Files
Odin/core/os/os2/process_windows.odin
2025-08-02 12:47:03 +01:00

775 lines
23 KiB
Odin

#+private file
package os2
import "base:runtime"
import "core:strings"
import win32 "core:sys/windows"
import "core:time"
@(private="package")
_exit :: proc "contextless" (code: int) -> ! {
win32.ExitProcess(u32(code))
}
@(private="package")
_get_uid :: proc() -> int {
return -1
}
@(private="package")
_get_euid :: proc() -> int {
return -1
}
@(private="package")
_get_gid :: proc() -> int {
return -1
}
@(private="package")
_get_egid :: proc() -> int {
return -1
}
@(private="package")
_get_pid :: proc() -> int {
return int(win32.GetCurrentProcessId())
}
@(private="package")
_get_ppid :: proc() -> int {
our_pid := win32.GetCurrentProcessId()
snap := win32.CreateToolhelp32Snapshot(win32.TH32CS_SNAPPROCESS, 0)
if snap == win32.INVALID_HANDLE_VALUE {
return -1
}
defer win32.CloseHandle(snap)
entry := win32.PROCESSENTRY32W { dwSize = size_of(win32.PROCESSENTRY32W) }
for status := win32.Process32FirstW(snap, &entry); status; /**/ {
if entry.th32ProcessID == our_pid {
return int(entry.th32ParentProcessID)
}
status = win32.Process32NextW(snap, &entry)
}
return -1
}
@(private="package")
_process_list :: proc(allocator: runtime.Allocator) -> (list: []int, err: Error) {
snap := win32.CreateToolhelp32Snapshot(win32.TH32CS_SNAPPROCESS, 0)
if snap == win32.INVALID_HANDLE_VALUE {
err = _get_platform_error()
return
}
list_d := make([dynamic]int, allocator) or_return
entry := win32.PROCESSENTRY32W{dwSize = size_of(win32.PROCESSENTRY32W)}
status := win32.Process32FirstW(snap, &entry)
for status {
append(&list_d, int(entry.th32ProcessID))
status = win32.Process32NextW(snap, &entry)
}
list = list_d[:]
return
}
@(require_results)
read_memory_as_struct :: proc(h: win32.HANDLE, addr: rawptr, dest: ^$T) -> (bytes_read: uint, err: Error) {
if !win32.ReadProcessMemory(h, addr, dest, size_of(T), &bytes_read) {
err = _get_platform_error()
}
return
}
@(require_results)
read_memory_as_slice :: proc(h: win32.HANDLE, addr: rawptr, dest: []$T) -> (bytes_read: uint, err: Error) {
if !win32.ReadProcessMemory(h, addr, raw_data(dest), len(dest)*size_of(T), &bytes_read) {
err = _get_platform_error()
}
return
}
@(private="package")
_process_info_by_pid :: proc(pid: int, selection: Process_Info_Fields, allocator: runtime.Allocator) -> (info: Process_Info, err: Error) {
info.pid = pid
// Note(flysand): Open the process handle right away to prevent some race
// conditions. Once the handle is open, the process will be kept alive by
// the OS.
ph := win32.INVALID_HANDLE_VALUE
if selection >= {.Command_Line, .Environment, .Working_Dir, .Username} {
ph = win32.OpenProcess(
win32.PROCESS_QUERY_LIMITED_INFORMATION | win32.PROCESS_VM_READ,
false,
u32(pid),
)
if ph == win32.INVALID_HANDLE_VALUE {
err = _get_platform_error()
return
}
}
defer if ph != win32.INVALID_HANDLE_VALUE {
win32.CloseHandle(ph)
}
snapshot_process: if selection >= {.PPid, .Priority} {
entry, entry_err := _process_entry_by_pid(info.pid)
if entry_err != nil {
err = entry_err
if entry_err == General_Error.Not_Exist {
return
} else {
break snapshot_process
}
}
if .PPid in selection {
info.fields += {.PPid}
info.ppid = int(entry.th32ParentProcessID)
}
if .Priority in selection {
info.fields += {.Priority}
info.priority = int(entry.pcPriClassBase)
}
}
snapshot_modules: if .Executable_Path in selection {
exe_path: string
exe_path, err = _process_exe_by_pid(pid, allocator)
if _, ok := err.(runtime.Allocator_Error); ok {
return
} else if err != nil {
break snapshot_modules
}
info.executable_path = exe_path
info.fields += {.Executable_Path}
}
read_peb: if selection >= {.Command_Line, .Environment, .Working_Dir} {
process_info_size: u32
process_info: win32.PROCESS_BASIC_INFORMATION
status := win32.NtQueryInformationProcess(ph, .ProcessBasicInformation, &process_info, size_of(process_info), &process_info_size)
if status != 0 {
// TODO(flysand): There's probably a mismatch between NTSTATUS and
// windows userland error codes, I haven't checked.
err = Platform_Error(status)
break read_peb
}
assert(process_info.PebBaseAddress != nil)
process_peb: win32.PEB
_, err = read_memory_as_struct(ph, process_info.PebBaseAddress, &process_peb)
if err != nil {
break read_peb
}
process_params: win32.RTL_USER_PROCESS_PARAMETERS
_, err = read_memory_as_struct(ph, process_peb.ProcessParameters, &process_params)
if err != nil {
break read_peb
}
temp_allocator := TEMP_ALLOCATOR_GUARD({ allocator })
if selection >= {.Command_Line, .Command_Args} {
temp_allocator_scope(temp_allocator)
cmdline_w := make([]u16, process_params.CommandLine.Length, temp_allocator) or_return
_, err = read_memory_as_slice(ph, process_params.CommandLine.Buffer, cmdline_w)
if err != nil {
break read_peb
}
if .Command_Line in selection {
info.command_line = win32_utf16_to_utf8(cmdline_w, allocator) or_return
info.fields += {.Command_Line}
}
if .Command_Args in selection {
info.command_args = _parse_command_line(cstring16(raw_data(cmdline_w)), allocator) or_return
info.fields += {.Command_Args}
}
}
if .Environment in selection {
temp_allocator_scope(temp_allocator)
env_len := process_params.EnvironmentSize / 2
envs_w := make([]u16, env_len, temp_allocator) or_return
_, err = read_memory_as_slice(ph, process_params.Environment, envs_w)
if err != nil {
break read_peb
}
info.environment = _parse_environment_block(raw_data(envs_w), allocator) or_return
info.fields += {.Environment}
}
if .Working_Dir in selection {
temp_allocator_scope(temp_allocator)
cwd_w := make([]u16, process_params.CurrentDirectoryPath.Length, temp_allocator) or_return
_, err = read_memory_as_slice(ph, process_params.CurrentDirectoryPath.Buffer, cwd_w)
if err != nil {
break read_peb
}
info.working_dir = win32_utf16_to_utf8(cwd_w, allocator) or_return
info.fields += {.Working_Dir}
}
}
read_username: if .Username in selection {
username: string
username, err = _get_process_user(ph, allocator)
if _, ok := err.(runtime.Allocator_Error); ok {
return
} else if err != nil {
break read_username
}
info.username = username
info.fields += {.Username}
}
err = nil
return
}
@(private="package")
_process_info_by_handle :: proc(process: Process, selection: Process_Info_Fields, allocator: runtime.Allocator) -> (info: Process_Info, err: Error) {
pid := process.pid
info.pid = pid
// Data obtained from process snapshots
snapshot_process: if selection >= {.PPid, .Priority} {
entry, entry_err := _process_entry_by_pid(info.pid)
if entry_err != nil {
err = entry_err
if entry_err == General_Error.Not_Exist {
return
} else {
break snapshot_process
}
}
if .PPid in selection {
info.fields += {.PPid}
info.ppid = int(entry.th32ParentProcessID)
}
if .Priority in selection {
info.fields += {.Priority}
info.priority = int(entry.pcPriClassBase)
}
}
snapshot_module: if .Executable_Path in selection {
exe_path: string
exe_path, err = _process_exe_by_pid(pid, allocator)
if _, ok := err.(runtime.Allocator_Error); ok {
return
} else if err != nil {
break snapshot_module
}
info.executable_path = exe_path
info.fields += {.Executable_Path}
}
ph := win32.HANDLE(process.handle)
read_peb: if selection >= {.Command_Line, .Environment, .Working_Dir} {
process_info_size: u32
process_info: win32.PROCESS_BASIC_INFORMATION
status := win32.NtQueryInformationProcess(ph, .ProcessBasicInformation, &process_info, size_of(process_info), &process_info_size)
if status != 0 {
// TODO(flysand): There's probably a mismatch between NTSTATUS and
// windows userland error codes, I haven't checked.
err = Platform_Error(status)
return
}
assert(process_info.PebBaseAddress != nil)
process_peb: win32.PEB
_, err = read_memory_as_struct(ph, process_info.PebBaseAddress, &process_peb)
if err != nil {
break read_peb
}
process_params: win32.RTL_USER_PROCESS_PARAMETERS
_, err = read_memory_as_struct(ph, process_peb.ProcessParameters, &process_params)
if err != nil {
break read_peb
}
temp_allocator := TEMP_ALLOCATOR_GUARD({ allocator })
if selection >= {.Command_Line, .Command_Args} {
temp_allocator_scope(temp_allocator)
cmdline_w := make([]u16, process_params.CommandLine.Length, temp_allocator) or_return
_, err = read_memory_as_slice(ph, process_params.CommandLine.Buffer, cmdline_w)
if err != nil {
break read_peb
}
if .Command_Line in selection {
info.command_line = win32_utf16_to_utf8(cmdline_w, allocator) or_return
info.fields += {.Command_Line}
}
if .Command_Args in selection {
info.command_args = _parse_command_line(cstring16(raw_data(cmdline_w)), allocator) or_return
info.fields += {.Command_Args}
}
}
if .Environment in selection {
temp_allocator_scope(temp_allocator)
env_len := process_params.EnvironmentSize / 2
envs_w := make([]u16, env_len, temp_allocator) or_return
_, err = read_memory_as_slice(ph, process_params.Environment, envs_w)
if err != nil {
break read_peb
}
info.environment = _parse_environment_block(raw_data(envs_w), allocator) or_return
info.fields += {.Environment}
}
if .Working_Dir in selection {
temp_allocator_scope(temp_allocator)
cwd_w := make([]u16, process_params.CurrentDirectoryPath.Length, temp_allocator) or_return
_, err = read_memory_as_slice(ph, process_params.CurrentDirectoryPath.Buffer, cwd_w)
if err != nil {
break read_peb
}
info.working_dir = win32_utf16_to_utf8(cwd_w, allocator) or_return
info.fields += {.Working_Dir}
}
}
read_username: if .Username in selection {
username: string
username, err = _get_process_user(ph, allocator)
if _, ok := err.(runtime.Allocator_Error); ok {
return
} else if err != nil {
break read_username
}
info.username = username
info.fields += {.Username}
}
err = nil
return
}
@(private="package")
_current_process_info :: proc(selection: Process_Info_Fields, allocator: runtime.Allocator) -> (info: Process_Info, err: Error) {
info.pid = get_pid()
snapshot_process: if selection >= {.PPid, .Priority} {
entry, entry_err := _process_entry_by_pid(info.pid)
if entry_err != nil {
err = entry_err
if entry_err == General_Error.Not_Exist {
return
} else {
break snapshot_process
}
}
if .PPid in selection {
info.fields += {.PPid}
info.ppid = int(entry.th32ProcessID)
}
if .Priority in selection {
info.fields += {.Priority}
info.priority = int(entry.pcPriClassBase)
}
}
module_filename: if .Executable_Path in selection {
exe_filename_w: [256]u16
path_len := win32.GetModuleFileNameW(nil, raw_data(exe_filename_w[:]), len(exe_filename_w))
assert(path_len > 0)
info.executable_path = win32_utf16_to_utf8(exe_filename_w[:path_len], allocator) or_return
info.fields += {.Executable_Path}
}
command_line: if selection >= {.Command_Line, .Command_Args} {
command_line_w := win32.GetCommandLineW()
assert(command_line_w != nil)
if .Command_Line in selection {
info.command_line = win32_wstring_to_utf8(command_line_w, allocator) or_return
info.fields += {.Command_Line}
}
if .Command_Args in selection {
info.command_args = _parse_command_line(command_line_w, allocator) or_return
info.fields += {.Command_Args}
}
}
read_environment: if .Environment in selection {
env_block := win32.GetEnvironmentStringsW()
assert(env_block != nil)
info.environment = _parse_environment_block(env_block, allocator) or_return
info.fields += {.Environment}
}
read_username: if .Username in selection {
process_handle := win32.GetCurrentProcess()
username: string
username, err = _get_process_user(process_handle, allocator)
if _, ok := err.(runtime.Allocator_Error); ok {
return
} else if err != nil {
break read_username
}
info.username = username
info.fields += {.Username}
}
if .Working_Dir in selection {
// TODO(flysand): Implement this by reading PEB
err = .Mode_Not_Implemented
return
}
err = nil
return
}
@(private="package")
_process_open :: proc(pid: int, flags: Process_Open_Flags) -> (process: Process, err: Error) {
// Note(flysand): The handle will be used for querying information so we
// take the necessary permissions right away.
dwDesiredAccess := win32.PROCESS_QUERY_LIMITED_INFORMATION | win32.SYNCHRONIZE
if .Mem_Read in flags {
dwDesiredAccess |= win32.PROCESS_VM_READ
}
if .Mem_Write in flags {
dwDesiredAccess |= win32.PROCESS_VM_WRITE
}
handle := win32.OpenProcess(
dwDesiredAccess,
false,
u32(pid),
)
if handle == win32.INVALID_HANDLE_VALUE {
err = _get_platform_error()
} else {
process = {pid = pid, handle = uintptr(handle)}
}
return
}
@(private="package")
_process_start :: proc(desc: Process_Desc) -> (process: Process, err: Error) {
temp_allocator := TEMP_ALLOCATOR_GUARD({})
command_line := _build_command_line(desc.command, temp_allocator)
command_line_w := win32_utf8_to_wstring(command_line, temp_allocator) or_return
environment := desc.env
if desc.env == nil {
environment = environ(temp_allocator) or_return
}
environment_block := _build_environment_block(environment, temp_allocator)
environment_block_w := win32_utf8_to_utf16(environment_block, temp_allocator) or_return
stderr_handle: win32.HANDLE
stdout_handle: win32.HANDLE
stdin_handle: win32.HANDLE
null_handle: win32.HANDLE
if desc.stdout == nil || desc.stderr == nil || desc.stdin == nil {
null_handle = win32.CreateFileW(
win32.L("NUL"),
win32.GENERIC_READ|win32.GENERIC_WRITE,
win32.FILE_SHARE_READ|win32.FILE_SHARE_WRITE,
&win32.SECURITY_ATTRIBUTES{
nLength = size_of(win32.SECURITY_ATTRIBUTES),
bInheritHandle = true,
},
win32.OPEN_EXISTING,
win32.FILE_ATTRIBUTE_NORMAL,
nil,
)
// Opening NUL should always succeed.
assert(null_handle != nil)
}
// NOTE(laytan): I believe it is fine to close this handle right after CreateProcess,
// and we don't have to hold onto this until the process exits.
defer if null_handle != nil {
win32.CloseHandle(null_handle)
}
if desc.stdout == nil {
stdout_handle = null_handle
} else {
stdout_handle = win32.HANDLE((^File_Impl)(desc.stdout.impl).fd)
}
if desc.stderr == nil {
stderr_handle = null_handle
} else {
stderr_handle = win32.HANDLE((^File_Impl)(desc.stderr.impl).fd)
}
if desc.stdin == nil {
stdin_handle = null_handle
} else {
stdin_handle = win32.HANDLE((^File_Impl)(desc.stdin.impl).fd)
}
working_dir_w := (win32_utf8_to_wstring(desc.working_dir, temp_allocator) or_else nil) if len(desc.working_dir) > 0 else nil
process_info: win32.PROCESS_INFORMATION
ok := win32.CreateProcessW(
nil,
command_line_w,
nil,
nil,
true,
win32.CREATE_UNICODE_ENVIRONMENT|win32.NORMAL_PRIORITY_CLASS,
raw_data(environment_block_w),
working_dir_w,
&win32.STARTUPINFOW{
cb = size_of(win32.STARTUPINFOW),
hStdError = stderr_handle,
hStdOutput = stdout_handle,
hStdInput = stdin_handle,
dwFlags = win32.STARTF_USESTDHANDLES,
},
&process_info,
)
if !ok {
err = _get_platform_error()
return
}
process = {pid = int(process_info.dwProcessId), handle = uintptr(process_info.hProcess)}
return
}
@(private="package")
_process_wait :: proc(process: Process, timeout: time.Duration) -> (process_state: Process_State, err: Error) {
handle := win32.HANDLE(process.handle)
timeout_ms := u32(timeout / time.Millisecond) if timeout >= 0 else win32.INFINITE
switch win32.WaitForSingleObject(handle, timeout_ms) {
case win32.WAIT_OBJECT_0:
exit_code: u32
if !win32.GetExitCodeProcess(handle, &exit_code) {
err =_get_platform_error()
return
}
time_created: win32.FILETIME
time_exited: win32.FILETIME
time_kernel: win32.FILETIME
time_user: win32.FILETIME
if !win32.GetProcessTimes(handle, &time_created, &time_exited, &time_kernel, &time_user) {
err = _get_platform_error()
return
}
process_state = {
exit_code = int(exit_code),
exited = true,
pid = process.pid,
success = true,
system_time = _filetime_to_duration(time_kernel),
user_time = _filetime_to_duration(time_user),
}
return
case win32.WAIT_TIMEOUT:
err = General_Error.Timeout
return
case:
err = _get_platform_error()
return
}
}
@(private="package")
_process_close :: proc(process: Process) -> Error {
if !win32.CloseHandle(win32.HANDLE(process.handle)) {
return _get_platform_error()
}
return nil
}
@(private="package")
_process_kill :: proc(process: Process) -> Error {
// Note(flysand): This is different than what the task manager's "kill process"
// functionality does, as we don't try to send WM_CLOSE message first. This
// is quite a rough way to kill the process, which should be consistent with
// linux. The error code 9 is to mimic SIGKILL event.
if !win32.TerminateProcess(win32.HANDLE(process.handle), 9) {
return _get_platform_error()
}
return nil
}
_filetime_to_duration :: proc(filetime: win32.FILETIME) -> time.Duration {
ticks := u64(filetime.dwHighDateTime)<<32 | u64(filetime.dwLowDateTime)
return time.Duration(ticks * 100)
}
_process_entry_by_pid :: proc(pid: int) -> (entry: win32.PROCESSENTRY32W, err: Error) {
snap := win32.CreateToolhelp32Snapshot(win32.TH32CS_SNAPPROCESS, 0)
if snap == win32.INVALID_HANDLE_VALUE {
err = _get_platform_error()
return
}
defer win32.CloseHandle(snap)
entry = win32.PROCESSENTRY32W{dwSize = size_of(win32.PROCESSENTRY32W)}
status := win32.Process32FirstW(snap, &entry)
for status {
if u32(pid) == entry.th32ProcessID {
return
}
status = win32.Process32NextW(snap, &entry)
}
err = General_Error.Not_Exist
return
}
// Note(flysand): Not sure which way it's better to get the executable path:
// via toolhelp snapshots or by reading other process' PEB memory. I have
// a slight suspicion that if both exe path and command line are desired,
// it's faster to just read both from PEB, but maybe the toolhelp snapshots
// are just better...?
@(private="package")
_process_exe_by_pid :: proc(pid: int, allocator: runtime.Allocator) -> (exe_path: string, err: Error) {
snap := win32.CreateToolhelp32Snapshot(
win32.TH32CS_SNAPMODULE|win32.TH32CS_SNAPMODULE32,
u32(pid),
)
if snap == win32.INVALID_HANDLE_VALUE {
err =_get_platform_error()
return
}
defer win32.CloseHandle(snap)
entry := win32.MODULEENTRY32W { dwSize = size_of(win32.MODULEENTRY32W) }
status := win32.Module32FirstW(snap, &entry)
if !status {
err =_get_platform_error()
return
}
return win32_wstring_to_utf8(cstring16(raw_data(entry.szExePath[:])), allocator)
}
_get_process_user :: proc(process_handle: win32.HANDLE, allocator: runtime.Allocator) -> (full_username: string, err: Error) {
temp_allocator := TEMP_ALLOCATOR_GUARD({ allocator })
token_handle: win32.HANDLE
if !win32.OpenProcessToken(process_handle, win32.TOKEN_QUERY, &token_handle) {
err = _get_platform_error()
return
}
token_user_size: u32
if !win32.GetTokenInformation(token_handle, .TokenUser, nil, 0, &token_user_size) {
// Note(flysand): Make sure the buffer too small error comes out, and not any other error
err = _get_platform_error()
if v, ok := is_platform_error(err); !ok || v != i32(win32.ERROR_INSUFFICIENT_BUFFER) {
return
}
err = nil
}
token_user := (^win32.TOKEN_USER)(raw_data(make([]u8, token_user_size, temp_allocator) or_return))
if !win32.GetTokenInformation(token_handle, .TokenUser, token_user, token_user_size, &token_user_size) {
err = _get_platform_error()
return
}
sid_type: win32.SID_NAME_USE
username_w: [256]u16
domain_w: [256]u16
username_chrs := u32(256)
domain_chrs := u32(256)
if !win32.LookupAccountSidW(nil, token_user.User.Sid, &username_w[0], &username_chrs, &domain_w[0], &domain_chrs, &sid_type) {
err = _get_platform_error()
return
}
username := win32_utf16_to_utf8(username_w[:username_chrs], temp_allocator) or_return
domain := win32_utf16_to_utf8(domain_w[:domain_chrs], temp_allocator) or_return
return strings.concatenate({domain, "\\", username}, allocator)
}
_parse_command_line :: proc(cmd_line_w: cstring16, allocator: runtime.Allocator) -> (argv: []string, err: Error) {
argc: i32
argv_w := win32.CommandLineToArgvW(cmd_line_w, &argc)
if argv_w == nil {
return nil, _get_platform_error()
}
argv = make([]string, argc, allocator) or_return
defer if err != nil {
for arg in argv {
delete(arg, allocator)
}
delete(argv, allocator)
}
for arg_w, i in argv_w[:argc] {
argv[i] = win32_wstring_to_utf8(arg_w, allocator) or_return
}
return
}
_build_command_line :: proc(command: []string, allocator: runtime.Allocator) -> string {
_write_byte_n_times :: #force_inline proc(builder: ^strings.Builder, b: byte, n: int) {
for _ in 0 ..< n {
strings.write_byte(builder, b)
}
}
builder := strings.builder_make(allocator)
for arg, i in command {
if i != 0 {
strings.write_byte(&builder, ' ')
}
j := 0
if strings.contains_any(arg, "()[]{}^=;!'+,`~\" ") {
strings.write_byte(&builder, '"')
for j < len(arg) {
backslashes := 0
for j < len(arg) && arg[j] == '\\' {
backslashes += 1
j += 1
}
if j == len(arg) {
_write_byte_n_times(&builder, '\\', 2*backslashes)
break
} else if arg[j] == '"' {
_write_byte_n_times(&builder, '\\', 2*backslashes+1)
strings.write_byte(&builder, arg[j])
} else {
_write_byte_n_times(&builder, '\\', backslashes)
strings.write_byte(&builder, arg[j])
}
j += 1
}
strings.write_byte(&builder, '"')
} else {
strings.write_string(&builder, arg)
}
}
return strings.to_string(builder)
}
_parse_environment_block :: proc(block: [^]u16, allocator: runtime.Allocator) -> (envs: []string, err: Error) {
zt_count := 0
for idx := 0; true; {
if block[idx] == 0x0000 {
zt_count += 1
if block[idx+1] == 0x0000 {
zt_count += 1
break
}
}
idx += 1
}
// Note(flysand): Each string in the environment block is terminated
// by a NUL character. In addition, the environment block itself is
// terminated by a NUL character. So the number of strings in the
// environment block is the number of NUL character minus the
// block terminator.
env_count := zt_count - 1
envs = make([]string, env_count, allocator) or_return
defer if err != nil {
for env in envs {
delete(env, allocator)
}
delete(envs, allocator)
}
env_idx := 0
last_idx := 0
idx := 0
for block[idx] != 0x0000 {
for block[idx] != 0x0000 {
idx += 1
}
env_w := block[last_idx:idx]
envs[env_idx] = win32_utf16_to_utf8(env_w, allocator) or_return
env_idx += 1
idx += 1
last_idx = idx
}
return
}
_build_environment_block :: proc(environment: []string, allocator: runtime.Allocator) -> string {
builder := strings.builder_make(allocator)
loop: #reverse for kv, cur_idx in environment {
eq_idx := strings.index_byte(kv, '=')
assert(eq_idx >= 0, "Malformed environment string. Expected '=' to separate keys and values")
key := kv[:eq_idx]
for old_kv in environment[cur_idx+1:] {
old_key := old_kv[:strings.index_byte(old_kv, '=')]
if key == old_key {
continue loop
}
}
strings.write_string(&builder, kv)
strings.write_byte(&builder, 0)
}
// Note(flysand): In addition to the NUL-terminator for each string, the
// environment block itself is NUL-terminated.
strings.write_byte(&builder, 0)
return strings.to_string(builder)
}