refactor: improve bash code (#125)

* refactor: extract guard_path to utils/guard_path.sh

* add utils/guard_operation.sh

utils/guard_operation.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+# Guard an operation with a confirmation prompt.
+
+main() {
+    if [ -t 1 ]; then
+        confirmation_prompt="${1:-"Are you sure you want to continue?"}"
+        read -r -p "$confirmation_prompt [Y/n] " ans
+        if [[ "$ans" == "N" || "$ans" == "n" ]]; then
+            echo "error: aborted!" 2>&1
+            exit 1
+        fi
+    fi
+}
+
+main "$@"

utils/guard_path.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+
+main() {
+    if [[ "$#" -ne 2 ]]; then
+        echo "Usage: guard_path.sh <path> <confirmation_prompt>" >&2
+        exit 1
+    fi
+    if [ -t 1 ]; then
+        path="$(_to_realpath "$1")"
+        confirmation_prompt="$2"
+        if [[ ! "$path" == "$(pwd)"* ]]; then
+            read -r -p "$confirmation_prompt [Y/n] " ans
+            if [[ "$ans" == "N" || "$ans" == "n" ]]; then
+                echo "error: aborted!" >&2
+                exit 1
+            fi
+        fi
+    fi
+}
+
+_to_realpath() {
+    path="$1"
+    if [[ $OS == "Windows_NT" ]]; then
+        path="$(cygpath -u "$path")"
+    fi
+    awk -v path="$path" -v pwd="$PWD" '
+BEGIN {
+    if (path !~ /^\//) {
+        path = pwd "/" path
+    }
+    if (path ~ /\/\.{1,2}?$/) {
+        isDir = 1
+    }
+    split(path, parts, "/")
+    newPartsLength = 0
+    for (i = 1; i <= length(parts); i++) {
+        part = parts[i]
+        if (part == "..") {
+            if (newPartsLength > 0) {
+                delete newParts[newPartsLength--]
+            }
+        } else if (part != "." && part != "") {
+            newParts[++newPartsLength] = part
+        }
+    }
+    if (isDir == 1 || newPartsLength == 0) {
+        newParts[++newPartsLength] = ""
+    }
+    printf "/"
+    for (i = 1; i <= newPartsLength; i++) {
+        newPart = newParts[i]
+        printf newPart
+        if (i < newPartsLength) {
+            printf "/"
+        }
+    }
+}'
+}
+
+main "$@"

utils/patch.awk

@@ -55,7 +55,7 @@ END {
     }
 
     if (hunkIndex == 0) {
-        print "No patch" > "/dev/stderr"
+        print "error: no patch" > "/dev/stderr"
         exit 1
     }
 
@@ -90,7 +90,7 @@ END {
     }
 
     if (hunkIndex != totalHunks + 1) {
-        print "Failed to patch the file" > "/dev/stderr"
+        print "error: unable to apply patch" > "/dev/stderr"
         exit 1
     }
 }