Get QEMU pty paths from the monitor

This change makes the QEMU driver get pty paths from the output of the
monitor 'info chardev' command. This output is structured, and contains
both the name of the device and the path on the same line. This is
considerably more reliable than parsing the startup log output, which
requires the parsing code to know which order QEMU will print pty
information in.

Note that we still need to parse the log output as the monitor itself
may be on a pty. This should be rare, however, and the new code will
replace all pty paths parsed by the log output method once the monitor
is available.

* src/qemu/qemu_monitor.(c|h) src/qemu_monitor_text.(c|h): Implement
  qemuMonitorGetPtyPaths().
* src/qemu/qemu_driver.c: Get pty path information using
  qemuMonitorGetPtyPaths().

src/qemu/qemu_driver.c

@@ -1406,6 +1406,40 @@ qemudExtractTTYPath(virConnectPtr conn,
     return 1;
 }
 
+static int
+qemudFindCharDevicePTYsMonitor(virConnectPtr conn,
+                               virDomainObjPtr vm,
+                               virHashTablePtr paths)
+{
+    int i;
+
+#define LOOKUP_PTYS(array, arraylen, idprefix)                            \
+    for (i = 0 ; i < (arraylen) ; i++) {                                  \
+        virDomainChrDefPtr chr = (array)[i];                              \
+        if (chr->type == VIR_DOMAIN_CHR_TYPE_PTY) {                       \
+            char id[16];                                                  \
+                                                                          \
+            if (snprintf(id, sizeof(id), idprefix "%i", i) >= sizeof(id)) \
+                return -1;                                                \
+                                                                          \
+            const char *path = (const char *) virHashLookup(paths, id);   \
+            if (path == NULL) {                                           \
+                qemudReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,\
+                                 _("no assigned pty for device %s"), id); \
+                return -1;                                                \
+            }                                                             \
+                                                                          \
+            chr->data.file.path = strdup(path);                           \
+        }                                                                 \
+    }
+
+    LOOKUP_PTYS(vm->def->serials,   vm->def->nserials,   "serial");
+    LOOKUP_PTYS(vm->def->parallels, vm->def->nparallels, "parallel");
+    LOOKUP_PTYS(vm->def->channels,  vm->def->nchannels,  "channel");
+
+    return 0;
+}
+
 static int
 qemudFindCharDevicePTYs(virConnectPtr conn,
                         virDomainObjPtr vm,
@@ -1452,6 +1486,11 @@ qemudFindCharDevicePTYs(virConnectPtr conn,
     return 0;
 }
 
+static void qemudFreePtyPath(void *payload, const char *name ATTRIBUTE_UNUSED)
+{
+    VIR_FREE(payload);
+}
+
 static int
 qemudWaitForMonitor(virConnectPtr conn,
                     struct qemud_driver* driver,
@@ -1459,7 +1498,7 @@ qemudWaitForMonitor(virConnectPtr conn,
 {
     char buf[4096]; /* Plenty of space to get startup greeting */
     int logfd;
-    int ret;
+    int ret = -1;
 
     if ((logfd = qemudLogReadFD(conn, driver->logDir, vm->def->name, pos))
         < 0)
@@ -1485,7 +1524,32 @@ qemudWaitForMonitor(virConnectPtr conn,
     if (qemuConnectMonitor(vm) < 0)
         return -1;
 
-    return 0;
+    /* Try to get the pty path mappings again via the monitor. This is much more
+     * reliable if it's available.
+     * Note that the monitor itself can be on a pty, so we still need to try the
+     * log output method. */
+    virHashTablePtr paths = virHashCreate(0);
+    if (paths == NULL) {
+        virReportOOMError(NULL);
+        goto cleanup;
+    }
+
+    qemuDomainObjEnterMonitor(vm);
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    ret = qemuMonitorGetPtyPaths(priv->mon, paths);
+    qemuDomainObjExitMonitor(vm);
+
+    VIR_DEBUG("qemuMonitorGetPtyPaths returned %i", ret);
+    if (ret == 0) {
+        ret = qemudFindCharDevicePTYsMonitor(conn, vm, paths);
+    }
+
+cleanup:
+    if (paths) {
+        virHashFree(paths, qemudFreePtyPath);
+    }
+
+    return ret;
 }
 
 static int

src/qemu/qemu_monitor.c

@@ -1267,3 +1267,12 @@ int qemuMonitorRemoveHostNetwork(qemuMonitorPtr mon,
         ret = qemuMonitorTextRemoveHostNetwork(mon, vlan, netname);
     return ret;
 }
+
+int qemuMonitorGetPtyPaths(qemuMonitorPtr mon,
+                           virHashTablePtr paths)
+{
+    DEBUG("mon=%p, fd=%d",
+          mon, mon->fd);
+
+    return qemuMonitorTextGetPtyPaths(mon, paths);
+}

src/qemu/qemu_monitor.h

@@ -28,6 +28,7 @@
 #include "internal.h"
 
 #include "domain_conf.h"
+#include "hash.h"
 
 typedef struct _qemuMonitor qemuMonitor;
 typedef qemuMonitor *qemuMonitorPtr;
@@ -272,5 +273,7 @@ int qemuMonitorRemoveHostNetwork(qemuMonitorPtr mon,
                                  int vlan,
                                  const char *netname);
 
+int qemuMonitorGetPtyPaths(qemuMonitorPtr mon,
+                           virHashTablePtr paths);
 
 #endif /* QEMU_MONITOR_H */

src/qemu/qemu_monitor_text.c

@@ -1594,3 +1594,74 @@ cleanup:
     VIR_FREE(reply);
     return ret;
 }
+
+
+/* Parse the output of "info chardev" and return a hash of pty paths.
+ *
+ * Output is:
+ * foo: filename=pty:/dev/pts/7
+ * monitor: filename=stdio
+ * serial0: filename=vc
+ * parallel0: filename=vc
+ *
+ * Non-pty lines are ignored. In the above example, key is 'foo', value is
+ * '/dev/pty/7'. The hash will contain only a single value.
+ */
+
+int qemuMonitorTextGetPtyPaths(qemuMonitorPtr mon,
+                               virHashTablePtr paths)
+{
+    const char *cmd = "info chardev";
+    char *reply = NULL;
+    int ret = -1;
+
+    if (qemuMonitorCommand(mon, cmd, &reply) < 0) {
+        qemudReportError(NULL, NULL, NULL, VIR_ERR_OPERATION_FAILED,
+                         _("failed to retrieve chardev info in qemu with '%s'"),
+                         cmd);
+        goto cleanup;
+    }
+
+    char *pos = reply;                  /* The current start of searching */
+    char *end = pos + strlen(reply);    /* The end of the reply string */
+    char *eol;                   /* The character which ends the current line */
+
+    while (pos < end) {
+        /* Split the output into lines */
+        eol = memchr(pos, '\n', end - pos);
+        if (eol == NULL)
+            eol = end;
+
+        /* Look for 'filename=pty:' */
+#define NEEDLE "filename=pty:"
+        char *needle = memmem(pos, eol - pos, NEEDLE, strlen(NEEDLE));
+
+        /* If it's not there we can ignore this line */
+        if (!needle)
+            goto next;
+
+        /* id is everthing from the beginning of the line to the ':'
+         * find ':' and turn it into a terminator */
+        char *colon = memchr(pos, ':', needle - pos);
+        if (colon == NULL)
+            goto next;
+        *colon = '\0';
+        char *id = pos;
+
+        /* Path is everything after needle to the end of the line */
+        *eol = '\0';
+        char *path = needle + strlen(NEEDLE);
+
+        virHashAddEntry(paths, id, strdup(path));
+#undef NEEDLE
+
+    next:
+        pos = eol + 1;
+    }
+
+    ret = 0;
+
+cleanup:
+    VIR_FREE(reply);
+    return ret;
+}

src/qemu/qemu_monitor_text.h

@@ -28,6 +28,7 @@
 #include "internal.h"
 
 #include "qemu_monitor.h"
+#include "hash.h"
 
 int qemuMonitorTextIOProcess(qemuMonitorPtr mon,
                              const char *data,
@@ -153,4 +154,7 @@ int qemuMonitorTextRemoveHostNetwork(qemuMonitorPtr mon,
                                      int vlan,
                                      const char *netname);
 
+int qemuMonitorTextGetPtyPaths(qemuMonitorPtr mon,
+                               virHashTablePtr paths);
+
 #endif /* QEMU_MONITOR_TEXT_H */