mvect.c

[詳解]

/*++
/* NAME
/*  mvect 3
/* SUMMARY
/*  memory vector management
/* SYNOPSIS
/*  #include <mvect.h>
/*
/*  char    *mvect_alloc(vector, elsize, nelm, init_fn, wipe_fn)
/*  MVECT   *vector;
/*  ssize_t elsize;
/*  ssize_t nelm;
/*  void    (*init_fn)(char *ptr, ssize_t count);
/*  void    (*wipe_fn)(char *ptr, ssize_t count);
/*
/*  char    *mvect_realloc(vector, nelm)
/*  MVECT   *vector;
/*  ssize_t nelm;
/*
/*  char    *mvect_free(vector)
/*  MVECT   *vector;
/* DESCRIPTION
/*  This module supports memory management for arrays of arbitrary
/*  objects.  It is up to the application to provide specific code
/*  that initializes and uses object memory.
/*
/*  mvect_alloc() initializes memory for a vector with elements
/*  of \fIelsize\fR bytes, and with at least \fInelm\fR elements.
/*  \fIinit_fn\fR is a null pointer, or a pointer to a function
/*  that initializes \fIcount\fR vector elements.
/*  \fIwipe_fn\fR is a null pointer, or a pointer to a function
/*  that is complementary to \fIinit_fn\fR. This routine is called
/*  by mvect_free(). The result of mvect_alloc() is a pointer to
/*  the allocated vector.
/*
/*  mvect_realloc() guarantees that the specified vector has space
/*  for at least \fInelm\fR elements. The result is a pointer to the
/*  allocated vector, which may change across calls.
/*
/*  mvect_free() releases storage for the named vector. The result
/*  is a convenient null pointer.
/* SEE ALSO
/*  mymalloc(3) memory management
/* DIAGNOSTICS
/*  Problems are reported via the msg(3) diagnostics routines:
/*  the requested amount of memory is not available; improper use
/*  is detected; other fatal errors.
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*
/*  Wietse Venema
/*  Google, Inc.
/*  111 8th Avenue
/*  New York, NY 10011, USA
/*--*/

/* System library. */

#include <sys_defs.h>

/* Utility library. */

#include "mymalloc.h"
#include "mvect.h"

/* mvect_alloc - allocate memory vector */

char   *mvect_alloc(MVECT *vect, ssize_t elsize, ssize_t nelm,
               void (*init_fn) (char *, ssize_t), void (*wipe_fn) (char *, ssize_t))
{
    vect->init_fn = init_fn;
    vect->wipe_fn = wipe_fn;
    vect->nelm = 0;
    vect->ptr = mymalloc(elsize * nelm);
    vect->nelm = nelm;
    vect->elsize = elsize;
    if (vect->init_fn)
    vect->init_fn(vect->ptr, vect->nelm);
    return (vect->ptr);
}

/* mvect_realloc - adjust memory vector allocation */

char   *mvect_realloc(MVECT *vect, ssize_t nelm)
{
    ssize_t old_len = vect->nelm;
    ssize_t incr = nelm - old_len;
    ssize_t new_nelm;

    if (incr > 0) {
    if (incr < old_len)
        incr = old_len;
    new_nelm = vect->nelm + incr;
    vect->ptr = myrealloc(vect->ptr, vect->elsize * new_nelm);
    vect->nelm = new_nelm;
    if (vect->init_fn)
        vect->init_fn(vect->ptr + old_len * vect->elsize, incr);
    }
    return (vect->ptr);
}

/* mvect_free - release memory vector storage */

char   *mvect_free(MVECT *vect)
{
    if (vect->wipe_fn)
    vect->wipe_fn(vect->ptr, vect->nelm);
    myfree(vect->ptr);
    return (0);
}