win32: Add routines to abstract memory-mapped file functions

In particular, the git__mmap() and git__munmap() routines provide
the interface to platform specific memory-mapped file facilities.
We provide implementations for unix and win32, which can be found
in their own sub-directories.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/src/unix/map.c b/src/unix/map.c
new file mode 100644
index 000000000..a41bae0b8
--- /dev/null
+++ b/src/unix/map.c
@@ -0,0 +1,61 @@
+
+#include "map.h"
+#include <sys/mman.h>
+#include <errno.h>
+
+
+int git__mmap(git_map *out, size_t len, int prot, int flags, int fd, off_t offset)
+{
+	int mprot = 0;
+	int mflag = 0;
+
+	assert((out != NULL) && (len > 0));
+
+	if ((out == NULL) || (len == 0)) {
+		errno = EINVAL;
+		return GIT_ERROR;
+	}
+
+	out->data = NULL;
+	out->len = 0;
+
+	if (prot & GIT_PROT_WRITE)
+		mprot = PROT_WRITE;
+	else if (prot & GIT_PROT_READ)
+		mprot = PROT_READ;
+	else {
+		errno = EINVAL;
+		return GIT_ERROR;
+	}
+
+	if ((flags & GIT_MAP_TYPE) == GIT_MAP_SHARED)
+		mflag = MAP_SHARED;
+	else if ((flags & GIT_MAP_TYPE) == GIT_MAP_PRIVATE)
+		mflag = MAP_PRIVATE;
+
+	if (flags & GIT_MAP_FIXED) {
+		errno = EINVAL;
+		return GIT_ERROR;
+	}
+
+	out->data = mmap(NULL, len, mprot, mflag, fd, offset);
+	if (!out->data || out->data == MAP_FAILED)
+		return git_os_error();
+	out->len = len;
+
+	return GIT_SUCCESS;
+}
+
+int git__munmap(git_map *map)
+{
+	assert(map != NULL);
+
+	if (!map)
+		return GIT_ERROR;
+
+	munmap(map->data, map->len);
+
+	return GIT_SUCCESS;
+}
+
+