1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "sysdeps/errno.h"
18
19#include <windows.h>
20
21#include <string>
22
23// Overrides strerror() to handle error codes not supported by the Windows C
24// Runtime (MSVCRT.DLL).
25char* adb_strerror(int err) {
26// sysdeps.h defines strerror to adb_strerror, but in this function, we
27// want to call the real C Runtime strerror().
28#pragma push_macro("strerror")
29#undef strerror
30    const int saved_err = errno;  // Save because we overwrite it later.
31
32    // Lookup the string for an unknown error.
33    char* errmsg = strerror(-1);
34    const std::string unknown_error = (errmsg == nullptr) ? "" : errmsg;
35
36    // Lookup the string for this error to see if the C Runtime has it.
37    errmsg = strerror(err);
38    if (errmsg != nullptr && unknown_error != errmsg) {
39        // The CRT returned an error message and it is different than the error
40        // message for an unknown error, so it is probably valid, so use it.
41    } else {
42        // Check if we have a string for this error code.
43        const char* custom_msg = nullptr;
44        switch (err) {
45#pragma push_macro("ERR")
46#undef ERR
47#define ERR(errnum, desc) case errnum: custom_msg = desc; break
48            // These error strings are from AOSP bionic/libc/include/sys/_errdefs.h.
49            // Note that these cannot be longer than 94 characters because we
50            // pass this to _strerror() which has that requirement.
51            ERR(ECONNRESET,    "Connection reset by peer");
52            ERR(EHOSTUNREACH,  "No route to host");
53            ERR(ENETDOWN,      "Network is down");
54            ERR(ENETRESET,     "Network dropped connection because of reset");
55            ERR(ENOBUFS,       "No buffer space available");
56            ERR(ENOPROTOOPT,   "Protocol not available");
57            ERR(ENOTCONN,      "Transport endpoint is not connected");
58            ERR(ENOTSOCK,      "Socket operation on non-socket");
59            ERR(EOPNOTSUPP,    "Operation not supported on transport endpoint");
60#pragma pop_macro("ERR")
61        }
62
63        if (custom_msg != nullptr) {
64            // Use _strerror() to write our string into the writable per-thread
65            // buffer used by strerror()/_strerror(). _strerror() appends the
66            // msg for the current value of errno, so set errno to a consistent
67            // value for every call so that our code-path is always the same.
68            errno = 0;
69            errmsg = _strerror(custom_msg);
70            const size_t custom_msg_len = strlen(custom_msg);
71            // Just in case _strerror() returned a read-only string, check if
72            // the returned string starts with our custom message because that
73            // implies that the string is not read-only.
74            if ((errmsg != nullptr) && !strncmp(custom_msg, errmsg, custom_msg_len)) {
75                // _strerror() puts other text after our custom message, so
76                // remove that by terminating after our message.
77                errmsg[custom_msg_len] = '\0';
78            } else {
79                // For some reason nullptr was returned or a pointer to a
80                // read-only string was returned, so fallback to whatever
81                // strerror() can muster (probably "Unknown error" or some
82                // generic CRT error string).
83                errmsg = strerror(err);
84            }
85        } else {
86            // We don't have a custom message, so use whatever strerror(err)
87            // returned earlier.
88        }
89    }
90
91    errno = saved_err;  // restore
92
93    return errmsg;
94#pragma pop_macro("strerror")
95}
96