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// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "remoting/host/base/username.h"
#include <vector>
#include "base/logging.h"
#include "base/notimplemented.h"
#include "build/build_config.h"
#if BUILDFLAG(IS_POSIX)
#include <pwd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#endif // BUILDFLAG(IS_POSIX)
namespace remoting {
std::string GetUsername() {
#if BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_ANDROID)
long buf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
if (buf_size <= 0) {
PLOG(ERROR) << "sysconf(_SC_GETPW_R_SIZE_MAX) failed";
return std::string();
}
std::vector<char> buf(buf_size);
struct passwd passwd;
struct passwd* passwd_result;
uid_t user_id = getuid();
// Verify that `user_id` has a valid passwd database record, which matches
// the UID for this process. It is possible for multiple usernames to share
// the same user id, and some systems may not reliably support lookups by UID.
// Therefore, use the username from the environment (which is set by the
// parent process in remoting_user_session.cc), and do a lookup by name to ID.
// The logic is similar to FindCurrentUsername() from
// remoting_user_session.cc, except the re-entrant "_r" lookup functions are
// used here, for safety in a multi-threaded program.
for (const char* var : {"USER", "LOGNAME"}) {
const char* username_from_env = getenv(var);
if (!username_from_env) {
LOG(WARNING) << "Name '" << var << "' not found in environment.";
continue;
}
passwd_result = nullptr;
errno = getpwnam_r(username_from_env, &passwd, &(buf[0]), buf_size,
&passwd_result);
if (!passwd_result) {
PLOG(WARNING) << "getpwnam_r() failed for username: "
<< username_from_env;
continue;
}
if (passwd_result->pw_uid != user_id) {
LOG(WARNING) << "getpwnam_r() for user '" << username_from_env
<< "' returned pw_uid " << passwd_result->pw_uid
<< " which does not match user id " << user_id;
continue;
}
return passwd_result->pw_name;
}
// The method above failed, fall back to a simple id->name lookup.
passwd_result = nullptr;
errno = getpwuid_r(user_id, &passwd, &(buf[0]), buf_size, &passwd_result);
if (!passwd_result) {
PLOG(ERROR) << "getpwuid_r() failed for user " << user_id;
return std::string();
}
std::string result(passwd_result->pw_name);
if (result.empty()) {
LOG(ERROR) << "getpwuid_r() returned empty pw_name for user " << user_id;
}
return result;
#else
NOTIMPLEMENTED();
return std::string();
#endif // BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_ANDROID)
}
} // namespace remoting
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