Revision 447ac906e189535e77dcb1f4bbe3f1bc917d4c12 authored by Patrick Steinhardt on 01 December 2022, 14:45:31 UTC, committed by Junio C Hamano on 05 December 2022, 06:14:16 UTC
The `struct attr_stack` tracks the stack of all patterns together with their attributes. When parsing a gitattributes file that has more than 2^31 such patterns though we may trigger multiple out-of-bounds reads on 64 bit platforms. This is because while the `num_matches` variable is an unsigned integer, we always use a signed integer to iterate over them. I have not been able to reproduce this issue due to memory constraints on my systems. But despite the out-of-bounds reads, the worst thing that can seemingly happen is to call free(3P) with a garbage pointer when calling `attr_stack_free()`. Fix this bug by using unsigned integers to iterate over the array. While this makes the iteration somewhat awkward when iterating in reverse, it is at least better than knowingly running into an out-of-bounds read. While at it, convert the call to `ALLOC_GROW` to use `ALLOC_GROW_BY` instead. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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string-list.h
#ifndef STRING_LIST_H
#define STRING_LIST_H
/**
* The string_list API offers a data structure and functions to handle
* sorted and unsorted arrays of strings. A "sorted" list is one whose
* entries are sorted by string value in the order specified by the `cmp`
* member (`strcmp()` by default).
*
* The caller:
*
* . Allocates and clears a `struct string_list` variable.
*
* . Initializes the members. You might want to set the flag `strdup_strings`
* if the strings should be strdup()ed. For example, this is necessary
* when you add something like git_path("..."), since that function returns
* a static buffer that will change with the next call to git_path().
*
* If you need something advanced, you can manually malloc() the `items`
* member (you need this if you add things later) and you should set the
* `nr` and `alloc` members in that case, too.
*
* . Adds new items to the list, using `string_list_append`,
* `string_list_append_nodup`, `string_list_insert`,
* `string_list_split`, and/or `string_list_split_in_place`.
*
* . Can check if a string is in the list using `string_list_has_string` or
* `unsorted_string_list_has_string` and get it from the list using
* `string_list_lookup` for sorted lists.
*
* . Can sort an unsorted list using `string_list_sort`.
*
* . Can remove duplicate items from a sorted list using
* `string_list_remove_duplicates`.
*
* . Can remove individual items of an unsorted list using
* `unsorted_string_list_delete_item`.
*
* . Can remove items not matching a criterion from a sorted or unsorted
* list using `filter_string_list`, or remove empty strings using
* `string_list_remove_empty_items`.
*
* . Finally it should free the list using `string_list_clear`.
*
* Example:
*
* struct string_list list = STRING_LIST_INIT_NODUP;
* int i;
*
* string_list_append(&list, "foo");
* string_list_append(&list, "bar");
* for (i = 0; i < list.nr; i++)
* printf("%s\n", list.items[i].string)
*
* NOTE: It is more efficient to build an unsorted list and sort it
* afterwards, instead of building a sorted list (`O(n log n)` instead of
* `O(n^2)`).
*
* However, if you use the list to check if a certain string was added
* already, you should not do that (using unsorted_string_list_has_string()),
* because the complexity would be quadratic again (but with a worse factor).
*/
/**
* Represents an item of the list. The `string` member is a pointer to the
* string, and you may use the `util` member for any purpose, if you want.
*/
struct string_list_item {
char *string;
void *util;
};
typedef int (*compare_strings_fn)(const char *, const char *);
/**
* Represents the list itself.
*
* . The array of items are available via the `items` member.
* . The `nr` member contains the number of items stored in the list.
* . The `alloc` member is used to avoid reallocating at every insertion.
* You should not tamper with it.
* . Setting the `strdup_strings` member to 1 will strdup() the strings
* before adding them, see above.
* . The `compare_strings_fn` member is used to specify a custom compare
* function, otherwise `strcmp()` is used as the default function.
*/
struct string_list {
struct string_list_item *items;
unsigned int nr, alloc;
unsigned int strdup_strings:1;
compare_strings_fn cmp; /* NULL uses strcmp() */
};
#define STRING_LIST_INIT_NODUP { NULL, 0, 0, 0, NULL }
#define STRING_LIST_INIT_DUP { NULL, 0, 0, 1, NULL }
/* General functions which work with both sorted and unsorted lists. */
/**
* Initialize the members of the string_list, set `strdup_strings`
* member according to the value of the second parameter.
*/
void string_list_init(struct string_list *list, int strdup_strings);
/** Callback function type for for_each_string_list */
typedef int (*string_list_each_func_t)(struct string_list_item *, void *);
/**
* Apply `want` to each item in `list`, retaining only the ones for which
* the function returns true. If `free_util` is true, call free() on
* the util members of any items that have to be deleted. Preserve
* the order of the items that are retained.
*/
void filter_string_list(struct string_list *list, int free_util,
string_list_each_func_t want, void *cb_data);
/**
* Free a string_list. The `string` pointer of the items will be freed
* in case the `strdup_strings` member of the string_list is set. The
* second parameter controls if the `util` pointer of the items should
* be freed or not.
*/
void string_list_clear(struct string_list *list, int free_util);
/**
* Callback type for `string_list_clear_func`. The string associated
* with the util pointer is passed as the second argument
*/
typedef void (*string_list_clear_func_t)(void *p, const char *str);
/** Call a custom clear function on each util pointer */
void string_list_clear_func(struct string_list *list, string_list_clear_func_t clearfunc);
/**
* Apply `func` to each item. If `func` returns nonzero, the
* iteration aborts and the return value is propagated.
*/
int for_each_string_list(struct string_list *list,
string_list_each_func_t func, void *cb_data);
/** Iterate over each item, as a macro. */
#define for_each_string_list_item(item,list) \
for (item = (list)->items; \
item && item < (list)->items + (list)->nr; \
++item)
/**
* Remove any empty strings from the list. If free_util is true, call
* free() on the util members of any items that have to be deleted.
* Preserve the order of the items that are retained.
*/
void string_list_remove_empty_items(struct string_list *list, int free_util);
/* Use these functions only on sorted lists: */
/** Determine if the string_list has a given string or not. */
int string_list_has_string(const struct string_list *list, const char *string);
int string_list_find_insert_index(const struct string_list *list, const char *string,
int negative_existing_index);
/**
* Insert a new element to the string_list. The returned pointer can
* be handy if you want to write something to the `util` pointer of
* the string_list_item containing the just added string. If the given
* string already exists the insertion will be skipped and the pointer
* to the existing item returned.
*
* Since this function uses xrealloc() (which die()s if it fails) if the
* list needs to grow, it is safe not to check the pointer. I.e. you may
* write `string_list_insert(...)->util = ...;`.
*/
struct string_list_item *string_list_insert(struct string_list *list, const char *string);
/**
* Remove the given string from the sorted list. If the string
* doesn't exist, the list is not altered.
*/
void string_list_remove(struct string_list *list, const char *string,
int free_util);
/**
* Check if the given string is part of a sorted list. If it is part of the list,
* return the corresponding string_list_item, NULL otherwise.
*/
struct string_list_item *string_list_lookup(struct string_list *list, const char *string);
/*
* Remove all but the first of consecutive entries with the same
* string value. If free_util is true, call free() on the util
* members of any items that have to be deleted.
*/
void string_list_remove_duplicates(struct string_list *sorted_list, int free_util);
/* Use these functions only on unsorted lists: */
/**
* Add string to the end of list. If list->strdup_string is set, then
* string is copied; otherwise the new string_list_entry refers to the
* input string.
*/
struct string_list_item *string_list_append(struct string_list *list, const char *string);
/**
* Like string_list_append(), except string is never copied. When
* list->strdup_strings is set, this function can be used to hand
* ownership of a malloc()ed string to list without making an extra
* copy.
*/
struct string_list_item *string_list_append_nodup(struct string_list *list, char *string);
/**
* Sort the list's entries by string value in order specified by list->cmp
* (strcmp() if list->cmp is NULL).
*/
void string_list_sort(struct string_list *list);
/**
* Like `string_list_has_string()` but for unsorted lists. Linear in
* size of the list.
*/
int unsorted_string_list_has_string(struct string_list *list, const char *string);
/**
* Like `string_list_lookup()` but for unsorted lists. Linear in size
* of the list.
*/
struct string_list_item *unsorted_string_list_lookup(struct string_list *list,
const char *string);
/**
* Remove an item from a string_list. The `string` pointer of the
* items will be freed in case the `strdup_strings` member of the
* string_list is set. The third parameter controls if the `util`
* pointer of the items should be freed or not.
*/
void unsorted_string_list_delete_item(struct string_list *list, int i, int free_util);
/**
* Split string into substrings on character `delim` and append the
* substrings to `list`. The input string is not modified.
* list->strdup_strings must be set, as new memory needs to be
* allocated to hold the substrings. If maxsplit is non-negative,
* then split at most maxsplit times. Return the number of substrings
* appended to list.
*
* Examples:
* string_list_split(l, "foo:bar:baz", ':', -1) -> ["foo", "bar", "baz"]
* string_list_split(l, "foo:bar:baz", ':', 0) -> ["foo:bar:baz"]
* string_list_split(l, "foo:bar:baz", ':', 1) -> ["foo", "bar:baz"]
* string_list_split(l, "foo:bar:", ':', -1) -> ["foo", "bar", ""]
* string_list_split(l, "", ':', -1) -> [""]
* string_list_split(l, ":", ':', -1) -> ["", ""]
*/
int string_list_split(struct string_list *list, const char *string,
int delim, int maxsplit);
/*
* Like string_list_split(), except that string is split in-place: the
* delimiter characters in string are overwritten with NULs, and the
* new string_list_items point into string (which therefore must not
* be modified or freed while the string_list is in use).
* list->strdup_strings must *not* be set.
*/
int string_list_split_in_place(struct string_list *list, char *string,
int delim, int maxsplit);
#endif /* STRING_LIST_H */
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