1 files changed, 63 insertions, 0 deletions
diff --git a/src/lib/mmap-util.c b/src/lib/mmap-util.c
new file mode 100644
index 0000000..8754226
--- /dev/null
+++ b/src/lib/mmap-util.c
@@ -0,0 +1,63 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "mmap-util.h"
+
+#include <sys/stat.h>
+
+void *mmap_file(int fd, size_t *length, int prot)
+{
+	struct stat st;
+
+	if (fstat(fd, &st) < 0)
+		return MAP_FAILED;
+
+#if OFF_T_MAX > SSIZE_T_MAX
+	if (st.st_size > SSIZE_T_MAX) {
+		/* too large file to map into memory */
+		errno = EFBIG;
+		return MAP_FAILED;
+	}
+#endif
+
+	*length = (size_t)st.st_size;
+	if (*length == 0)
+		return NULL;
+
+	i_assert(*length > 0 && *length < SSIZE_T_MAX);
+
+	return mmap(NULL, *length, prot, MAP_SHARED, fd, 0);
+}
+
+void *mmap_ro_file(int fd, size_t *length)
+{
+	return mmap_file(fd, length, PROT_READ);
+}
+
+void *mmap_rw_file(int fd, size_t *length)
+{
+	return mmap_file(fd, length, PROT_READ | PROT_WRITE);
+}
+
+#undef madvise
+int my_madvise(void *start ATTR_UNUSED, size_t length ATTR_UNUSED,
+	       int advice ATTR_UNUSED)
+{
+#ifdef HAVE_MADVISE
+	/* Ignore ENOSYS errors, which happen if the kernel hasn't implemented
+	   the syscall even if libc has. */
+	if (madvise(start, length, advice) < 0 && errno != ENOSYS)
+		return -1;
+#endif
+	return 0;
+}
+
+size_t mmap_get_page_size(void)
+{
+	static size_t size = 0;
+
+	if (size != 0)
+		return size;
+	size = getpagesize();
+	return size;
+}