Cleanup: move utilities back out of libsquashfs

This commit removes the allocation helpers and string table functions
out of libsquashfs back into a "libutil.a". The problem of libsquashfs
exporting stuff that it shouldn't is resolved by retaining the internal
attributes and directly adding the source to libsquashfs instead of
trying to somehow link against libutil.la.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

3 files changed, 217 insertions, 0 deletions

diff --git a/lib/util/Makemodule.am b/lib/util/Makemodule.am
new file mode 100644
index 0000000..f5a5680
--- /dev/null
+++ b/lib/util/Makemodule.am
@@ -0,0 +1,6 @@
+libutil_a_SOURCES = include/util.h include/str_table.h
+libutil_a_SOURCES += lib/util/str_table.c lib/util/alloc.c
+libutil_a_CFLAGS = $(AM_CFLAGS)
+libutil_a_CPPFLAGS = $(AM_CPPFLAGS)
+
+noinst_LIBRARIES += libutil.a
diff --git a/lib/util/alloc.c b/lib/util/alloc.c
new file mode 100644
index 0000000..e8305d8
--- /dev/null
+++ b/lib/util/alloc.c
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: LGPL-3.0-or-later */
+/*
+ * alloc.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "config.h"
+
+#include "util.h"
+
+#include <stdlib.h>
+#include <errno.h>
+
+void *alloc_flex(size_t base_size, size_t item_size, size_t nmemb)
+{
+	size_t size;
+
+	if (SZ_MUL_OV(nmemb, item_size, &size) ||
+	    SZ_ADD_OV(base_size, size, &size)) {
+		errno = EOVERFLOW;
+		return NULL;
+	}
+
+	return calloc(1, size);
+}
+
+void *alloc_array(size_t item_size, size_t nmemb)
+{
+	size_t size;
+
+	if (SZ_MUL_OV(nmemb, item_size, &size)) {
+		errno = EOVERFLOW;
+		return NULL;
+	}
+
+	return calloc(1, size);
+}
diff --git a/lib/util/str_table.c b/lib/util/str_table.c
new file mode 100644
index 0000000..c0a364f
--- /dev/null
+++ b/lib/util/str_table.c
@@ -0,0 +1,174 @@
+/* SPDX-License-Identifier: LGPL-3.0-or-later */
+/*
+ * str_table.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "config.h"
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "sqfs/error.h"
+#include "str_table.h"
+#include "util.h"
+
+/* R5 hash function (borrowed from reiserfs) */
+static sqfs_u32 strhash(const char *s)
+{
+	const signed char *str = (const signed char *)s;
+	sqfs_u32 a = 0;
+
+	while (*str != '\0') {
+		a += *str << 4;
+		a += *str >> 4;
+		a *= 11;
+		str++;
+	}
+
+	return a;
+}
+
+static int strings_grow(str_table_t *table)
+{
+	size_t newsz;
+	void *new;
+
+	if (table->num_strings < table->max_strings)
+		return 0;
+
+	newsz = table->max_strings ? (table->max_strings * 2) : 16;
+	new = realloc(table->strings, sizeof(table->strings[0]) * newsz);
+
+	if (new == NULL)
+		return SQFS_ERROR_ALLOC;
+
+	table->strings = new;
+	table->max_strings = newsz;
+	return 0;
+}
+
+int str_table_init(str_table_t *table, size_t size)
+{
+	memset(table, 0, sizeof(*table));
+
+	table->buckets = alloc_array(size, sizeof(table->buckets[0]));
+	table->num_buckets = size;
+
+	if (table->buckets == NULL)
+		return SQFS_ERROR_ALLOC;
+
+	return 0;
+}
+
+void str_table_cleanup(str_table_t *table)
+{
+	str_bucket_t *bucket;
+	size_t i;
+
+	for (i = 0; i < table->num_buckets; ++i) {
+		while (table->buckets[i] != NULL) {
+			bucket = table->buckets[i];
+			table->buckets[i] = bucket->next;
+
+			free(bucket->str);
+			free(bucket);
+		}
+	}
+
+	free(table->buckets);
+	free(table->strings);
+	memset(table, 0, sizeof(*table));
+}
+
+int str_table_get_index(str_table_t *table, const char *str, size_t *idx)
+{
+	str_bucket_t *bucket;
+	sqfs_u32 hash;
+	size_t index;
+	int err;
+
+	hash = strhash(str);
+	index = hash % table->num_buckets;
+	bucket = table->buckets[index];
+
+	while (bucket != NULL) {
+		if (strcmp(bucket->str, str) == 0) {
+			*idx = bucket->index;
+			return 0;
+		}
+
+		bucket = bucket->next;
+	}
+
+	err = strings_grow(table);
+	if (err)
+		return err;
+
+	bucket = calloc(1, sizeof(*bucket));
+	if (bucket == NULL)
+		goto fail_oom;
+
+	bucket->str = strdup(str);
+	if (bucket->str == NULL)
+		goto fail_oom;
+
+	bucket->index = table->num_strings;
+	table->strings[table->num_strings++] = bucket->str;
+	*idx = bucket->index;
+
+	bucket->next = table->buckets[index];
+	table->buckets[index] = bucket;
+	return 0;
+fail_oom:
+	free(bucket);
+	return SQFS_ERROR_ALLOC;
+}
+
+const char *str_table_get_string(str_table_t *table, size_t index)
+{
+	if (index >= table->num_strings)
+		return NULL;
+
+	return table->strings[index];
+}
+
+static str_bucket_t *bucket_by_index(str_table_t *table, size_t index)
+{
+	str_bucket_t *bucket = NULL;
+	sqfs_u32 hash;
+
+	if (index < table->num_strings) {
+		hash = strhash(table->strings[index]);
+		bucket = table->buckets[hash % table->num_buckets];
+
+		while (bucket != NULL && bucket->index != index)
+			bucket = bucket->next;
+	}
+
+	return bucket;
+}
+
+void str_table_add_ref(str_table_t *table, size_t index)
+{
+	str_bucket_t *bucket = bucket_by_index(table, index);
+
+	if (bucket != NULL && bucket->refcount < ~((size_t)0))
+		bucket->refcount += 1;
+}
+
+void str_table_del_ref(str_table_t *table, size_t index)
+{
+	str_bucket_t *bucket = bucket_by_index(table, index);
+
+	if (bucket != NULL && bucket->refcount > 0)
+		bucket->refcount -= 1;
+}
+
+size_t str_table_get_ref_count(str_table_t *table, size_t index)
+{
+	str_bucket_t *bucket = bucket_by_index(table, index);
+
+	return bucket != NULL ? bucket->refcount : 0;
+}