>  static inline int read_file_at(int dirfd, const char *path, char *buf,
>  			       size_t buflen)
>  {
> @@ -73,19 +81,31 @@ static inline int read_u64_at(int dirfd, const char *path,
>  			      unsigned long long *out)
>  {
>  	char buf[32] = {0}, *end;
> -	int fd, ret;
> +	int ret;
>  
> -	fd = openat(dirfd, path, O_RDONLY);
> -	if (fd < 0)
> +	ret = read_file_at(dirfd, path, buf, sizeof(buf));
> +	if (ret <= 0)
>  		return -1;
>  
> -	ret = read(fd, buf, sizeof(buf) - 1);
> -	close(fd);
> +	errno = 0;
> +	*out = strtoull(buf, &end, 10);
> +	if (errno || end == buf)
> +		return -1;
> +	return 0;
> +}
> +
> +static inline int read_s32_at(int dirfd, const char *path,
> +			      int *out)
> +{
> +	char buf[32] = {0}, *end;
> +	int ret;
> +
> +	ret = read_file_at(dirfd, path, buf, sizeof(buf));
>  	if (ret <= 0)
>  		return -1;
>  
>  	errno = 0;
> -	*out = strtoull(buf, &end, 10);
> +	*out = strtol(buf, &end, 10);
>  	if (errno || end == buf)
>  		return -1;
>  	return 0;
> @@ -134,6 +154,53 @@ static inline int enter_cgroup(int cgv2_fd, int ctid)
>  	return ret;
>  }
>  
> +/*
> + * Run function in VE cgroup and new namespaces.
> + *
> + * Namespaces are provided via unshare_flags.
> + * Return values:
> + *  -  0 if function returns zero
> + *  - -1 if function returns negative value
> + *  -  1 if setup fails or function returns positive value
> + */
> +static inline int run_in_ve(int cgv2_fd, int ctid, int unshare_flags,
> +		int (*fn)(void *), void *arg)
> +{
> +	int status;
> +	pid_t pid;
> +
> +	pid = fork();
> +	if (pid < 0) {
> +		fprintf(stderr, "%s: fork failed\n", __func__);
> +		return 1;
> +	}
> +	if (pid == 0) {
> +		int ret;
> +
> +		if (enter_cgroup(cgv2_fd, ctid) < 0) {
> +			fprintf(stderr, "%s: enter_cgroup failed\n", __func__);
> +			_exit(255);
> +		}
> +		if (unshare(unshare_flags) < 0) {
> +			fprintf(stderr, "%s: unshare(%d) failed\n",
> +				__func__, unshare_flags);
> +			_exit(255);
> +		}

If unshare_flags has no CLONE_NEWVE, this whole function is doing not what it
says it is doing (not entering VE, only VE cgroup), maybe we should have VE
namespace flag by default?

> +		ret = fn(arg);
> +		if (ret < 0)
> +			ret = 1;
> +		else if (ret > 0)
> +			ret = 255;
> +		_exit(ret);
> +	}
> +	if (waitpid(pid, &status, 0) < 0 || !WIFEXITED(status) || WEXITSTATUS(status) == 255)
> +		return 1;
> +	if (WEXITSTATUS(status))
> +		return -1;
> +	return 0;
> +
> +}
> +
>  /*
>   * Create a fresh VE cgroup at the first free id at or after @from and unhide
>   * its ve.* control files. Return the new id, or -1.

-- 
Best regards, Pavel Tikhomirov
Senior Software Developer, Virtuozzo.