Re: [PATCH] copy.c: use `sendfile()` for in-kernel file copying on Linux

Ah, more importantly, FreeBSD's sendfile only operates on sockets.

Both systems also need fallback code for un-handled cases.

Chris

On Sat, Feb 14, 2026 at 1:22 AM George Hu [off-list ref] wrote:

On 2/13/26 11:36 PM, Chris Torek wrote:

quoted

On Fri, Feb 13, 2026 at 4:47 AM George Hu [off-list ref] wrote:

quoted

The `sendfile()` system call copies data between one file descriptor
and another within the kernel, which is more efficient than the
combination of `read()` and `write()`.

sendfile() is found on other systems (notably BSDs), so perhaps ...

quoted

Signed-off-by: George Hu <redacted>
---
  copy.c | 17 +++++++++++++++++
  1 file changed, 17 insertions(+)

diff --git a/copy.c b/copy.c
index b668209b6c..d4b7cde764 100644
--- a/copy.c
+++ b/copy.c

@@ -7,8 +7,23 @@
  #include "strbuf.h"
  #include "abspath.h"

+#ifdef __linux__

... this and the subsequent ifdef should be based on the feature,
rather than the OS.

Chris

Hello,

Although the `sendfile()` system call exists in both Linux and BSDs,
their semantics and APIs differ.
The Linux prototype of `sendfile()` is:

ssize_t sendfile(int out_fd, int in_fd, off_t *_Nullable offset, size_t
count);

While FreeBSD exposes:

int sendfile(int fd, int s, off_t offset, size_t nbytes, struct sf_hdtr
*hdtr, off_t *sbytes, int flags);

George