// Copyright (c) Microsoft Corporation. All rights reserved.

// Licensed under the MIT License.

//! @brief returns the username for a uid

#include "getpwuid.h"

#include <errno.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <pwd.h>

#include <string.h>

#include <unistd.h>

//! @brief GetPwUid returns the username for a uid

//!

//! GetPwUid

//!

//! @param[in] uid

//! @parblock

//! The user identifier to lookup.

//! @endparblock

//!

//! @retval username as UTF-8 string, or NULL if unsuccessful

//!

char* GetPwUid(uid_t uid)

{

int32_t ret = 0;

struct passwd pwd;

struct passwd* result = NULL;

char* buf;

int buflen = sysconf(_SC_GETPW_R_SIZE_MAX);

if (buflen < 1)

{

buflen = 2048;

}

allocate:

buf = (char*)calloc(buflen, sizeof(char));

errno = 0;

ret = getpwuid_r(uid, &pwd, buf, buflen, &result);

if (ret != 0)

{

if (errno == ERANGE)

{

free(buf);

buflen *= 2;

goto allocate;

}

return NULL;

}

// no result

if (result == NULL)

{

return NULL;

}

// allocate copy on heap so CLR can free it

size_t userlen = strnlen(pwd.pw_name, buflen);

char* username = strndup(pwd.pw_name, userlen);

free(buf);

return username;

}