[PATCH v3 0/3] check-attr: integrate with sparse-index

[Shuqi Liang <cheskaqiqi@gmail.com>]

change against v2:

* add SP at appropriate places

* add in-code comment around magic "adjustment"

Shuqi Liang (3):
  attr.c: read attributes in a sparse directory
  t1092: add tests for `git check-attr`
  check-attr: integrate with sparse-index

 attr.c                                   | 47 ++++++++++++--------
 builtin/check-attr.c                     |  3 ++
 t/perf/p2000-sparse-operations.sh        |  1 +
 t/t1092-sparse-checkout-compatibility.sh | 55 ++++++++++++++++++++++++
 4 files changed, 87 insertions(+), 19 deletions(-)

Range-diff against v2:
1:  0ff2ab9430 ! 1:  199cc90a5b Enable gitattributes read from sparse directories
    @@ Metadata
     Author: Shuqi Liang <cheskaqiqi@gmail.com>
     
      ## Commit message ##
    -    Enable gitattributes read from sparse directories
    +    attr.c: read attributes in a sparse directory
     
         'git check-attr' cannot currently find attributes of a file within a
         sparse directory. This is due to .gitattributes files are irrelevant in
    @@ attr.c: static struct attr_stack *read_attr_from_blob(struct index_state *istate
      	if (!istate)
      		return NULL;
      
    --	/*
    + 	/*
     -	 * The .gitattributes file only applies to files within its
     -	 * parent directory. In the case of cone-mode sparse-checkout,
     -	 * the .gitattributes file is sparse if and only if all paths
    @@ attr.c: static struct attr_stack *read_attr_from_blob(struct index_state *istate
     -	 * In the case of a sparse index, it is critical that we don't go
     -	 * looking for a .gitattributes file, as doing so would cause the
     -	 * index to expand.
    --	 */
    ++	 * If the pos value is negative, it means the path is not in the index. 
    ++	 * However, the absolute value of pos minus 1 gives us the position where the path 
    ++	 * would be inserted in lexicographic order. By subtracting another 1 from this 
    ++	 * value (pos = -pos - 2), we find the position of the last index entry 
    ++	 * which is lexicographically smaller than the provided path. This would be 
    ++	 * the sparse directory containing the path.
    + 	 */
     -	if (!path_in_cone_mode_sparse_checkout(path, istate))
     -		return NULL;
     +	pos = index_name_pos_sparse(istate, path, strlen(path));
    -+	pos = -pos-2;
    -+	if (!path_in_cone_mode_sparse_checkout(path, istate) && pos>=0) {
    -+		if (!S_ISSPARSEDIR(istate->cache[pos]->ce_mode))
    -+			return NULL;
    ++	pos = - pos - 2;
      
     -	buf = read_blob_data_from_index(istate, path, &size);
     -	if (!buf)
    @@ attr.c: static struct attr_stack *read_attr_from_blob(struct index_state *istate
     -	if (size >= ATTR_MAX_FILE_SIZE) {
     -		warning(_("ignoring overly large gitattributes blob '%s'"), path);
     -		return NULL;
    +-	}
    ++	if (!path_in_cone_mode_sparse_checkout(path, istate) && 0 <= pos) {
    ++		if (!S_ISSPARSEDIR(istate->cache[pos]->ce_mode))
    ++			return NULL;
    + 
    +-	return read_attr_from_buf(buf, path, flags);
     +		if (strncmp(istate->cache[pos]->name, path, ce_namelen(istate->cache[pos])) == 0) {
     +			const char *relative_path = path + ce_namelen(istate->cache[pos]);  
     +			stack = read_attr_from_blob(istate, &istate->cache[pos]->oid, relative_path, flags);
    @@ attr.c: static struct attr_stack *read_attr_from_blob(struct index_state *istate
     +			return NULL;
     +		}
     +		stack = read_attr_from_buf(buf, path, flags);
    - 	}
    --
    --	return read_attr_from_buf(buf, path, flags);
    ++	}
     +	return stack;
      }
      
2:  835e1176b0 = 2:  eefce85083 t1092: add tests for `git check-attr`
3:  672d692e51 = 3:  65c2624504 check-attr: integrate with sparse-index
-- 
2.39.0