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* Copyright (C) 2016 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include "sysdeps/errno.h"
#include <windows.h>
#include <string>
// Overrides strerror() to handle error codes not supported by the Windows C
// Runtime (MSVCRT.DLL).
char* adb_strerror(int err) {
// sysdeps.h defines strerror to adb_strerror, but in this function, we
// want to call the real C Runtime strerror().
#pragma push_macro("strerror")
#undef strerror
const int saved_err = errno; // Save because we overwrite it later.
// Lookup the string for an unknown error.
char* errmsg = strerror(-1);
const std::string unknown_error = (errmsg == nullptr) ? "" : errmsg;
// Lookup the string for this error to see if the C Runtime has it.
errmsg = strerror(err);
if (errmsg != nullptr && unknown_error != errmsg) {
// The CRT returned an error message and it is different than the error
// message for an unknown error, so it is probably valid, so use it.
} else {
// Check if we have a string for this error code.
const char* custom_msg = nullptr;
switch (err) {
#pragma push_macro("ERR")
#undef ERR
#define ERR(errnum, desc) case errnum: custom_msg = desc; break
// These error strings are from AOSP bionic/libc/include/sys/_errdefs.h.
// Note that these cannot be longer than 94 characters because we
// pass this to _strerror() which has that requirement.
ERR(ECONNRESET, "Connection reset by peer");
ERR(EHOSTUNREACH, "No route to host");
ERR(ENETDOWN, "Network is down");
ERR(ENETRESET, "Network dropped connection because of reset");
ERR(ENOBUFS, "No buffer space available");
ERR(ENOPROTOOPT, "Protocol not available");
ERR(ENOTCONN, "Transport endpoint is not connected");
ERR(ENOTSOCK, "Socket operation on non-socket");
ERR(EOPNOTSUPP, "Operation not supported on transport endpoint");
#pragma pop_macro("ERR")
if (custom_msg != nullptr) {
// Use _strerror() to write our string into the writable per-thread
// buffer used by strerror()/_strerror(). _strerror() appends the
// msg for the current value of errno, so set errno to a consistent
// value for every call so that our code-path is always the same.
errno = 0;
errmsg = _strerror(custom_msg);
const size_t custom_msg_len = strlen(custom_msg);
// Just in case _strerror() returned a read-only string, check if
// the returned string starts with our custom message because that
// implies that the string is not read-only.
if ((errmsg != nullptr) && !strncmp(custom_msg, errmsg, custom_msg_len)) {
// _strerror() puts other text after our custom message, so
// remove that by terminating after our message.
errmsg[custom_msg_len] = '\0';
} else {
// For some reason nullptr was returned or a pointer to a
// read-only string was returned, so fallback to whatever
// strerror() can muster (probably "Unknown error" or some
// generic CRT error string).
errmsg = strerror(err);
} else {
// We don't have a custom message, so use whatever strerror(err)
// returned earlier.
errno = saved_err; // restore
return errmsg;
#pragma pop_macro("strerror")