Fix BSD compatibility

On macOS, Perl-compatible regex option (-P) in GNU grep is not available
by default. It can be replaced with sed. While using 'tr', it is
necessary to set the locale to "C" ensures that tr interprets the byte
stream in a consistent, ASCII-only manner. This prevents errors like
"Illegal byte sequence" on BSD systems such as macOS.

Change-Id: I1c134092a5fb2afc8018a638e172fb0b380e0fdd

Author: jserv

scripts/check-repo.sh

@@ -65,7 +65,7 @@ REPO_NAME="lab0-c"
 repo_html=$(curl -s "https://github.com/${REPO_OWNER}/${REPO_NAME}")
 
 # Extract the default branch name from data-default-branch="..."
-DEFAULT_BRANCH=$(echo "$repo_html" | grep -oP "/${REPO_OWNER}/${REPO_NAME}/blob/\K[^/]+(?=/LICENSE)" | head -n 1)
+DEFAULT_BRANCH=$(echo "$repo_html" | sed -nE "s#.*${REPO_OWNER}/${REPO_NAME}/blob/([^/]+)/LICENSE.*#\1#p" | head -n 1)
 
 if [ "$DEFAULT_BRANCH" != "master" ]; then
   echo "$DEFAULT_BRANCH"
@@ -80,8 +80,7 @@ curl -sSL -o "$temp_file" "$COMMITS_URL"
 
 # general grep pattern that finds commit links
 upstream_hash=$(
-  grep -Po 'href="[^"]*/commit/\K[0-9a-f]{40}' "$temp_file" \
-  | head -n 1
+  sed -nE 's/.*href="[^"]*\/commit\/([0-9a-f]{40}).*/\1/p' "$temp_file" | head -n 1
 )
 
 rm -f "$temp_file"

scripts/common.sh

@@ -89,14 +89,14 @@ make_random_string() {
 
   if [ -z "$sub_str" ]; then
     # Produce an exact random string of length total_len
-    cat /dev/urandom | tr -dc 'a-z0-9' | head -c "$total_len"
+    cat /dev/urandom | LC_ALL=C tr -dc 'a-z0-9' | head -c "$total_len"
   else
     # Insert the substring at a random position
     local sub_len=${#sub_str}
     local rand_len=$(( total_len - sub_len ))
 
     local raw_rand
-    raw_rand=$(cat /dev/urandom | tr -dc 'a-z0-9' | head -c "$rand_len")
+    raw_rand=$(cat /dev/urandom | LC_ALL=C tr -dc 'a-z0-9' | head -c "$rand_len")
 
     local pos=$(( RANDOM % (rand_len + 1) ))
     echo "${raw_rand:0:pos}${sub_str}${raw_rand:pos}"