modules/adb/sysdeps.h

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

/* this file contains system-dependent definitions used by ADB
 * they're related to threads, sockets and file descriptors
 */

#ifdef __CYGWIN__
#  undef _WIN32
#endif

// Include this protobuf header first, because it uses some write() calls
// that we will redefine later. Not all modules that include sysdeps.h use
// protobufs, so only include it if it exists.
#if __has_include("google/protobuf/io/coded_stream.h")
#include "google/protobuf/io/coded_stream.h"
#endif

#include <errno.h>

#include <optional>
#include <string>
#include <string_view>
#include <vector>

// Include this before open/close/isatty/unlink are defined as macros below.
#include <android-base/errors.h>
#include <android-base/logging.h>
#include <android-base/macros.h>
#include <android-base/off64_t.h>
#include <android-base/unique_fd.h>
#include <android-base/utf8.h>
#if __has_include(<print>)
#include <print>
#endif

#include "adb_unique_fd.h"
#include "sysdeps/errno.h"
#include "sysdeps/network.h"
#include "sysdeps/stat.h"

#if defined(__APPLE__)
static inline void* mempcpy(void* dst, const void* src, size_t n) {
    return static_cast<char*>(memcpy(dst, src, n)) + n;
}
#endif

std::optional<ssize_t> network_peek(borrowed_fd fd);

#ifdef _WIN32

#include <ctype.h>
#include <direct.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <io.h>
#include <mswsock.h>
#include <process.h>
#include <stdint.h>
#include <sys/stat.h>
#include <utime.h>
#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>

#include <memory>   // unique_ptr
#include <string>

#define OS_PATH_SEPARATORS "\\/"
#define OS_PATH_SEPARATOR '\\'
#define OS_PATH_SEPARATOR_STR "\\"
#define ENV_PATH_SEPARATOR_STR ";"

static inline bool adb_is_separator(char c) {
    return c == '\\' || c == '/';
}

extern int adb_thread_setname(const std::string& name);

static inline void close_on_exec(borrowed_fd fd) {
    /* nothing really */
}

extern int adb_unlink(const char* path);
#undef unlink
#define unlink ___xxx_unlink

extern int adb_mkdir(const std::string& path, int mode);
#undef mkdir
#define mkdir ___xxx_mkdir

extern int adb_rename(const char* oldpath, const char* newpath);

// See the comments for the !defined(_WIN32) versions of adb_*().
extern int adb_open(const char* path, int options);
extern int adb_creat(const char* path, int mode);
extern int adb_read(borrowed_fd fd, void* buf, int len);
extern int adb_pread(borrowed_fd fd, void* buf, int len, off64_t offset);
extern int adb_write(borrowed_fd fd, const void* buf, int len);
extern int adb_pwrite(borrowed_fd fd, const void* buf, int len, off64_t offset);
extern int64_t adb_lseek(borrowed_fd fd, int64_t pos, int where);
extern int adb_shutdown(borrowed_fd fd, int direction = SHUT_RDWR);
extern int adb_close(int fd);
extern int adb_register_socket(SOCKET s);
extern HANDLE adb_get_os_handle(borrowed_fd fd);

extern int adb_gethostname(char* name, size_t len);
extern int adb_getlogin_r(char* buf, size_t bufsize);

// See the comments for the !defined(_WIN32) version of unix_close().
static inline int unix_close(int fd) {
    return close(fd);
}
#undef close
#define close ____xxx_close

// Like unix_read(), but may return EINTR.
extern int unix_read_interruptible(borrowed_fd fd, void* buf, size_t len);

// See the comments for the !defined(_WIN32) version of unix_read().
static inline int unix_read(borrowed_fd fd, void* buf, size_t len) {
    return TEMP_FAILURE_RETRY(unix_read_interruptible(fd, buf, len));
}

#undef   read
#define  read  ___xxx_read

#undef pread
#define pread ___xxx_pread

// See the comments for the !defined(_WIN32) version of unix_write().
static inline int unix_write(borrowed_fd fd, const void* buf, size_t len) {
    return write(fd.get(), buf, len);
}
#undef   write
#define  write  ___xxx_write

#undef pwrite
#define pwrite ___xxx_pwrite

// See the comments for the !defined(_WIN32) version of unix_lseek().
static inline int unix_lseek(borrowed_fd fd, int pos, int where) {
    return lseek(fd.get(), pos, where);
}
#undef lseek
#define lseek ___xxx_lseek

// See the comments for the !defined(_WIN32) version of adb_open_mode().
static inline int adb_open_mode(const char* path, int options, int mode) {
    return adb_open(path, options);
}

// See the comments for the !defined(_WIN32) version of unix_open().
extern int unix_open(std::string_view path, int options, ...);
#define  open    ___xxx_unix_open

// Checks if |fd| corresponds to a console.
// Standard Windows isatty() returns 1 for both console FDs and character
// devices like NUL. unix_isatty() performs some extra checking to only match
// console FDs.
// |fd| must be a real file descriptor, meaning STDxx_FILENO or unix_open() FDs
// will work but adb_open() FDs will not. Additionally the OS handle associated
// with |fd| must have GENERIC_READ access (which console FDs have by default).
// Returns 1 if |fd| is a console FD, 0 otherwise. The value of errno after
// calling this function is unreliable and should not be used.
int unix_isatty(borrowed_fd fd);
#define  isatty  ___xxx_isatty

int network_inaddr_any_server(int port, int type, std::string* error);

inline int network_local_client(const char* name, int namespace_id, int type, std::string* error) {
    abort(); // Windows-only, and libbase logging conflicts with Win32 ERROR.
}

inline int network_local_server(const char* name, int namespace_id, int type, std::string* error) {
    abort(); // Windows-only, and libbase logging conflicts with Win32 ERROR.
}

int network_connect(const std::string& host, int port, int type, int timeout,
                    std::string* error);

extern int adb_socket_accept(borrowed_fd serverfd, struct sockaddr* addr, socklen_t* addrlen);

#undef   accept
#define  accept  ___xxx_accept

int adb_getsockname(borrowed_fd fd, struct sockaddr* sockaddr, socklen_t* addrlen);

// Returns the local port number of a bound socket, or -1 on failure.
int adb_socket_get_local_port(borrowed_fd fd);

extern int adb_setsockopt(borrowed_fd fd, int level, int optname, const void* optval,
                          socklen_t optlen);

#undef   setsockopt
#define  setsockopt  ___xxx_setsockopt

// Wrapper around socket() call. On Windows, ADB has an indirection layer for file descriptors.
extern int adb_socket(int domain, int type, int protocol);

// Wrapper around bind() call, as Windows has indirection layer.
extern int adb_bind(borrowed_fd fd, const sockaddr* addr, int namelen);

extern int adb_socketpair(int sv[2]);

// Posix compatibility layer for msghdr
struct adb_msghdr {
    void* msg_name;
    socklen_t msg_namelen;
    struct adb_iovec* msg_iov;
    size_t msg_iovlen;
    void* msg_control;
    size_t msg_controllen;
    int msg_flags;
};

ssize_t adb_sendmsg(borrowed_fd fd, const adb_msghdr* msg, int flags);
ssize_t adb_recvmsg(borrowed_fd fd, adb_msghdr* msg, int flags);

using adb_cmsghdr = WSACMSGHDR;

extern adb_cmsghdr* adb_CMSG_FIRSTHDR(adb_msghdr* msgh);
extern adb_cmsghdr* adb_CMSG_NXTHDR(adb_msghdr* msgh, adb_cmsghdr* cmsg);
extern unsigned char* adb_CMSG_DATA(adb_cmsghdr* cmsg);

struct adb_pollfd {
    int fd;
    short events;
    short revents;
};
extern int adb_poll(adb_pollfd* fds, size_t nfds, int timeout);
#define poll ___xxx_poll

static inline int adb_is_absolute_host_path(const char* path) {
    return isalpha(path[0]) && path[1] == ':' && path[2] == '\\';
}

// UTF-8 versions of POSIX APIs.
extern DIR* adb_opendir(const char* dirname);
extern struct dirent* adb_readdir(DIR* dir);
extern int adb_closedir(DIR* dir);

extern int adb_utime(const char *, struct utimbuf *);
extern int adb_chmod(const char *, int);

extern int adb_vfprintf(FILE* stream, const char* format, va_list ap)
        __attribute__((__format__(__printf__, 2, 0)));
extern int adb_vprintf(const char* format, va_list ap) __attribute__((__format__(__printf__, 1, 0)));
extern int adb_fprintf(FILE* stream, const char* format, ...)
        __attribute__((__format__(__printf__, 2, 3)));
extern int adb_printf(const char* format, ...) __attribute__((__format__(__printf__, 1, 2)));

extern int adb_fputs(const char* buf, FILE* stream);
extern int adb_fputc(int ch, FILE* stream);
extern int adb_putchar(int ch);
extern int adb_puts(const char* buf);
extern size_t adb_fwrite(const void* ptr, size_t size, size_t nmemb, FILE* stream);

extern FILE* adb_fopen(const char* f, const char* m);

extern char* adb_getenv(const char* name);

extern char* adb_getcwd(char* buf, int size);

// Remap calls to POSIX APIs to our UTF-8 versions.
#define opendir adb_opendir
#define readdir adb_readdir
#define closedir adb_closedir
#define rewinddir rewinddir_utf8_not_yet_implemented
#define telldir telldir_utf8_not_yet_implemented
// Some compiler's C++ headers have members named seekdir, so we can't do the
// macro technique and instead cause a link error if seekdir is called.
inline void seekdir(DIR*, long) {
    extern int seekdir_utf8_not_yet_implemented;
    seekdir_utf8_not_yet_implemented = 1;
}

#define utime adb_utime
#define chmod adb_chmod

#define vfprintf adb_vfprintf
#define vprintf adb_vprintf
#define fprintf adb_fprintf
#define printf adb_printf
#define fputs adb_fputs
#define fputc adb_fputc
// putc may be a macro, so if so, undefine it, so that we can redefine it.
#undef putc
#define putc(c, s) adb_fputc(c, s)
#define putchar adb_putchar
#define puts adb_puts
#define fwrite adb_fwrite

#define fopen adb_fopen
#define freopen freopen_utf8_not_yet_implemented

#define getenv adb_getenv
#define putenv putenv_utf8_not_yet_implemented
#define setenv setenv_utf8_not_yet_implemented
#define unsetenv unsetenv_utf8_not_yet_implemented

#define getcwd adb_getcwd

// A very simple wrapper over a launched child process
class Process {
  public:
    constexpr explicit Process(HANDLE h = nullptr) : h_(h) {}
    constexpr Process(Process&& other) : h_(std::exchange(other.h_, nullptr)) {}
    ~Process() { close(); }
    constexpr explicit operator bool() const { return h_ != nullptr; }

    void wait() {
        if (*this) {
            ::WaitForSingleObject(h_, INFINITE);
            close();
        }
    }
    void kill() {
        if (*this) {
            ::TerminateProcess(h_, -1);
        }
    }

  private:
    DISALLOW_COPY_AND_ASSIGN(Process);

    void close() {
        if (*this) {
            ::CloseHandle(h_);
            h_ = nullptr;
        }
    }

    HANDLE h_;
};

Process adb_launch_process(std::string_view executable, std::vector<std::string> args,
                           std::initializer_list<int> fds_to_inherit = {});

// Helper class to convert UTF-16 argv from wmain() to UTF-8 args that can be
// passed to main().
class NarrowArgs {
public:
    NarrowArgs(int argc, wchar_t** argv);
    ~NarrowArgs();

    inline char** data() {
        return narrow_args;
    }

private:
    char** narrow_args;
};

// Windows HANDLE values only use 32-bits of the type, even on 64-bit machines,
// so they can fit in an int. To convert back, we just need to sign-extend.
// https://msdn.microsoft.com/en-us/library/windows/desktop/aa384203%28v=vs.85%29.aspx
// Note that this does not make a HANDLE value work with APIs like open(), nor
// does this make a value from open() passable to APIs taking a HANDLE. This
// just lets you take a HANDLE, pass it around as an int, and then use it again
// as a HANDLE.
inline int cast_handle_to_int(const HANDLE h) {
    // truncate
    return static_cast<int>(reinterpret_cast<INT_PTR>(h));
}

inline HANDLE cast_int_to_handle(const int fd) {
    // sign-extend
    return reinterpret_cast<HANDLE>(static_cast<INT_PTR>(fd));
}

// Deleter for unique_handle. Adapted from many sources, including:
// http://stackoverflow.com/questions/14841396/stdunique-ptr-deleters-and-the-win32-api
// https://visualstudiomagazine.com/articles/2013/09/01/get-a-handle-on-the-windows-api.aspx
class handle_deleter {
public:
    typedef HANDLE pointer;

    void operator()(HANDLE h);
};

// Like std::unique_ptr, but for Windows HANDLE objects that should be
// CloseHandle()'d. Operator bool() only checks if the handle != nullptr,
// but does not check if the handle != INVALID_HANDLE_VALUE.
typedef std::unique_ptr<HANDLE, handle_deleter> unique_handle;

namespace internal {

size_t ParseCompleteUTF8(const char* first, const char* last, std::vector<char>* remaining_bytes);

}

#else /* !_WIN32 a.k.a. Unix */

#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <poll.h>
#include <pthread.h>
#include <signal.h>
#include <stdarg.h>
#include <stdint.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>

#include <string>

#include <cutils/sockets.h>

#define OS_PATH_SEPARATORS "/"
#define OS_PATH_SEPARATOR '/'
#define OS_PATH_SEPARATOR_STR "/"
#define ENV_PATH_SEPARATOR_STR ":"

static inline bool adb_is_separator(char c) {
    return c == '/';
}

static inline int get_fd_flags(borrowed_fd fd) {
    return fcntl(fd.get(), F_GETFD);
}

static inline void close_on_exec(borrowed_fd fd) {
    int flags = get_fd_flags(fd);
    if (flags >= 0 && (flags & FD_CLOEXEC) == 0) {
        fcntl(fd.get(), F_SETFD, flags | FD_CLOEXEC);
    }
}

// Open a file and return a file descriptor that may be used with unix_read(),
// unix_write(), unix_close(), but not adb_read(), adb_write(), adb_close().
//
// On Unix, this is based on open(), so the file descriptor is a real OS file
// descriptor, but the Windows implementation (in sysdeps_win32.cpp) returns a
// file descriptor that can only be used with C Runtime APIs (which are wrapped
// by unix_read(), unix_write(), unix_close()). Also, the C Runtime has
// configurable CR/LF translation which defaults to text mode, but is settable
// with _setmode().
static inline int unix_open(std::string_view path, int options, ...) {
    std::string zero_terminated(path.begin(), path.end());
    if ((options & O_CREAT) == 0) {
        return TEMP_FAILURE_RETRY(open(zero_terminated.c_str(), options));
    } else {
        int mode;
        va_list args;
        va_start(args, options);
        mode = va_arg(args, int);
        va_end(args);
        return TEMP_FAILURE_RETRY(open(zero_terminated.c_str(), options, mode));
    }
}

// Similar to the two-argument adb_open(), but takes a mode parameter for file
// creation. See adb_open() for more info.
static inline int adb_open_mode(const char* pathname, int options, int mode) {
    return TEMP_FAILURE_RETRY(open(pathname, options, mode));
}

// Open a file and return a file descriptor that may be used with adb_read(),
// adb_write(), adb_close(), but not unix_read(), unix_write(), unix_close().
//
// On Unix, this is based on open(), but the Windows implementation (in
// sysdeps_win32.cpp) uses Windows native file I/O and bypasses the C Runtime
// and its CR/LF translation. The returned file descriptor should be used with
// adb_read(), adb_write(), adb_close(), etc.
static inline int adb_open(const char* pathname, int options) {
    int fd = TEMP_FAILURE_RETRY(open(pathname, options));
    if (fd < 0) return -1;
    close_on_exec(fd);
    return fd;
}
#undef open
#define open ___xxx_open

static inline int adb_shutdown(borrowed_fd fd, int direction = SHUT_RDWR) {
    return shutdown(fd.get(), direction);
}

#undef shutdown
#define shutdown ____xxx_shutdown

// Closes a file descriptor that came from adb_open() or adb_open_mode(), but
// not designed to take a file descriptor from unix_open(). See the comments
// for adb_open() for more info.
inline int adb_close(int fd) {
    return close(fd);
}
#undef close
#define close ____xxx_close

// On Windows, ADB has an indirection layer for file descriptors. If we get a
// Win32 SOCKET object from an external library, we have to map it in to that
// indirection layer, which this does.
inline int adb_register_socket(int s) {
    return s;
}

static inline int adb_gethostname(char* name, size_t len) {
    return gethostname(name, len);
}

static inline int adb_getlogin_r(char* buf, size_t bufsize) {
    return getlogin_r(buf, bufsize);
}

static inline int adb_read(borrowed_fd fd, void* buf, size_t len) {
    return TEMP_FAILURE_RETRY(read(fd.get(), buf, len));
}

static inline int adb_pread(borrowed_fd fd, void* buf, size_t len, off64_t offset) {
#if defined(__APPLE__)
    return TEMP_FAILURE_RETRY(pread(fd.get(), buf, len, offset));
#else
    return TEMP_FAILURE_RETRY(pread64(fd.get(), buf, len, offset));
#endif
}

// Like unix_read(), but does not handle EINTR.
static inline int unix_read_interruptible(borrowed_fd fd, void* buf, size_t len) {
    return read(fd.get(), buf, len);
}

#undef read
#define read ___xxx_read
#undef pread
#define pread ___xxx_pread

static inline int adb_write(borrowed_fd fd, const void* buf, size_t len) {
    return TEMP_FAILURE_RETRY(write(fd.get(), buf, len));
}

static inline int adb_pwrite(int fd, const void* buf, size_t len, off64_t offset) {
#if defined(__APPLE__)
    return TEMP_FAILURE_RETRY(pwrite(fd, buf, len, offset));
#else
    return TEMP_FAILURE_RETRY(pwrite64(fd, buf, len, offset));
#endif
}

#undef   write
#define  write  ___xxx_write
#undef pwrite
#define pwrite ___xxx_pwrite

static inline int64_t adb_lseek(borrowed_fd fd, int64_t pos, int where) {
#if defined(__APPLE__)
    return lseek(fd.get(), pos, where);
#else
    return lseek64(fd.get(), pos, where);
#endif
}
#undef lseek
#define lseek ___xxx_lseek

static inline int adb_unlink(const char* path) {
    return unlink(path);
}
#undef unlink
#define unlink ___xxx_unlink

static inline int adb_creat(const char* path, int mode) {
    int fd = TEMP_FAILURE_RETRY(creat(path, mode));

    if (fd < 0) return -1;

    close_on_exec(fd);
    return fd;
}
#undef creat
#define creat ___xxx_creat

static inline int unix_isatty(borrowed_fd fd) {
    return isatty(fd.get());
}
#define isatty ___xxx_isatty

// Helper for network_* functions.
inline int _fd_set_error_str(int fd, std::string* error) {
    if (fd == -1) {
        *error = strerror(errno);
    }
    return fd;
}

inline int network_inaddr_any_server(int port, int type, std::string* error) {
    return _fd_set_error_str(socket_inaddr_any_server(port, type), error);
}

inline int network_local_client(const char* name, int namespace_id, int type, std::string* error) {
    return _fd_set_error_str(socket_local_client(name, namespace_id, type), error);
}

inline int network_local_server(const char* name, int namespace_id, int type, std::string* error) {
    return _fd_set_error_str(socket_local_server(name, namespace_id, type), error);
}

int network_connect(const std::string& host, int port, int type, int timeout, std::string* error);

static inline int adb_socket_accept(borrowed_fd serverfd, struct sockaddr* addr,
                                    socklen_t* addrlen) {
    int fd;

    fd = TEMP_FAILURE_RETRY(accept(serverfd.get(), addr, addrlen));
    if (fd >= 0) close_on_exec(fd);

    return fd;
}

#undef accept
#define accept ___xxx_accept

inline int adb_getsockname(borrowed_fd fd, struct sockaddr* sockaddr, socklen_t* addrlen) {
    return getsockname(fd.get(), sockaddr, addrlen);
}

inline int adb_socket_get_local_port(borrowed_fd fd) {
    return socket_get_local_port(fd.get());
}

// Operate on a file descriptor returned from unix_open() or a well-known file
// descriptor such as STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO.
//
// On Unix, unix_read(), unix_write(), unix_close() map to adb_read(),
// adb_write(), adb_close() (which all map to Unix system calls), but the
// Windows implementations (in the ifdef above and in sysdeps_win32.cpp) call
// into the C Runtime and its configurable CR/LF translation (which is settable
// via _setmode()).
#define unix_read adb_read
#define unix_write adb_write
#define unix_lseek adb_lseek
#define unix_close adb_close

static inline int adb_thread_setname(const std::string& name) {
#ifdef __APPLE__
    return pthread_setname_np(name.c_str());
#else
    // Both bionic and glibc's pthread_setname_np fails rather than truncating long strings.
    // glibc doesn't have strlcpy, so we have to fake it.
    char buf[16];  // MAX_TASK_COMM_LEN, but that's not exported by the kernel headers.
    strncpy(buf, name.c_str(), sizeof(buf) - 1);
    buf[sizeof(buf) - 1] = '\0';
    return pthread_setname_np(pthread_self(), buf);
#endif
}

static inline int adb_setsockopt(borrowed_fd fd, int level, int optname, const void* optval,
                                 socklen_t optlen) {
    return setsockopt(fd.get(), level, optname, optval, optlen);
}

#undef setsockopt
#define setsockopt ___xxx_setsockopt

static inline int adb_socket(int domain, int type, int protocol) {
    return socket(domain, type, protocol);
}

static inline int adb_bind(borrowed_fd fd, const sockaddr* addr, int namelen) {
    return bind(fd.get(), addr, namelen);
}

static inline int unix_socketpair(int d, int type, int protocol, int sv[2]) {
    return socketpair(d, type, protocol, sv);
}

static inline int adb_socketpair(int sv[2]) {
    int rc;

    rc = unix_socketpair(AF_UNIX, SOCK_STREAM, 0, sv);
    if (rc < 0) return -1;

    close_on_exec(sv[0]);
    close_on_exec(sv[1]);
    return 0;
}

#undef socketpair
#define socketpair ___xxx_socketpair

typedef struct msghdr adb_msghdr;
inline ssize_t adb_sendmsg(borrowed_fd fd, const adb_msghdr* msg, int flags) {
    return sendmsg(fd.get(), msg, flags);
}

inline ssize_t adb_recvmsg(borrowed_fd fd, adb_msghdr* msg, int flags) {
    ssize_t ret = recvmsg(fd.get(), msg, flags);
    if (ret == -1) {
        PLOG(ERROR) << "adb_recmsg error";
    }
    return ret;
}

using adb_cmsghdr = cmsghdr;

inline adb_cmsghdr* adb_CMSG_FIRSTHDR(adb_msghdr* msgh) {
    return CMSG_FIRSTHDR(msgh);
}

inline adb_cmsghdr* adb_CMSG_NXTHDR(adb_msghdr* msgh, adb_cmsghdr* cmsg) {
    return CMSG_NXTHDR(msgh, cmsg);
}

inline unsigned char* adb_CMSG_DATA(adb_cmsghdr* cmsg) {
    return CMSG_DATA(cmsg);
}

typedef struct pollfd adb_pollfd;
static inline int adb_poll(adb_pollfd* fds, size_t nfds, int timeout) {
    return TEMP_FAILURE_RETRY(poll(fds, nfds, timeout));
}

#define poll ___xxx_poll

static inline int adb_mkdir(const std::string& path, int mode) {
    return mkdir(path.c_str(), mode);
}

#undef mkdir
#define mkdir ___xxx_mkdir

static inline int adb_rename(const char* oldpath, const char* newpath) {
    return rename(oldpath, newpath);
}

static inline int adb_is_absolute_host_path(const char* path) {
    return path[0] == '/';
}

static inline int adb_get_os_handle(borrowed_fd fd) {
    return fd.get();
}

static inline int cast_handle_to_int(int fd) {
    return fd;
}

// A very simple wrapper over a launched child process
class Process {
  public:
    constexpr explicit Process(pid_t pid) : pid_(pid) {}
    constexpr Process(Process&& other) : pid_(std::exchange(other.pid_, -1)) {}

    constexpr explicit operator bool() const { return pid_ >= 0; }

    void wait() {
        if (*this) {
            int status;
            ::waitpid(pid_, &status, 0);
            pid_ = -1;
        }
    }
    void kill() {
        if (*this) {
            ::kill(pid_, SIGTERM);
        }
    }

  private:
    DISALLOW_COPY_AND_ASSIGN(Process);

    pid_t pid_;
};

Process adb_launch_process(std::string_view executable, std::vector<std::string> args,
                           std::initializer_list<int> fds_to_inherit = {});

#endif /* !_WIN32 */

static inline void disable_tcp_nagle(borrowed_fd fd) {
    int off = 1;
    adb_setsockopt(fd.get(), IPPROTO_TCP, TCP_NODELAY, &off, sizeof(off));
}

// Sets TCP socket |fd| to send a keepalive TCP message every |interval_sec| seconds. Set
// |interval_sec| to 0 to disable keepalives. If keepalives are enabled, the connection will be
// configured to drop after 10 missed keepalives. Returns true on success.
bool set_tcp_keepalive(borrowed_fd fd, int interval_sec);

// Returns a human-readable OS version string.
extern std::string GetOSVersion();

#if defined(_WIN32)
// Win32 defines ERROR, which we don't need, but which conflicts with google3 logging.
#undef ERROR
#endif