Subversion Repositories openrisc

// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build darwin freebsd linux
// +build cgo

package user

import (
        "fmt"
        "strconv"
        "strings"
        "syscall"
        "unsafe"
)

/*
#include <unistd.h>
#include <sys/types.h>
#include <pwd.h>
#include <stdlib.h>

static int mygetpwuid_r(int uid, struct passwd *pwd,
        char *buf, size_t buflen, struct passwd **result) {
 return getpwuid_r(uid, pwd, buf, buflen, result);
}
*/

//extern getpwnam_r
func libc_getpwnam_r(name *byte, pwd *syscall.Passwd, buf *byte, buflen syscall.Size_t, result **syscall.Passwd) int

//extern getpwuid_r
func libc_getpwuid_r(uid syscall.Uid_t, pwd *syscall.Passwd, buf *byte, buflen syscall.Size_t, result **syscall.Passwd) int

// bytePtrToString takes a NUL-terminated array of bytes and convert
// it to a Go string.
func bytePtrToString(p *byte) string {
        a := (*[10000]byte)(unsafe.Pointer(p))
        i := 0
        for a[i] != 0 {
                i++
        }
        return string(a[:i])
}

// Current returns the current user. 
func Current() (*User, error) {
        return lookup(syscall.Getuid(), "", false)
}

// Lookup looks up a user by username. If the user cannot be found,
// the returned error is of type UnknownUserError.
func Lookup(username string) (*User, error) {
        return lookup(-1, username, true)
}

// LookupId looks up a user by userid. If the user cannot be found,
// the returned error is of type UnknownUserIdError.
func LookupId(uid string) (*User, error) {
        i, e := strconv.Atoi(uid)
        if e != nil {
                return nil, e
        }
        return lookup(i, "", false)
}

func lookup(uid int, username string, lookupByName bool) (*User, error) {
        var pwd syscall.Passwd
        var result *syscall.Passwd

        // FIXME: Should let buf grow if necessary.
        const bufSize = 1024
        buf := make([]byte, bufSize)
        if lookupByName {
                rv := libc_getpwnam_r(syscall.StringBytePtr(username),
                        &pwd,
                        &buf[0],
                        bufSize,
                        &result)
                if rv != 0 {
                        return nil, fmt.Errorf("user: lookup username %s: %s", username, syscall.GetErrno())
                }
                if result == nil {
                        return nil, UnknownUserError(username)
                }
        } else {
                rv := libc_getpwuid_r(syscall.Uid_t(uid),
                        &pwd,
                        &buf[0],
                        bufSize,
                        &result)
                if rv != 0 {
                        return nil, fmt.Errorf("user: lookup userid %d: %s", uid, syscall.GetErrno())
                }
                if result == nil {
                        return nil, UnknownUserIdError(uid)
                }
        }
        u := &User{
                Uid:      strconv.Itoa(int(pwd.Pw_uid)),
                Gid:      strconv.Itoa(int(pwd.Pw_gid)),
                Username: bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_name))),
                Name:     bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_gecos))),
                HomeDir:  bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_dir))),
        }
        // The pw_gecos field isn't quite standardized.  Some docs
        // say: "It is expected to be a comma separated list of
        // personal data where the first item is the full name of the
        // user."
        if i := strings.Index(u.Name, ","); i >= 0 {
                u.Name = u.Name[:i]
        }
        return u, nil
}