patch 7.4.1310
Problem:    Jobs don't open a channel.
Solution:   Create pipes and add them to the channel.  Add ch_logfile().
            Only Unix for now.
diff --git a/src/eval.c b/src/eval.c
index ece87de..4a939a7 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -503,8 +503,10 @@
 static void f_ceil(typval_T *argvars, typval_T *rettv);
 #endif
 #ifdef FEAT_CHANNEL
-static void f_ch_open(typval_T *argvars, typval_T *rettv);
 static void f_ch_close(typval_T *argvars, typval_T *rettv);
+static void f_ch_logfile(typval_T *argvars, typval_T *rettv);
+static void f_ch_open(typval_T *argvars, typval_T *rettv);
+static void f_ch_readraw(typval_T *argvars, typval_T *rettv);
 static void f_ch_sendexpr(typval_T *argvars, typval_T *rettv);
 static void f_ch_sendraw(typval_T *argvars, typval_T *rettv);
 #endif
@@ -624,6 +626,7 @@
 static void f_islocked(typval_T *argvars, typval_T *rettv);
 static void f_items(typval_T *argvars, typval_T *rettv);
 #ifdef FEAT_JOB
+static void f_job_getchannel(typval_T *argvars, typval_T *rettv);
 static void f_job_start(typval_T *argvars, typval_T *rettv);
 static void f_job_stop(typval_T *argvars, typval_T *rettv);
 static void f_job_status(typval_T *argvars, typval_T *rettv);
@@ -7720,6 +7723,8 @@
     static void
 job_free(job_T *job)
 {
+    if (job->jv_channel >= 0)
+	channel_close(job->jv_channel);
     mch_clear_job(job);
     vim_free(job);
 }
@@ -8083,7 +8088,9 @@
 #endif
 #ifdef FEAT_CHANNEL
     {"ch_close",	1, 1, f_ch_close},
+    {"ch_logfile",	1, 2, f_ch_logfile},
     {"ch_open",		1, 2, f_ch_open},
+    {"ch_readraw",	1, 2, f_ch_readraw},
     {"ch_sendexpr",	2, 3, f_ch_sendexpr},
     {"ch_sendraw",	2, 3, f_ch_sendraw},
 #endif
@@ -8207,6 +8214,7 @@
     {"islocked",	1, 1, f_islocked},
     {"items",		1, 1, f_items},
 #ifdef FEAT_JOB
+    {"job_getchannel",	1, 1, f_job_getchannel},
     {"job_start",	1, 2, f_job_start},
     {"job_status",	1, 1, f_job_status},
     {"job_stop",	1, 2, f_job_stop},
@@ -9788,7 +9796,7 @@
     }
     ch_idx = tv->vval.v_number;
 
-    if (!channel_is_open(ch_idx))
+    if (!channel_can_write_to(ch_idx))
     {
 	EMSGN(_("E906: not an open channel"), ch_idx);
 	return -1;
@@ -9825,6 +9833,32 @@
 }
 
 /*
+ * "ch_logfile()" function
+ */
+    static void
+f_ch_logfile(typval_T *argvars, typval_T *rettv UNUSED)
+{
+    char_u *fname;
+    char_u *opt = (char_u *)"";
+    char_u buf[NUMBUFLEN];
+    FILE   *file = NULL;
+
+    fname = get_tv_string(&argvars[0]);
+    if (argvars[1].v_type == VAR_STRING)
+	opt = get_tv_string_buf(&argvars[1], buf);
+    if (*fname != NUL)
+    {
+	file = fopen((char *)fname, *opt == 'w' ? "w" : "a");
+	if (file == NULL)
+	{
+	    EMSG2(_(e_notopen), fname);
+	    return;
+	}
+    }
+    ch_logfile(file);
+}
+
+/*
  * "ch_open()" function
  */
     static void
@@ -9914,6 +9948,27 @@
 }
 
 /*
+ * "ch_readraw()" function
+ */
+    static void
+f_ch_readraw(typval_T *argvars, typval_T *rettv)
+{
+    int		ch_idx;
+
+    /* return an empty string by default */
+    rettv->v_type = VAR_STRING;
+    rettv->vval.v_string = NULL;
+
+    ch_idx = get_channel_arg(&argvars[0]);
+    if (ch_idx < 0)
+    {
+	EMSG(_(e_invarg));
+	return;
+    }
+    rettv->vval.v_string = channel_read_block(ch_idx);
+}
+
+/*
  * common for "sendexpr()" and "sendraw()"
  * Returns the channel index if the caller should read the response.
  * Otherwise returns -1.
@@ -14300,6 +14355,23 @@
 
 #ifdef FEAT_JOB
 /*
+ * "job_getchannel()" function
+ */
+    static void
+f_job_getchannel(typval_T *argvars, typval_T *rettv)
+{
+    if (argvars[0].v_type != VAR_JOB)
+	EMSG(_(e_invarg));
+    else
+    {
+	job_T *job = argvars[0].vval.v_job;
+
+	rettv->v_type = VAR_NUMBER;
+	rettv->vval.v_number = job->jv_channel;
+    }
+}
+
+/*
  * "job_start()" function
  */
     static void
@@ -14401,7 +14473,7 @@
  * "job_status()" function
  */
     static void
-f_job_status(typval_T *argvars UNUSED, typval_T *rettv UNUSED)
+f_job_status(typval_T *argvars, typval_T *rettv)
 {
     char *result;