Create a micro abstraction around the POSIX file APIs

This way we can start to write IO code to read and write files in the
Git object database, but provide a hook to inject native Win32 APIs
instead so libgit2 can be ported to run natively on that platform.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

1 files changed, 47 insertions, 0 deletions

diff --git a/src/os/unix.c b/src/os/unix.c
new file mode 100644
index 000000000..d132e9755
--- /dev/null
+++ b/src/os/unix.c
@@ -0,0 +1,47 @@
+/*
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2,
+ * as published by the Free Software Foundation.
+ *
+ * In addition to the permissions in the GNU General Public License,
+ * the authors give you unlimited permission to link the compiled
+ * version of this file into combinations with other programs,
+ * and to distribute those combinations without any restriction
+ * coming from the use of this file.  (The General Public License
+ * restrictions do apply in other respects; for example, they cover
+ * modification of the file, and distribution when not linked into
+ * a combined executable.)
+ *
+ * This file 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include <errno.h>
+#include "git/common.h"
+
+ssize_t git_fread(git_file fd, void *buf, size_t cnt)
+{
+	for (;;) {
+		ssize_t r = read(fd, buf, cnt);
+		if (r < 0 && (errno == EINTR || errno == EAGAIN))
+			continue;
+		return r;
+	}
+}
+
+ssize_t git_fwrite(git_file fd, void *buf, size_t cnt)
+{
+	for (;;) {
+		ssize_t r = write(fd, buf, cnt);
+		if (r < 0 && (errno == EINTR || errno == EAGAIN))
+			continue;
+		return r;
+	}
+}