From a519746560fedf03c8f6e3c470db8d9dcefd836d Mon Sep 17 00:00:00 2001
From: Andrew Dunham <andrew@du.nham.ca>
Date: Mon, 12 Jul 2021 22:54:25 -0400
Subject: [PATCH] lib: more helper functions

---
 lib              | 40 ++++++++++++++++++++++++++++++++++++++++
 test/lib_test.sh | 28 ++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/lib b/lib
index cc90f9d..b93ab6a 100755
--- a/lib
+++ b/lib
@@ -40,3 +40,43 @@ substituteInPlace() {
     # Overwrite now that we've succeeded
     mv "$tmpfile" "$fpath"
 }
+
+# Shell-quotes an arbitrary string.
+#
+# From: http://www.etalabs.net/sh_tricks.html
+#
+#     This function simply replaces every instance of «'» (single quote) within
+#     the string with «'\''» (single quote, backslash, single quote, single
+#     quote), then puts single quotes at the beginning and end of the string.
+#     Since the only character whose meaning is special within single quotes is
+#     the single quote character itself, this is totally safe. Trailing
+#     newlines are handled correctly, and the single quote at the end doubles
+#     as a safety character to prevent command substitution from clobbering the
+#     trailing newlines, should one want to do something like:
+#         quoted=$(quote "$var")
+quote() {
+    printf "%s\n" "$1" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/'/"
+}
+
+
+# Returns whether or not a string matches a glob; similar to the bash [[ test,
+# but portable.
+fnmatch() {
+    # We explicitly want this to act as a glob
+    # shellcheck disable=SC2254
+    case "$2" in
+        $1) return 0 ;;
+        *)  return 1 ;;
+    esac
+}
+
+# Portable equivalent to GNU's `date +"%s"`
+#
+# From: http://www.etalabs.net/sh_tricks.html
+epochseconds() {
+    # This is horrible, but... it tells 'date' to generate a string that
+    # contains shell math to generate the actual epoch date.
+    #
+    # TODO(andrew-d): break down and verify the math here
+    echo $(( $(TZ=GMT0 date +"((%Y-1600)*365+(%Y-1600)/4-(%Y-1600)/100+(%Y-1600)/400+1%j-1000-135140)*86400+(1%H-100)*3600+(1%M-100)*60+(1%S-100)") ))
+}
diff --git a/test/lib_test.sh b/test/lib_test.sh
index d63065c..872551d 100755
--- a/test/lib_test.sh
+++ b/test/lib_test.sh
@@ -67,5 +67,33 @@ testSubstituteInPlace() {
     assertEquals "hi hi hi" "$(cat "$TEST_TMPDIR/sub.txt")"
 }
 
+testQuote() {
+    local input expected
+
+    { input="$(cat)"; } <<EOF
+foo'bar"baz'
+EOF
+
+    { expected="$(cat)"; } <<EOF
+'foo'\\''bar"baz'\\'''
+EOF
+
+    assertEquals "$expected" "$(quote "$input")"
+}
+
+testFnmatch() {
+    assertTrue 'fnmatch "f??*" "foobar"'
+    assertFalse 'fnmatch "f??*" "fo"'
+    assertFalse 'fnmatch "f??*" "loob"'
+}
+
+testEpochseconds() {
+    # TODO(andrew-d): better test
+
+    # Assert that it's numeric by deleting all numbers and verifying that
+    # there's nothing left.
+    assertEquals "" "$(epochseconds | tr -d '[0-9]')"
+}
+
 # Load shUnit2
 . ./shunit2