Bug#855424: mutt: don't check errno if read/write didn't error

[Edward Betts]

Package: mutt
Version: 1.7.2-1
Severity: normal
Tags: patch

The code in raw_socket_read function invokes the read system call and
checks if there was an error, indicated by a return value of -1.

If read doesn't return an error, but the global variable errno is set
to EINTR then error handling runs. This is incorrect, error handling
should only happen if read returns -1. When read doesn't result in an
error it doesn't set errno.

The same is true for raw_socket_write and the write sytem call.

This makes mutt close to unusable when interacting with a non-SSL IMAP
server. Mutt gives this message "Error talking to localhost (Interrupted
system call)" and closes the mailbox.

There is a patch to fix this problem.

--- mutt-1.7.2/mutt_socket.c    2017-02-17 20:34:41.000000000 +0000
+++ new/mutt_socket.c   2017-02-17 20:34:31.791530257 +0000
@@ -397,46 +397,36 @@
 int raw_socket_read (CONNECTION* conn, char* buf, size_t len)
 {
   int rc;
 
   mutt_allow_interrupt (1);
   if ((rc = read (conn->fd, buf, len)) == -1)
   {
     mutt_error (_("Error talking to %s (%s)"), conn->account.host,
                strerror (errno));
     mutt_sleep (2);
-  } else if (errno == EINTR) {
-    rc = -1;
-    mutt_error (_("Error talking to %s (%s)"), conn->account.host,
-               strerror (errno));
-    mutt_sleep (2);
-   }
+  }
   mutt_allow_interrupt (0);
 
   return rc;
 }
 
 int raw_socket_write (CONNECTION* conn, const char* buf, size_t count)
 {
   int rc;
 
   mutt_allow_interrupt (1);
   if ((rc = write (conn->fd, buf, count)) == -1)
   {
     mutt_error (_("Error talking to %s (%s)"), conn->account.host,
                strerror (errno));
     mutt_sleep (2);
-  } else if (errno == EINTR) {
-    rc = -1;
-    mutt_error (_("Error talking to %s (%s)"), conn->account.host,
-               strerror (errno));
-    mutt_sleep (2);
   }
   mutt_allow_interrupt (0);
 
   return rc;
 }
 
 int raw_socket_poll (CONNECTION* conn)
 {
   fd_set rfds;
   struct timeval tv = { 0, 0 };