From b57c9e7b7775337e4067cc99418f95efa0701b15 Mon Sep 17 00:00:00 2001
From: Kload <kload@kload.fr>
Date: Fri, 6 Dec 2013 11:01:43 +0000
Subject: [PATCH] Log reader

---
 action_map.yml      |  7 ++++++
 yunohost_service.py | 56 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/action_map.yml b/action_map.yml
index 6666c8ca..7a55027f 100644
--- a/action_map.yml
+++ b/action_map.yml
@@ -587,6 +587,13 @@ service:
                     nargs: "*"
                     metavar: NAME
 
+        ### service_log()
+        log:
+            action_help: Show status information about one or more services (all by default)
+            arguments:
+                 name:
+                     help: Service name to log
+
 
 #############################
 #         Firewall          #
diff --git a/yunohost_service.py b/yunohost_service.py
index edae4106..3f04d101 100644
--- a/yunohost_service.py
+++ b/yunohost_service.py
@@ -143,6 +143,37 @@ def service_status(names=None):
     return result
 
 
+def service_log(name):
+    """
+    Log every log files of a service
+
+    Keyword argument:
+        name -- Services name to log
+
+    """
+    services = _get_services()
+
+    if name not in services.keys():
+        raise YunoHostError(1, _("Unknown service '%s'") % service)
+    
+    if 'log' in services[name]:
+        log_list = services[name]['log']
+        result = {}
+        if not isinstance(log_list, list):
+            log_list = [log_list]
+
+        for log_path in log_list:
+            if os.path.isdir(log_path):
+                for log in [ f for f in os.listdir(log_path) if os.path.isfile(os.path.join(log_path, f)) and f[-4:] == '.log' ]:
+                    result[os.path.join(log_path, log)] = _tail(os.path.join(log_path, log), 50)
+            else:
+                result[log_path] = _tail(log_path, 50)
+    else:
+        raise YunoHostError(1, _("Nothing to log for service '%s'") % name)
+
+    return result
+
+
 def _run_service_command(action, service):
     """
     Run services management command (start, stop,  enable, disable)
@@ -184,3 +215,28 @@ def _get_services():
     with open('/etc/yunohost/services.yml', 'r') as f:
         services = yaml.load(f)
     return services
+
+
+def _tail(file, n, offset=None):
+    """Reads a n lines from f with an offset of offset lines.  The return
+    value is a tuple in the form ``(lines, has_more)`` where `has_more` is
+    an indicator that is `True` if there are more lines in the file.
+    """
+    avg_line_length = 74
+    to_read = n + (offset or 0)
+
+    with open(file, 'r') as f:
+        while 1:
+            try:
+                f.seek(-(avg_line_length * to_read), 2)
+            except IOError:
+                # woops.  apparently file is smaller than what we want
+                # to step back, go to the beginning instead
+                f.seek(0)
+            pos = f.tell()
+            lines = f.read().splitlines()
+            if len(lines) >= to_read or pos == 0:
+                return lines[-to_read:offset and -offset or None] 
+                #return lines[-to_read:offset and -offset or None], \
+                #       len(lines) > to_read or pos > 0
+            avg_line_length *= 1.3