Merge pull request #18087 from Homebrew/even_better_git_describe_cache

Library/Homebrew/brew.sh

@@ -439,32 +439,56 @@ setup_git
 
 GIT_DESCRIBE_CACHE="${HOMEBREW_REPOSITORY}/.git/describe-cache"
 GIT_REVISION=$("${HOMEBREW_GIT}" -C "${HOMEBREW_REPOSITORY}" rev-parse HEAD 2>/dev/null)
+
+# safe fallback in case git rev-parse fails e.g. if this is not considered a safe git directory
+if [[ -z "${GIT_REVISION}" ]]
+then
+ GIT_HEAD="$(cat "${HOMEBREW_REPOSITORY}/.git/HEAD" 2>/dev/null)"
+ if [[ "${GIT_HEAD}" == "ref: refs/heads/master" ]]
+ then
+ GIT_REVISION="$(cat "${HOMEBREW_REPOSITORY}/.git/refs/heads/master" 2>/dev/null)"
+ elif [[ "${GIT_HEAD}" == "ref: refs/heads/stable" ]]
+ then
+ GIT_REVISION="$(cat "${HOMEBREW_REPOSITORY}/.git/refs/heads/stable" 2>/dev/null)"
+ fi
+ unset GIT_HEAD
+fi
+
 if [[ -n "${GIT_REVISION}" ]]
 then
  GIT_DESCRIBE_CACHE_FILE="${GIT_DESCRIBE_CACHE}/${GIT_REVISION}"
- if [[ -f "${GIT_DESCRIBE_CACHE_FILE}" ]]
+ if [[ -r "${GIT_DESCRIBE_CACHE_FILE}" ]]
+ then
+ GIT_DESCRIBE_CACHE_HOMEBREW_VERSION="$(cat "${GIT_DESCRIBE_CACHE_FILE}")"
+ if [[ -n "${GIT_DESCRIBE_CACHE_HOMEBREW_VERSION}" && "${GIT_DESCRIBE_CACHE_HOMEBREW_VERSION}" != *"-dirty" ]]
+ then
+ HOMEBREW_VERSION="${GIT_DESCRIBE_CACHE_HOMEBREW_VERSION}"
+ fi
+ unset GIT_DESCRIBE_CACHE_HOMEBREW_VERSION
+ fi
+
+ if [[ -z "${HOMEBREW_VERSION}" ]]
  then
- HOMEBREW_VERSION="$(cat "${GIT_DESCRIBE_CACHE_FILE}")"
- else
  HOMEBREW_VERSION="$("${HOMEBREW_GIT}" -C "${HOMEBREW_REPOSITORY}" describe --tags --dirty --abbrev=7 2>/dev/null)"
- # Don't output any permissions errors here.
- # The user may not have write permissions to the cache but we don't care
- # because it's an optional performance improvement.
+ # Don't output any permissions errors here. The user may not have write
+ # permissions to the cache but we don't care because it's an optional
+ # performance improvement.
  rm -rf "${GIT_DESCRIBE_CACHE}" 2>/dev/null
  mkdir -p "${GIT_DESCRIBE_CACHE}" 2>/dev/null
- echo "${HOMEBREW_VERSION}" >"${GIT_DESCRIBE_CACHE_FILE}" 2>/dev/null
+ echo "${HOMEBREW_VERSION}" | tee "${GIT_DESCRIBE_CACHE_FILE}" &>/dev/null
  fi
  unset GIT_DESCRIBE_CACHE_FILE
 else
- rm -rf "${GIT_DESCRIBE_CACHE}"
+ # Don't care about permission errors here either.
+ rm -rf "${GIT_DESCRIBE_CACHE}" 2>/dev/null
 fi
 unset GIT_REVISION
 unset GIT_DESCRIBE_CACHE
 
 HOMEBREW_USER_AGENT_VERSION="${HOMEBREW_VERSION}"
 if [[ -z "${HOMEBREW_VERSION}" ]]
 then
- HOMEBREW_VERSION=">=4.1.0 (shallow or no git repository)"
+ HOMEBREW_VERSION=">=4.3.0 (shallow or no git repository)"
  HOMEBREW_USER_AGENT_VERSION="4.X.Y"
 fi