DragonFly On-Line Manual Pages

sf_mem(3)             DragonFly Library Functions Manual             sf_mem(3)

NAME
     sf_malloc, sf_calloc, sf_realloc, sf_strdup, strndup, strfunc_ctl -
     string duplication and safe memory allocation.

SYNOPSIS
     #include <strfunc.h>

     Safe malloc(3) analog:
     void *
     sf_malloc(size_t size);

     Safe calloc(3) analog:
     void *
     sf_calloc(size_t number, size_t size);

     Safe realloc(3) analog:
     void *
     sf_realloc(void *ptr, size_t size);

     Duplicate a specified number of characters from the string:
     char *
     strndup(const char *a, size_t num);

     Safe strdup(3) analog:
     char *
     sf_strdup(const char *a);

     int
     strfunc_ctl(int request, int *optArg);

DESCRIPTION
     Those functions are used internally by virtually all libstrfunc functions
     to manipulate memory. They are wrappers around the native library calls
     malloc(3), calloc(3), realloc(3) and provide additional flexibility in
     those cases when system is low in memory.

     strndup() used to copy the specified number of characters to a newly-
     created buffer.

     sf_strdup(), sf_malloc() and sf_realloc() are used instead of strdup(3),
     malloc(3) and realloc(3) analogs to achieve more control and safety when
     computer becomes low in memory.

     All functions are defaulted to call abort(3) upon the unsatisfied memory
     request. This default behavior can be easily changed by using
     strfunc_ctl() call with SF_SET_MEMORY_FAILURE_BEHAVIOR.

     int strfunc_ctl(int request, int *optArg) used to change default
     behaviour of the previously described functions in cases of resource
     shortage.

     The request argument can be the following constant:

             SF_GET_MEMORY_FAILURE_BEHAVIOR
             SF_SET_MEMORY_FAILURE_BEHAVIOR
             SF_GET_MEMORY_FAILURE_TRIES
             SF_SET_MEMORY_FAILURE_TRIES

     to get or set the memory allocation behaviour appropriately.  While the
     third and fourth values are used to get or specify the number of tries of
     allocating resources before falling into a failure case, the first two
     values can be used to switch the default behaviour to call abort(3) in
     case of failure.  SF_GET_MEMORY_FAILURE_BEHAVIOR returns with and
     SF_SET_MEMORY_FAILURE_BEHAVIOR accept the following values:

             SF_ARG_MFB_ABORT      /* call abort(3) on failure, the default */
             SF_ARG_MFB_ENOMEM     /* return NULL with errno set to ENOMEM */
             SF_ARG_MFB_TRY_ABORT  /* try N times before calling abort(3) */
             SF_ARG_MFB_TRY_ENOMEM /* do the same before returning an error */
             SF_ARG_MFB_TRY_NOFAIL /* loop indefinitely */

     Again, virually all functions defined in libstrfunc are aware of this
     memory control technique, so, for example, you may respect that some
     strfunc library function will not return NULL when you've earlier
     executed something like

       int memory_control_type = SF_ARG_MFB_TRY_NOFAIL;
       strfunc_ctl(SF_SET_MEMORY_FAILURE_BEHAVIOR, &memory_control_type);

SEE ALSO
     strfunc(3), malloc(3).

AUTHORS
     Lev Walkin <vlm@lionet.info>

DragonFly 6.5-DEVELOPMENT        May 15, 2001        DragonFly 6.5-DEVELOPMENT