From: Joel Rosdahl <joel@rosdahl.net>
Date: Sun, 27 Sep 2020 14:53:09 +0000 (+0200)
Subject: Handle short read when writing result files
X-Git-Tag: v4.0~62
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d53af3e59e1584cef4f0f6a82df536d00edaebf3;p=thirdparty%2Fccache.git

Handle short read when writing result files

Result::Write::write_embedded_file_entry assumes that read(2) never
performs a “short read” (fewer bytes than the supplied count) for files.
A short read can however happen if the process is interrupted by a
signal, for instance on NFS with the “intr” mount option.

Fix this by properly reducing the remaining bytes counter by the amount
of actually read bytes.
---

diff --git a/src/Result.cpp b/src/Result.cpp
index 8af93fbb2..f0b89751b 100644
--- a/src/Result.cpp
+++ b/src/Result.cpp
@@ -382,8 +382,8 @@ Result::Writer::write_embedded_file_entry(CacheEntryWriter& writer,
     if (bytes_read == 0) {
       throw Error("Error reading from {}: end of file", path);
     }
-    writer.write(buf, n);
-    remain -= n;
+    writer.write(buf, bytes_read);
+    remain -= bytes_read;
   }
 }