pack-objects: Allow use of pre-generated pack.

git-pack-objects can reuse pack files stored in $GIT_DIR/pack-cache
directory, when a necessary pack is found.  This is hopefully useful
when upload-pack (called from git-daemon) is expected to receive
requests for the same set of objects many times (e.g full cloning
request of any project, or updates from the set of heads previous day
to the latest for a slow moving project).

Currently git-pack-objects does *not* keep pack files it creates for
reusing.  It might be useful to add --update-cache option to it,
which would allow it store pack files it created in the pack-cache
directory, and prune rarely used ones from it.

Signed-off-by: Junio C Hamano <junkio@cox.net>

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;
+}
+