skip initial comment in pg_session file (#1245)

* skip initial comment in pg_session file

* add test

5 files changed, 58 insertions, 5 deletions

diff --git a/changelog.rst b/changelog.rst
index 18640252..ee94ae3f 100644
--- a/changelog.rst
+++ b/changelog.rst
@@ -6,6 +6,7 @@ Features:
 
 * Consider `update` queries destructive and issue a warning. Change
   `destructive_warning` setting to `all|moderate|off`, vs `true|false`. (#1239)
+* Skip initial comment in .pg_session even if it doesn't start with '#'
 
 Bug fixes:
 ----------
diff --git a/pgcli/config.py b/pgcli/config.py
index 0fc42dde..56eede53 100644
--- a/pgcli/config.py
+++ b/pgcli/config.py
@@ -3,6 +3,8 @@ import shutil
 import os
 import platform
 from os.path import expanduser, exists, dirname
+import re
+from typing import TextIO
 from configobj import ConfigObj
 
 
@@ -62,3 +64,28 @@ def get_casing_file(config):
     if casing_file == "default":
         casing_file = config_location() + "casing"
     return casing_file
+
+
+def skip_initial_comment(f_stream: TextIO) -> int:
+    """
+    Initial comment in ~/.pg_service.conf is not always marked with '#'
+    which crashes the parser. This function takes a file object and
+    "rewinds" it to the beginning of the first section,
+    from where on it can be parsed safely
+
+    :return: number of skipped lines
+    """
+    section_regex = r"\s*\["
+    pos = f_stream.tell()
+    lines_skipped = 0
+    while True:
+        line = f_stream.readline()
+        if line == "":
+            break
+        if re.match(section_regex, line) is not None:
+            f_stream.seek(pos)
+            break
+        else:
+            pos += len(line)
+            lines_skipped += 1
+    return lines_skipped
diff --git a/pgcli/main.py b/pgcli/main.py
index 40e2483a..4cf528d9 100644
--- a/pgcli/main.py
+++ b/pgcli/main.py
@@ -2,8 +2,9 @@ import platform
 import warnings
 from os.path import expanduser
 
-from configobj import ConfigObj
+from configobj import ConfigObj, ParseError
 from pgspecial.namedqueries import NamedQueries
+from .config import skip_initial_comment
 
 warnings.filterwarnings("ignore", category=UserWarning, module="psycopg2")
 
@@ -1508,10 +1509,16 @@ def parse_service_info(service):
             service_file = os.path.join(os.getenv("PGSYSCONFDIR"), ".pg_service.conf")
         else:
             service_file = expanduser("~/.pg_service.conf")
-    if not service:
+    if not service or not os.path.exists(service_file):
         # nothing to do
         return None, service_file
-    service_file_config = ConfigObj(service_file)
+    with open(service_file) as f:
+        skipped_lines = skip_initial_comment(f)
+        try:
+            service_file_config = ConfigObj(f)
+        except ParseError as err:
+            err.line_number += skipped_lines
+            raise err
     if service not in service_file_config:
         return None, service_file
     service_conf = service_file_config.get(service)
diff --git a/tests/test_config.py b/tests/test_config.py
index 48408141..08fe74e6 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -1,9 +1,10 @@
+import io
 import os
 import stat
 
 import pytest
 
-from pgcli.config import ensure_dir_exists
+from pgcli.config import ensure_dir_exists, skip_initial_comment
 
 
 def test_ensure_file_parent(tmpdir):
@@ -28,3 +29,15 @@ def test_ensure_other_create_error(tmpdir):
 
     with pytest.raises(OSError):
         ensure_dir_exists(str(rcfile))
+
+
+@pytest.mark.parametrize(
+    "text, skipped_lines",
+    (
+        ("abc\n", 1),
+        ("#[section]\ndef\n[section]", 2),
+        ("[section]", 0),
+    ),
+)
+def test_skip_initial_comment(text, skipped_lines):
+    assert skip_initial_comment(io.StringIO(text)) == skipped_lines
diff --git a/tests/test_main.py b/tests/test_main.py
index 965ff8fa..c48accbe 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -288,7 +288,12 @@ def test_pg_service_file(tmpdir):
         cli = PGCli(pgclirc_file=str(tmpdir.join("rcfile")))
         with open(tmpdir.join(".pg_service.conf").strpath, "w") as service_conf:
             service_conf.write(
-                """[myservice]
+                """File begins with a comment
+            that is not a comment
+            # or maybe a comment after all
+            because psql is crazy
+
+            [myservice]
             host=a_host
             user=a_user
             port=5433