Fri Jun 19 12:10:53 2009

Asterisk developer's documentation


stringfields.h File Reference

String fields in structures. More...

#include "asterisk/inline_api.h"

Go to the source code of this file.

Data Structures

struct  ast_string_field_mgr
struct  ast_string_field_pool

Defines

#define AST_DECLARE_STRING_FIELDS(field_list)
 Declare the fields needed in a structure.
#define AST_STRING_FIELD(name)   const ast_string_field name
 Declare a string field.
#define ast_string_field_build(x, field, fmt, args...)   __ast_string_field_ptr_build(&(x)->__field_mgr, &(x)->__field_mgr_pool, (ast_string_field *) &(x)->field, fmt, args)
 Set a field to a complex (built) value.
#define ast_string_field_build_va(x, field, fmt, args1, args2)   __ast_string_field_ptr_build_va(&(x)->__field_mgr, &(x)->__field_mgr_pool, (ast_string_field *) &(x)->field, fmt, args1, args2)
 Set a field to a complex (built) value.
#define ast_string_field_free_memory(x)   __ast_string_field_init(&(x)->__field_mgr, &(x)->__field_mgr_pool, -1)
 free all memory - to be called before destroying the object
#define ast_string_field_init(x, size)   __ast_string_field_init(&(x)->__field_mgr, &(x)->__field_mgr_pool, size)
 Initialize a field pool and fields.
#define ast_string_field_ptr_build(x, ptr, fmt, args...)   __ast_string_field_ptr_build(&(x)->__field_mgr, &(x)->__field_mgr_pool, (ast_string_field *) ptr, fmt, args)
 Set a field to a complex (built) value.
#define ast_string_field_ptr_build_va(x, ptr, fmt, args1, args2)   __ast_string_field_ptr_build_va(&(x)->__field_mgr, &(x)->__field_mgr_pool, (ast_string_field *) ptr, fmt, args1, args2)
 Set a field to a complex (built) value with prebuilt va_lists.
#define ast_string_field_ptr_set(x, ptr, data)
 Set a field to a simple string value.
#define ast_string_field_set(x, field, data)
 Set a field to a simple string value.

Typedefs

typedef const char * ast_string_field

Functions

ast_string_field __ast_string_field_alloc_space (struct ast_string_field_mgr *mgr, struct ast_string_field_pool **pool_head, size_t needed)
int __ast_string_field_init (struct ast_string_field_mgr *mgr, struct ast_string_field_pool **pool_head, int needed)
void __ast_string_field_ptr_build (struct ast_string_field_mgr *mgr, struct ast_string_field_pool **pool_head, ast_string_field *ptr, const char *format,...)
void __ast_string_field_ptr_build_va (struct ast_string_field_mgr *mgr, struct ast_string_field_pool **pool_head, ast_string_field *ptr, const char *format, va_list a1, va_list a2)
int __ast_string_field_ptr_grow (struct ast_string_field_mgr *mgr, size_t needed, const ast_string_field *ptr)

Variables

const char __ast_string_field_empty []


Detailed Description

String fields in structures.

This file contains objects and macros used to manage string fields in structures without requiring them to be allocated as fixed-size buffers or requiring individual allocations for for each field.

Using this functionality is quite simple. An example structure with three fields is defined like this:

  struct sample_fields {
     int x1;
     AST_DECLARE_STRING_FIELDS(
        AST_STRING_FIELD(foo);
        AST_STRING_FIELD(bar);
        AST_STRING_FIELD(blah);
     );
     long x2;
  };

When an instance of this structure is allocated (either statically or dynamically), the fields and the pool of storage for them must be initialized:

  struct sample_fields *x;
  
  x = ast_calloc(1, sizeof(*x));
  if (x == NULL || ast_string_field_init(x, 252)) {
   if (x)
      ast_free(x);
   x = NULL;
   ... handle error
  }

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 never contain NULL (this feature is not used in this code, but comes from external requirements).

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).

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_va() is the varargs version of the above (for portability reasons it uses two vararg); variants of these function allow passing a pointer to the field as an argument.

  ast_string_field_set(x, foo, "infinite loop");
  ast_string_field_set(x, foo, NULL); // set to an empty string
  ast_string_field_ptr_set(x, &x->bar, "right way");

  ast_string_field_build(x, blah, "%d %s", zipcode, city);
  ast_string_field_ptr_build(x, &x->blah, "%d %s", zipcode, city);

  ast_string_field_build_va(x, bar, fmt, args1, args2)
  ast_string_field_ptr_build_va(x, &x->bar, fmt, args1, args2)

When the structure instance is no longer needed, the fields and their storage pool must be freed:

  ast_string_field_free_memory(x);
  ast_free(x);

This completes the API description.

Definition in file stringfields.h.


Define Documentation

#define AST_DECLARE_STRING_FIELDS ( field_list   ) 

Value:

struct ast_string_field_pool *__field_mgr_pool; \
   field_list              \
   struct ast_string_field_mgr __field_mgr
Declare the fields needed in a structure.

Parameters:
field_list The list of fields to declare, using AST_STRING_FIELD() for each one. Internally, string fields are stored as a pointer to the head of the pool, followed by individual string fields, and then a struct ast_string_field_mgr which describes the space allocated. We split the two variables so they can be used as markers around the field_list, and this allows us to determine how many entries are in the field, and play with them. In particular, for writing to the fields, we rely on __field_mgr_pool to be a non-const pointer, so we know it has the same size as ast_string_field, and we can use it to locate the fields.

Definition at line 222 of file stringfields.h.

#define AST_STRING_FIELD ( name   )     const ast_string_field name

Declare a string field.

Parameters:
name The field name

Definition at line 207 of file stringfields.h.

#define ast_string_field_build ( x,
field,
fmt,
args...   )     __ast_string_field_ptr_build(&(x)->__field_mgr, &(x)->__field_mgr_pool, (ast_string_field *) &(x)->field, fmt, args)

Set a field to a complex (built) value.

Parameters:
x Pointer to a structure containing fields
field Name of the field to set
fmt printf-style format string
args Arguments for format string
Returns:
nothing

Definition at line 300 of file stringfields.h.

Referenced by ast_channel_alloc(), build_callid_pvt(), build_callid_registry(), build_contact(), build_rpid(), build_user(), check_auth(), create_addr_from_peer(), handle_request_subscribe(), handle_response(), mgcp_new(), parse_moved_contact(), parse_register_contact(), pri_fixup_principle(), sip_sendhtml(), sip_sipredirect(), transmit_fake_auth_response(), and unistim_new().

#define ast_string_field_build_va ( x,
field,
fmt,
args1,
args2   )     __ast_string_field_ptr_build_va(&(x)->__field_mgr, &(x)->__field_mgr_pool, (ast_string_field *) &(x)->field, fmt, args1, args2)

Set a field to a complex (built) value.

Parameters:
x Pointer to a structure containing fields
field Name of the field to set
fmt printf-style format string
args1 argument one
args2 argument two
Returns:
nothing

Definition at line 324 of file stringfields.h.

Referenced by ast_channel_alloc().

#define ast_string_field_free_memory (  )     __ast_string_field_init(&(x)->__field_mgr, &(x)->__field_mgr_pool, -1)

free all memory - to be called before destroying the object

Definition at line 240 of file stringfields.h.

Referenced by __sip_destroy(), ast_channel_alloc(), ast_channel_free(), ast_unregister_groups(), build_user(), delete_extension(), delete_file(), destroy_jack_data(), destroy_mailbox_mapping(), destroy_queue(), destroy_station(), destroy_trunk(), exception_store_free(), load_module(), peer_destructor(), profile_destructor(), pvt_destructor(), route_destructor(), sip_registry_destroy(), tds_unload_module(), temp_pvt_cleanup(), and user_destructor().

#define ast_string_field_init ( x,
size   )     __ast_string_field_init(&(x)->__field_mgr, &(x)->__field_mgr_pool, size)

Initialize a field pool and fields.

Parameters:
x Pointer to a structure containing fields
size Amount of storage to allocate. Use 0 to reset fields to the default value, and release all but the most recent pool. size<0 (used internally) means free all pools.
Returns:
0 on success, non-zero on failure

Definition at line 236 of file stringfields.h.

Referenced by alloc_queue(), append_mailbox_mapping(), ast_channel_alloc(), build_extension(), build_peer(), build_profile(), build_route(), build_user(), init_pvt(), jack_data_alloc(), load_module(), new_iax(), pbx_builtin_raise_exception(), register_group(), register_group_feature(), sip_alloc(), sip_register(), sla_build_station(), sla_build_trunk(), tds_load_module(), temp_pvt_init(), and transmit_response_using_temp().

#define ast_string_field_ptr_build ( x,
ptr,
fmt,
args...   )     __ast_string_field_ptr_build(&(x)->__field_mgr, &(x)->__field_mgr_pool, (ast_string_field *) ptr, fmt, args)

Set a field to a complex (built) value.

Parameters:
x Pointer to a structure containing fields
ptr Pointer to a field within the structure
fmt printf-style format string
args Arguments for format string
Returns:
nothing

Definition at line 289 of file stringfields.h.

#define ast_string_field_ptr_build_va ( x,
ptr,
fmt,
args1,
args2   )     __ast_string_field_ptr_build_va(&(x)->__field_mgr, &(x)->__field_mgr_pool, (ast_string_field *) ptr, fmt, args1, args2)

Set a field to a complex (built) value with prebuilt va_lists.

Parameters:
x Pointer to a structure containing fields
ptr Pointer to a field within the structure
fmt printf-style format string
args1 Arguments for format string in va_list format
args2 a second copy of the va_list for the sake of bsd, with no va_list copy operation
Returns:
nothing

Definition at line 312 of file stringfields.h.

#define ast_string_field_ptr_set ( x,
ptr,
data   ) 

Set a field to a simple string value.

Parameters:
x Pointer to a structure containing fields
ptr Pointer to a field within the structure
data String value to be copied into the field
Returns:
nothing

Definition at line 254 of file stringfields.h.

Referenced by reply_digest().

#define ast_string_field_set ( x,
field,
data   ) 

Value:

do {     \
   ast_string_field_ptr_set(x, &(x)->field, data);    \
   } while (0)
Set a field to a simple string value.

Parameters:
x Pointer to a structure containing fields
field Name of the field to set
data String value to be copied into the field
Returns:
nothing

Definition at line 277 of file stringfields.h.

Referenced by __find_callno(), __oh323_new(), acf_channel_write(), agent_new(), alloc_queue(), alsa_new(), append_mailbox_mapping(), ast_cdr_setaccount(), ast_change_name(), ast_channel_alloc(), ast_do_masquerade(), ast_feature_request_and_dial(), ast_iax2_new(), authenticate_reply(), authenticate_request(), authenticate_verify(), begin_dial_channel(), build_extension(), build_peer(), build_profile(), build_route(), build_rpid(), build_user(), cache_get_callno_locked(), check_access(), check_peer_ok(), check_user_full(), conf_start_moh(), console_new(), create_addr(), create_addr_from_peer(), dahdi_new(), dial_exec_full(), do_forward(), extract_uri(), get_also_info(), get_destination(), get_rdnis(), gtalk_new(), handle_incoming(), handle_options(), handle_request_bye(), handle_request_invite(), handle_request_options(), handle_request_refer(), handle_response(), handle_response_invite(), handle_response_notify(), iax2_call(), iax2_request(), init_pvt(), init_queue(), initreqprep(), jingle_new(), load_module(), local_call(), mgcp_new(), monitor_dial(), nbs_new(), new_iax(), oss_new(), parse_moved_contact(), parse_ok_contact(), parse_register_contact(), pbx_builtin_raise_exception(), phone_new(), queue_set_param(), read_config(), register_group(), register_group_feature(), register_verify(), registry_authrequest(), replace_cid(), reply_digest(), reqprep(), respprep(), ring_entry(), save_osptoken(), set_moh_exec(), set_pvt_defaults(), sip_alloc(), sip_call(), sip_new(), sip_poke_peer(), sip_register(), sip_request_call(), sip_set_redirstr(), skinny_new(), sla_build_station(), sla_build_trunk(), socket_process(), store_callerid(), tds_load_module(), transmit_refer(), transmit_register(), transmit_response_using_temp(), unistim_new(), usbradio_new(), vm_execmain(), and wait_for_answer().


Typedef Documentation

typedef const char* ast_string_field

Definition at line 114 of file stringfields.h.


Function Documentation

ast_string_field __ast_string_field_alloc_space ( struct ast_string_field_mgr mgr,
struct ast_string_field_pool **  pool_head,
size_t  needed 
)

Definition at line 1543 of file utils.c.

References add_string_pool(), ast_string_field_mgr::last_alloc, ast_string_field_mgr::size, and ast_string_field_mgr::used.

01545 {
01546    char *result = NULL;
01547    size_t space = mgr->size - mgr->used;
01548 
01549    if (__builtin_expect(needed > space, 0)) {
01550       size_t new_size = mgr->size * 2;
01551 
01552       while (new_size < needed)
01553          new_size *= 2;
01554 
01555       if (add_string_pool(mgr, pool_head, new_size))
01556          return NULL;
01557    }
01558 
01559    result = (*pool_head)->base + mgr->used;
01560    mgr->used += needed;
01561    mgr->last_alloc = result;
01562    return result;
01563 }

int __ast_string_field_init ( struct ast_string_field_mgr mgr,
struct ast_string_field_pool **  pool_head,
int  needed 
)

Definition at line 1506 of file utils.c.

References add_string_pool(), ast_free, ast_log(), ast_string_field_mgr::last_alloc, LOG_WARNING, ast_string_field_pool::prev, and ast_string_field_mgr::used.

01509 {
01510    const char **p = (const char **) pool_head + 1;
01511    struct ast_string_field_pool *cur = *pool_head;
01512 
01513    /* clear fields - this is always necessary */
01514    while ((struct ast_string_field_mgr *) p != mgr)
01515       *p++ = __ast_string_field_empty;
01516    mgr->last_alloc = NULL;
01517    if (size > 0) {         /* allocate the initial pool */
01518       *pool_head = NULL;
01519       return add_string_pool(mgr, pool_head, size);
01520    }
01521    if (size < 0) {         /* reset all pools */
01522       *pool_head = NULL;
01523    } else {       /* preserve the first pool */
01524       if (cur == NULL) {
01525          ast_log(LOG_WARNING, "trying to reset empty pool\n");
01526          return -1;
01527       }
01528       cur = cur->prev;
01529       (*pool_head)->prev = NULL;
01530       mgr->used = 0;
01531    }
01532 
01533    while (cur) {
01534       struct ast_string_field_pool *prev = cur->prev;
01535 
01536       ast_free(cur);
01537       cur = prev;
01538    }
01539 
01540    return 0;
01541 }

void __ast_string_field_ptr_build ( struct ast_string_field_mgr mgr,
struct ast_string_field_pool **  pool_head,
ast_string_field ptr,
const char *  format,
  ... 
)

Definition at line 1639 of file utils.c.

References __ast_string_field_ptr_build_va().

01642 {
01643    va_list ap1, ap2;
01644 
01645    va_start(ap1, format);
01646    va_start(ap2, format);     /* va_copy does not exist on FreeBSD */
01647 
01648    __ast_string_field_ptr_build_va(mgr, pool_head, ptr, format, ap1, ap2);
01649 
01650    va_end(ap1);
01651    va_end(ap2);
01652 }

void __ast_string_field_ptr_build_va ( struct ast_string_field_mgr mgr,
struct ast_string_field_pool **  pool_head,
ast_string_field ptr,
const char *  format,
va_list  a1,
va_list  a2 
)

Definition at line 1588 of file utils.c.

References add_string_pool(), available(), ast_string_field_mgr::last_alloc, ast_string_field_mgr::size, and ast_string_field_mgr::used.

Referenced by __ast_string_field_ptr_build().

01591 {
01592    size_t needed;
01593    size_t available;
01594    size_t space = mgr->size - mgr->used;
01595    char *target;
01596 
01597    /* if the field already has space allocated, try to reuse it;
01598       otherwise, use the empty space at the end of the current
01599       pool
01600    */
01601    if ((*ptr)[0] != '\0') {
01602       target = (char *) *ptr;
01603       available = strlen(target) + 1;
01604    } else {
01605       target = (*pool_head)->base + mgr->used;
01606       available = space;
01607    }
01608 
01609    needed = vsnprintf(target, available, format, ap1) + 1;
01610 
01611    va_end(ap1);
01612 
01613    if (needed > available) {
01614       /* if the space needed can be satisfied by using the current
01615          pool (which could only occur if we tried to use the field's
01616          allocated space and failed), then use that space; otherwise
01617          allocate a new pool
01618       */
01619       if (needed > space) {
01620          size_t new_size = mgr->size * 2;
01621 
01622          while (new_size < needed)
01623             new_size *= 2;
01624          
01625          if (add_string_pool(mgr, pool_head, new_size))
01626             return;
01627       }
01628 
01629       target = (*pool_head)->base + mgr->used;
01630       vsprintf(target, format, ap2);
01631    }
01632 
01633    if (*ptr != target) {
01634       mgr->last_alloc = *ptr = target;
01635       mgr->used += needed;
01636    }
01637 }

int __ast_string_field_ptr_grow ( struct ast_string_field_mgr mgr,
size_t  needed,
const ast_string_field ptr 
)

Definition at line 1565 of file utils.c.

References ast_string_field_mgr::last_alloc, ast_string_field_mgr::size, and ast_string_field_mgr::used.

01567 {
01568    int grow = needed - (strlen(*ptr) + 1);
01569    size_t space = mgr->size - mgr->used;
01570 
01571    if (grow <= 0) {
01572       return 0;
01573    }
01574 
01575    if (*ptr != mgr->last_alloc) {
01576       return 1;
01577    }
01578 
01579    if (space < grow) {
01580       return 1;
01581    }
01582 
01583    mgr->used += grow;
01584 
01585    return 0;
01586 }


Variable Documentation

const char __ast_string_field_empty[]

the empty string

Definition at line 1472 of file utils.c.


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