New resizable memory storage.

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@1360 ec53bebd-3082-4978-b11e-865c3cabbd6b

lib/krb5/store_emem.c

@@ -0,0 +1,82 @@
+#include "krb5_locl.h"
+
+RCSID("$Id$");
+
+typedef struct emem_storage{
+    unsigned char *base;
+    size_t size;
+    size_t len;
+    unsigned char *ptr;
+}emem_storage;
+
+static size_t
+emem_fetch(krb5_storage *sp, void *data, size_t size)
+{
+    emem_storage *s = (emem_storage*)sp->data;
+    if(s->base + s->len - s->ptr < size)
+	size = s->base + s->len - s->ptr;
+    memmove(data, s->ptr, size);
+    sp->seek(sp, size, SEEK_CUR);
+    return size;
+}
+
+static size_t
+emem_store(krb5_storage *sp, void *data, size_t size)
+{
+    emem_storage *s = (emem_storage*)sp->data;
+    size_t sz = size - (s->base + s->size - s->ptr);
+    if(sz > 0){
+	s->size = 2 * (s->size + sz);
+	s->base = realloc(s->base, s->size);
+    }
+    memmove(s->ptr, data, size);
+    sp->seek(sp, size, SEEK_CUR);
+    return size;
+}
+
+static off_t
+emem_seek(krb5_storage *sp, off_t offset, int whence)
+{
+    emem_storage *s = (emem_storage*)sp->data;
+    switch(whence){
+    case SEEK_SET:
+	if(offset > s->len)
+	    offset = s->len;
+	if(offset < 0)
+	    offset = 0;
+	s->ptr = s->base + offset;
+	break;
+    case SEEK_CUR:
+	sp->seek(sp,s->ptr - s->base + offset, SEEK_SET);
+	break;
+    case SEEK_END:
+	sp->seek(sp, s->len + offset, SEEK_SET);
+    default:
+	errno = EINVAL;
+	return -1;
+    }
+    return s->ptr - s->base;
+}
+
+static void
+emem_free(krb5_storage *sp)
+{
+    free(((emem_storage*)sp->data)->base);
+}
+
+krb5_storage *
+krb5_storage_emem(void)
+{
+    krb5_storage *sp = malloc(sizeof(krb5_storage));
+    emem_storage *s = malloc(sizeof(*s));
+    sp->data = s;
+    s->size = 1024;
+    s->base = malloc(s->size);
+    s->len = 0;
+    s->ptr = s->base;
+    sp->fetch = emem_fetch;
+    sp->store = emem_store;
+    sp->seek = emem_seek;
+    sp->free = emem_free;
+    return sp;
+}