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Typedefs | Functions

Typedefs

typedef struct _wmem_map_t wmem_map_t
 

Functions

WS_DLL_PUBLIC wmem_map_twmem_map_new (wmem_allocator_t *allocator, GHashFunc hash_func, GEqualFunc eql_func) G_GNUC_MALLOC
 
WS_DLL_PUBLIC wmem_map_twmem_map_new_autoreset (wmem_allocator_t *metadata_scope, wmem_allocator_t *data_scope, GHashFunc hash_func, GEqualFunc eql_func) G_GNUC_MALLOC
 
WS_DLL_PUBLIC void * wmem_map_insert (wmem_map_t *map, const void *key, void *value)
 
WS_DLL_PUBLIC bool wmem_map_contains (wmem_map_t *map, const void *key)
 
WS_DLL_PUBLIC void * wmem_map_lookup (wmem_map_t *map, const void *key)
 
WS_DLL_PUBLIC bool wmem_map_lookup_extended (wmem_map_t *map, const void *key, const void **orig_key, void **value)
 
WS_DLL_PUBLIC void * wmem_map_remove (wmem_map_t *map, const void *key)
 
WS_DLL_PUBLIC bool wmem_map_steal (wmem_map_t *map, const void *key)
 
WS_DLL_PUBLIC wmem_list_twmem_map_get_keys (wmem_allocator_t *list_allocator, wmem_map_t *map)
 
WS_DLL_PUBLIC void wmem_map_foreach (wmem_map_t *map, GHFunc foreach_func, void *user_data)
 
WS_DLL_PUBLIC unsigned wmem_map_foreach_remove (wmem_map_t *map, GHRFunc foreach_func, void *user_data)
 
WS_DLL_PUBLIC void * wmem_map_find (wmem_map_t *map, GHRFunc foreach_func, void *user_data)
 
WS_DLL_PUBLIC unsigned wmem_map_size (wmem_map_t *map)
 
WS_DLL_PUBLIC uint32_t wmem_strong_hash (const uint8_t *buf, const size_t len)
 
WS_DLL_PUBLIC unsigned wmem_str_hash (const void *key)
 
WS_DLL_PUBLIC unsigned wmem_int64_hash (const void *key)
 
WS_DLL_PUBLIC unsigned wmem_double_hash (const void *key)
 

Detailed Description

A hash map implementation on top of wmem. Provides insertion, deletion and lookup in expected amortized constant time. Uses universal hashing to map keys into buckets, and provides a generic strong hash function that makes it secure against algorithmic complexity attacks, and suitable for use even with untrusted data.

Function Documentation

◆ wmem_double_hash()

WS_DLL_PUBLIC unsigned wmem_double_hash ( const void *  key)

An implementation of GHashFunc using wmem_strong_hash. Prefer this over g_double_hash when the data comes from an untrusted source.

◆ wmem_int64_hash()

WS_DLL_PUBLIC unsigned wmem_int64_hash ( const void *  key)

An implementation of GHashFunc using wmem_strong_hash. Prefer this over g_int64_hash when the data comes from an untrusted source.

◆ wmem_map_contains()

WS_DLL_PUBLIC bool wmem_map_contains ( wmem_map_t map,
const void *  key 
)

Check if a value is in the map.

Parameters
mapThe map to search in. May be NULL.
keyThe key to lookup.
Returns
true if the key is in the map, otherwise false.

◆ wmem_map_find()

WS_DLL_PUBLIC void * wmem_map_find ( wmem_map_t map,
GHRFunc  foreach_func,
void *  user_data 
)

Run a function against all key/value pairs in the map until the function returns true, at which point the value of matching pair is returned. If no pair that matches the function is found, NULL is returned. The order of the calls is unpredictable, since it is based on the internal storage of data.

Parameters
mapThe map to use. May be NULL.
foreach_functhe function to call for each key/value pair
user_datauser data to pass to the function
Returns
The value of the first key/value pair found for which foreach_func returns TRUE. NULL if no matching pair is found.

◆ wmem_map_foreach()

WS_DLL_PUBLIC void wmem_map_foreach ( wmem_map_t map,
GHFunc  foreach_func,
void *  user_data 
)

Run a function against all key/value pairs in the map. The order of the calls is unpredictable, since it is based on the internal storage of data.

Parameters
mapThe map to use. May be NULL.
foreach_functhe function to call for each key/value pair
user_datauser data to pass to the function

◆ wmem_map_foreach_remove()

WS_DLL_PUBLIC unsigned wmem_map_foreach_remove ( wmem_map_t map,
GHRFunc  foreach_func,
void *  user_data 
)

Run a function against all key/value pairs in the map. If the function returns true, then the key/value pair is removed from the map. The order of the calls is unpredictable, since it is based on the internal storage of data.

Parameters
mapThe map to use. May be NULL.
foreach_functhe function to call for each key/value pair
user_datauser data to pass to the function
Returns
The number of items removed

◆ wmem_map_get_keys()

WS_DLL_PUBLIC wmem_list_t * wmem_map_get_keys ( wmem_allocator_t list_allocator,
wmem_map_t map 
)

Retrieves a list of keys inside the map

Parameters
list_allocatorThe allocator scope for the returned list.
mapThe map to extract keys from
Returns
list of keys in the map

◆ wmem_map_insert()

WS_DLL_PUBLIC void * wmem_map_insert ( wmem_map_t map,
const void *  key,
void *  value 
)

Inserts a value into the map.

Parameters
mapThe map to insert into. Must not be NULL.
keyThe key to insert by.
valueThe value to insert.
Returns
The previous value stored at this key if any, or NULL.

◆ wmem_map_lookup()

WS_DLL_PUBLIC void * wmem_map_lookup ( wmem_map_t map,
const void *  key 
)

Lookup a value in the map.

Parameters
mapThe map to search in. May be NULL.
keyThe key to lookup.
Returns
The value stored at the key if any, or NULL.

◆ wmem_map_lookup_extended()

WS_DLL_PUBLIC bool wmem_map_lookup_extended ( wmem_map_t map,
const void *  key,
const void **  orig_key,
void **  value 
)

Lookup a value in the map, returning the key, value, and a boolean which is true if the key is found.

Parameters
mapThe map to search in. May be NULL.
keyThe key to lookup.
orig_key(optional) The key that was determined to be a match, if any.
value(optional) The value stored at the key, if any.
Returns
true if the key is in the map, otherwise false.

◆ wmem_map_new()

WS_DLL_PUBLIC wmem_map_t * wmem_map_new ( wmem_allocator_t allocator,
GHashFunc  hash_func,
GEqualFunc  eql_func 
)

Creates a map with the given allocator scope. When the scope is emptied, the map is fully destroyed. Items stored in it will not be freed unless they were allocated from the same scope. For details on the GHashFunc and GEqualFunc parameters, see the glib documentation at: https://developer-old.gnome.org/glib/stable/glib-Hash-Tables.html

If the keys are coming from untrusted data, do not use glib's default hash functions for strings, int64s or doubles. Wmem provides stronger equivalents below. Feel free to use the g_direct_hash, g_int_hash, and any of the g_*_equal functions though, as they should be safe.

Parameters
allocatorThe allocator scope with which to create the map.
hash_funcThe hash function used to place inserted keys.
eql_funcThe equality function used to compare inserted keys.
Returns
The newly-allocated map.

◆ wmem_map_new_autoreset()

WS_DLL_PUBLIC wmem_map_t * wmem_map_new_autoreset ( wmem_allocator_t metadata_scope,
wmem_allocator_t data_scope,
GHashFunc  hash_func,
GEqualFunc  eql_func 
)

Creates a map with two allocator scopes. The base structure lives in the metadata scope, and the map data lives in the data scope. Every time free_all occurs in the data scope the map is transparently emptied without affecting the location of the base / metadata structure.

WARNING: None of the map (even the part in the metadata scope) can be used after the data scope has been destroyed.

The primary use for this function is to create maps that reset for each new capture file that is loaded. This can be done by specifying wmem_epan_scope() as the metadata scope and wmem_file_scope() as the data scope.

◆ wmem_map_remove()

WS_DLL_PUBLIC void * wmem_map_remove ( wmem_map_t map,
const void *  key 
)

Remove a value from the map. If no value is stored at that key, nothing happens.

Parameters
mapThe map to remove from. May be NULL.
keyThe key of the value to remove.
Returns
The (removed) value stored at the key if any, or NULL.

◆ wmem_map_size()

WS_DLL_PUBLIC unsigned wmem_map_size ( wmem_map_t map)

Return the number of elements of the map.

Parameters
mapThe map to use
Returns
the number of elements

◆ wmem_map_steal()

WS_DLL_PUBLIC bool wmem_map_steal ( wmem_map_t map,
const void *  key 
)

Remove a key and value from the map but does not destroy (free) them. If no value is stored at that key, nothing happens.

Parameters
mapThe map to remove from. May be NULL.
keyThe key of the value to remove.
Returns
true if key is found false if not.

◆ wmem_str_hash()

WS_DLL_PUBLIC unsigned wmem_str_hash ( const void *  key)

An implementation of GHashFunc using wmem_strong_hash. Prefer this over g_str_hash when the data comes from an untrusted source.

◆ wmem_strong_hash()

WS_DLL_PUBLIC uint32_t wmem_strong_hash ( const uint8_t *  buf,
const size_t  len 
)

Compute a strong hash value for an arbitrary sequence of bytes. Use of this hash value should be secure against algorithmic complexity attacks, even for short keys. The computation uses a random seed which is generated on wmem initialization, so the same key will hash to different values on different runs of the application.

Parameters
bufThe buffer of bytes (does not have to be aligned).
lenThe length of buf to use for the hash computation.
Returns
The hash value.