From 0d7c3fc4d897309835f233788e722444569e6e6c Mon Sep 17 00:00:00 2001
From: Thomas Parisot <oncletom@users.noreply.github.com>
Date: Thu, 22 Mar 2018 18:48:30 +0000
Subject: [PATCH] Ignore global libvips during install via
 SHARP_IGNORE_GLOBAL_LIBVIPS (#1165)

---
 docs/install.md      | 17 ++++++++++++-----
 lib/libvips.js       |  4 ++++
 test/unit/libvips.js |  8 ++++++++
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/docs/install.md b/docs/install.md
index 78ef3a48..1463e103 100644
--- a/docs/install.md
+++ b/docs/install.md
@@ -54,7 +54,7 @@ To use a globally-installed version of libvips instead of the provided binaries,
 make sure it is at least the version listed under `config.libvips` in the `package.json` file
 and that it can be located using `pkg-config --modversion vips-cpp`.
 
-If you are using non-stadard paths (anything other than `/usr` or `/usr/local`),
+If you are using non-standard paths (anything other than `/usr` or `/usr/local`),
 you might need to set `PKG_CONFIG_PATH` during `npm install`
 and `LD_LIBRARY_PATH` at runtime.
 
@@ -211,10 +211,17 @@ to the directory containing the `policy.xml` file.
 
 ### Pre-compiled libvips binaries
 
-If a global installation of libvips that meets the
-minimum version requirement cannot be found,
-this module will attempt to download a pre-compiled bundle of libvips
-and its dependencies on Linux and Windows machines.
+This module will attempt to download a pre-compiled bundle of libvips
+and its dependencies on Linux and Windows machines under either of these
+conditions:
+
+1. If a global installation of libvips that meets the
+minimum version requirement cannot be found;
+1. If `SHARP_IGNORE_GLOBAL_LIBVIPS` environment variable is set.
+
+```sh
+SHARP_IGNORE_GLOBAL_LIBVIPS=1 npm install sharp
+```
 
 Should you need to manually download and inspect these files,
 you can do so via https://github.com/lovell/sharp-libvips/releases
diff --git a/lib/libvips.js b/lib/libvips.js
index f91a4572..d8ddbd57 100644
--- a/lib/libvips.js
+++ b/lib/libvips.js
@@ -46,6 +46,10 @@ const pkgConfigPath = function () {
 };
 
 const useGlobalLibvips = function () {
+  if (Boolean(process.env.SHARP_IGNORE_GLOBAL_LIBVIPS) === true) {
+    return false;
+  }
+
   const globalVipsVersion = globalLibvipsVersion();
   return !!globalVipsVersion && semver.gte(globalVipsVersion, minimumLibvipsVersion);
 };
diff --git a/test/unit/libvips.js b/test/unit/libvips.js
index 4f1a1144..f95c7641 100644
--- a/test/unit/libvips.js
+++ b/test/unit/libvips.js
@@ -58,5 +58,13 @@ describe('libvips binaries', function () {
       const hasVendoredLibvips = libvips.hasVendoredLibvips();
       assert.strictEqual('boolean', typeof hasVendoredLibvips);
     });
+    it('useGlobalLibvips can be ignored via an env var', function () {
+      process.env.SHARP_IGNORE_GLOBAL_LIBVIPS = 1;
+
+      const useGlobalLibvips = libvips.useGlobalLibvips();
+      assert.strictEqual(false, useGlobalLibvips);
+
+      delete process.env.SHARP_IGNORE_GLOBAL_LIBVIPS;
+    });
   });
 });