parser: refactor / factor out validation and error reporting

Move validation and error reporting to their own files; also rework
the validation passes slightly to validate as much as we can of the
netplan grammar in parser passes (so we get context info for errors),
and leave the backend rules sanity checking only to after the parsing.

This way we'll get the error context, unless things are backend-specific
rules for which it's just hard to get the info (and not as helpful).

Makefile

@@ -26,7 +26,7 @@ NOSETESTS3 ?= $(shell which nosetests-3 || which nosetests3 || echo true)
 
 default: generate doc/netplan.html doc/netplan.5 doc/netplan-generate.8 doc/netplan-apply.8 doc/netplan-try.8
 
-generate: src/generate.[hc] src/parse.[hc] src/util.[hc] src/networkd.[hc] src/nm.[hc]
+generate: src/generate.[hc] src/parse.[hc] src/util.[hc] src/networkd.[hc] src/nm.[hc] src/validation.[hc] src/error.[hc]
 	$(CC) $(BUILDFLAGS) $(CFLAGS) -o $@ $(filter %.c, $^) `pkg-config --cflags --libs glib-2.0 gio-2.0 yaml-0.1 uuid`
 
 clean:

src/error.c

@@ -0,0 +1,174 @@
+/*
+ * Copyright (C) 2019 Canonical, Ltd.
+ * Author: Mathieu Trudel-Lapierre <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <glib.h>
+#include <glib/gstdio.h>
+#include <gio/gio.h>
+
+#include <yaml.h>
+
+#include "parse.h"
+
+
+/****************************************************
+ * Loading and error handling
+ ****************************************************/
+
+static void
+write_error_marker(GString *message, int column)
+{
+    int i;
+
+    for (i = 0; (column > 0 && i < column); i++)
+        g_string_append_printf(message, " ");
+
+    g_string_append_printf(message, "^");
+}
+
+static char *
+get_syntax_error_context(const int line_num, const int column, GError **error)
+{
+    GString *message = NULL;
+    GFile *cur_file = g_file_new_for_path(current_file);
+    GFileInputStream *file_stream;
+    GDataInputStream *stream;
+    gsize len;
+    gchar* line = NULL;
+
+    message = g_string_sized_new(200);
+    file_stream = g_file_read(cur_file, NULL, error);
+    stream = g_data_input_stream_new (G_INPUT_STREAM(file_stream));
+    g_object_unref(file_stream);
+
+    for (int i = 0; i < line_num + 1; i++) {
+        g_free(line);
+        line = g_data_input_stream_read_line(stream, &len, NULL, error);
+    }
+    g_string_append_printf(message, "%s\n", line);
+
+    write_error_marker(message, column);
+
+    g_object_unref(stream);
+    g_object_unref(cur_file);
+
+    return g_string_free(message, FALSE);
+}
+
+static char *
+get_parser_error_context(const yaml_parser_t *parser, GError **error)
+{
+    GString *message = NULL;
+    unsigned char* line = parser->buffer.pointer;
+    unsigned char* current = line;
+
+    message = g_string_sized_new(200);
+
+    while (current > parser->buffer.start) {
+        current--;
+        if (*current == '\n') {
+            line = current + 1;
+            break;
+        }
+    }
+    if (current <= parser->buffer.start)
+        line = parser->buffer.start;
+    current = line + 1;
+    while (current <= parser->buffer.last) {
+        if (*current == '\n') {
+            *current = '\0';
+            break;
+        }
+        current++;
+    }
+
+    g_string_append_printf(message, "%s\n", line);
+
+    write_error_marker(message, parser->problem_mark.column);
+
+    return g_string_free(message, FALSE);
+}
+
+gboolean
+parser_error(const yaml_parser_t* parser, const char* yaml, GError** error)
+{
+    char *error_context = get_parser_error_context(parser, error);
+    if ((char)*parser->buffer.pointer == '\t')
+        g_set_error(error, G_MARKUP_ERROR, G_MARKUP_ERROR_PARSE,
+                    "%s:%zu:%zu: Invalid YAML: tabs are not allowed for indent:\n%s",
+                    yaml,
+                    parser->problem_mark.line + 1,
+                    parser->problem_mark.column + 1,
+                    error_context);
+    else if (((char)*parser->buffer.pointer == ' ' || (char)*parser->buffer.pointer == '\0')
+             && !parser->token_available)
+        g_set_error(error, G_MARKUP_ERROR, G_MARKUP_ERROR_PARSE,
+                    "%s:%zu:%zu: Invalid YAML: aliases are not supported:\n%s",
+                    yaml,
+                    parser->problem_mark.line + 1,
+                    parser->problem_mark.column + 1,
+                    error_context);
+    else if (parser->state == YAML_PARSE_BLOCK_MAPPING_KEY_STATE)
+        g_set_error(error, G_MARKUP_ERROR, G_MARKUP_ERROR_PARSE,
+                    "%s:%zu:%zu: Invalid YAML: inconsistent indentation:\n%s",
+                    yaml,
+                    parser->problem_mark.line + 1,
+                    parser->problem_mark.column + 1,
+                    error_context);
+    else {
+        g_set_error(error, G_MARKUP_ERROR, G_MARKUP_ERROR_PARSE,
+                    "%s:%zu:%zu: Invalid YAML: %s:\n%s",
+                    yaml,
+                    parser->problem_mark.line + 1,
+                    parser->problem_mark.column + 1,
+                    parser->problem,
+                    error_context);
+    }
+    g_free(error_context);
+
+    return FALSE;
+}
+
+/**
+ * Put a YAML specific error message for @node into @error.
+ */
+gboolean
+yaml_error(const yaml_node_t* node, GError** error, const char* msg, ...)
+{
+    va_list argp;
+    char* s;
+    char* error_context = NULL;
+
+    va_start(argp, msg);
+    g_vasprintf(&s, msg, argp);
+    if (node != NULL) {
+        error_context = get_syntax_error_context(node->start_mark.line, node->start_mark.column, error);
+        g_set_error(error, G_MARKUP_ERROR, G_MARKUP_ERROR_PARSE,
+                    "%s:%zu:%zu: Error in network definition: %s\n%s",
+                    current_file,
+                    node->start_mark.line + 1,
+                    node->start_mark.column + 1,
+                    s,
+                    error_context);
+    } else {
+        g_set_error(error, G_MARKUP_ERROR, G_MARKUP_ERROR_PARSE,
+                    "Error in network definition: %s", s);
+    }
+    g_free(s);
+    va_end(argp);
+    return FALSE;
+}
+

src/error.h

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2019 Canonical, Ltd.
+ * Author: Mathieu Trudel-Lapierre <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <glib.h>
+#include <glib/gstdio.h>
+#include <gio/gio.h>
+
+#include <yaml.h>
+
+
+gboolean
+parser_error(const yaml_parser_t* parser, const char* yaml, GError** error);
+
+gboolean
+yaml_error(const yaml_node_t* node, GError** error, const char* msg, ...);