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31faeb2088
Previously, the memory management of the object_array_entry::name
field was inconsistent and undocumented. object_array_entries are
ultimately created by a single function, add_object_array_with_mode(),
which has an argument "const char *name". This function used to
simply set the name field to reference the string pointed to by the
name parameter, and nobody on the object_array side ever freed the
memory. Thus, it assumed that the memory for the name field would be
managed by the caller, and that the lifetime of that string would be
at least as long as the lifetime of the object_array_entry. But
callers were inconsistent:
* Some passed pointers to constant strings or argv entries, which was
OK.
* Some passed pointers to newly-allocated memory, but didn't arrange
for the memory ever to be freed.
* Some passed the return value of sha1_to_hex(), which is a pointer to
a statically-allocated buffer that can be overwritten at any time.
* Some passed pointers to refnames that they received from a
for_each_ref()-type iteration, but the lifetimes of such refnames is
not guaranteed by the refs API.
Bring consistency to this mess by changing object_array to make its
own copy for the object_array_entry::name field and free this memory
when an object_array_entry is deleted from the array.
Many callers were passing the empty string as the name parameter, so
as a performance optimization, treat the empty string specially.
Instead of making a copy, store a pointer to a statically-allocated
empty string to object_array_entry::name. When deleting such an
entry, skip the free().
Change the callers that were already passing copies to
add_object_array_with_mode() to either skip the copy, or (if the
memory needed to be allocated anyway) freeing the memory itself.
A part of this commit effectively reverts
70d26c6e76 read_revisions_from_stdin: make copies for handle_revision_arg
because the copying introduced by that commit (which is still
necessary) is now done at a deeper level.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
114 lines
3.5 KiB
C
114 lines
3.5 KiB
C
#ifndef OBJECT_H
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#define OBJECT_H
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struct object_list {
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struct object *item;
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struct object_list *next;
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};
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struct object_array {
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unsigned int nr;
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unsigned int alloc;
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struct object_array_entry {
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struct object *item;
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/*
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* name or NULL. If non-NULL, the memory pointed to
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* is owned by this object *except* if it points at
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* object_array_slopbuf, which is a static copy of the
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* empty string.
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*/
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char *name;
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unsigned mode;
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} *objects;
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};
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#define OBJECT_ARRAY_INIT { 0, 0, NULL }
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#define TYPE_BITS 3
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#define FLAG_BITS 27
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/*
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* The object type is stored in 3 bits.
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*/
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struct object {
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unsigned parsed : 1;
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unsigned used : 1;
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unsigned type : TYPE_BITS;
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unsigned flags : FLAG_BITS;
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unsigned char sha1[20];
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};
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extern const char *typename(unsigned int type);
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extern int type_from_string(const char *str);
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extern unsigned int get_max_object_index(void);
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extern struct object *get_indexed_object(unsigned int);
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/*
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* This can be used to see if we have heard of the object before, but
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* it can return "yes we have, and here is a half-initialised object"
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* for an object that we haven't loaded/parsed yet.
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*
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* When parsing a commit to create an in-core commit object, its
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* parents list holds commit objects that represent its parents, but
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* they are expected to be lazily initialized and do not know what
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* their trees or parents are yet. When this function returns such a
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* half-initialised objects, the caller is expected to initialize them
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* by calling parse_object() on them.
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*/
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struct object *lookup_object(const unsigned char *sha1);
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extern void *create_object(const unsigned char *sha1, int type, void *obj);
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/*
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* Returns the object, having parsed it to find out what it is.
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*
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* Returns NULL if the object is missing or corrupt.
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*/
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struct object *parse_object(const unsigned char *sha1);
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/*
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* Like parse_object, but will die() instead of returning NULL. If the
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* "name" parameter is not NULL, it is included in the error message
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* (otherwise, the sha1 hex is given).
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*/
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struct object *parse_object_or_die(const unsigned char *sha1, const char *name);
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/* Given the result of read_sha1_file(), returns the object after
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* parsing it. eaten_p indicates if the object has a borrowed copy
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* of buffer and the caller should not free() it.
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*/
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struct object *parse_object_buffer(const unsigned char *sha1, enum object_type type, unsigned long size, void *buffer, int *eaten_p);
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/** Returns the object, with potentially excess memory allocated. **/
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struct object *lookup_unknown_object(const unsigned char *sha1);
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struct object_list *object_list_insert(struct object *item,
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struct object_list **list_p);
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int object_list_contains(struct object_list *list, struct object *obj);
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/* Object array handling .. */
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void add_object_array(struct object *obj, const char *name, struct object_array *array);
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void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode);
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typedef int (*object_array_each_func_t)(struct object_array_entry *, void *);
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/*
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* Apply want to each entry in array, retaining only the entries for
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* which the function returns true. Preserve the order of the entries
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* that are retained.
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*/
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void object_array_filter(struct object_array *array,
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object_array_each_func_t want, void *cb_data);
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/*
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* Remove from array all but the first entry with a given name.
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* Warning: this function uses an O(N^2) algorithm.
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*/
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void object_array_remove_duplicates(struct object_array *array);
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void clear_object_flags(unsigned flags);
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#endif /* OBJECT_H */
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