Re: [PATCH v3 1/2] btrfs-progs: export util functions about file extent items

[Sidong Yang <realwakka@gmail.com>]

On Thu, Jul 15, 2021 at 06:46:08AM +0800, Qu Wenruo wrote:
> 
> 
> On 2021/7/14 下午10:54, Sidong Yang wrote:
> > This patch export two functions that convert enum about file extents to
> > string. It can be used in other code like inspect-internal command. And
> > this patch also make compress_type_to_str() function more safe by using
> > strncpy() than strcpy().
> > 
> > Signed-off-by: Sidong Yang <realwakka@gmail.com>
> > ---
> > v2:
> >   - Prints type and compression
> >   - Use the terms from file_extents_item like disk_bytenr not like
> >     "physical"
> > v3:
> >   - export util functions for removing duplication
> >   - change the way to loop with search ioctl
> > ---
> >   kernel-shared/print-tree.c | 18 ++++++++++--------
> >   kernel-shared/print-tree.h |  3 +++
> >   2 files changed, 13 insertions(+), 8 deletions(-)
> > 
> > diff --git a/kernel-shared/print-tree.c b/kernel-shared/print-tree.c
> > index e5d4b453..bfef7d26 100644
> > --- a/kernel-shared/print-tree.c
> > +++ b/kernel-shared/print-tree.c
> > @@ -27,6 +27,8 @@
> >   #include "kernel-shared/print-tree.h"
> >   #include "common/utils.h"
> > +#define COMPRESS_STR_LEN 5
> 
> It's already too small to contain all the strings.
> 
> We have a default branch:
> 
>  	default:
>  		sprintf(ret, "UNKNOWN.%d", compress_type);
> 
> In that case, our minimal value should be strlen("UNKNOWN.255") + 1, which
> is 12 bytes.
> 
> Your old rounded up 16 bytes is in fact perfect in this case.
> 
> Despite that, this patch looks good to me.

Thanks for review.

I've been thought about this. should COMPRESS_STR_LEN be exported?
Developer that use this function needs to know max length of string.
Or we can choose the simple implementation that just return const char*
like btrfs_file_extent_type_to_str(). But it will be hard to print
unknown compress_type.

Thanks,
Sidong
> 
> Thanks,
> Qu
> > +
> >   static void print_dir_item_type(struct extent_buffer *eb,
> >                                   struct btrfs_dir_item *di)
> >   {
> > @@ -338,27 +340,27 @@ static void print_uuids(struct extent_buffer *eb)
> >   	printf("fs uuid %s\nchunk uuid %s\n", fs_uuid, chunk_uuid);
> >   }
> > -static void compress_type_to_str(u8 compress_type, char *ret)
> > +void btrfs_compress_type_to_str(u8 compress_type, char *ret)
> >   {
> >   	switch (compress_type) {
> >   	case BTRFS_COMPRESS_NONE:
> > -		strcpy(ret, "none");
> > +		strncpy(ret, "none", COMPRESS_STR_LEN);
> >   		break;
> >   	case BTRFS_COMPRESS_ZLIB:
> > -		strcpy(ret, "zlib");
> > +		strncpy(ret, "zlib", COMPRESS_STR_LEN);
> >   		break;
> >   	case BTRFS_COMPRESS_LZO:
> > -		strcpy(ret, "lzo");
> > +		strncpy(ret, "lzo", COMPRESS_STR_LEN);
> >   		break;
> >   	case BTRFS_COMPRESS_ZSTD:
> > -		strcpy(ret, "zstd");
> > +		strncpy(ret, "zstd", COMPRESS_STR_LEN);
> >   		break;
> >   	default:
> >   		sprintf(ret, "UNKNOWN.%d", compress_type);
> >   	}
> >   }
> > -static const char* file_extent_type_to_str(u8 type)
> > +const char* btrfs_file_extent_type_to_str(u8 type)
> >   {
> >   	switch (type) {
> >   	case BTRFS_FILE_EXTENT_INLINE: return "inline";
> > @@ -376,12 +378,12 @@ static void print_file_extent_item(struct extent_buffer *eb,
> >   	unsigned char extent_type = btrfs_file_extent_type(eb, fi);
> >   	char compress_str[16];
> > -	compress_type_to_str(btrfs_file_extent_compression(eb, fi),
> > +	btrfs_compress_type_to_str(btrfs_file_extent_compression(eb, fi),
> >   			     compress_str);
> >   	printf("\t\tgeneration %llu type %hhu (%s)\n",
> >   			btrfs_file_extent_generation(eb, fi),
> > -			extent_type, file_extent_type_to_str(extent_type));
> > +			extent_type, btrfs_file_extent_type_to_str(extent_type));
> >   	if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
> >   		printf("\t\tinline extent data size %u ram_bytes %llu compression %hhu (%s)\n",
> > diff --git a/kernel-shared/print-tree.h b/kernel-shared/print-tree.h
> > index 80fb6ef7..dbb2f183 100644
> > --- a/kernel-shared/print-tree.h
> > +++ b/kernel-shared/print-tree.h
> > @@ -43,4 +43,7 @@ void print_objectid(FILE *stream, u64 objectid, u8 type);
> >   void print_key_type(FILE *stream, u64 objectid, u8 type);
> >   void btrfs_print_superblock(struct btrfs_super_block *sb, int full);
> > +void btrfs_compress_type_to_str(u8 compress_type, char *ret);
> > +const char* btrfs_file_extent_type_to_str(u8 type);
> > +
> >   #endif
> > 
>