[PATCH] devshell: list commands when throwing NoSupportedTerminals

[Stephano Cetola <stephano.cetola@linux.intel.com>]

When attempting to run devshell, if no terminal is available, the
error being thrown was not very specific. This adds a list of
commands that failed, informing the user of what they can install to
fix the error.

Signed-off-by: Stephano Cetola <stephano.cetola@linux.intel.com>
---
 meta/classes/terminal.bbclass |  7 +++++--
 meta/lib/oe/terminal.py       | 15 ++++++++++++---
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/meta/classes/terminal.bbclass b/meta/classes/terminal.bbclass
index a94f755..5cfc7ac 100644
--- a/meta/classes/terminal.bbclass
+++ b/meta/classes/terminal.bbclass
@@ -88,8 +88,11 @@ def oe_terminal(command, title, d):
 
     try:
         oe.terminal.spawn_preferred(command, title, None, d)
-    except oe.terminal.NoSupportedTerminals:
-        bb.fatal('No valid terminal found, unable to open devshell')
+    except oe.terminal.NoSupportedTerminals as nosup:
+        cmds = '\n\t'.join(nosup.terms).replace("{command}",
+                    "do_terminal").replace("{title}", title)
+        bb.fatal('No valid terminal found, unable to open devshell.\n' +
+                'Tried the following commands:\n\t%s' % cmds)
     except oe.terminal.ExecutionError as exc:
         bb.fatal('Unable to spawn terminal %s: %s' % (terminal, exc))
 
diff --git a/meta/lib/oe/terminal.py b/meta/lib/oe/terminal.py
index 7446c44..e772a37 100644
--- a/meta/lib/oe/terminal.py
+++ b/meta/lib/oe/terminal.py
@@ -11,7 +11,8 @@ class UnsupportedTerminal(Exception):
     pass
 
 class NoSupportedTerminals(Exception):
-    pass
+    def __init__(self, terms):
+        self.terms = terms
 
 
 class Registry(oe.classutils.ClassRegistry):
@@ -191,7 +192,7 @@ class Tmux(Terminal):
             logger.warn(msg)
 
 class Custom(Terminal):
-    command = 'false' # This is a placeholder
+    command = None # This is a placeholder
     priority = 3
 
     def __init__(self, sh_cmd, title=None, env=None, d=None):
@@ -209,6 +210,14 @@ class Custom(Terminal):
 def prioritized():
     return Registry.prioritized()
 
+def get_cmd_list():
+    terms = Registry.prioritized()
+    cmds = []
+    for term in terms:
+        if term.command:
+            cmds.append(term.command)
+    return cmds
+
 def spawn_preferred(sh_cmd, title=None, env=None, d=None):
     """Spawn the first supported terminal, by priority"""
     for terminal in prioritized():
@@ -218,7 +227,7 @@ def spawn_preferred(sh_cmd, title=None, env=None, d=None):
         except UnsupportedTerminal:
             continue
     else:
-        raise NoSupportedTerminals()
+        raise NoSupportedTerminals(get_cmd_list())
 
 def spawn(name, sh_cmd, title=None, env=None, d=None):
     """Spawn the specified terminal, by name"""
-- 
2.10.2