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1# functions used by the udev rule generator
2
3# Copyright (C) 2006 Marco d'Itri <md@Linux.IT>
4
5# This program is free software: you can redistribute it and/or modify
6# it under the terms of the GNU General Public License as published by
7# the Free Software Foundation, either version 2 of the License, or
8# (at your option) any later version.
9
10# This program is distributed in the hope that it will be useful,
11# but WITHOUT ANY WARRANTY; without even the implied warranty of
12# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13# GNU General Public License for more details.
14
15# You should have received a copy of the GNU General Public License
16# along with this program.  If not, see <http://www.gnu.org/licenses/>.
17
18PATH='/sbin:/bin'
19#
20
21PATH='/sbin:/bin'
22
23# Read a single line from file $1 in the $DEVPATH directory.
24# The function must not return an error even if the file does not exist.
25sysread() {
26	local file="$1"
27	[ -e "/sys$DEVPATH/$file" ] || return 0
28	local value
29	read value < "/sys$DEVPATH/$file" || return 0
30	echo "$value"
31}
32
33sysreadlink() {
34	local file="$1"
35	[ -e "/sys$DEVPATH/$file" ] || return 0
36	readlink -f /sys$DEVPATH/$file 2> /dev/null || true
37}
38
39# Return true if a directory is writeable.
40writeable() {
41	if ln -s test-link $1/.is-writeable 2> /dev/null; then
42		rm -f $1/.is-writeable
43		return 0
44	else
45		return 1
46	fi
47}
48
49# Create a lock file for the current rules file.
50lock_rules_file() {
51	RUNDIR="/run/udev/"
52
53	RULES_LOCK="$RUNDIR/.lock-${RULES_FILE##*/}"
54
55	retry=30
56	while ! mkdir $RULES_LOCK 2> /dev/null; do
57		if [ $retry -eq 0 ]; then
58			 echo "Cannot lock $RULES_FILE!" >&2
59			 exit 2
60		fi
61		sleep 1
62		retry=$(($retry - 1))
63	done
64}
65
66unlock_rules_file() {
67	[ "$RULES_LOCK" ] || return 0
68	rmdir $RULES_LOCK || true
69}
70
71# Choose the real rules file if it is writeable or a temporary file if not.
72# Both files should be checked later when looking for existing rules.
73choose_rules_file() {
74	RUNDIR="/run/udev/"
75
76	local tmp_rules_file="$RUNDIR/tmp-rules--${RULES_FILE##*/}"
77	[ -e "$RULES_FILE" -o -e "$tmp_rules_file" ] || PRINT_HEADER=1
78
79	[ -d "${RULES_FILE%/*}" ] || if writeable ${RULES_FILE%/rules.d/*}; then
80		mkdir -p "${RULES_FILE%/*}"
81	fi
82
83	if writeable ${RULES_FILE%/*}; then
84		RO_RULES_FILE='/dev/null'
85	else
86		RO_RULES_FILE=$RULES_FILE
87		RULES_FILE=$tmp_rules_file
88	fi
89}
90
91# Return the name of the first free device.
92raw_find_next_available() {
93	local links="$1"
94
95	local basename=${links%%[ 0-9]*}
96	local max=-1
97	for name in $links; do
98		local num=${name#$basename}
99		[ "$num" ] || num=0
100		[ $num -gt $max ] && max=$num
101	done
102
103	local max=$(($max + 1))
104	# "name0" actually is just "name"
105	[ $max -eq 0 ] && return
106	echo "$max"
107}
108
109# Find all rules matching a key (with action) and a pattern.
110find_all_rules() {
111	local key="$1"
112	local linkre="$2"
113	local match="$3"
114
115	local search='.*[[:space:],]'"$key"'"('"$linkre"')".*'
116	echo $(sed -n -r -e 's/^#.*//' -e "${match}s/${search}/\1/p" \
117		$RO_RULES_FILE \
118		$([ -e $RULES_FILE ] && echo $RULES_FILE) \
119		2>/dev/null)
120}
121