#curl_download: default try_partial to false

When its `try_partial` argument is `true`, `#curl_download` makes a
`HEAD` request before downloading the file using `#curl`. Currently
`try_partial` defaults to `true`, so any `#curl_download` call that
doesn't explicitly specify `try_partial: false` will make a `HEAD`
request first. This can potentially involve several requests if the
URL redirects, so it can be a bit of unnecessary overhead when a
partial download isn't needed.

Partial downloads are generally only useful when we're working with
larger files, however there's currently only one place in brew where
`#curl_download` is used and this is the case:
`CurlDownloadStrategy`. The other `#curl_download` calls are fetching
smaller [text] files and don't need to support partial downloads.

This commit changes the default `try_partial` value to `false`,
making partial downloads opt-in rather than opt-out.

We want `try_partial` to continue to default to `true` in
`CurlDownloadStrategy` and there are various ways to accomplish this.
In this commit, I've chosen to update its `#initialize` method to
accept a `try_partial` argument that defaults to `true`, as this
value can also be used in classes that inherit from
`CurlDownloadStrategy` (e.g., `HomebrewCurlDownloadStrategy`). This
instance variable is passed to `#curl_download` in related methods,
effectively maintaining the previous `try_partial: true` value, while
also allowing this value to be overridden when necessary.

Other uses of `#curl_download` in brew are
`Formulary::FromUrlLoader#load_file` and
`Cask::CaskLoader::FromURILoader#load`, which did not provide a
`try_partial` argument but should have been using
`try_partial: false`. With the `try_partial: false` default in this
commit, these calls are now fine without a `try_partial` argument.

The only other use of `#curl_download` in brew is
`SPDX#download_latest_license_data!`. These calls were previously
using `try_partial: false` but we can now omit this argument with
the new `false` default (aligning with the above).

Library/Homebrew/download_strategy.rb

@@ -375,6 +375,7 @@ class CurlDownloadStrategy < AbstractFileDownloadStrategy
 
   def initialize(url, name, version, **meta)
     super
+    @try_partial = true
     @mirrors = meta.fetch(:mirrors, [])
   end
 
@@ -523,7 +524,7 @@ class CurlDownloadStrategy < AbstractFileDownloadStrategy
   end
 
   def _curl_download(resolved_url, to, timeout)
-    curl_download resolved_url, to: to, timeout: timeout
+    curl_download resolved_url, to: to, try_partial: @try_partial, timeout: timeout
   end
 
   # Curl options to be always passed to curl,
@@ -577,7 +578,7 @@ class HomebrewCurlDownloadStrategy < CurlDownloadStrategy
   def _curl_download(resolved_url, to, timeout)
     raise HomebrewCurlDownloadStrategyError, url unless Formula["curl"].any_version_installed?
 
-    curl_download resolved_url, to: to, timeout: timeout, use_homebrew_curl: true
+    curl_download resolved_url, to: to, try_partial: @try_partial, timeout: timeout, use_homebrew_curl: true
   end
 end
 
@@ -656,7 +657,7 @@ class CurlPostDownloadStrategy < CurlDownloadStrategy
       query.nil? ? [url, "-X", "POST"] : [url, "-d", query]
     end
 
-    curl_download(*args, to: temporary_path, timeout: timeout)
+    curl_download(*args, to: temporary_path, try_partial: @try_partial, timeout: timeout)
   end
 end
 

Library/Homebrew/utils/curl.rb

@@ -161,7 +161,7 @@ module Utils
       result
     end
 
-    def curl_download(*args, to: nil, try_partial: true, **options)
+    def curl_download(*args, to: nil, try_partial: false, **options)
       destination = Pathname(to)
       destination.dirname.mkpath
 

Library/Homebrew/utils/spdx.rb

@@ -34,8 +34,8 @@ module SPDX
 
   def download_latest_license_data!(to: DATA_PATH)
     data_url = "https://raw.githubusercontent.com/spdx/license-list-data/#{latest_tag}/json/"
-    curl_download("#{data_url}licenses.json", to: to/"spdx_licenses.json", try_partial: false)
+    curl_download("#{data_url}licenses.json", to: to/"spdx_licenses.json")
-    curl_download("#{data_url}exceptions.json", to: to/"spdx_exceptions.json", try_partial: false)
+    curl_download("#{data_url}exceptions.json", to: to/"spdx_exceptions.json")
   end
 
   def parse_license_expression(license_expression)