mapper: add a file mapper that freads file chunks

It needs to be tested if this is faster or slower than the mmap.

include/sqsh_error.h

@@ -101,6 +101,7 @@ enum SqshError {
 	SQSH_ERROR_INODE_PARENT_MISMATCH,
 	SQSH_ERROR_INODE_PARENT_UNSET,
 	SQSH_ERROR_NOT_A_SYMLINK,
+	SQSH_ERROR_READ_FAILED,
 };
 
 /**

include/sqsh_mapper.h

@@ -145,6 +145,15 @@ extern const struct SqshMemoryMapperImpl *const sqsh_mapper_impl_mmap;
  */
 extern const struct SqshMemoryMapperImpl *const sqsh_mapper_impl_static;
 
+/***************************************
+ * mapper/static_file.c
+ */
+
+/**
+ * @brief a mapper that uses a static buffer.
+ */
+extern const struct SqshMemoryMapperImpl *const sqsh_mapper_impl_file;
+
 #ifdef __cplusplus
 }
 #endif

libsqsh/src/mapper/file_mapper.c

@@ -0,0 +1,123 @@
+/******************************************************************************
+ *                                                                            *
+ * Copyright (c) 2023, Enno Boland <[email protected]>                                 *
+ *                                                                            *
+ * Redistribution and use in source and binary forms, with or without         *
+ * modification, are permitted provided that the following conditions are     *
+ * met:                                                                       *
+ *                                                                            *
+ * * Redistributions of source code must retain the above copyright notice,   *
+ *   this list of conditions and the following disclaimer.                    *
+ * * Redistributions in binary form must reproduce the above copyright        *
+ *   notice, this list of conditions and the following disclaimer in the      *
+ *   documentation and/or other materials provided with the distribution.     *
+ *                                                                            *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS    *
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,  *
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR     *
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR          *
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,      *
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,        *
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR         *
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF     *
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING       *
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS         *
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.               *
+ *                                                                            *
+ ******************************************************************************/
+
+/**
+ * @author       Enno Boland ([email protected])
+ * @file         mmap_mapper.c
+ */
+
+#define _DEFAULT_SOURCE
+
+#include <sqsh_common_private.h>
+#include <sqsh_error.h>
+#include <sqsh_mapper.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <sys/stat.h>
+
+static int
+sqsh_mapper_file_init(
+		struct SqshMapper *mapper, const void *input, size_t *size) {
+	(void)size;
+	int rv = 0;
+	FILE *file;
+	int fd;
+	struct stat st = {0};
+
+	file = fopen(input, "r");
+	if (file == NULL) {
+		rv = -errno;
+		goto out;
+	}
+
+	fd = fileno(file);
+
+	if (fstat(fd, &st) < 0) {
+		fclose(file);
+		rv = -errno;
+		goto out;
+	}
+
+	// TODO: check for overflow.
+	*size = (size_t)st.st_size;
+	sqsh_mapper_set_user_data(mapper, file);
+
+out:
+	return rv;
+}
+static int
+sqsh_mapping_file_map(
+		const struct SqshMapper *mapper, sqsh_index_t offset, size_t size,
+		uint8_t **data) {
+	int rv = 0;
+	FILE *file = sqsh_mapper_user_data(mapper);
+
+	if (size != 0) {
+		*data = calloc(size, sizeof(uint8_t));
+		if (*data == NULL) {
+			rv = -SQSH_ERROR_MALLOC_FAILED;
+			goto out;
+		}
+		fseek(file, (long)offset, SEEK_SET);
+		if (fread(*data, sizeof(uint8_t), size, file) != size) {
+			rv = -SQSH_ERROR_READ_FAILED;
+			goto out;
+		}
+	}
+
+out:
+	if (rv < 0) {
+		free(*data);
+	}
+	return rv;
+}
+
+static int
+sqsh_mapper_file_cleanup(struct SqshMapper *mapper) {
+	FILE *file = sqsh_mapper_user_data(mapper);
+	fclose(file);
+	return 0;
+}
+
+static int
+sqsh_mapping_file_unmap(
+		const struct SqshMapper *mapper, uint8_t *data, size_t size) {
+	(void)mapper;
+	(void)size;
+	free(data);
+	return 0;
+}
+
+static const struct SqshMemoryMapperImpl impl = {
+		/* 1 MiB */
+		.block_size_hint = 1024 * 1024,      .init = sqsh_mapper_file_init,
+		.map = sqsh_mapping_file_map,        .unmap = sqsh_mapping_file_unmap,
+		.cleanup = sqsh_mapper_file_cleanup,
+};
+const struct SqshMemoryMapperImpl *const sqsh_mapper_impl_file = &impl;

libsqsh/src/meson.build

@@ -28,6 +28,7 @@ libsqsh_sources = files(
     'file/inode_null.c',
     'file/inode_symlink.c',
     'mapper/curl_mapper.c',
+    'mapper/file_mapper.c',
     'mapper/map_iterator.c',
     'mapper/map_manager.c',
     'mapper/map_reader.c',

libsqsh/src/utils/error.c

@@ -158,6 +158,8 @@ sqsh_error_str(int error_code) {
 		return "Not a symlink";
 	case SQSH_ERROR_INODE_PARENT_UNSET:
 		return "Inode parent unset";
+	case SQSH_ERROR_READ_FAILED:
+		return "Read failed";
 	}
 	snprintf(err_str, sizeof(err_str), UNKNOWN_ERROR_FORMAT, error_code);
 	return err_str;

tools/src/common.c

@@ -38,7 +38,6 @@ struct SqshArchive *
 open_archive(const char *image_path, uint64_t offset, int *err) {
 	struct SqshConfig config = {
 			.source_mapper = NULL,
-			.mapper_block_size = 1024 * 256,
 			.archive_offset = offset,
 	};
 	if (sqsh_mapper_impl_curl != NULL) {