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Commit bc2132df authored by Siddharth Agarwal's avatar Siddharth Agarwal
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alias: expand "$@" as list of parameters quoted individually (BC) (issue4200)

Before this patch, there was no way to pass in all the positional parameters as
separate words down to another command.

(1) $@ (without quotes) would expand to all the parameters separated by a space.
    This would work fine for arguments without spaces, but arguments with spaces
    in them would be split up by POSIX shells into separate words.
(2) '$@' (in single quotes) would expand to all the parameters within a pair of
    single quotes. POSIX shells would then treat the entire list of arguments
    as one word.
(3) "$@" (in double quotes) would expand similarly to (2).

With this patch, we expand "$@" (in double quotes) as all positional
parameters, quoted individually with util.shellquote, and separated by spaces.
Under standard field-splitting conditions, POSIX shells will tokenize each
argument into exactly one word.

This is a backwards-incompatible change, but the old behavior was arguably a
bug: Bourne-derived shells have expanded "$@" as a tokenized list of positional
parameters for a very long time. I could find this behavior specified in IEEE
Std 1003.1-2001, and this probably goes back to much further before that.
parent bd45d928
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......@@ -331,6 +331,27 @@
args = shlex.split(cmd)
return args + givenargs
def aliasinterpolate(name, args, cmd):
'''interpolate args into cmd for shell aliases
This also handles $0, $@ and "$@".
'''
# util.interpolate can't deal with "$@" (with quotes) because it's only
# built to match prefix + patterns.
replacemap = dict(('$%d' % (i + 1), arg) for i, arg in enumerate(args))
replacemap['$0'] = name
replacemap['$$'] = '$'
replacemap['$@'] = ' '.join(args)
# Typical Unix shells interpolate "$@" (with quotes) as all the positional
# parameters, separated out into words. Emulate the same behavior here by
# quoting the arguments individually. POSIX shells will then typically
# tokenize each argument into exactly one word.
replacemap['"$@"'] = ' '.join(util.shellquote(arg) for arg in args)
# escape '\$' for regex
regex = '|'.join(replacemap.keys()).replace('$', r'\$')
r = re.compile(regex)
return r.sub(lambda x: replacemap[x.group()], cmd)
class cmdalias(object):
def __init__(self, name, definition, cmdtable):
self.name = self.cmd = name
......@@ -376,10 +397,7 @@
% (int(m.groups()[0]), self.name))
return ''
cmd = re.sub(r'\$(\d+|\$)', _checkvar, self.definition[1:])
replace = dict((str(i + 1), arg) for i, arg in enumerate(args))
replace['0'] = self.name
replace['@'] = ' '.join(args)
cmd = util.interpolate(r'\$', replace, cmd, escape_prefix=True)
cmd = aliasinterpolate(self.name, args, cmd)
return util.system(cmd, environ=env, out=ui.fout)
self.fn = fn
return
......
......@@ -229,8 +229,9 @@
Positional arguments like ``$1``, ``$2``, etc. in the alias definition
expand to the command arguments. Unmatched arguments are
removed. ``$0`` expands to the alias name and ``$@`` expands to all
arguments separated by a space. These expansions happen before the
command is passed to the shell.
arguments separated by a space. ``"$@"`` (with quotes) expands to all
arguments quoted individually and separated by a space. These expansions
happen before the command is passed to the shell.
Shell aliases are executed in an environment where ``$HG`` expands to
the path of the Mercurial that was used to execute the alias. This is
......
......@@ -30,6 +30,7 @@
> echo1 = !printf '\$1\n'
> echo2 = !printf '\$2\n'
> echo13 = !printf '\$1 \$3\n'
> echotokens = !printf "%s\n" "\$@"
> count = !hg log -r "\$@" --template=. | wc -c | sed -e 's/ //g'
> mcount = !hg log \$@ --template=. | wc -c | sed -e 's/ //g'
> rt = root
......@@ -241,6 +242,22 @@
foo baz
$ hg echo2 foo
$ hg echotokens
$ hg echotokens foo 'bar $1 baz'
foo
bar $1 baz
$ hg echotokens 'test $2' foo
test $2
foo
$ hg echotokens 'test $@' foo '$@'
test $@
foo
$@
$ hg echotokens 'test "$@"' foo '"$@"'
test "$@"
foo
"$@"
$ echo bar > bar
$ hg commit -qA -m bar
$ hg count .
......
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