diff options
Diffstat (limited to 'include/asterisk/stringfields.h')
| -rw-r--r-- | include/asterisk/stringfields.h | 89 |
1 files changed, 58 insertions, 31 deletions
diff --git a/include/asterisk/stringfields.h b/include/asterisk/stringfields.h index 9c48bfda2..2b9b7b230 100644 --- a/include/asterisk/stringfields.h +++ b/include/asterisk/stringfields.h @@ -57,25 +57,23 @@ Fields will default to pointing to an empty string, and will revert to that when ast_string_field_set() is called with a NULL argument. - A string field will \b never contain NULL (this feature is not used - in this code, but comes from external requirements). + A string field will \b never contain NULL. ast_string_field_init(x, 0) will reset fields to the initial value while keeping the pool allocated. Reading the fields is much like using 'const char * const' fields in the - structure: you cannot write to the field or to the memory it points to - (XXX perhaps the latter is too much of a restriction since values - are not shared). + structure: you cannot write to the field or to the memory it points to. Writing to the fields must be done using the wrapper macros listed below; and assignments are always by value (i.e. strings are copied): * ast_string_field_set() stores a simple value; - * ast_string_field_build() builds the string using a printf-style; + * ast_string_field_build() builds the string using a printf-style format; * ast_string_field_build_va() is the varargs version of the above (for - portability reasons it uses two vararg); + portability reasons it uses two vararg arguments); * variants of these function allow passing a pointer to the field as an argument. + \code ast_string_field_set(x, foo, "infinite loop"); ast_string_field_set(x, foo, NULL); // set to an empty string @@ -110,6 +108,9 @@ Don't declare instances of this type directly; use the AST_STRING_FIELD() macro instead. + + In addition to the string itself, the amount of space allocated for the + field is stored in the two bytes immediately preceding it. */ typedef const char * ast_string_field; @@ -117,7 +118,7 @@ typedef const char * ast_string_field; \internal \brief A constant empty string used for fields that have no other value */ -extern const char __ast_string_field_empty[]; +extern const char *__ast_string_field_empty; /*! \internal @@ -125,18 +126,17 @@ extern const char __ast_string_field_empty[]; */ struct ast_string_field_pool { struct ast_string_field_pool *prev; /*!< pointer to the previous pool, if any */ + size_t size; /*!< the total size of the pool */ + size_t used; /*!< the space used in the pool */ + size_t active; /*!< the amount of space actively in use by fields */ char base[0]; /*!< storage space for the fields */ }; /*! \internal \brief Structure used to manage the storage for a set of string fields. - Because of the way pools are managed, we can only allocate from the topmost - pool, so the numbers here reflect just that. */ struct ast_string_field_mgr { - size_t size; /*!< the total size of the current pool */ - size_t used; /*!< the space used in the current pool */ ast_string_field last_alloc; /*!< the last field allocated */ }; @@ -154,7 +154,8 @@ struct ast_string_field_mgr { the pool has enough space available. If so, the additional space will be allocated to this field and the field's address will not be changed. */ -int __ast_string_field_ptr_grow(struct ast_string_field_mgr *mgr, size_t needed, +int __ast_string_field_ptr_grow(struct ast_string_field_mgr *mgr, + struct ast_string_field_pool **pool_head, size_t needed, const ast_string_field *ptr); /*! @@ -176,7 +177,7 @@ ast_string_field __ast_string_field_alloc_space(struct ast_string_field_mgr *mgr \internal \brief Set a field to a complex (built) value \param mgr Pointer to the pool manager structure - \param fields Pointer to the first entry of the field array + \param pool_head Pointer to the current pool \param ptr Pointer to a field within the structure \param format printf-style format string \return nothing @@ -189,7 +190,7 @@ void __ast_string_field_ptr_build(struct ast_string_field_mgr *mgr, \internal \brief Set a field to a complex (built) value \param mgr Pointer to the pool manager structure - \param fields Pointer to the first entry of the field array + \param pool_head Pointer to the current pool \param ptr Pointer to a field within the structure \param format printf-style format string \param args va_list of the args for the format_string @@ -242,29 +243,55 @@ void __ast_string_field_ptr_build_va(struct ast_string_field_mgr *mgr, /*! \internal \brief internal version of ast_string_field_init */ int __ast_string_field_init(struct ast_string_field_mgr *mgr, - struct ast_string_field_pool **pool_head, int needed); + struct ast_string_field_pool **pool_head, int needed); + +/*! + \internal + \brief Release a field's allocation from a pool + \param pool_head Pointer to the current pool + \param ptr Field to be released + \return nothing + + This function will search the pool list to find the pool that contains + the allocation for the specified field, then remove the field's allocation + from that pool's 'active' count. If the pool's active count reaches zero, + and it is not the current pool, then it will be freed. + */ +void __ast_string_field_release_active(struct ast_string_field_pool *pool_head, + const ast_string_field ptr); + +/* the type of storage used to track how many bytes were allocated for a field */ + +typedef uint16_t ast_string_field_allocation; + +/*! + \brief Macro to provide access to the allocation field that lives immediately in front of a string field + \param x Pointer to the string field +*/ +#define AST_STRING_FIELD_ALLOCATION(x) *((ast_string_field_allocation *) (x - sizeof(ast_string_field_allocation))) /*! \brief Set a field to a simple string value \param x Pointer to a structure containing fields \param ptr Pointer to a field within the structure - \param data String value to be copied into the field + \param data String value to be copied into the field \return nothing */ -#define ast_string_field_ptr_set(x, ptr, data) do { \ - const char *__d__ = (data); \ - size_t __dlen__ = (__d__) ? strlen(__d__) + 1 : 1; \ - const char **__p__ = (const char **) (ptr); \ - char *__q__; \ - if (__dlen__ == 1) \ - *__p__ = __ast_string_field_empty; \ - else if (!__ast_string_field_ptr_grow(&(x)->__field_mgr, __dlen__, ptr)) { \ - __q__ = (char *) *__p__; \ - memcpy(__q__, __d__, __dlen__); \ - } else if ((*__p__ = __ast_string_field_alloc_space(&(x)->__field_mgr, &(x)->__field_mgr_pool, __dlen__))) { \ - __q__ = (char *) *__p__; \ - memcpy(__q__, __d__, __dlen__); \ - } \ +#define ast_string_field_ptr_set(x, ptr, data) do { \ + const char *__d__ = (data); \ + size_t __dlen__ = (__d__) ? strlen(__d__) + 1 : 1; \ + ast_string_field *__p__ = (ast_string_field *) (ptr); \ + if (__dlen__ == 1) { \ + __ast_string_field_release_active((x)->__field_mgr_pool, *__p__); \ + *__p__ = __ast_string_field_empty; \ + } else if ((__dlen__ <= AST_STRING_FIELD_ALLOCATION(*__p__)) || \ + (!__ast_string_field_ptr_grow(&(x)->__field_mgr, &(x)->__field_mgr_pool, __dlen__, __p__)) || \ + (*__p__ = __ast_string_field_alloc_space(&(x)->__field_mgr, &(x)->__field_mgr_pool, __dlen__))) { \ + if (*__p__ != (*ptr)) { \ + __ast_string_field_release_active((x)->__field_mgr_pool, (*ptr)); \ + } \ + memcpy((void *) *__p__, __d__, __dlen__); \ + } \ } while (0) /*! |