[stable-1] Various backports from community.postgres (#1789)

* postgresql modules: various backports from community.postgresql

* Add postgresql_set community/postgresql/pull/52 backport

* Fix

* Update plugins/modules/database/postgresql/postgresql_set.py

Co-authored-by: Felix Fontein <felix@fontein.de>

* Update plugins/modules/database/postgresql/postgresql_set.py

Co-authored-by: Felix Fontein <felix@fontein.de>

* Update changelogs/fragments/1-community-postgresql_backports.yml

Co-authored-by: Felix Fontein <felix@fontein.de>

Co-authored-by: Felix Fontein <felix@fontein.de>

plugins/modules/database/postgresql/postgresql_set.py

@@ -180,7 +180,7 @@ from ansible.module_utils._text import to_native
 PG_REQ_VER = 90400
 
 # To allow to set value like 1mb instead of 1MB, etc:
-POSSIBLE_SIZE_UNITS = ("mb", "gb", "tb")
+LOWERCASE_SIZE_UNITS = ("mb", "gb", "tb")
 
 # ===========================================
 # PostgreSQL module specific support methods.
@@ -199,6 +199,11 @@ def param_get(cursor, module, name):
     except Exception as e:
         module.fail_json(msg="Unable to get %s value due to : %s" % (name, to_native(e)))
 
+    if not info:
+        module.fail_json(msg="No such parameter: %s. "
+                             "Please check its spelling or presence in your PostgreSQL version "
+                             "(https://www.postgresql.org/docs/current/runtime-config.html)" % name)
+
     raw_val = info[0][1]
     unit = info[0][2]
     context = info[0][3]
@@ -233,32 +238,55 @@ def pretty_to_bytes(pretty_val):
     # if the value contains 'B', 'kB', 'MB', 'GB', 'TB'.
     # Otherwise it returns the passed argument.
 
-    val_in_bytes = None
-
-    if 'kB' in pretty_val:
-        num_part = int(''.join(d for d in pretty_val if d.isdigit()))
-        val_in_bytes = num_part * 1024
-
-    elif 'MB' in pretty_val.upper():
-        num_part = int(''.join(d for d in pretty_val if d.isdigit()))
-        val_in_bytes = num_part * 1024 * 1024
-
-    elif 'GB' in pretty_val.upper():
-        num_part = int(''.join(d for d in pretty_val if d.isdigit()))
-        val_in_bytes = num_part * 1024 * 1024 * 1024
-
-    elif 'TB' in pretty_val.upper():
-        num_part = int(''.join(d for d in pretty_val if d.isdigit()))
-        val_in_bytes = num_part * 1024 * 1024 * 1024 * 1024
-
-    elif 'B' in pretty_val.upper():
-        num_part = int(''.join(d for d in pretty_val if d.isdigit()))
-        val_in_bytes = num_part
-
-    else:
+    # It's sometimes possible to have an empty values
+    if not pretty_val:
         return pretty_val
 
-    return val_in_bytes
+    # If the first char is not a digit, it does not make sense
+    # to parse further, so just return a passed value
+    if not pretty_val[0].isdigit():
+        return pretty_val
+
+    # If the last char is not an alphabetical symbol, it means that
+    # it does not contain any suffixes, so no sense to parse further
+    if not pretty_val[-1].isalpha():
+        return pretty_val
+
+    # Extract digits
+    num_part = []
+    for c in pretty_val:
+        # When we reach the first non-digit element,
+        # e.g. in 1024kB, stop iterating
+        if not c.isdigit():
+            break
+        else:
+            num_part.append(c)
+
+    num_part = ''.join(num_part)
+
+    val_in_bytes = None
+
+    if len(pretty_val) >= 2:
+        if 'kB' in pretty_val[-2:]:
+            val_in_bytes = num_part * 1024
+
+        elif 'MB' in pretty_val[-2:]:
+            val_in_bytes = num_part * 1024 * 1024
+
+        elif 'GB' in pretty_val[-2:]:
+            val_in_bytes = num_part * 1024 * 1024 * 1024
+
+        elif 'TB' in pretty_val[-2:]:
+            val_in_bytes = num_part * 1024 * 1024 * 1024 * 1024
+
+    # For cases like "1B"
+    if not val_in_bytes and 'B' in pretty_val[-1]:
+        val_in_bytes = num_part
+
+    if val_in_bytes is not None:
+        return val_in_bytes
+    else:
+        return pretty_val
 
 
 def param_set(cursor, module, name, value, context):
@@ -308,11 +336,14 @@ def main():
         # Check input for potentially dangerous elements:
         check_input(module, name, value, session_role)
 
-    # Allow to pass values like 1mb instead of 1MB, etc:
     if value:
-        for unit in POSSIBLE_SIZE_UNITS:
-            if value[:-2].isdigit() and unit in value[-2:]:
-                value = value.upper()
+        # Convert a value like 1mb (Postgres does not support) to 1MB, etc:
+        if len(value) > 2 and value[:-2].isdigit() and value[-2:] in LOWERCASE_SIZE_UNITS:
+            value = value.upper()
+
+        # Convert a value like 1b (Postgres does not support) to 1B:
+        elif len(value) > 1 and ('b' in value[-1] and value[:-1].isdigit()):
+            value = value.upper()
 
     if value is not None and reset:
         module.fail_json(msg="%s: value and reset params are mutually exclusive" % name)