1 files changed, 95 insertions, 0 deletions
diff --git a/src/buffer.c b/src/buffer.c
new file mode 100644
index 0000000..598db14
--- /dev/null
+++ b/src/buffer.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) Christos Zoulas 2017.
+ * All Rights Reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice immediately at the beginning of the file, without modification,
+ *    this list of conditions, and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#include "file.h"
+
+#ifndef	lint
+FILE_RCSID("@(#)$File: buffer.c,v 1.13 2023/07/02 12:48:39 christos Exp $")
+#endif	/* lint */
+
+#include "magic.h"
+#include <unistd.h>
+#include <string.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+
+void
+buffer_init(struct buffer *b, int fd, const struct stat *st, const void *data,
+    size_t len)
+{
+	b->fd = fd;
+	if (st)
+		memcpy(&b->st, st, sizeof(b->st));
+	else if (b->fd == -1 || fstat(b->fd, &b->st) == -1)
+		memset(&b->st, 0, sizeof(b->st));
+	b->fbuf = data;
+	b->flen = len;
+	b->eoff = 0;
+	b->ebuf = NULL;
+	b->elen = 0;
+}
+
+void
+buffer_fini(struct buffer *b)
+{
+	free(b->ebuf);
+	b->ebuf = NULL;
+	b->elen = 0;
+}
+
+int
+buffer_fill(const struct buffer *bb)
+{
+	struct buffer *b = CCAST(struct buffer *, bb);
+
+	if (b->elen != 0)
+		return b->elen == FILE_BADSIZE ? -1 : 0;
+
+	if (!S_ISREG(b->st.st_mode))
+		goto out;
+
+	b->elen = CAST(size_t, b->st.st_size) < b->flen ?
+	    CAST(size_t, b->st.st_size) : b->flen;
+	if (b->elen == 0) {
+		free(b->ebuf);
+		b->ebuf = NULL;
+		return 0;
+	}
+	if ((b->ebuf = malloc(b->elen)) == NULL)
+		goto out;
+
+	b->eoff = b->st.st_size - b->elen;
+	if (pread(b->fd, b->ebuf, b->elen, b->eoff) == -1) {
+		free(b->ebuf);
+		b->ebuf = NULL;
+		goto out;
+	}
+
+	return 0;
+out:
+	b->elen = FILE_BADSIZE;
+	return -1;
+}