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// Copyright 2010 Jonas mg
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
package user
import (
"io"
"os"
"strconv"
)
// nextUID returns the next free user id to use, according to whether it is a
// system's user.
func nextUID(isSystem bool) (db *dbfile, uid int, err error) {
loadConfig()
db, err = openDBFile(fileUser, os.O_RDWR)
if err != nil {
return
}
// Seek to file half size.
info, err := db.file.Stat()
if err != nil {
db.close()
return nil, 0, err
}
if _, err = db.file.Seek(info.Size()/2, io.SeekStart); err != nil {
db.close()
return nil, 0, err
}
// To starting to read from a new line
if _, _, err = db.rd.ReadLine(); err != nil {
db.close()
return nil, 0, err
}
var minUid, maxUid int
if isSystem {
minUid, maxUid = config.login.SYS_UID_MIN, config.login.SYS_UID_MAX
} else {
minUid, maxUid = config.login.UID_MIN, config.login.UID_MAX
}
for {
line, _, err := db.rd.ReadLine()
if err == io.EOF {
break
}
u, err := parseUser(string(line))
if err != nil {
db.close()
return nil, 0, err
}
if u.UID >= minUid && u.UID <= maxUid {
uid = u.UID
}
}
uid++
if uid == maxUid {
return nil, 0, &IdRangeError{maxUid, isSystem, true}
}
return
}
// nextGUID returns the next free group id to use, according to whether it is a
// system's group.
func nextGUID(isSystem bool) (db *dbfile, gid int, err error) {
loadConfig()
db, err = openDBFile(fileGroup, os.O_RDWR)
if err != nil {
return
}
// Seek to file half size.
info, err := db.file.Stat()
if err != nil {
db.close()
return nil, 0, err
}
if _, err = db.file.Seek(info.Size()/2, io.SeekStart); err != nil {
db.close()
return nil, 0, err
}
// To starting to read from a new line
if _, _, err = db.rd.ReadLine(); err != nil {
db.close()
return nil, 0, err
}
var minGid, maxGid int
if isSystem {
minGid, maxGid = config.login.SYS_GID_MIN, config.login.SYS_GID_MAX
} else {
minGid, maxGid = config.login.GID_MIN, config.login.GID_MAX
}
for {
line, _, err := db.rd.ReadLine()
if err == io.EOF {
break
}
gr, err := parseGroup(string(line))
if err != nil {
db.close()
return nil, 0, err
}
if gr.GID >= minGid && gr.GID <= maxGid {
gid = gr.GID
}
}
gid++
if gid == maxGid {
return nil, 0, &IdRangeError{maxGid, isSystem, false}
}
return
}
// NextSystemUID returns the next free system user id to use.
func NextSystemUID() (int, error) {
db, uid, err := nextUID(true)
db.close()
return uid, err
}
// NextSystemGID returns the next free system group id to use.
func NextSystemGID() (int, error) {
db, gid, err := nextGUID(true)
db.close()
return gid, err
}
// NextUID returns the next free user id to use.
func NextUID() (int, error) {
db, uid, err := nextUID(false)
db.close()
return uid, err
}
// NextGID returns the next free group id to use.
func NextGID() (int, error) {
db, gid, err := nextGUID(false)
db.close()
return gid, err
}
// * * *
// IdRangeError records an error during the search for a free id to use.
type IdRangeError struct {
LastId int
IsSystem bool
IsUser bool
}
func (e *IdRangeError) Error() string {
str := ""
if e.IsSystem {
str = "system "
}
if e.IsUser {
str += "user: "
} else {
str += "group: "
}
str += strconv.Itoa(e.LastId)
return "reached maximum identifier in " + str
}
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