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-rw-r--r--util/cbfstool/fmd.c401
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+/*
+ * fmd.c, parser frontend and utility functions for flashmap descriptor language
+ *
+ * Copyright (C) 2015 Google, Inc.
+ *
+ * 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 2 of the License.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA, 02110-1301 USA
+ */
+
+#include "fmd.h"
+
+#include "fmd_parser.h"
+#include "fmd_scanner.h"
+#include "option.h"
+
+#include <assert.h>
+#include <search.h>
+#include <string.h>
+
+/*
+ * Validate the given flashmap descriptor node's properties. In particular:
+ * - Ensure its name is globally unique.
+ * - Ensure its offset, if known, isn't located before the end of the previous
+ * section, if this can be determined.
+ * - Ensure its offset, if known, isn't located after the beginning of the next
+ * section or off the end of its parent section, if this can be determined.
+ * - Ensure its size is nonzero.
+ * - Ensure that the combination of its size and offset, if they are both
+ * known, doesn't place its end after the beginning of the next section or
+ * off the end of its parent section, if this can be determined.
+ * In the case of a validation error, the particular problem is reported to
+ * standard error and this function returns false. It should be noted that this
+ * function makes no claim that the members of the node's child list are valid:
+ * under no circumstances is any recursive validation performed.
+ *
+ * @param node The flashmap descriptor node to be validated
+ * @param start Optional minimum permissible base of the section to be
+ * validated, to be provided if known
+ * @param end Optional maximum permissible offset to the end of the section to
+ * be validated, to be provided if known
+ * @return Whether the node is valid
+ */
+static bool validate_descriptor_node(const struct flashmap_descriptor *node,
+ struct unsigned_option start, struct unsigned_option end) {
+ assert(node);
+
+ ENTRY search_key = {node->name, NULL};
+ if (hsearch(search_key, FIND)) {
+ fprintf(stderr, "ERROR: Multiple sections with name '%s'\n",
+ node->name);
+ return false;
+ }
+ if (!hsearch(search_key, ENTER))
+ assert(false);
+
+ if (node->offset_known) {
+ if (start.val_known && node->offset < start.val) {
+ fprintf(stderr, "ERROR: Section '%s' starts too low\n",
+ node->name);
+ return false;
+ } else if (end.val_known && node->offset > end.val) {
+ fprintf(stderr, "ERROR: Section '%s' starts too high\n",
+ node->name);
+ return false;
+ }
+ }
+
+ if (node->size_known) {
+ if (node->size == 0) {
+ fprintf(stderr, "ERROR: Section '%s' given no space\n",
+ node->name);
+ return false;
+ } else if (node->offset_known) {
+ unsigned node_end = node->offset + node->size;
+ if (end.val_known && node_end > end.val) {
+ fprintf(stderr, "ERROR: Section '%s' too big\n",
+ node->name);
+ return false;
+ }
+ }
+ }
+
+ return true;
+}
+
+/*
+ * Performs reverse lateral processing of sibling nodes, as described by the
+ * documentation of its caller, validate_and_complete_info(). If it encounters
+ * a node that is invalid in a way that couldn't have been discovered earlier,
+ * it explains the problem to standard output and returns false.
+ *
+ * @param first_incomplete_it First node whose offset or size couldn't be
+ * determined during forward processing
+ * @param cur_incomplete_it Last node whose offset or size is unknown
+ * @param end_watermark Offset to the end of the unresolved region
+ * @return Whether all completed nodes were still valid
+ */
+static bool complete_missing_info_backward(
+ flashmap_descriptor_iterator_t first_incomplete_it,
+ flashmap_descriptor_iterator_t cur_incomplete_it,
+ unsigned end_watermark)
+{
+ assert(first_incomplete_it);
+ assert(cur_incomplete_it);
+ assert(cur_incomplete_it >= first_incomplete_it);
+
+ do {
+ struct flashmap_descriptor *cur = *cur_incomplete_it;
+
+ assert(cur->offset_known || cur->size_known);
+ if (!cur->offset_known) {
+ if (cur->size > end_watermark) {
+ fprintf(stderr, "ERROR: Section '%s' too big\n",
+ cur->name);
+ return false;
+ }
+ cur->offset_known = true;
+ cur->offset = end_watermark -= cur->size;
+ } else if (!cur->size_known) {
+ if (cur->offset > end_watermark) {
+ fprintf(stderr,
+ "ERROR: Section '%s' starts too high\n",
+ cur->name);
+ return false;
+ }
+ cur->size_known = true;
+ cur->size = end_watermark - cur->offset;
+ end_watermark = cur->offset;
+ }
+ } while (--cur_incomplete_it >= first_incomplete_it);
+
+ return true;
+}
+
+/*
+ * Recursively examine each descendant of the provided flashmap descriptor node
+ * to ensure its position and size are known, attempt to infer them otherwise,
+ * and validate their values once they've been populated.
+ * This processes nodes according to the following algorithm:
+ * - At each level of the tree, it moves laterally between siblings, keeping
+ * a watermark of its current offset relative to the previous section, which
+ * it uses to fill in any unknown offsets it encounters along the way.
+ * - The first time it encounters a sibling with unknown size, it loses track
+ * of the watermark, and is therefore unable to complete further offsets;
+ * instead, if the watermark was known before, it marks the current node as
+ * the first that couldn't be completed in the initial pass.
+ * - If the current watermark is unknown (i.e. a node has been marked as the
+ * first incomplete one) and one with a fixed offset is encountered, a
+ * reverse lateral traversal is dispatched that uses that provided offset as
+ * a reverse watermark to complete all unknown fields until it finishes with
+ * the node marked as the first incomplete one: at this point, that flag is
+ * cleared, the watermark is updated, and forward processing resumes from
+ * where it left off.
+ * - If the watermark is unknown (i.e. node(s) are incomplete) after traversing
+ * all children of a particular parent node, reverse processing is employed
+ * as described above, except that the reverse watermark is initialized to
+ * the parent node's size instead of the (nonexistent) next node's offset.
+ * - Once all of a node's children have been processed, the algorithm applies
+ * itself recursively to each of the child nodes; thus, lower levels of the
+ * tree are processed only after their containing levels are finished.
+ * This approach can fail in two possible ways (in which case the problem is
+ * reported to standard output and this function returns false):
+ * - Processing reveals that some node's provided value is invalid in some way.
+ * - Processing determines that one or more provided values require an omitted
+ * field to take a nonsensical value.
+ * - Processing determines that it is impossible to determine a group of
+ * omitted values. This state is detected when a node whose offset *and*
+ * value are omitted is encountered during forward processing and while the
+ * current watermark is unknown: in such a case, neither can be known without
+ * being provided with either the other or more context.
+ * The function notably performs neither validation nor completion on the parent
+ * node it is passed; thus, it is important to ensure that that node is valid.
+ * (At the very least, it must have a valid size field in order for the
+ * algorithm to work on its children.)
+ *
+ * @param cur_level Parent node, which must minimally already have a valid size
+ * @return Whether completing and validating the children succeeded
+ */
+static bool validate_and_complete_info(struct flashmap_descriptor *cur_level)
+{
+ assert(cur_level);
+ assert(cur_level->size_known);
+
+ // Our watermark is only known when first_incomplete_it is NULL.
+ flashmap_descriptor_iterator_t first_incomplete_it = NULL;
+ unsigned watermark = 0;
+
+ fmd_foreach_child_iterator(cur_it, cur_level) {
+ struct flashmap_descriptor *cur_section = *cur_it;
+
+ if (first_incomplete_it) {
+ if (cur_section->offset_known) {
+ if (complete_missing_info_backward(
+ first_incomplete_it, cur_it - 1,
+ cur_section->offset)) {
+ first_incomplete_it = NULL;
+ watermark = cur_section->offset;
+ } else {
+ return false;
+ }
+ }
+ // Otherwise, we can't go back until a provided offset.
+ } else if (!cur_section->offset_known) {
+ cur_section->offset_known = true;
+ cur_section->offset = watermark;
+ }
+
+ assert(cur_level->size_known);
+ struct unsigned_option max_endpoint = {true, cur_level->size};
+ if (cur_it != cur_level->list + cur_level->list_len - 1) {
+ struct flashmap_descriptor *next_section = cur_it[1];
+ max_endpoint.val_known = next_section->offset_known;
+ max_endpoint.val = next_section->offset;
+ }
+ if (!validate_descriptor_node(cur_section,
+ (struct unsigned_option)
+ {!first_incomplete_it, watermark},
+ max_endpoint))
+ return false;
+
+ if (!cur_section->size_known) {
+ if (!cur_section->offset_known) {
+ fprintf(stderr,
+ "ERROR: Cannot determine either offset or size of section '%s'\n",
+ cur_section->name);
+ return false;
+ } else if (!first_incomplete_it) {
+ first_incomplete_it = cur_it;
+ } else {
+ // We shouldn't find an unknown size within an
+ // incomplete region because the backward
+ // traversal at the beginning of this node's
+ // processing should have concluded said region.
+ assert(!first_incomplete_it);
+ }
+ } else if (!first_incomplete_it) {
+ watermark = cur_section->offset + cur_section->size;
+ }
+ }
+
+ if (first_incomplete_it &&
+ !complete_missing_info_backward(first_incomplete_it,
+ cur_level->list + cur_level->list_len - 1,
+ cur_level->size))
+ return false;
+
+ fmd_foreach_child(cur_section, cur_level) {
+ assert(cur_section->offset_known);
+ assert(cur_section->size_known);
+
+ if (!validate_and_complete_info(cur_section))
+ return false;
+ }
+
+ return true;
+}
+
+static void print_with_prefix(const struct flashmap_descriptor *tree,
+ const char *pre)
+{
+ assert(tree);
+ assert(pre);
+
+ printf("%ssection '%s' has ", pre, tree->name);
+
+ if (tree->offset_known)
+ printf("offset %uB, ", tree->offset);
+ else
+ fputs("unknown offset, ", stdout);
+
+ if (tree->size_known)
+ printf("size %uB, ", tree->size);
+ else
+ fputs("unknown size, ", stdout);
+
+ printf("and %zu subsections", tree->list_len);
+ if (tree->list_len) {
+ puts(":");
+
+ char child_prefix[strlen(pre) + 1];
+ strcpy(child_prefix, pre);
+ strcat(child_prefix, "\t");
+ fmd_foreach_child(each, tree)
+ print_with_prefix(each, child_prefix);
+ } else {
+ puts("");
+ }
+}
+
+struct flashmap_descriptor *fmd_create(FILE *stream)
+{
+ assert(stream);
+
+ yyin = stream;
+
+ struct flashmap_descriptor *ret = NULL;
+ if (yyparse() == 0)
+ ret = res;
+
+ yylex_destroy();
+ yyin = NULL;
+ res = NULL;
+
+ if (ret) {
+ // This hash table is used to store the declared name of each
+ // section and ensure that each is globally unique.
+ if (!hcreate(fmd_count_nodes(ret))) {
+ perror("ERROR: While initializing hashtable");
+ fmd_cleanup(ret);
+ return NULL;
+ }
+
+ // Even though we haven't checked that the root node (ret) has
+ // a size field as required by this function, the parser
+ // warrants that it does because the grammar requires it.
+ if (!validate_and_complete_info(ret)) {
+ hdestroy();
+ fmd_cleanup(ret);
+ return NULL;
+ }
+
+ hdestroy();
+ }
+
+ return ret;
+}
+
+void fmd_cleanup(struct flashmap_descriptor *victim)
+{
+ if (!victim)
+ return;
+
+ free(victim->name);
+ for (unsigned idx = 0; idx < victim->list_len; ++idx)
+ fmd_cleanup(victim->list[idx]);
+ free(victim->list);
+ free(victim);
+}
+
+size_t fmd_count_nodes(const struct flashmap_descriptor *tree)
+{
+ assert(tree);
+
+ if (!tree->list_len)
+ return 1;
+
+ unsigned count = 1;
+ fmd_foreach_child(lower, tree)
+ count += fmd_count_nodes(lower);
+ return count;
+}
+
+const struct flashmap_descriptor *fmd_find_node(
+ const struct flashmap_descriptor *root, const char *name)
+{
+ assert(root);
+ assert(name);
+
+ if (strcmp(root->name, name) == 0)
+ return root;
+
+ fmd_foreach_child(descendant, root) {
+ const struct flashmap_descriptor *match =
+ fmd_find_node(descendant, name);
+ if (match)
+ return match;
+ }
+ return NULL;
+}
+
+unsigned fmd_calc_absolute_offset(const struct flashmap_descriptor *root,
+ const char *name)
+{
+ assert(root);
+ assert(name);
+
+ if (strcmp(root->name, name) == 0)
+ return 0;
+
+ fmd_foreach_child(descendant, root) {
+ unsigned subtotal = fmd_calc_absolute_offset(descendant, name);
+ if (subtotal != FMD_NOTFOUND)
+ return descendant->offset + subtotal;
+ }
+ return FMD_NOTFOUND;
+}
+
+void fmd_print(const struct flashmap_descriptor *tree)
+{
+ print_with_prefix(tree, "");
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-05 03:09:24 +0000