NetBSD/gnu/libexec/uucp/libuucp/buffer.c

110 lines
2.3 KiB
C

/* buffer.c
Manipulate buffers used to hold strings.
Copyright (C) 1992 Ian Lance Taylor
This file is part of Taylor UUCP.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License
as published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
The author of the program may be contacted at ian@airs.com or
c/o Infinity Development Systems, P.O. Box 520, Waltham, MA 02254.
*/
#include "uucp.h"
#include "uudefs.h"
/* We keep a linked list of buffers. The union is a hack because the
default definition of offsetof, in uucp.h, takes the address of the
field, and some C compilers will not let you take the address of an
array. */
struct sbuf
{
struct sbuf *qnext;
size_t c;
union
{
char ab[4];
char bdummy;
}
u;
};
static struct sbuf *qBlist;
/* Get a buffer of a given size. The buffer is returned with the
ubuffree function. */
char *
zbufalc (c)
size_t c;
{
register struct sbuf *q;
if (qBlist == NULL)
{
q = (struct sbuf *) xmalloc (sizeof (struct sbuf) + c - 4);
q->c = c;
}
else
{
q = qBlist;
qBlist = q->qnext;
if (q->c < c)
{
q = (struct sbuf *) xrealloc ((pointer) q,
sizeof (struct sbuf) + c - 4);
q->c = c;
}
}
return q->u.ab;
}
/* Get a buffer holding a given string. */
char *
zbufcpy (z)
const char *z;
{
size_t csize;
char *zret;
if (z == NULL)
return NULL;
csize = strlen (z) + 1;
zret = zbufalc (csize);
memcpy (zret, z, csize);
return zret;
}
/* Free up a buffer back onto the linked list. */
void
ubuffree (z)
char *z;
{
size_t ioff;
struct sbuf *q;
if (z == NULL)
return;
ioff = offsetof (struct sbuf, u);
q = (struct sbuf *) (pointer) (z - ioff);
q->qnext = qBlist;
qBlist = q;
}