Subject: Re: [PATCH v4 12/24] read-cache: read index-v5

From: Thomas Gummerer <[email-masked]>
Date: Sat, 30 Nov 2013 11:40:32 +0100

Duy Nguyen <[email-masked]> writes:

> On Wed, Nov 27, 2013 at 7:00 PM, Thomas Gummerer <[email-masked]> wrote:
>> --- a/cache.h
>> +++ b/cache.h
>> @@ -132,11 +141,17 @@ struct cache_entry {
>>         char name[FLEX_ARRAY]; /* more */
>>  };
>>
>> +#define CE_NAMEMASK  (0x0fff)
>
> CE_NAMEMASK is redefined in read-cache-v2.c in "read-cache: move index
> v2 specific functions to their own file". My gcc is smart enough to
> see the two defines are about the same value and does not warn me. But
> we should remove one (likely this one as I see no use of this macro
> outside read-cache-v2.c)

Thanks for catching that, there's no need to have it here.  I'll remove
it in the re-roll.

>>  #define CE_STAGEMASK (0x3000)
>>  #define CE_EXTENDED  (0x4000)
>>  #define CE_VALID     (0x8000)
>> +#define CE_SMUDGED   (0x0400) /* index v5 only flag */
>>  #define CE_STAGESHIFT 12
>>
>> +#define CONFLICT_CONFLICTED (0x8000)
>> +#define CONFLICT_STAGESHIFT 13
>> +#define CONFLICT_STAGEMASK (0x6000)
>> +
>>  /*
>>   * Range 0xFFFF0000 in ce_flags is divided into
>>   * two parts: in-memory flags and on-disk ones.
>
>> diff --git a/read-cache-v5.c b/read-cache-v5.c
>> new file mode 100644
>> index 0000000..9d8c8f0
>> --- /dev/null
>> +++ b/read-cache-v5.c
>> +static int read_index_v5(struct index_state *istate, void *mmap,
>> +                        unsigned long mmap_size, struct filter_opts *opts)
>> +{
>> +       unsigned int entry_offset, foffsetblock, nr = 0, *extoffsets;
>> +       unsigned int dir_offset, dir_table_offset;
>> +       int need_root = 0, i;
>> +       uint32_t *offset;
>> +       struct directory_entry *root_directory, *de, *last_de;
>> +       const char **paths = NULL;
>> +       struct pathspec adjusted_pathspec;
>> +       struct cache_header *hdr;
>> +       struct cache_header_v5 *hdr_v5;
>> +
>> +       hdr = mmap;
>> +       hdr_v5 = ptr_add(mmap, sizeof(*hdr));
>> +       istate->cache_alloc = alloc_nr(ntohl(hdr->hdr_entries));
>> +       istate->cache = xcalloc(istate->cache_alloc, sizeof(struct cache_entry *));
>> +       extoffsets = xcalloc(ntohl(hdr_v5->hdr_nextension), sizeof(int));
>> +       for (i = 0; i < ntohl(hdr_v5->hdr_nextension); i++) {
>> +               offset = ptr_add(mmap, sizeof(*hdr) + sizeof(*hdr_v5));
>> +               extoffsets[i] = htonl(*offset);
>> +       }
>> +
>> +       /* Skip size of the header + crc sum + size of offsets to extensions + size of offsets */
>> +       dir_offset = sizeof(*hdr) + sizeof(*hdr_v5) + ntohl(hdr_v5->hdr_nextension) * 4 + 4
>> +               + (ntohl(hdr_v5->hdr_ndir) + 1) * 4;
>> +       dir_table_offset = sizeof(*hdr) + sizeof(*hdr_v5) + ntohl(hdr_v5->hdr_nextension) * 4 + 4;
>> +       root_directory = read_directories(&dir_offset, &dir_table_offset,
>> +                                         mmap, mmap_size);
>> +
>> +       entry_offset = ntohl(hdr_v5->hdr_fblockoffset);
>> +       foffsetblock = dir_offset;
>> +
>> +       if (opts && opts->pathspec && opts->pathspec->nr) {
>> +               paths = xmalloc((opts->pathspec->nr + 1)*sizeof(char *));
>> +               paths[opts->pathspec->nr] = NULL;
>
> Put this statement here
>
> GUARD_PATHSPEC(opts->pathspec,
>       PATHSPEC_FROMTOP |
>       PATHSPEC_MAXDEPTH |
>       PATHSPEC_LITERAL |
>       PATHSPEC_GLOB |
>       PATHSPEC_ICASE);
>
> This says the mentioned magic is safe in this code. New magic may or
> may not be and needs to be checked (soonest by me, I'm going to add
> negative pathspec and I'll need to look into how it should be handled
> in this code block).

Thanks, I'll add the statement in the re-roll.

>> +               for (i = 0; i < opts->pathspec->nr; i++) {
>> +                       char *super = strdup(opts->pathspec->items[i].match);
>> +                       int len = strlen(super);
>
> You should only check as far as items[i].nowildcard_len, not strlen().
> The rest could be wildcards and stuff and not so reliable.

Ok, will change it in the re-roll.

>> +                       while (len && super[len - 1] == '/' && super[len - 2] == '/')
>> +                               super[--len] = '\0'; /* strip all but one trailing slash */
>> +                       while (len && super[--len] != '/')
>> +                               ; /* scan backwards to next / */
>> +                       if (len >= 0)
>> +                               super[len--] = '\0';
>> +                       if (len <= 0) {
>> +                               need_root = 1;
>> +                               break;
>> +                       }
>> +                       paths[i] = super;
>> +               }
>
> And maybe put the comment "FIXME: consider merging this code with
> create_simplify() in dir.c" somewhere. It's for me to look for things
> to do when I'm bored ;-)

Heh, thanks, will do.

>> +       }
>> +
>> +       if (!need_root)
>> +               parse_pathspec(&adjusted_pathspec, PATHSPEC_ALL_MAGIC, PATHSPEC_PREFER_CWD, NULL, paths);
>
> I would go with PATHSPEC_PREFER_FULL instead of _CWD as it's safer.
> Looking only at this function without caller context, it's hard to say
> if _CWD is the right choice.

Ok, thanks, will change.

>> +
>> +       de = root_directory;
>> +       last_de = de;
>
> This statement is redundant. last_de is only used in one code block
> below and it's always re-initialized before entering the loop to skip
> subdirs.

Right, good catch!  Will remove it.

>> +       while (de) {
>> +               if (need_root ||
>> +                   match_pathspec_depth(&adjusted_pathspec, de->pathname, de->de_pathlen, 0, NULL)) {
>> +                       if (read_entries(istate, de, entry_offset,
>> +                                        mmap, mmap_size, &nr,
>> +                                        foffsetblock) < 0)
>> +                               return -1;
>> +               } else {
>> +                       last_de = de;
>> +                       for (i = 0; i < de->de_nsubtrees; i++) {
>> +                               de->sub[i]->next = last_de->next;
>> +                               last_de->next = de->sub[i];
>> +                               last_de = last_de->next;
>> +                       }
>> +               }
>> +               de = de->next;
>> +       }
>> +       free_directory_tree(root_directory);
>> +       istate->cache_nr = nr;
>> +       return 0;
>> +}
> -- 
> Duy