Add the fetch() function

This function makes it trivial to issue a network request - such as HTTP
GET - in a manner that is quiet and which yields a useful exit status
value. It prefers curl if present but supports wget also.

Signed-off-by: Kerin Millar <kfm@plushkava.net>

1 files changed, 42 insertions, 0 deletions

diff --git a/functions.sh b/functions.sh
index 7e09611..9336174 100644
--- a/functions.sh
+++ b/functions.sh
@@ -48,6 +48,48 @@ chdir()
 }
 
 #
+# Considers the first parameter as an URL then attempts to fetch it with either
+# curl(1) or wget(1). If the URL does not contain a scheme then the https://
+# scheme shall be presumed. Both utilities shall be invoked in a manner that
+# suppresses all output unless an error occurs, and whereby HTTP redirections
+# are honoured. Upon success, the body of the response shall be printed to the
+# standard output. Otherwise, the return value shall be greater than 0.
+#
+fetch()
+{
+	if hash curl 2>/dev/null; then
+		fetch()
+		{
+			if [ "$#" -gt 0 ]; then
+				# Discard any extraneous parameters.
+				set -- "$1"
+			fi
+			curl -f -sS -L --connect-timeout 10 --proto-default https -- "$@"
+		}
+	elif hash wget 2>/dev/null; then
+		fetch()
+		{
+			if [ "$#" -gt 0 ]; then
+				# Discard any extraneous parameters.
+				case $1 in
+					''|ftp://*|ftps://*|https://*)
+						set -- "$1"
+						;;
+					*)
+						set -- "https://$1"
+				esac
+			fi
+			wget -nv -O - --connect-timeout 10 -- "$@"
+		}
+	else
+		warn "fetch: this function requires that curl or wget to be installed"
+		return 127
+	fi
+
+	fetch "$@"
+}
+
+#
 # Determines whether the current shell is a subprocess of portage.
 #
 from_portage()