1__require_tool_version_compare ()
2{
3  (
4    # Locally ignore failures, otherwise we'll exit whenever $1 and $2
5    # are not equal!
6    set +e
7
8awk_strverscmp='
9  # Use only awk features that work with 7th edition Unix awk (1978).
10  # My, what an old awk you have, Mr. Solaris!
11  END {
12    while (length(v1) || length(v2)) {
13      # Set d1 to be the next thing to compare from v1, and likewise for d2.
14      # Normally this is a single character, but if v1 and v2 contain digits,
15      # compare them as integers and fractions as strverscmp does.
16      if (v1 ~ /^[0-9]/ && v2 ~ /^[0-9]/) {
17	# Split v1 and v2 into their leading digit string components d1 and d2,
18	# and advance v1 and v2 past the leading digit strings.
19	for (len1 = 1; substr(v1, len1 + 1) ~ /^[0-9]/; len1++) continue
20	for (len2 = 1; substr(v2, len2 + 1) ~ /^[0-9]/; len2++) continue
21	d1 = substr(v1, 1, len1); v1 = substr(v1, len1 + 1)
22	d2 = substr(v2, 1, len2); v2 = substr(v2, len2 + 1)
23	if (d1 ~ /^0/) {
24	  if (d2 ~ /^0/) {
25	    # Compare two fractions.
26	    while (d1 ~ /^0/ && d2 ~ /^0/) {
27	      d1 = substr(d1, 2); len1--
28	      d2 = substr(d2, 2); len2--
29	    }
30	    if (len1 != len2 && ! (len1 && len2 && substr(d1, 1, 1) == substr(d2, 1, 1))) {
31	      # The two components differ in length, and the common prefix
32	      # contains only leading zeros.  Consider the longer to be less.
33	      d1 = -len1
34	      d2 = -len2
35	    } else {
36	      # Otherwise, compare as strings.
37	      d1 = "x" d1
38	      d2 = "x" d2
39	    }
40	  } else {
41	    # A fraction is less than an integer.
42	    exit 1
43	  }
44	} else {
45	  if (d2 ~ /^0/) {
46	    # An integer is greater than a fraction.
47	    exit 2
48	  } else {
49	    # Compare two integers.
50	    d1 += 0
51	    d2 += 0
52	  }
53	}
54      } else {
55	# The normal case, without worrying about digits.
56	if (v1 == "") d1 = v1; else { d1 = substr(v1, 1, 1); v1 = substr(v1,2) }
57	if (v2 == "") d2 = v2; else { d2 = substr(v2, 1, 1); v2 = substr(v2,2) }
58      }
59      if (d1 < d2) exit 1
60      if (d1 > d2) exit 2
61    }
62  }
63'
64    awk "$awk_strverscmp" v1="$1" v2="$2" /dev/null
65    case $? in
66      1)  echo '<';;
67      0)  echo '=';;
68      2)  echo '>';;
69    esac
70  )
71}
72
73
74__require_tool_fatal ()
75{
76    echo $@ >/dev/stderr
77    return 1
78}
79
80# Usage: require_tool program version
81# Returns: 0 if $1 version if greater equals than $2, 1 otherwise.
82# In case of error, message is written on error output.
83#
84# Example: require_tool gcc 4.6
85# Use GCC environment variable if defined instead of lookup for the tool
86# in the environment.
87require_tool ()
88{
89  envvar_name=$(echo $1 | tr '[:lower:]' '[:upper:]')
90  tool=$(printenv $envvar_name || echo $1)
91  local version=$($tool --version 2>/dev/null| \
92    sed -n 's/.*[^0-9.]\([0-9]*\.[0-9.]*\).*/\1/p;q')
93  if test x"$version" = x ; then
94      echo "$tool is required" >/dev/stderr
95      return 1
96  fi
97  case $(__require_tool_version_compare "$2" "$version") in
98    '>')
99	  echo "$1 $2 or better is required: this is $tool $version" >/dev/stderr
100	  return 1
101	  ;;
102  esac
103}
104
105usage() {
106    cat <<EOF
107NAME
108    require_tool.sh - Ensure version of a tool is greater than the one expected
109
110SYNOPSYS
111    require_tool.sh [ -h ]
112                    [ --help ]
113                    [ TOOL MIN_VERSION ]
114
115DESCRIPTION
116    TOOL is the name or path of the program to check. If the name is specified, its
117    path is deduced from PATH environment variable. If environment variable TOOL
118    (in upper-case characters) is defined, considers its value as path to the tool.
119
120    MIN_VERSION is a string representing the minimum required version.
121
122BEHAVIOR
123    * locate path to the program.
124    * execute $ TOOL_PATH --version
125    * extract version from standard output.
126    * compare this version to the expected one.
127
128OPTIONS
129    -h --help
130        Display this message and exit 0
131
132ERRORS
133    if program is not found or its version is prior to expected version,
134    a message is written to error output.
135
136EXIT VALUE
137    returns 0 if program version if greater equals than expected version,
138    returns 1 otherwise.
139
140EXAMPLE
141    $ require_tool.sh emacs 23
142    $ CC=g++ require_tool.sh cc 4.6
143    $ require_tool.sh zsh 4.5
144
145EOF
146}
147
148for arg in $@; do
149    case $arg in
150        -h|--help)
151            usage
152            exit 0
153            ;;
154    esac
155done
156if [ $# -gt 2 ] ; then
157    echo "ERROR: expecting 2 parameters. Please see option --help"
158    exit 1
159fi
160
161require_tool $@
162