From 7757fdd491862fa5c33f1f894503346b89898a01 Mon Sep 17 00:00:00 2001
From: Ludovic Courtès <ludo@gnu.org>
Date: Mon, 13 May 2024 12:02:30 +0200
Subject: daemon: Loop over ‘copy_file_range’ upon short writes.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Fixes <https://issues.guix.gnu.org/70877>.

* nix/libutil/util.cc (copyFile): Loop over ‘copy_file_range’ instead of
throwing upon short write.

Reported-by: Ricardo Wurmus <rekado@elephly.net>
Change-Id: Id7b8a65ea59006c2d91bc23732309a68665b9ca0
---
 nix/libutil/util.cc | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/nix/libutil/util.cc b/nix/libutil/util.cc
index 578d657293..3206dea11b 100644
--- a/nix/libutil/util.cc
+++ b/nix/libutil/util.cc
@@ -397,9 +397,14 @@ static void copyFile(int sourceFd, int destinationFd)
     } else {
 	if (result < 0)
 	    throw SysError(format("copy_file_range `%1%' to `%2%'") % sourceFd % destinationFd);
-	if (result < st.st_size)
-	    throw SysError(format("short write in copy_file_range `%1%' to `%2%'")
-			   % sourceFd % destinationFd);
+
+	/* If 'copy_file_range' copied less than requested, try again.  */
+	for (ssize_t copied = result; copied < st.st_size; copied += result) {
+	    result = copy_file_range(sourceFd, NULL, destinationFd, NULL,
+				     st.st_size - copied, 0);
+	    if (result < 0)
+		throw SysError(format("copy_file_range `%1%' to `%2%'") % sourceFd % destinationFd);
+	}
     }
 }
 
-- 
cgit v1.2.3

diff/nix/local.mk?id=bc3896db25c788c181c7bcd65754e7cd378e9d9f'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/nix/local.mk'>
<input type='hidden' name='id' value='bc3896db25c788c181c7bcd65754e7cd378e9d9f'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=bc3896db25c788c181c7bcd65754e7cd378e9d9f'>root</a>/<a href='/guix/log/nix?id=bc3896db25c788c181c7bcd65754e7cd378e9d9f'>nix</a>/<a href='/guix/log/nix/local.mk?id=bc3896db25c788c181c7bcd65754e7cd378e9d9f'>local.mk</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/nix/local.mk?id=bc3896db25c788c181c7bcd65754e7cd378e9d9f&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-10-27 18:00:29 +0100'>2020-10-27</span></td><td><a href='/guix/commit/nix/local.mk?id=c40ad1df60e81e2089780ee884504729c7a66695'>maint: Add 'etc/gnu-store.mount.in' to the distribution.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-09-17 14:10:42 +0200'>2020-09-17</span></td><td><a href='/guix/commit/nix/local.mk?id=cabac732deffafc796537658a6c33c6c4aec821e'>guix-install.sh: Support OpenRC.</a><span class='msg-avail'>...</span></td><td>Morgan Smith</td></tr>
<tr><td><span title='2020-06-27 23:42:20 +0200'>2020-06-27</span></td><td><a href='/guix/commit/nix/local.mk?id=8dc6c387852bb9505be44567a5f56913633cc23a'>daemon: Remove OpenSSL hash compatibility wrappers.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-05-23 15:37:58 +0200'>2020-05-23</span></td><td><a href='/guix/commit/nix/local.mk?id=9927e5b11b88a85fffb959b515430c2312c8dff3'>build: Add a comment above the sysvinit section.</a><span class='msg-avail'>...</span></td><td>Vincent Legoll</td></tr>
<tr><td><span title='2020-05-17 14:12:35 +0200'>2020-05-17</span></td><td><a href='/guix/commit/nix/local.mk?id=ebbf91542269fcb36d64928d4a4992e6afbf2acf'>etc: Install mount unit only if it exists.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-05-16 15:37:41 +0200'>2020-05-16</span></td><td><a href='/guix/commit/nix/local.mk?id=1a1faa78b0498fbb71f1533beb4b65817c1d3f2a'>etc: Add a systemd unit to bind-mount @storedir@ read-only.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-03-11 02:45:33 +0100'>2020-03-11</span></td><td><a href='/guix/commit/nix/local.mk?id=73fbe04107d38f4561636c74d28d7a4935cbb1ef'>Add system start-up files for guix-daemon.</a><span class='msg-avail'>...</span></td><td>Danny Milosavljevic</td></tr>