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diff --git a/exefmt.txt b/exefmt.txt new file mode 100644 index 0000000..51fa9a7 --- /dev/null +++ b/exefmt.txt @@ -0,0 +1,593 @@ +INF: Executable-File Header Format [P_WinSDK] + +3.00 +WINDOWS +PSSONLY | Windows 3 Developers Notes softlib ENDUSER + +Summary: + +Note: This article is part of a set of seven articles, collectively +called the "Windows 3.00 Developer's Notes." More information about +the contents of the other articles, and procedures for ordering a +hard-copy set, can be found in the knowledge base article titled "INF: +The Windows 3.00 Developer's Notes" (Q65260). + +This article can be found in the Software/Data Library by searching on +the word EXEFMT or S12688. EXEFMT was archived using the PKware +file-compression utility. + +More Information: + +Microsoft defined the segmented executable file format for Windows +applications and dynamic-link libraries (DLLs). This file format is +also referred to as the New Executable Format. This new format is an +extension of the existing MS-DOS .EXE format (old-style format). The +purpose of the segmented executable format is to provide the +information needed to support the dynamic linking and segmentation +capabilities of the Windows environment. + +An executable file contains Microsoft Windows code and data, or +Windows code, data, and resources. Specific fields have been added to +the old-style .EXE format header to indicate the existence of the +segmented file format. The old-style header may contain a valid +executable program, called a stub program, that will be executed if +the program is run on MS-DOS (without Windows). This stub program +usually prints a message indicating that Microsoft Windows is required +to run the program. The segmented executable format extensions also +begin with a header that describes the contents and location of the +executable image in the file. The loader uses this header information +when it loads the executable segments in memory. + + +====================================================================== + OLD-STYLE HEADER EXTENSIONS +====================================================================== + +The old-style header contains information the loader expects for a DOS +executable file. It describes a stub program (WINSTUB) the loader can +place in memory when necessary, it points to the new-style header, and +it contains the stub programs relocation table. + +The following illustrates the distinct parts of the old-style +executable format: + + +-------------------------+ + 00h | Old-style header info | + +-------------------------+ + 20h | Reserved | + +-------------------------+ + 3Ch | Offset to segmented | + | .EXE header | + +-------------------------+ + 40h | Relocation table and | + | DOS stub program | + +-------------------------+ + | Segmented .EXE Header | + | . | + | . | + | . | + +The word at offset 18h in the old-style .EXE header contains the +relative byte offset to the stub program's relocation table. If this +offset is 40h, then the double word at offset 3Ch is assumed to be the +relative byte offset from the beginning of the file to the beginning +of the segmented executable header. A new-format .EXE file is +identified if the segmented executable header contains a valid +signature. If the signature is not valid, the file is assumed to be an +old-style format .EXE file. The remainder of the old-style format +header will describe a DOS program, the stub. The stub may be any +valid program but will typically be a program that displays an error +message. + +====================================================================== + SEGMENTED EXE FORMAT +====================================================================== + +Because Windows executable files are often larger than one segment +(64K), additional information (that does not appear in the old-style +header) is required so that the loader can load each segment properly. +The segmented EXE format was developed to provide the loader with this +information. + +The segmented .EXE file has the following format: + + +-----------------+ + 00h | Old-style EXE | + | Header | + +-----------------+ + 20h | Reserved | + +-----------------+ + 3Ch | Offset to | ---+ + | Segmented Header| | + +-----------------+ | + 40h | Relocation Table| | + | & Stub Program | | + +-----------------+ | + | | | + +-----------------+ | + xxh | Segmented EXE | <--+ + | Header | + +-----------------+ + | Segment Table | + +-----------------+ + | Resource Table | + +-----------------+ + | Resident Name | + | Table | + +-----------------+ + | Module Reference| + | Table | + +-----------------+ + | Imported Names | + | Table | + +-----------------+ + | Entry Table | + +-----------------+ + | Non-Resident | + | Name Table | + +-----------------+ + | Seg #1 Data | + | Seg #1 Info | + +-----------------+ + . + . + . + +-----------------+ + | Seg #n Data | + | Seg #n Info | + +-----------------+ + + +The following sections describe each of the components that make up +the segmented EXE format. Each section contains a description of the +component and the fields in the structures that make up that +component. + +Note: All unused fields and flag bits are reserved for future use and +must contain 0 (zero) values. + +====================================================================== + SEGMENTED EXE HEADER +====================================================================== + +The segmented EXE header contains general information about the EXE +file and contains information on the location and size of the other +sections. The Windows loader copies this section, along with other +data, into the module table in the system data. The module table is +internal data used by the loader to manage the loaded executable +modules in the system and to support dynamic linking. + +The following describes the format of the segmented executable header. +For each field, the offset is given relative to the beginning of the +segmented header, the size of the field is defined, and a description +is given. + + Offset Size Description + ------ ---- ----------- + + 00h DW Signature word. + "N" is low-order byte. + "E" is high-order byte. + + 02h DB Version number of the linker. + + 03h DB Revision number of the linker. + + 04h DW Entry Table file offset, relative to the beginning of + the segmented EXE header. + 06h DW Number of bytes in the entry table. + + 08h DD 32-bit CRC of entire contents of file. + These words are taken as 00 during the calculation. + + 0Ch DW Flag word. + 0000h = NOAUTODATA + 0001h = SINGLEDATA (Shared automatic data segment) + 0002h = MULTIPLEDATA (Instanced automatic data + segment) + 2000h = Errors detected at link time, module will not + load. + 8000h = Library module. + The SS:SP information is invalid, CS:IP points + to an initialization procedure that is called + with AX equal to the module handle. This + initialization procedure must perform a far + return to the caller, with AX not equal to + zero to indicate success, or AX equal to zero + to indicate failure to initialize. DS is set + to the library's data segment if the + SINGLEDATA flag is set. Otherwise, DS is set + to the caller's data segment. + + A program or DLL can only contain dynamic + links to executable files that have this + library module flag set. One program cannot + dynamic-link to another program. + + 0Eh DW Segment number of automatic data segment. + This value is set to zero if SINGLEDATA and + MULTIPLEDATA flag bits are clear, NOAUTODATA is + indicated in the flags word. + + A Segment number is an index into the module's segment + table. The first entry in the segment table is segment + number 1. + + 10h DW Initial size, in bytes, of dynamic heap added to the + data segment. This value is zero if no initial local + heap is allocated. + + 12h DW Initial size, in bytes, of stack added to the data + segment. This value is zero to indicate no initial + stack allocation, or when SS is not equal to DS. + + 14h DD Segment number:offset of CS:IP. + + 18h DD Segment number:offset of SS:SP. + If SS equals the automatic data segment and SP equals + zero, the stack pointer is set to the top of the + automatic data segment just below the additional heap + area. + + +--------------------------+ + | additional dynamic heap | + +--------------------------+ <- SP + | additional stack | + +--------------------------+ + | loaded auto data segment | + +--------------------------+ <- DS, SS + + 1Ch DW Number of entries in the Segment Table. + + 1Eh DW Number of entries in the Module Reference Table. + 20h DW Number of bytes in the Non-Resident Name Table. + + 22h DW Segment Table file offset, relative to the beginning + of the segmented EXE header. + + 24h DW Resource Table file offset, relative to the beginning + of the segmented EXE header. + + 26h DW Resident Name Table file offset, relative to the + beginning of the segmented EXE header. + + 28h DW Module Reference Table file offset, relative to the + beginning of the segmented EXE header. + + 2Ah DW Imported Names Table file offset, relative to the + beginning of the segmented EXE header. + + 2Ch DD Non-Resident Name Table offset, relative to the + beginning of the file. + + 30h DW Number of movable entries in the Entry Table. + + 32h DW Logical sector alignment shift count, log(base 2) of + the segment sector size (default 9). + + 34h DW Number of resource entries. + + 36h DB Executable type, used by loader. + 02h = WINDOWS + + 37h-3Fh DB Reserved, currently 0's. + + +====================================================================== + SEGMENT TABLE +====================================================================== + +The segment table contains an entry for each segment in the executable +file. The number of segment table entries are defined in the segmented +EXE header. The first entry in the segment table is segment number 1. +The following is the structure of a segment table entry. + + Size Description + ---- ----------- + + DW Logical-sector offset (n byte) to the contents of the segment + data, relative to the beginning of the file. Zero means no + file data. + + DW Length of the segment in the file, in bytes. Zero means 64K. + + DW Flag word. + 0007h = TYPE_MASK Segment-type field. + 0000h = CODE Code-segment type. + 0001h = DATA Data-segment type. + 0010h = MOVEABLE Segment is not fixed. + 0040h = PRELOAD Segment will be preloaded; read-only if + this is a data segment. + 0100h = RELOCINFO Set if segment has relocation records. + F000h = DISCARD Discard priority. + + DW Minimum allocation size of the segment, in bytes. Total size + of the segment. Zero means 64K. + + +====================================================================== + RESOURCE TABLE +====================================================================== + +The resource table follows the segment table and contains entries for +each resource in the executable file. The resource table consists of +an alignment shift count, followed by a table of resource records. The +resource records define the type ID for a set of resources. Each +resource record contains a table of resource entries of the defined +type. The resource entry defines the resource ID or name ID for the +resource. It also defines the location and size of the resource. The +following describes the contents of each of these structures: + + Size Description + ---- ----------- + + DW Alignment shift count for resource data. + + A table of resource type information blocks follows. The following + is the format of each type information block: + + DW Type ID. This is an integer type if the high-order bit is + set (8000h); otherwise, it is an offset to the type string, + the offset is relative to the beginning of the resource + table. A zero type ID marks the end of the resource type + information blocks. + + DW Number of resources for this type. + + DD Reserved. + + A table of resources for this type follows. The following is + the format of each resource (8 bytes each): + + DW File offset to the contents of the resource data, + relative to beginning of file. The offset is in terms + of the alignment shift count value specified at + beginning of the resource table. + + DW Length of the resource in the file (in bytes). + + DW Flag word. + 0010h = MOVEABLE Resource is not fixed. + 0020h = PURE Resource can be shared. + 0040h = PRELOAD Resource is preloaded. + + DW Resource ID. This is an integer type if the high-order + bit is set (8000h), otherwise it is the offset to the + resource string, the offset is relative to the + beginning of the resource table. + + DD Reserved. + + Resource type and name strings are stored at the end of the + resource table. Note that these strings are NOT null terminated and + are case sensitive. + + DB Length of the type or name string that follows. A zero value + indicates the end of the resource type and name string, also + the end of the resource table. + + DB ASCII text of the type or name string. + + +====================================================================== + RESIDENT-NAME TABLE +====================================================================== + +The resident-name table follows the resource table, and contains this +module's name string and resident exported procedure name strings. The +first string in this table is this module's name. These name strings +are case-sensitive and are not null-terminated. The following +describes the format of the name strings: + + Size Description + ---- ----------- + + DB Length of the name string that follows. A zero value indicates + the end of the name table. + + DB ASCII text of the name string. + + DW Ordinal number (index into entry table). This value is ignored + for the module name. + + +====================================================================== + MODULE-REFERENCE TABLE +====================================================================== + +The module-reference table follows the resident-name table. Each entry +contains an offset for the module-name string within the imported- +names table; each entry is 2 bytes long. + + Size Description + ---- ----------- + + DW Offset within Imported Names Table to referenced module name + string. + + +====================================================================== + IMPORTED-NAME TABLE +====================================================================== + +The imported-name table follows the module-reference table. This table +contains the names of modules and procedures that are imported by the +executable file. Each entry is composed of a 1-byte field that +contains the length of the string, followed by any number of +characters. The strings are not null-terminated and are case +sensitive. + + Size Description + ---- ----------- + + DB Length of the name string that follows. + + DB ASCII text of the name string. + + +====================================================================== + ENTRY TABLE +====================================================================== + +The entry table follows the imported-name table. This table contains +bundles of entry-point definitions. Bundling is done to save space in +the entry table. The entry table is accessed by an ordinal value. +Ordinal number one is defined to index the first entry in the entry +table. To find an entry point, the bundles are scanned searching for a +specific entry point using an ordinal number. The ordinal number is +adjusted as each bundle is checked. When the bundle that contains the +entry point is found, the ordinal number is multiplied by the size of +the bundle's entries to index the proper entry. + +The linker forms bundles in the most dense manner it can, under the +restriction that it cannot reorder entry points to improve bundling. +The reason for this restriction is that other .EXE files may refer to +entry points within this bundle by their ordinal number. The following +describes the format of the entry table bundles. + + Size Description + ---- ----------- + + DB Number of entries in this bundle. All records in one bundle + are either moveable or refer to the same fixed segment. A zero + value in this field indicates the end of the entry table. + + DB Segment indicator for this bundle. This defines the type of + entry table entry data within the bundle. There are three + types of entries that are defined. + + 000h = Unused entries. There is no entry data in an unused + bundle. The next bundle follows this field. This is + used by the linker to skip ordinal numbers. + + 001h-0FEh = Segment number for fixed segment entries. A fixed + segment entry is 3 bytes long and has the following + format. + + DB Flag word. + 01h = Set if the entry is exported. + 02h = Set if the entry uses a global (shared) data + segments. + The first assembly-language instruction in the + entry point prologue must be "MOV AX,data + segment number". This may be set only for + SINGLEDATA library modules. + + DW Offset within segment to entry point. + + 0FFH = Moveable segment entries. The entry data contains the + segment number for the entry points. A moveable segment + entry is 6 bytes long and has the following format. + + DB Flag word. + 01h = Set if the entry is exported. + 02h = Set if the entry uses a global (shared) data + segments. + + INT 3FH. + + DB Segment number. + + DW Offset within segment to entry point. + + +====================================================================== + NONRESIDENT-NAME TABLE +====================================================================== + +The nonresident-name table follows the entry table, and contains a +module description and nonresident exported procedure name strings. +The first string in this table is a module description. These name +strings are case-sensitive and are not null-terminated. The name +strings follow the same format as those defined in the resident name +table. + + +====================================================================== + PER SEGMENT DATA +====================================================================== + +The location and size of the per-segment data is defined in the +segment table entry for the segment. If the segment has relocation +fixups, as defined in the segment table entry flags, they directly +follow the segment data in the file. The relocation fixup information +is defined as follows: + + + Size Description + ---- ----------- + + DW Number of relocation records that follow. + + A table of relocation records follows. The following is the format + of each relocation record. + + DB Source type. + 0Fh = SOURCE_MASK + 00h = LOBYTE + 02h = SEGMENT + 03h = FAR_ADDR (32-bit pointer) + 05h = OFFSET (16-bit offset) + + DB Flags byte. + 03h = TARGET_MASK + 00h = INTERNALREF + 01h = IMPORTORDINAL + 02h = IMPORTNAME + 03h = OSFIXUP + 04h = ADDITIVE + + DW Offset within this segment of the source chain. + If the ADDITIVE flag is set, then target value is added to + the source contents, instead of replacing the source and + following the chain. The source chain is an 0FFFFh + terminated linked list within this segment of all + references to the target. + + The target value has four types that are defined in the flag + byte field. The following are the formats for each target + type: + + INTERNALREF + + DB Segment number for a fixed segment, or 0FFh for a + movable segment. + + DB 0 + + DW Offset into segment if fixed segment, or ordinal + number index into Entry Table if movable segment. + + IMPORTNAME + + DW Index into module reference table for the imported + module. + + DW Offset within Imported Names Table to procedure name + string. + + IMPORTORDINAL + + DW Index into module reference table for the imported + module. + DW Procedure ordinal number. + + OSFIXUP + + DW Operating system fixup type. + Floating-point fixups. + 0001h = FIARQQ, FJARQQ + 0002h = FISRQQ, FJSRQQ + 0003h = FICRQQ, FJCRQQ + 0004h = FIERQQ + 0005h = FIDRQQ + 0006h = FIWRQQ + + DW 0 + +====================================================================== + +Microsoft is a registered trademark and Windows is a trademark of +Microsoft Corporation. + +Additional reference words: 3.0 |