ENT-3417: Added allow_non_convergent to pattern_matching promise in edit_line

cf-agent/files_editline.c

@@ -1263,6 +1263,7 @@ static bool ReplacePatterns(EvalContext *ctx, Item *file_start, Item *file_end,
     assert(a != NULL);
     assert(pp != NULL);
     assert(edcontext != NULL);
+    bool allow_non_convergent = PromiseGetConstraintAsBoolean(ctx, "allow_non_convergent", pp);
 
     char line_buff[CF_EXPANDSIZE];
     char after[CF_BUFSIZE];
@@ -1330,17 +1331,32 @@ static bool ReplacePatterns(EvalContext *ctx, Item *file_start, Item *file_end,
                 break;
             }
         }
-
+        char line_buff_cp[CF_EXPANDSIZE];
         if (NotAnchored(pp->promiser) && BlockTextMatch(ctx, pp->promiser, line_buff, &start_off, &end_off))
         {
-            RecordInterruption(ctx, pp, a,
-                               "Promised replacement '%s' on line '%s' for pattern '%s'"
-                               " is not convergent while editing '%s'"
-                               " (regular expression matches the replacement string)",
-                               line_buff, ip->name, pp->promiser, edcontext->filename);
-            *result = PromiseResultUpdate(*result, PROMISE_RESULT_INTERRUPTED);
-            PromiseRef(LOG_LEVEL_ERR, pp);
-            break;
+            strlcpy(line_buff_cp, line_buff, sizeof(line_buff_cp));
+            strlcpy(after, line_buff_cp + end_off, sizeof(after));
+            int needed = snprintf(line_buff_cp + start_off, sizeof(line_buff_cp) - start_off,
+                 "%s%s", BufferData(replace), after);
+
+            if (needed >= sizeof(line_buff_cp) - start_off) {
+                RecordInterruption(ctx, pp, a, "Buffer overflow: replacement string is too large. '%s' in '%s'",
+                               a->column.column_separator, edcontext->filename);
+                *result = PromiseResultUpdate(*result, PROMISE_RESULT_INTERRUPTED);
+                break;
+            }
+
+            if (!allow_non_convergent || (strlen(line_buff) != strlen(line_buff_cp)))
+            {
+                RecordInterruption(ctx, pp, a,
+                                "Promised replacement '%s' on line '%s' for pattern '%s'"
+                                " is not convergent while editing '%s'"
+                                " (regular expression matches the replacement string)",
+                                line_buff, ip->name, pp->promiser, edcontext->filename);
+                *result = PromiseResultUpdate(*result, PROMISE_RESULT_INTERRUPTED);
+                PromiseRef(LOG_LEVEL_ERR, pp);
+                break;
+            }
         }
 
         if (!MakingChanges(ctx, pp, a, result, "replace pattern '%s' in '%s'", pp->promiser,
@@ -1366,8 +1382,21 @@ static bool ReplacePatterns(EvalContext *ctx, Item *file_start, Item *file_end,
                 break;
             }
 
-            if (BlockTextMatch(ctx, pp->promiser, ip->name, &start_off, &end_off))
+            if (BlockTextMatch(ctx, pp->promiser, ip->name, &start_off, &end_off) && (!allow_non_convergent
+                || (strlen(line_buff) != strlen(line_buff_cp))))
             {
+                strlcpy(line_buff_cp, line_buff, sizeof(line_buff_cp));
+                strlcpy(after, line_buff_cp + end_off, sizeof(after));
+                int needed = snprintf(line_buff_cp + start_off, sizeof(line_buff_cp) - start_off,
+                    "%s%s", BufferData(replace), after);
+
+                if (needed >= sizeof(line_buff_cp) - start_off) {
+                    RecordInterruption(ctx, pp, a, "Buffer overflow: replacement string is too large. '%s' in '%s'",
+                                a->column.column_separator, edcontext->filename);
+                    *result = PromiseResultUpdate(*result, PROMISE_RESULT_INTERRUPTED);
+                    break;
+                }
+
                 RecordInterruption(ctx, pp, a,
                                    "Promised replacement '%s' for pattern '%s' is not properly convergent while editing '%s'"
                                    " (pattern still matches the end-state replacement string '%s', consider use"

libpromises/mod_files.c

@@ -131,6 +131,7 @@ static const ConstraintSyntax CF_COLUMN_BODIES[] =
 static const ConstraintSyntax CF_REPLACE_BODIES[] =
 {
     ConstraintSyntaxNewBody("replace_with", &replace_with_body, "Search-replace pattern", SYNTAX_STATUS_NORMAL),
+    ConstraintSyntaxNewBool("allow_non_convergent", "Allow to use non-convergent regular expressions in replace_patterns. Defaults to false", SYNTAX_STATUS_NORMAL),
     ConstraintSyntaxNewNull()
 };
 

tests/acceptance/10_files/replace_patterns/allow_non_convergent.cf

@@ -0,0 +1,69 @@
+#######################################################
+#
+# Replace a pattern using non-convergent regexes
+#
+#######################################################
+
+body common control
+{
+      inputs => { "../../default.cf.sub" };
+      bundlesequence  => { default("$(this.promise_filename)") };
+      version => "1.0";
+}
+
+######################################################
+
+bundle agent init
+{
+  files:
+    "/tmp/example.txt"
+      content => "foo PORT=23 bar";
+
+}
+
+######################################################
+
+bundle agent test
+{
+  files:
+    "/tmp/example.txt"
+      edit_line => _regex_replace( "PORT=[0-9]+", "PORT=22" );
+}
+
+bundle edit_line _regex_replace(find,replace)
+{
+  replace_patterns:
+    "$(find)"
+      replace_with => _value("$(replace)"),
+      comment => "Search and replace string",
+      allow_non_convergent => "true";
+}
+
+body replace_with _value(x)
+{
+        replace_value => "$(x)";
+        occurrences => "all";
+}
+
+######################################################
+
+bundle agent check
+{
+  vars:
+    "file_content"
+      string => readfile( "/tmp/example.txt" , "999" );
+
+  classes:
+    "ok" expression => strcmp("$(file_content)", "foo PORT=22 bar");
+
+  files:
+    "/tmp/example.txt"
+      delete => tidy;
+
+  reports:
+    ok::
+      "$(this.promise_filename) Pass";
+    !ok::
+      "$(this.promise_filename) FAIL";
+}
+