X-Git-Url: https://wimlib.net/git/?p=wimlib;a=blobdiff_plain;f=src%2Fheader.c;h=0066d75a3ba7b6d9d5db40a506c4fb9b75154327;hp=c0518ecbabb820bec1933cc5c91d18aeb77173a7;hb=30ba1eb06caca0b20a47d8dd75a117c82d730da7;hpb=2e44f90c21db693058037f83f92ad136c818ce9d diff --git a/src/header.c b/src/header.c index c0518ecb..0066d75a 100644 --- a/src/header.c +++ b/src/header.c @@ -29,7 +29,7 @@ #include "wimlib.h" #include "wimlib/assert.h" -#include "wimlib/buffer_io.h" +#include "wimlib/endianness.h" #include "wimlib/error.h" #include "wimlib/file_io.h" #include "wimlib/header.h" @@ -37,73 +37,131 @@ #include "wimlib/wim.h" #include +#include + +/* WIM magic characters, translated to a single 64-bit little endian number. */ +#define WIM_MAGIC \ + cpu_to_le64(((u64)'M' << 0) | \ + ((u64)'S' << 8) | \ + ((u64)'W' << 16) | \ + ((u64)'I' << 24) | \ + ((u64)'M' << 32) | \ + ((u64)'\0' << 40) | \ + ((u64)'\0' << 48) | \ + ((u64)'\0' << 54)) + +/* On-disk format of the WIM header. */ +struct wim_header_disk { + + /* Magic characters "MSWIM\0\0\0" */ + le64 magic; + + /* Size of the WIM header, in bytes; WIM_HEADER_DISK_SIZE expected + * (currently the only supported value). */ + u32 hdr_size; + + /* Version of the WIM file; WIM_VERSION expected (currently the only + * supported value). */ + u32 wim_version; + + /* Flags for the WIM file (WIM_HDR_FLAG_*) */ + u32 wim_flags; + + /* Uncompressed chunk size of resources in the WIM. 0 if the WIM is + * uncompressed. If compressed, WIM_CHUNK_SIZE is expected (currently + * the only supported value). */ + u32 chunk_size; + + /* Globally unique identifier for the WIM file. Basically bunch of + * random bytes. */ + u8 guid[WIM_GID_LEN]; + + /* Number of this WIM part in the split WIM file, indexed from 1, or 1 + * if the WIM is not split. */ + u16 part_number; + + /* Total number of parts of the split WIM file, or 1 if the WIM is not + * split. */ + u16 total_parts; + + /* Number of images in the WIM. */ + u32 image_count; + + /* Location and size of the WIM's lookup table. */ + struct resource_entry_disk lookup_table_res_entry; + + /* Location and size of the WIM's XML data. */ + struct resource_entry_disk xml_data_res_entry; + + /* Location and size of metadata resource for the bootable image of the + * WIM, or all zeroes if no image is bootable. */ + struct resource_entry_disk boot_metadata_res_entry; + + /* 1-based index of the bootable image of the WIM, or 0 if no image is + * bootable. */ + u32 boot_idx; + + /* Location and size of the WIM's integrity table, or all zeroes if the + * WIM has no integrity table. */ + + /* Note the integrity_table_res_entry here is 4-byte aligned even though + * it would ordinarily be 8-byte aligned--- hence, the _packed_attribute + * on the `struct wim_header_disk' is essential. */ + struct resource_entry_disk integrity_table_res_entry; -/* First 8 bytes in every WIM file. */ -static const u8 wim_magic_chars[WIM_MAGIC_LEN] = { - 'M', 'S', 'W', 'I', 'M', '\0', '\0', '\0' }; + /* Unused bytes. */ + u8 unused[60]; +} _packed_attribute; /* Reads the header from a WIM file. */ int read_header(const tchar *filename, int in_fd, struct wim_header *hdr, int open_flags) { - size_t bytes_read; - u8 buf[WIM_HEADER_DISK_SIZE]; - const void *p; + struct wim_header_disk disk_hdr _aligned_attribute(8); - u32 hdr_size; - u32 wim_version; - u32 chunk_size; - - DEBUG("Reading WIM header from \"%"TS"\".", filename); + DEBUG("Reading WIM header from \"%"TS"\"", filename); - bytes_read = full_pread(in_fd, buf, WIM_HEADER_DISK_SIZE, 0); - - if (bytes_read != WIM_HEADER_DISK_SIZE) { + if (full_pread(in_fd, &disk_hdr, sizeof(disk_hdr), 0) != sizeof(disk_hdr)) { ERROR_WITH_ERRNO("\"%"TS"\": Error reading header", filename); return WIMLIB_ERR_READ; } - p = buf; - if (memcmp(p, wim_magic_chars, WIM_MAGIC_LEN)) { + if (disk_hdr.magic != WIM_MAGIC) { ERROR("\"%"TS"\": Invalid magic characters in header", filename); return WIMLIB_ERR_NOT_A_WIM_FILE; } - /* Byte 8 */ - p = get_u32(p + 8, &hdr_size); - if (hdr_size != WIM_HEADER_DISK_SIZE) { - ERROR("\"%"TS"\": Header is %u bytes (expected %u bytes)", - filename, hdr_size, WIM_HEADER_DISK_SIZE); + BUILD_BUG_ON(sizeof(struct wim_header_disk) != WIM_HEADER_DISK_SIZE); + if (le32_to_cpu(disk_hdr.hdr_size) != sizeof(struct wim_header_disk)) { + ERROR("\"%"TS"\": Header size is invalid (%u bytes)", + filename, le32_to_cpu(disk_hdr.hdr_size)); return WIMLIB_ERR_INVALID_HEADER_SIZE; } - /* Byte 12 */ - p = get_u32(buf + WIM_MAGIC_LEN + sizeof(u32), &wim_version); - if (wim_version != WIM_VERSION) { + if (le32_to_cpu(disk_hdr.wim_version) != WIM_VERSION) { ERROR("\"%"TS"\": The WIM header says the WIM version is %u, " "but wimlib only knows about version %u", - filename, wim_version, WIM_VERSION); + filename, le32_to_cpu(disk_hdr.wim_version), WIM_VERSION); return WIMLIB_ERR_UNKNOWN_VERSION; } - p = get_u32(p, &hdr->flags); - p = get_u32(p, &chunk_size); - if (chunk_size != WIM_CHUNK_SIZE && + hdr->flags = le32_to_cpu(disk_hdr.wim_flags); + if (le32_to_cpu(disk_hdr.chunk_size) != WIM_CHUNK_SIZE && (hdr->flags & WIM_HDR_FLAG_COMPRESSION)) { ERROR("\"%"TS"\": Unexpected chunk size of %u! Ask the author to " "implement support for other chunk sizes.", - filename, chunk_size); + filename, le32_to_cpu(disk_hdr.chunk_size)); ERROR("(Or it might just be that the WIM header is invalid.)"); return WIMLIB_ERR_INVALID_CHUNK_SIZE; } - p = get_bytes(p, WIM_GID_LEN, hdr->guid); - p = get_u16(p, &hdr->part_number); - p = get_u16(p, &hdr->total_parts); + memcpy(hdr->guid, disk_hdr.guid, WIM_GID_LEN); + + hdr->part_number = le16_to_cpu(disk_hdr.part_number); + hdr->total_parts = le16_to_cpu(disk_hdr.total_parts); - if (hdr->total_parts == 0 || - hdr->part_number == 0 || + if (hdr->total_parts == 0 || hdr->part_number == 0 || hdr->part_number > hdr->total_parts) { ERROR("\"%"TS"\": Invalid WIM part number: %hu of %hu", @@ -111,15 +169,14 @@ read_header(const tchar *filename, int in_fd, return WIMLIB_ERR_INVALID_PART_NUMBER; } - if (!(open_flags & WIMLIB_OPEN_FLAG_SPLIT_OK) && - hdr->total_parts != 1) + if (!(open_flags & WIMLIB_OPEN_FLAG_SPLIT_OK) && hdr->total_parts != 1) { ERROR("\"%"TS"\": This WIM is part %u of a %u-part WIM", filename, hdr->part_number, hdr->total_parts); return WIMLIB_ERR_SPLIT_UNSUPPORTED; } - p = get_u32(p, &hdr->image_count); + hdr->image_count = le32_to_cpu(disk_hdr.image_count); DEBUG("part_number = %u, total_parts = %u, image_count = %u", hdr->part_number, hdr->total_parts, hdr->image_count); @@ -130,26 +187,11 @@ read_header(const tchar *filename, int in_fd, return WIMLIB_ERR_IMAGE_COUNT; } - /* Byte 48 */ - - p = get_resource_entry(p, &hdr->lookup_table_res_entry); - p = get_resource_entry(p, &hdr->xml_res_entry); - p = get_resource_entry(p, &hdr->boot_metadata_res_entry); - - /* Byte 120 */ - - p = get_u32(p, &hdr->boot_idx); - - /* Byte 124 */ - - p = get_resource_entry(p, &hdr->integrity); - - /* Byte 148 */ - - /* 60 bytes of unused stuff. */ - - /* Byte 208 */ - + get_resource_entry(&disk_hdr.lookup_table_res_entry, &hdr->lookup_table_res_entry); + get_resource_entry(&disk_hdr.xml_data_res_entry, &hdr->xml_res_entry); + get_resource_entry(&disk_hdr.boot_metadata_res_entry, &hdr->boot_metadata_res_entry); + hdr->boot_idx = le32_to_cpu(disk_hdr.boot_idx); + get_resource_entry(&disk_hdr.integrity_table_res_entry, &hdr->integrity); return 0; } @@ -164,34 +206,28 @@ read_header(const tchar *filename, int in_fd, int write_header(const struct wim_header *hdr, int out_fd) { - u8 buf[WIM_HEADER_DISK_SIZE]; - u8 *p; + struct wim_header_disk disk_hdr _aligned_attribute(8); DEBUG("Writing WIM header."); - p = put_bytes(buf, WIM_MAGIC_LEN, wim_magic_chars); - p = put_u32(p, WIM_HEADER_DISK_SIZE); - p = put_u32(p, WIM_VERSION); - p = put_u32(p, hdr->flags); - p = put_u32(p, (hdr->flags & WIM_HDR_FLAG_COMPRESSION) ? - WIM_CHUNK_SIZE : 0); - /* Byte 24 */ - - p = put_bytes(p, WIM_GID_LEN, hdr->guid); - p = put_u16(p, hdr->part_number); - - /* Byte 40 */ - - p = put_u16(p, hdr->total_parts); - p = put_u32(p, hdr->image_count); - p = put_resource_entry(p, &hdr->lookup_table_res_entry); - p = put_resource_entry(p, &hdr->xml_res_entry); - p = put_resource_entry(p, &hdr->boot_metadata_res_entry); - p = put_u32(p, hdr->boot_idx); - p = put_resource_entry(p, &hdr->integrity); - p = put_zeroes(p, WIM_UNUSED_LEN); - wimlib_assert(p - buf == sizeof(buf)); - - if (full_pwrite(out_fd, buf, sizeof(buf), 0) != sizeof(buf)) { + disk_hdr.magic = WIM_MAGIC; + disk_hdr.hdr_size = cpu_to_le32(sizeof(struct wim_header_disk)); + disk_hdr.wim_version = cpu_to_le32(WIM_VERSION); + disk_hdr.wim_flags = cpu_to_le32(hdr->flags); + disk_hdr.chunk_size = cpu_to_le32((hdr->flags & WIM_HDR_FLAG_COMPRESSION) ? + WIM_CHUNK_SIZE : 0); + memcpy(disk_hdr.guid, hdr->guid, WIM_GID_LEN); + + disk_hdr.part_number = cpu_to_le16(hdr->part_number); + disk_hdr.total_parts = cpu_to_le16(hdr->total_parts); + disk_hdr.image_count = cpu_to_le32(hdr->image_count); + put_resource_entry(&hdr->lookup_table_res_entry, &disk_hdr.lookup_table_res_entry); + put_resource_entry(&hdr->xml_res_entry, &disk_hdr.xml_data_res_entry); + put_resource_entry(&hdr->boot_metadata_res_entry, &disk_hdr.boot_metadata_res_entry); + disk_hdr.boot_idx = cpu_to_le32(hdr->boot_idx); + put_resource_entry(&hdr->integrity, &disk_hdr.integrity_table_res_entry); + memset(disk_hdr.unused, 0, sizeof(disk_hdr.unused)); + + if (full_pwrite(out_fd, &disk_hdr, sizeof(disk_hdr), 0) != sizeof(disk_hdr)) { ERROR_WITH_ERRNO("Failed to write WIM header"); return WIMLIB_ERR_WRITE; }