1# Copyright 2012 Google Inc.
2# All rights reserved.
3#
4# Redistribution and use in source and binary forms, with or without
5# modification, are permitted provided that the following conditions are
6# met:
7#
8# * Redistributions of source code must retain the above copyright
9#   notice, this list of conditions and the following disclaimer.
10# * Redistributions in binary form must reproduce the above copyright
11#   notice, this list of conditions and the following disclaimer in the
12#   documentation and/or other materials provided with the distribution.
13# * Neither the name of Google Inc. nor the names of its contributors
14#   may be used to endorse or promote products derived from this software
15#   without specific prior written permission.
16#
17# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
29# \file lib.subr
30# Common initialization and functions for shell scripts.
31
32
33set -e
34
35
36# Directory where the running script lives.
37Lib_DirName="$(dirname ${0})"
38
39
40# Base name of the running script.
41Lib_ProgName="${0##*/}"
42
43
44# Path to the temporary directory for this execution.
45Lib_TempDir=
46
47
48# List of cleanup functions to execute on exit.
49_Lib_Cleanup_Hooks=
50
51
52# Catch unexpected exits and perform the required cleanups.  In particular,
53# ensure that the temporary directory in Lib_TempDir, if any, is removed.
54trap 'lib_cleanup ; exit 2' HUP INT QUIT TERM
55
56
57# Prints an informational message.
58#
59# \param ... The message to print.  Can be provided as multiple words and, in
60#     that case, they are joined together by a single whitespace.
61lib_info() {
62    echo "${Lib_ProgName}: I: $*" 1>&2
63}
64
65
66# Prints a runtime error and exits.
67#
68# \param ... The message to print.  Can be provided as multiple words and, in
69#     that case, they are joined together by a single whitespace.
70lib_error() {
71    echo "${Lib_ProgName}: E: $*" 1>&2
72    exit 1
73}
74
75
76# Prints a runtime warning.
77#
78# \param ... The message to print.  Can be provided as multiple words and, in
79#     that case, they are joined together by a single whitespace.
80lib_warning() {
81    echo "${Lib_ProgName}: W: $*" 1>&2
82}
83
84
85# Prints an usage error and exits.
86#
87# \param ... The message to print.  Can be provided as multiple words and, in
88#     that case, they are joined together by a single whitespace.
89lib_usage_error() {
90    echo "${Lib_ProgName}: E: $*" 1>&2
91    usage "${Lib_ProgName}" 1>&2
92    exit 1
93}
94
95
96# Executes the registered cleanup hooks.
97lib_cleanup() {
98    local hook
99    for hook in ${_Lib_Cleanup_Hooks}; do
100        "${hook}"
101    done
102}
103
104
105# Installs a new cleanup hook.
106#
107# \param ... The names of the cleanup functions to register.
108lib_register_cleanup() {
109    _Lib_Cleanup_Hooks="${_Lib_Cleanup_Hooks} ${*}"
110}
111
112
113# Creates a temporary directory for this execution.
114#
115# The temporary directory is unique to this script and execution.  A cleanup
116# hook is installed to delete such directory whenever lib_cleanup is called or
117# when the program abruptly exits.
118#
119# \post Lib_TempDir is set to the path of the created temporary directory.
120lib_init_tempdir() {
121    Lib_TempDir=$(mktemp -d -t "${_Lib_ProgName}.XXXXXX")
122    lib_register_cleanup "lib_clean_tempdir"
123}
124
125
126# Cleanup hook to delete the temporary directory.
127#
128# This operation is idempotent.
129lib_clean_tempdir() {
130    if [ -n "${Lib_TempDir}" ]; then
131        rm -rf "${Lib_TempDir}"
132        Lib_TempDir=
133    fi
134}
135