fix(strategy): take scrape captures without sed

docs/WORKFLOW.md

@@ -494,9 +494,11 @@ upstream:
 
 1. Fetches the page: HTTPS only, at most 5 redirects and 5 MB.
 2. Finds every match with `grep -oE`.
-3. Extracts the first capture group with `sed -E`.
+3. Takes the first capture group of each match with bash `[[ =~ ]]`, so the pattern may hold any character, `/` included.
 4. Sorts with `sort -Vu` and returns the highest version.
 
+`validate-pkg.sh` compiles the pattern with bash, which refuses some patterns that `grep -E` takes, `(?:...)` among them.
+
 **Example YAML:**
 
 ```yaml

scripts/lib.sh

@@ -133,6 +133,30 @@ release_tags() {
   grep -E '^v?[0-9]+(\.[0-9]+)*$' <<<"$1" || true
 }
 
+# The first capture group of every match of an ERE in stdin, one per line.
+# grep finds the matches and bash takes the group, so no delimiter of a sed
+# command limits the pattern.
+# Args: $1=ERE with a capture group
+capture_matches() {
+  local pattern="$1" match
+  while IFS= read -r match; do
+    if [[ "$match" =~ $pattern ]]; then
+      printf '%s\n' "${BASH_REMATCH[1]}"
+    fi
+  done < <(grep -oE -e "$pattern")
+}
+
+# Succeeds when bash accepts an ERE, as capture_matches needs. bash refuses
+# some patterns that grep -E takes, (?:x) and *x among them.
+# Args: $1=ERE
+ere_valid() {
+  local rc=0
+  # [[ =~ ]] returns 2 for a pattern bash cannot compile
+  # shellcheck disable=SC2319
+  [[ "" =~ $1 ]] 2>/dev/null || rc=$?
+  ((rc != 2))
+}
+
 # =============================================================================
 # CHECKSUMS
 # =============================================================================

scripts/validate-pkg.sh

@@ -209,10 +209,8 @@ validate_pkg() {
         log_err "$file: strategy 'webpage-scrape' requires 'upstream.pattern'"
         ((errors++))
       else
-        # Validate regex syntax: grep exits 2 on invalid regex
-        local grep_rc=0
-        echo "" | grep -qE -e "$pattern" 2>/dev/null || grep_rc=$?
-        if [[ "$grep_rc" -eq 2 ]]; then
+        # The strategy runs the pattern through grep and bash
+        if ! ere_valid "$pattern"; then
           log_err "$file: upstream.pattern is not valid ERE regex: $pattern"
           ((errors++))
         fi

strategies/webpage-scrape.sh

@@ -41,9 +41,8 @@ page=$(http_get "$url" --max-redirs 5 --max-filesize "$MAX_SIZE" -A "Mozilla/5.0
   exit 1
 }
 
-# Extract versions using ERE, capture group via sed. The pattern can close
-# the s command; --sandbox refuses e, r and w
-versions=$(echo "$page" | grep -oE -e "$pattern" | sed --sandbox -E "s/$pattern/\\1/" | sort -Vu)
+# The first capture group of every match
+versions=$(echo "$page" | capture_matches "$pattern" | sort -Vu)
 
 if [[ -z "$versions" ]]; then
   echo "No versions matched pattern '$pattern' at $url" >&2

tests/strategies.bats

@@ -246,6 +246,16 @@ teardown() {
   [ "$output" = "7.0.0" ]
 }
 
+@test "webpage-scrape: a pattern may hold a slash" {
+  create_test_package "test-scrape-path" "webpage-scrape" "upstream:
+  url: https://example.com/releases
+  pattern: 'download/test-scrape-([0-9.]+)\\.tar\\.gz'"
+
+  run "$TEST_TMPDIR/strategies/webpage-scrape.sh" "test-scrape-path"
+  [ "$status" -eq 0 ]
+  [ "$output" = "7.0.0" ]
+}
+
 # === git-latest ===
 
 @test "git-latest: returns rCOUNT.HASH format from git repo" {
@@ -384,8 +394,9 @@ teardown() {
 
   cd "$TEST_TMPDIR"
   run "$TEST_TMPDIR/strategies/webpage-scrape.sh" "test-scrape-exec"
-  [ "$status" -ne 0 ]
   [ ! -e "$TEST_TMPDIR/pwned" ]
+  [ "$status" -eq 0 ]
+  [ "$output" = "7" ]
 }
 
 @test "webpage-scrape: a pattern may start with a dash" {

tests/validate-pkg.bats

@@ -389,6 +389,27 @@ EOF
   [ "$status" -eq 0 ]
 }
 
+# grep -E takes these and bash refuses them
+@test "validate: webpage-scrape rejects a pattern that bash cannot compile" {
+  local pattern
+  for pattern in '(?:v)?pkg-([0-9.]+)' '*pkg-([0-9.]+)' 'pkg-([0-9]{1)'; do
+    create_test_package "mypkg" "webpage-scrape" "upstream:
+  url: https://example.com/releases
+  pattern: '$pattern'"
+    run "$TEST_TMPDIR/scripts/validate-pkg.sh" "mypkg"
+    [ "$status" -ne 0 ]
+    [[ "$output" == *"not valid ERE regex"* ]]
+  done
+}
+
+@test "validate: webpage-scrape accepts a pattern with a slash" {
+  create_test_package "mypkg" "webpage-scrape" "upstream:
+  url: https://example.com/releases
+  pattern: 'download/pkg-([0-9.]+)\\.tar\\.gz'"
+  run "$TEST_TMPDIR/scripts/validate-pkg.sh" "mypkg"
+  [ "$status" -eq 0 ]
+}
+
 @test "validate: webpage-scrape rejects invalid regex pattern" {
   create_test_package "mypkg" "webpage-scrape" "upstream:
   url: https://example.com/releases