Avoid undefined behavior in 'send-process-region' (Bug#52369).

* src/process.c (send_process): Signal an error if the file descriptor
has already been closed.

diff --git a/src/process.c b/src/process.c
index 75ba191fa10157a9cae9d80520e59122d67f5c02..1d307d5242c7ad88b80473cfcae029adfe5da66b 100644 (file)
--- a/src/process.c
+++ b/src/process.c
@@ -6520,6 +6520,9 @@ send_process (Lisp_Object proc, const char *buf, ptrdiff_t len,
          /* Send this batch, using one or more write calls.  */
          ptrdiff_t written = 0;
          int outfd = p->outfd;
+          if (outfd < 0)
+            error ("Output file descriptor of %s is closed",
+                   SDATA (p->name));
          eassert (0 <= outfd && outfd < FD_SETSIZE);
 #ifdef DATAGRAM_SOCKETS
          if (DATAGRAM_CHAN_P (outfd))