Make bin/dist_get fall back to other downloaders if one fails

[mateon1]

Also refactored the code a bit, and added httpie.
Note: I used redirection for httpie, as http -d url -o output complained its output was redirected.

[whyrusleeping]

What is this doing?

[mateon1]

This sets arguments within this shell substitution from $3, allowing us to get the first word of the command (wget, curl, http) with $1.
Arguments outside this shell substitution are not clobbered.

[Kubuxu]

This might be reason it fails on circle, or other bashizm. CircleCI uses fsh as sh bin. You probably should change the hashbang to bash or remove the bashizm (preferably the latter)

[whyrusleeping]

Thanks @mateon1! I think this looks good, my only concern is what happens when one tool fails for some network or unrelated error (i.e. the tool works, but something else failed randomly).

[whyrusleeping]

Very weird circleCI failure... Worth investigating

[Kubuxu]

List of issues found by shellcheck, some of the might not be because of this PR.

In dist_get line 9:
	type "$1" > /dev/null 2> /dev/null
        ^-- SC2039: In POSIX sh, 'type' is undefined.


In dist_get line 20:
	util_name=$(set -- $3; echo $1)
                           ^-- SC2086: Double quote to prevent globbing and word splitting.
                                    ^-- SC2086: Double quote to prevent globbing and word splitting.


In dist_get line 22:
	if ! have_binary $util_name; then
                         ^-- SC2086: Double quote to prevent globbing and word splitting.


In dist_get line 40:
	test "$#" -eq "2" || die "download requires exactly two arguments, was given $@"
                                                                                     ^-- SC2145: Argument mixes string and array. Use * or separate argument.


In dist_get line 68:
				cat "$ua_infile" | tar -O -z -x -f - "$ua_distname/$ua_distname" > "$ua_outfile"
                                    ^-- SC2002: Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.


In dist_get line 158:
if [ $? -ne 0 ]; then
     ^-- SC2181: Check exit code directly with e.g. 'if mycmd;', not indirectly with $?.


In dist_get line 163:
if [ $? -ne 0 ]; then
     ^-- SC2181: Check exit code directly with e.g. 'if mycmd;', not indirectly with $?.

[Kubuxu]

You can try running Bash in a mode closer to POSIX with --posix flag.

The bashizm is only my guess why things failed, I am not sure.

[mateon1]

@Kubuxu That is odd, as the set -- command seems to work for me in both sh and bash --posix.
I am going to push some changes that fix shellcheck errors, at least those caused by me.

[whyrusleeping]

Tests look a bit greener this time. You happy with this one @Kubuxu ?