[v2,1/2] lib: Factor out is_supported() && Add tst_supported_fs for shell

1) Factor out is_supported() and rename it as tst_fs_is_supported(),
   so that some tests can check a specified filesystem by it.

2) Shell tests can check a specified filesystem or all supported
   fielsystems by tst_supported_fs binary.

Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
---
 include/tst_fs.h                 |  8 ++++++
 lib/tst_supported_fs_types.c     |  6 ++--
 testcases/lib/Makefile           |  2 +-
 testcases/lib/tst_supported_fs.c | 61 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 73 insertions(+), 4 deletions(-)
 create mode 100644 testcases/lib/tst_supported_fs.c

Hi!
> diff --git a/include/tst_fs.h b/include/tst_fs.h
> index 73916a6..599f28f 100644
> --- a/include/tst_fs.h
> +++ b/include/tst_fs.h
> @@ -49,6 +49,8 @@ enum {
>  	TST_GB = 1073741824,
>  };
>  
> +extern const char *const fs_type_whitelist[];

I do not think that we have to check the fs type against the whitelist
before we call tst_fs_is_supported() function. If we pass invalid fs we
will end up with "Filesystem foo is not supported" message anyways.

>  /*
>   * @path: path is the pathname of any file within the mounted file system
>   * @mult: mult should be TST_KB, TST_MB or TST_GB
> @@ -147,6 +149,12 @@ int tst_get_path(const char *prog_name, char *buf, size_t buf_len);
>  int tst_fill_file(const char *path, char pattern, size_t bs, size_t bcount);
>  
>  /*
> + * Return 1 if a specified fiilsystem is supported
> + * Return 0 if a specified fiilsystem isn't supported
> + */
> +int tst_fs_is_supported(const char *fs_type);
> +
> +/*
>   * Returns NULL-terminated array of kernel-supported filesystems.
>   */
>  const char **tst_get_supported_fs_types(void);
> diff --git a/lib/tst_supported_fs_types.c b/lib/tst_supported_fs_types.c
> index a23b1ed..c7123b2 100644
> --- a/lib/tst_supported_fs_types.c
> +++ b/lib/tst_supported_fs_types.c
> @@ -25,7 +25,7 @@
>  #include "tst_test.h"
>  #include "tst_fs.h"
>  
> -static const char *const fs_type_whitelist[] = {
> +const char *const fs_type_whitelist[] = {
>  	"ext2",
>  	"ext3",
>  	"ext4",
> @@ -100,7 +100,7 @@ static int has_kernel_support(const char *fs_type)
>  	return 1;
>  }
>  
> -static int is_supported(const char *fs_type)
> +int tst_fs_is_supported(const char *fs_type)
>  {
>  	return has_kernel_support(fs_type) && has_mkfs(fs_type);
>  }
> @@ -110,7 +110,7 @@ const char **tst_get_supported_fs_types(void)
>  	unsigned int i, j = 0;
>  
>  	for (i = 0; fs_type_whitelist[i]; i++) {
> -		if (is_supported(fs_type_whitelist[i]))
> +		if (tst_fs_is_supported(fs_type_whitelist[i]))
>  			fs_types[j++] = fs_type_whitelist[i];
>  	}
>  
> diff --git a/testcases/lib/Makefile b/testcases/lib/Makefile
> index 398150a..14352d5 100644
> --- a/testcases/lib/Makefile
> +++ b/testcases/lib/Makefile
> @@ -26,7 +26,7 @@ include $(top_srcdir)/include/mk/testcases.mk
>  
>  INSTALL_TARGETS		:= *.sh
>  
> -MAKE_TARGETS		:= tst_sleep tst_random tst_checkpoint tst_rod tst_kvcmp\
> +MAKE_TARGETS		:= tst_supported_fs tst_sleep tst_random tst_checkpoint tst_rod tst_kvcmp\
>  			   tst_device tst_net_iface_prefix tst_net_ip_prefix tst_net_vars
>  
>  include $(top_srcdir)/include/mk/generic_leaf_target.mk
> diff --git a/testcases/lib/tst_supported_fs.c b/testcases/lib/tst_supported_fs.c
> new file mode 100644
> index 0000000..df9ea48
> --- /dev/null
> +++ b/testcases/lib/tst_supported_fs.c
> @@ -0,0 +1,61 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2018 FUJITSU LIMITED. All rights reserved.
> + * Author: Xiao Yang <yangx.jy@cn.fujitsu.com>
> + */
> +
> +#include <errno.h>
> +#include <stdio.h>
> +#include <string.h>
> +
> +#define TST_NO_DEFAULT_MAIN
> +#include "tst_test.h"
> +#include "tst_fs.h"
> +
> +static void usage(void)
> +{
> +	printf("Usage: tst_supported_fs [fs_type]\n");
> +	printf("   If a specified fs_type is supported, return 1\n");
> +	printf("   If a specified fs_type isn't supported, return 0\n");
> +	printf("   If a fs_type isn't specified, print the list of supported filesystems\n");
> +	printf("   fs_type - a specified filesystem type\n");
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	const char *const *filesystems;
> +	int i, valid_flag = 0;
> +
> +	if (argc > 2) {
> +		printf("Can't specify multiple fs_type\n");

Error messages and help should rather go to stderr.

> +		usage();
> +		return 2;
> +	}
> +
> +	if (argv[1] && !strcmp(argv[1], "-h")) {
> +		usage();
> +		return 2;

This should probably be return 0 but that is minor.

> +	}
> +
> +	if (argv[1]) {
> +		for (i = 0; fs_type_whitelist[i]; i++) {
> +			if (!strcmp(argv[1], fs_type_whitelist[i])) {
> +				valid_flag = 1;
> +				break;
> +			}
> +		}
> +
> +		if (valid_flag)
> +			return tst_fs_is_supported(argv[1]);
> +
> +		printf("An invalid specified fs_type is %s\n", argv[1]);
> +		return 2;
> +	}
> +
> +	printf("List of supported fs_type:\n");

This message here would make it harder to use the helper actually, since
I would expect that we would like to use this as:

	for i in $(tst_supported_fs); do
		# Run the actual test for each filesystem
	done

> +	filesystems = tst_get_supported_fs_types();
> +	for (i = 0; filesystems[i]; i++)
> +		printf("%s\n", filesystems[i]);
> +
> +	return 2;

This should probably be return 0 as well.

> +}
> -- 
> 1.8.3.1
> 
> 
>

Hi!
> +	printf("Usage: tst_supported_fs [fs_type]\n");
> +	printf("   If a specified fs_type is supported, return 1\n");
> +	printf("   If a specified fs_type isn't supported, return 0\n");

Also this is a bit confusing since in shell 0 == true, hence it would be
a bit better to return !tst_fs_is_supported(argv[1]);