From 45f221c5f5f27258ea56a1552ec27a193b85853b Mon Sep 17 00:00:00 2001 From: CleverMouse Date: Mon, 24 Oct 2016 18:44:58 +0000 Subject: [PATCH] command line parser for the system library git-svn-id: svn://kolibrios.org@6614 a494cfbc-eb01-0410-851d-a64ba20cac60 --- programs/system/os/cmdline.inc | 229 ++++++++++++++++++++++++++++ programs/system/os/cmdline_test.asm | 121 +++++++++++++++ programs/system/os/fpo.inc | 8 +- programs/system/os/kolibri.asm | 183 ++++++++++++++++++---- programs/system/os/pe.inc | 12 ++ programs/system/os/peloader.inc | 141 +++++++++++++++++ 6 files changed, 660 insertions(+), 34 deletions(-) create mode 100644 programs/system/os/cmdline.inc create mode 100644 programs/system/os/cmdline_test.asm create mode 100644 programs/system/os/peloader.inc diff --git a/programs/system/os/cmdline.inc b/programs/system/os/cmdline.inc new file mode 100644 index 0000000000..d6d2e42e05 --- /dev/null +++ b/programs/system/os/cmdline.inc @@ -0,0 +1,229 @@ +; Splits command line to argv array. +; Uses standard Windows rules: +; * in normal mode, arguments are separated with spaces and tabs, +; duplicate spaces and tabs are ignored +; (two sequential spaces are the same as one); +; * unescaped quote " in normal mode starts quoted mode, +; it does not end the current argument, it is not included in the argument; +; * spaces and tabs in quoted mode are included in the argument as is; +; * unescaped quote " in quoted mode returns to normal mode, +; it does not end the current argument, it is not included in the argument; +; * quotes can be escaped with backslashes \ in both modes +; (the recommended way), \" means copying " to the argument +; without switching modes; +; * backslashes not before a quote are just regular characters, +; backslashes before a quote should be escaped by another backslash: +; " means unescaped quote +; \" means character " +; \\" means character \ plus unescaped quote +; \\\" means characters \" +; and so on; +; * quotes in quoted mode can also be escaped by doubling them, "" +; (the confusing way); note that in normal mode "" means empty argument. +; For example, the command line +; begin"quoted mode"end\ \"escaped" "quotes" "1\" "" """escaped quotes 2""" +; has 4 arguments: +; 1) beginquoted modeend\ +; 2) "escaped quotes 1" +; 3) +; 4) "escaped quotes 2" +; The recommended way to create a command line with the same arguments: +; "beginquoted modeend"\ "\"escaped quotes 1\"" "\"escaped quotes 2\"". +; +; in: esi -> command line +; in: edi -> data for arguments, maybe null +; in: edx -> pointers to arguments, maybe null +; out: ebx = argument count +; +; There are too many branches and labels here, +; isolate some of them into macro. +macro start_arg +; Increments argument count; +; if arguments are tracked, stores the current address. +{ +local .label + test edx, edx + jz .label + mov [edx], edi + add edx, 4 +.label: + inc ebx +} +; In typical cases decoded arguments and input line have large chunks in common. +; When going through the input string, we do not copy arguments immediately, +; but track size of last chunk that should be copied instead. +; This macros copies the last chunk of data if arguments are tracked. +; If arguments are tracked, ecx is reset to zero; +; otherwise, we do not care about ecx. +macro copy_arg_data +{ +local .label + test edi, edi + jz .label + dec esi + sub esi, ecx + rep movsb + inc esi +.label: +} +; Process backslash. +macro process_slash +{ +; 1. Count number of backslashes. +local .label1, .label2 + xor ecx, ecx +.label1: + inc ecx + mov al, byte [esi] + inc esi + cmp al, '\' + jz .label1 +; 2. If the next character is not ", backslash is a regular character; +; copy all of them. + cmp al, '"' + jnz .label2 +; 3. If the next character is ", then only half of backslashes +; should be copied, other are escaping characters. +; If number of backslashes is odd, include " to copied chunk +; and advance to the next character. + shr ecx, 1 + jnc .label2 + mov al, byte [esi] + inc esi + inc ecx +.label2: + copy_arg_data +} + +; Parser procedure. +proc parse_cmdline +; Registers: +; ebx = argc = argument count +; ecx = size of last chunk if edi is nonzero, garbage otherwise +; al = current input character = [esi-1] +; esi = pointer to input past the current character +; edi = zero or pointer to the next output data +; edx = zero or pointer to the next output pointer + xor ebx, ebx + xor ecx, ecx +; There are two large blocks of code for normal and quoted modes. +; We start in normal mode. +; 1. Processing in normal mode. +; 1a. Skip initial spaces and tabs. +.skip_spaces: + mov al, byte [esi] + inc esi + cmp al, ' ' + jz .skip_spaces + cmp al, 9 + jz .skip_spaces +; 1b. If the command line has ended, exit. + test al, al + jz .done +; 1c. Any character in this state starts a new argument. + start_arg +; 1d. Loop over the input string, watching for one of: +; (space), (tab), (terminator), ", \ +; All other characters should be copied as is. +; The first character here cannot be (space), (tab) or (terminator), +; but " and \ are possible. For these, skip 1e, because we have nothing +; to copy yet, and go directly where 1f would direct us. + cmp al, '"' + jz .enter_quoted_mode + cmp al, '\' + jz .slash_normal +.normal_mode: + inc ecx +.enter_normal_mode: + mov al, byte [esi] + inc esi +.reenter_normal_mode: + cmp al, ' ' + jz .copydata + cmp al, 9 + jz .copydata + test al, al + jz .copydata + cmp al, '\' + jz .copydata + cmp al, '"' + jnz .normal_mode +.copydata: +; 1e. Copy the found chunk. + copy_arg_data +; 1f. One of (space), (tab), (terminator), ", \ is found. +; For terminator, end the current argument and exit. +; For \, go to 1h. +; For ", switch to quoted mode. + test al, al + jz .done_termarg + cmp al, '\' + jz .slash_normal + cmp al, '"' + jz .enter_quoted_mode +; 1g. If we are here, (space) or (tab) has occured in 1d. +; End the current argument and restart processing from 1a. + test edi, edi + jz .skip_spaces + mov byte [edi], 0 + inc edi + jmp .skip_spaces +.done_termarg: + test edi, edi + jz .done + mov byte [edi], 0 + inc edi +.done: + ret +.slash_normal: +; 1h. Process chunk of slashes with possible ending " if escaped +; as described in process_slash macros. +; After that, return to loop in 1d; note that the next character can be space. + process_slash + jmp .reenter_normal_mode +; 2. Processing in quoted mode. +; This block is simpler because the current argument never ends in quoted mode, +; except when the input ends. +; 2a. Loop over the input string, watching for one of: +; (terminator), ", \. +.quoted_mode: + inc ecx +.enter_quoted_mode: + mov al, byte [esi] + inc esi +.reenter_quoted_mode: + test al, al + jz .copydata2 + cmp al, '\' + jz .copydata2 + cmp al, '"' + jnz .quoted_mode +.copydata2: +; 2b. Copy the found chunk. + copy_arg_data +; 2c. One of (terminator), ", \ is found. +; For terminator, end the current argument and exit. +; For \, go to 2d. + test al, al + jz .done_termarg + cmp al, '\' + jz .slash_quoted +; For ", check whether the next character is also ": +; for a single quote, switch to the normal mode 1d, +; for a double quote, skip the first quote +; and start a new chunk from the second one. + cmp byte [esi], '"' + jnz .enter_normal_mode +.double_quote: + inc esi + jmp .quoted_mode +.slash_quoted: +; 2d. Process chunk of slashes with possible ending " if escaped +; as described in process_slash macros. +; After that, return to loop in 2a. + process_slash + jmp .reenter_quoted_mode +endp +purge start_arg +purge copy_arg_data +purge process_slash diff --git a/programs/system/os/cmdline_test.asm b/programs/system/os/cmdline_test.asm new file mode 100644 index 0000000000..00fc4e6189 --- /dev/null +++ b/programs/system/os/cmdline_test.asm @@ -0,0 +1,121 @@ +; Just a test of cmdline.inc. +; Checks that parsing of some predefined command lines +; gives some predefined command arguments. +; Nothing to see here. +format PE console 4.0 +entry start + +include 'win32a.inc' +include '../../struct.inc' +include '../../proc32.inc' + +start: + stdcall run_test, empty_cmdline, empty_args + stdcall run_test, spaces_tabs_cmdline, empty_args + stdcall run_test, fancy_quotes_cmdline, fancy_quotes_args + stdcall run_test, fancy_slashes_cmdline, fancy_slashes_args + stdcall run_test, unmatched_quote_cmdline, unmatched_quote_args + xor eax, eax + ret + +proc run_test + mov esi, [esp+4] + xor edi, edi + xor edx, edx + call parse_cmdline + mov eax, [esp+8] + cmp ebx, [eax] + jnz .invalid_argc + test edx, edx + jnz .invalid_edx + mov eax, [esp+4] +@@: + inc eax + cmp byte [eax-1], 0 + jnz @b + cmp esi, eax + jnz .invalid_esi + mov esi, [esp+4] + mov edi, data_area + mov edx, argv_area + call parse_cmdline + mov eax, [esp+4] +@@: + inc eax + cmp byte [eax-1], 0 + jnz @b + cmp esi, eax + jnz .invalid_esi + mov eax, [esp+8] + cmp ebx, [eax] + jnz .invalid_argc + lea ecx, [argv_area+ebx*4] + cmp edx, ecx + jnz .invalid_edx + lea esi, [eax+4] + mov edi, data_area + mov edx, argv_area + test ebx, ebx + jz .args_done +.args_check: + cmp [edx], edi + jnz .invalid_argv + add edx, 4 +@@: + cmpsb + jnz .invalid_argv + cmp byte [esi-1], 0 + jnz @b + dec ebx + jnz .args_check +.args_done: + ret 8 +.invalid_argc: + mov eax, 1 + int3 + jmp $ +.invalid_edx: + mov eax, 2 + int3 + jmp $ +.invalid_esi: + mov eax, 3 + int3 + jmp $ +.invalid_argv: + mov eax, 4 + int3 + jmp $ +endp + +include 'cmdline.inc' + +empty_cmdline db 0 +spaces_tabs_cmdline db ' ',9,' ',9,0 +empty_args dd 0 + +fancy_quotes_cmdline db 'begin"quoted mode"end\ \"escaped" "quotes" "1\" "" """escaped quotes 2"""',0 +fancy_quotes_args dd 4 + db 'beginquoted modeend\',0 + db '"escaped quotes 1"',0 + db 0 + db '"escaped quotes 2"',0 + +fancy_slashes_cmdline db 'arg\\" "1\\x "arg 2\\x" arg3\" arg4\\\"',9,'"arg 5\"" "arg6\\\"" "arg 7\\"',0 +fancy_slashes_args dd 7 + db 'arg\ 1\\x',0 + db 'arg 2\\x',0 + db 'arg3"',0 + db 'arg4\"',0 + db 'arg 5"',0 + db 'arg6\"',0 + db 'arg 7\',0 + +unmatched_quote_cmdline db 'some string"test',0 +unmatched_quote_args dd 2 + db 'some',0 + db 'stringtest',0 + +align 4 +data_area rb 1024 +argv_area rd 256 diff --git a/programs/system/os/fpo.inc b/programs/system/os/fpo.inc index ca7f90fcd8..171c11336d 100644 --- a/programs/system/os/fpo.inc +++ b/programs/system/os/fpo.inc @@ -10,8 +10,12 @@ local loc,regcount regcount = regcount+1 push reg \} - parmbase@proc equ esp+4+regcount*4 - localbase@proc equ esp-localbytes + if loc + sub esp, loc + end if + parmbase@proc equ esp+4+loc+regcount*4 + localbase@proc equ esp + fpo_localsize = loc } macro fpo_epilogue procname,flag,parmbytes,localbytes,reglist { diff --git a/programs/system/os/kolibri.asm b/programs/system/os/kolibri.asm index c173969e5c..262356a3ae 100644 --- a/programs/system/os/kolibri.asm +++ b/programs/system/os/kolibri.asm @@ -37,15 +37,36 @@ stack_base dd ? stack_size dd ? exe_path dd ? command_line dd ? +environment dd ? ends include 'malloc.inc' +include 'peloader.inc' +include 'cmdline.inc' proc syscall_int40 int 0x40 ret endp +proc syscall_sysenter + push ebp + mov ebp, esp + push @f + sysenter +@@: + pop edx + pop ecx + ret +endp + +proc syscall_syscall + push ecx + syscall + pop ecx + ret +endp + proc kercall jmp FS_SYSCALL_PTR endp @@ -54,27 +75,52 @@ prologue@proc equ fpo_prologue epilogue@proc equ fpo_epilogue proc start stdcall, dll_base, reason, reserved +locals +exe_base dd ? +exe_path_size dd ? +endl ; 1. Do nothing unless called by the kernel for DLL_PROCESS_ATTACH. cmp [reason], DLL_PROCESS_ATTACH jnz .nothing -; 2. Validate version of the init struct. +; 2. Initialize process. +; 2a. Validate version of the init struct. ; If not known, say a debug message and die. mov ebp, [reserved] + mov esi, [dll_base] cmp [ebp+kernel_init_data.version], 1 jnz .version_mismatch -; 3. Setup common data based on the init struct. - mov eax, [ebp+kernel_init_data.stack_base] - mov FS_STACK_MIN, eax - add eax, [ebp+kernel_init_data.stack_size] - mov FS_STACK_MAX, eax +; 2b. Get the system call code. +; Note: relocations have not been fixed yet, +; so we cannot use absolute addresses, only RVAs. mov eax, [ebp+kernel_init_data.syscall_method] cmp eax, 0x10000 + jae .syscall_absolute + dec eax + mov edx, rva syscall_int40 + cmp eax, num_syscall_methods jae @f - mov eax, syscall_int40 + mov edx, [esi+eax*4+rva syscall_methods] @@: + lea eax, [edx+esi] +.syscall_absolute: mov FS_SYSCALL_PTR, eax -; 4. Initialize the process heap. +; 2c. Fixup relocations so that we can use absolute offsets instead of RVAs +; in rest of code. +; Note: this uses syscalls, so this step should be done after +; configuring FS_SYSCALL_PTR at step 2b. + push kolibri_dll + call fixup_pe_relocations + pop ecx + jc .die +; 2d. Allocate process data. + mov eax, 68 + mov ebx, 12 + mov ecx, 0x1000 + call FS_SYSCALL_PTR + mov FS_PROCESS_DATA, eax +; 2e. Initialize process heap. mov eax, [ebp+kernel_init_data.exe_base] + mov [exe_base], eax mov edx, [eax+STRIPPED_PE_HEADER.SizeOfHeapReserve] cmp word [eax], 'MZ' jnz @f @@ -82,39 +128,106 @@ proc start stdcall, dll_base, reason, reserved mov edx, [eax+IMAGE_NT_HEADERS.OptionalHeader.SizeOfHeapReserve] @@: malloc_init -; ...TBD... -; Call exe entry point. - mov eax, [ebp+kernel_init_data.exe_base] - mov edx, [eax+STRIPPED_PE_HEADER.AddressOfEntryPoint] - cmp word [eax], 'MZ' +; 2f. Copy rest of init struct and free memory. +; Parse command line to argc/argv here and move arguments to the heap +; in order to save memory: init struct and heap use different pages, +; but typically data from init struct are far from the entire page, +; so moving it to heap does not increase actual physical heap size +; and allows to free init struct. + mov eax, [ebp+kernel_init_data.stack_base] + mov FS_STACK_MIN, eax + add eax, [ebp+kernel_init_data.stack_size] + mov FS_STACK_MAX, eax + mov eax, [ebp+kernel_init_data.exe_path] +@@: + inc eax + cmp byte [eax-1], 0 + jnz @b + sub eax, [ebp+kernel_init_data.exe_path] + mov [exe_path_size], eax + mov esi, [ebp+kernel_init_data.command_line] + xor edx, edx + xor edi, edi + call parse_cmdline + inc ebx ; argv[0] = exe path +.argc equ dll_base +.argv equ reason +.envp equ reserved + mov [.argc], ebx + sub esi, [ebp+kernel_init_data.command_line] + lea esi, [esi+(ebx+1)*4] + add esi, [exe_path_size] + stdcall malloc, esi + mov [.argv], eax + mov edx, eax + lea edi, [eax+ebx*4] + mov esi, [ebp+kernel_init_data.exe_path] + mov [edx], edi + add edx, 4 + mov ecx, [exe_path_size] + rep movsb + mov esi, [ebp+kernel_init_data.command_line] + call parse_cmdline + and dword [edx], 0 ; argv[argc] = NULL + and [.envp], 0 + mov eax, 68 + mov ebx, 13 + mov ecx, ebp + call FS_SYSCALL_PTR +; 3. Configure modules: main EXE and possible statically linked DLLs. + mov esi, [exe_base] + mov eax, [.argv] + pushd [eax] + call fixup_pe_relocations + pop ecx + jc .die +; 4. Call exe entry point. + mov edx, [esi+STRIPPED_PE_HEADER.AddressOfEntryPoint] + cmp word [esi], 'MZ' jnz @f - mov ecx, [eax+IMAGE_DOS_HEADER.e_lfanew] - add ecx, eax + mov ecx, [esi+IMAGE_DOS_HEADER.e_lfanew] + add ecx, esi mov edx, [ecx+IMAGE_NT_HEADERS.OptionalHeader.AddressOfEntryPoint] @@: - add edx, eax + add edx, esi + add esp, fpo_localsize+4 call edx ; If exe entry point has returned control, die. - mov eax, -1 - call FS_SYSCALL_PTR + jmp .die .version_mismatch: - mov esi, version_mismatch_msg - mov eax, 63 - mov ebx, 1 -@@: - mov cl, [esi] - test cl, cl - jz @f - int 0x40 ; can't use FS_SYSCALL_PTR here, it has not yet been set - inc esi - jmp @b -@@: - mov eax, -1 - int 0x40 + lea eax, [esi + rva syscall_int40] + mov FS_SYSCALL_PTR, eax + add esi, rva msg_version_mismatch + call sys_msg_board_str +.die: + or eax, -1 + call FS_SYSCALL_PTR .nothing: ret endp +proc sys_msg_board_str + push eax ebx +@@: + push ecx + mov cl, [ecx] + test cl, cl + jz @f + mov eax, 63 + mov ebx, 1 + call FS_SYSCALL_PTR + pop ecx + inc ecx + jmp @b +@@: + pop ecx ebx eax + ret +endp + +align 4 +syscall_methods dd rva syscall_int40, rva syscall_sysenter, rva syscall_syscall +num_syscall_methods = ($ - syscall_methods) / 4 + align 4 data export export 'kolibri.dll' \ @@ -136,7 +249,13 @@ export 'kolibri.dll' \ end data -version_mismatch_msg db 'Version mismatch between kernel and kolibri.dll',13,10,0 +kolibri_dll db 'kolibri.dll',0 + +msg_version_mismatch db 'S : Version mismatch between kernel and kolibri.dll',13,10,0 +msg_bad_relocation1 db 'S : Bad relocation type in ',0 +msg_newline db 13,10,0 +msg_relocated1 db 'S : fixups for ',0 +msg_relocated2 db ' applied',13,10,0 if FOOTERS section '.data' data readable writable diff --git a/programs/system/os/pe.inc b/programs/system/os/pe.inc index a0c4108f34..08b0a4b759 100644 --- a/programs/system/os/pe.inc +++ b/programs/system/os/pe.inc @@ -59,6 +59,9 @@ struct IMAGE_OPTIONAL_HEADER32 DataDirectory IMAGE_DATA_DIRECTORY ? Directories rb sizeof.IMAGE_DATA_DIRECTORY*15 ends +IMAGE_DIRECTORY_ENTRY_EXPORT = 0 +IMAGE_DIRECTORY_ENTRY_IMPORT = 1 +IMAGE_DIRECTORY_ENTRY_BASERELOC = 5 struct IMAGE_FILE_HEADER Machine dw ? @@ -69,6 +72,8 @@ struct IMAGE_FILE_HEADER SizeOfOptionalHeader dw ? Characteristics dw ? ends +IMAGE_FILE_RELOCS_STRIPPED = 1 +IMAGE_FILE_DLL = 0x2000 struct IMAGE_NT_HEADERS Signature dd ? @@ -98,6 +103,13 @@ struct IMAGE_IMPORT_DIRECTORY FirstThunk dd ? ends +struct IMAGE_BASE_RELOCATION + VirtualAddress dd ? + SizeOfBlock dd ? +ends +IMAGE_REL_BASED_ABSOLUTE = 0 +IMAGE_REL_BASED_HIGHLOW = 3 + struct IMAGE_DOS_HEADER e_magic dw ? e_cblp dw ? diff --git a/programs/system/os/peloader.inc b/programs/system/os/peloader.inc new file mode 100644 index 0000000000..8f1d10adf5 --- /dev/null +++ b/programs/system/os/peloader.inc @@ -0,0 +1,141 @@ +; Check whether PE module has been loaded at preferred address. +; If not, relocate the module. +; +; in: esi = PE base address +; in: [esp+4] = module name for debug print +; out: CF=1 - fail +proc fixup_pe_relocations uses edi ebp +; 1. Fetch some data from PE header or stripped PE header. +; We need: +; * ImageBase - preferred address, compare with esi = actual load address; +; ebp will keep the delta +; * RVA and size of fixups directory +; * flag IMAGE_FILE_RELOCS_STRIPPED from Characteristics +; If the actual address equals the preferred address, do nothing. +; If fixups directory is present, proceed to 2. +; If there is no fixups directory, there are two options: +; * either the directory has not been created +; * or the module has no fixups (data-only module, for example). +; In the first case, IMAGE_FILE_RELOCS_STRIPPED is set, and this is an error. +; In the second case, IMAGE_FILE_RELOCS_STRIPPED is not set; do nothing. + mov ebp, esi + cmp word [esi], 'MZ' + jz .parse_mz + sub ebp, [esi+STRIPPED_PE_HEADER.ImageBase] + jnz @f +.nothing: + ret +@@: + mov dl, byte [esi+STRIPPED_PE_HEADER.Characteristics] + lea eax, [esi+sizeof.STRIPPED_PE_HEADER+SPE_DIRECTORY_BASERELOC*sizeof.IMAGE_DATA_DIRECTORY] + cmp [esi+STRIPPED_PE_HEADER.NumberOfRvaAndSizes], SPE_DIRECTORY_BASERELOC + ja .common +.norelocs: + test dl, IMAGE_FILE_RELOCS_STRIPPED + jz .nothing + stc + ret +.parse_mz: + mov eax, [esi+3Ch] + add eax, esi + sub ebp, [eax+IMAGE_NT_HEADERS.OptionalHeader.ImageBase] + jz .nothing + mov dl, byte [esi+IMAGE_NT_HEADERS.FileHeader.Characteristics] + cmp [eax+IMAGE_NT_HEADERS.OptionalHeader.NumberOfDirectories], IMAGE_DIRECTORY_ENTRY_BASERELOC + jbe .norelocs + add eax, IMAGE_NT_HEADERS.OptionalHeader.DataDirectory+IMAGE_DIRECTORY_ENTRY_BASERELOC*sizeof.IMAGE_DATA_DIRECTORY +.common: + mov edi, [eax+IMAGE_DATA_DIRECTORY.VirtualAddress] + push [eax+IMAGE_DATA_DIRECTORY.isize] +virtual at esp +.sizeleft dd ? +end virtual + add edi, esi + cmp [.sizeleft], 0 + jz .norelocs +; 2. We need to relocate and we have the relocation table. +; esi = PE base address +; edi = pointer to current data of relocation table +; 2a. Relocation table is organized into blocks describing every page. +; End of table is defined from table size fetched from the header. +; Loop 2b-2g over all blocks until no more data is left. +.pageloop: +; 2b. Load the header of the current block: address and size. +; Advance total size. +; Size in the block includes size of the header, subtract it. +; If there is no data in this block, go to 2g. + mov edx, [edi+IMAGE_BASE_RELOCATION.VirtualAddress] + mov ecx, [edi+IMAGE_BASE_RELOCATION.SizeOfBlock] + sub [.sizeleft], ecx + add edi, sizeof.IMAGE_BASE_RELOCATION + sub ecx, sizeof.IMAGE_BASE_RELOCATION + jbe .pagedone +; 2c. We are going to modify data, so mprotect the current page to be writable. +; Save the old protection, we will restore it after the block is processed. +; Ignore any error. +PROT_READ = 1 +PROT_WRITE = 2 +PROT_EXEC = 4 + push esi ecx + mov eax, 68 + mov ebx, 30 + mov ecx, PROT_READ+PROT_WRITE + add edx, esi + mov esi, 0x1000 + call FS_SYSCALL_PTR + pop ecx + push eax +; 2d. Block data is an array of word values. Repeat 2e for every of those. +.relocloop: + sub ecx, 2 + jb .relocdone +; 2e. Every value consists of a 4-bit type and 12-bit offset in the page. +; x86 uses two types: 0 = no data (used for padding), 3 = 32-bit relative. + movzx eax, word [edi] + add edi, 2 + mov ebx, eax + and ebx, 0xFFF + shr eax, 12 + jz .relocloop + cmp al, IMAGE_REL_BASED_HIGHLOW + jnz .badreloc + add [edx+ebx], ebp + jmp .relocloop +.relocdone: +; 2f. Restore memory protection changed in 2c. + pop ecx + cmp ecx, -1 + jz @f + mov eax, 68 + mov ebx, 30 + mov esi, 0x1000 + call FS_SYSCALL_PTR +@@: + pop esi +.pagedone: + cmp [.sizeleft], 0 + jnz .pageloop + pop eax ; pop .sizeleft +; 3. For performance reasons, relocation should be avoided +; by choosing an appropriate preferred address. +; If we have actually relocated something, yell to the debug board, +; so the programmer can notice that. + mov ecx, msg_relocated1 + call sys_msg_board_str + mov ecx, [esp+4] + call sys_msg_board_str + mov ecx, msg_relocated2 + call sys_msg_board_str + clc + ret +.badreloc: + pop eax + mov ecx, msg_bad_relocation1 + call sys_msg_board_str + mov ecx, [esp+4] + call sys_msg_board_str + mov ecx, msg_newline + call sys_msg_board_str + stc + ret +endp