1 files changed, 37 insertions, 0 deletions
diff --git a/copy.c b/copy.c
new file mode 100644
index 0000000000..20092757d3
--- /dev/null
+++ b/copy.c
@@ -0,0 +1,37 @@
+#include "cache.h"
+
+int copy_fd(int ifd, int ofd)
+{
+	while (1) {
+		int len;
+		char buffer[8192];
+		char *buf = buffer;
+		len = read(ifd, buffer, sizeof(buffer));
+		if (!len)
+			break;
+		if (len < 0) {
+			if (errno == EAGAIN)
+				continue;
+			return error("copy-fd: read returned %s",
+				     strerror(errno));
+		}
+		while (1) {
+			int written = write(ofd, buf, len);
+			if (written > 0) {
+				buf += written;
+				len -= written;
+				if (!len)
+					break;
+			}
+			if (!written)
+				return error("copy-fd: write returned 0");
+			if (errno == EAGAIN || errno == EINTR)
+				continue;
+			return error("copy-fd: write returned %s",
+				     strerror(errno));
+		}
+	}
+	close(ifd);
+	return 0;
+}
+