From 31503440acd1eb70b9b0114386f71f00e60f4009 Mon Sep 17 00:00:00 2001
From: edzer <edzer.pebesma@uni-muenster.de>
Date: Thu, 21 Dec 2023 11:01:28 +0100
Subject: [PATCH] address #2298

---
 NEWS.md  |  8 +++++++-
 R/init.R | 52 ++++++++++++++++++++++++++++------------------------
 2 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/NEWS.md b/NEWS.md
index 973cb336d..dfc274a66 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,6 +1,12 @@
 # version 1.0-16
 
-* add `st_line_project()` to find how far a point is when projected on a line, and `st_line_interpolate()` to obtain a point at a certain distance along a line; #2291
+* if environment variable `R_SF_USE_PROJ_DATA` is `true`, `GDAL_DATA`, `PROJ_DATA` (and deprecated `PROJ_LIB`) will not be ignored.
+
+* environment variables `PROJ_LIB` and `PROJ_DATA` are (again) ignored on `sf` binary CRAN installations (win + macos); #2298
+
+* add `st_line_project()` to find how far a point is when projected on a line; #2291
+
+* add `st_line_interpolate()` to obtain a point at a certain distance along a line; #2291
 
 # version 1.0-15
 
diff --git a/R/init.R b/R/init.R
index 3624a506f..d80ab61b6 100644
--- a/R/init.R
+++ b/R/init.R
@@ -72,19 +72,35 @@ sf_extSoftVersion = function() {
 		names = c("GEOS", "GDAL", "proj.4", "GDAL_with_GEOS", "USE_PROJ_H", "PROJ"))
 }
 
+if_exists_replace = function(var, new, where) {
+	if (Sys.getenv(var) != "") {
+		assign(paste0(".sf.", var), Sys.getenv(var), envir = where)
+		Sys.setenv(var = new)
+	}
+}
+
+if_exists_restore = function(vars, where) {
+	fn = function(var, where) {
+		lname = paste0(".sf.", var)
+		if (!is.null(get0(lname, envir = where)))
+			Sys.setenv(var = get(lname, envir = where))
+	}
+	lapply(vars, fn, where = where)
+}
+
 load_gdal <- function() {
-	if (file.exists(system.file("proj/nad.lst", package = "sf")[1])) {
-		# nocov start
-		prj = system.file("proj", package = "sf")[1]
-		if (! CPL_set_data_dir(prj)) { # if TRUE, uses C API to set path, leaving PROJ_LIB alone
-			assign(".sf.PROJ_LIB", Sys.getenv("PROJ_LIB"), envir=.sf_cache)
-			Sys.setenv("PROJ_LIB" = prj)
+	if (!identical(Sys.getenv("R_SF_USE_PROJ_DATA"), "true")) {
+		if (file.exists(prj <- system.file("proj/nad.lst", package = "sf")[1])) {
+			# nocov start
+			if (! CPL_set_data_dir(prj)) { # if TRUE, uses C API to set path, leaving PROJ_LIB / PROJ_DATA alone
+				if_exists_replace("PROJ_LIB", prj, .sf_cache)
+				if_exists_replace("PROJ_DATA", prj, .sf_cache)
+			}
+			CPL_use_proj4_init_rules(1L)
+			# nocov end
 		}
-		CPL_use_proj4_init_rules(1L)
-		assign(".sf.GDAL_DATA", Sys.getenv("GDAL_DATA"), envir=.sf_cache)
-		gdl = system.file("gdal", package = "sf")[1]
-		Sys.setenv("GDAL_DATA" = gdl)
-		# nocov end
+		if (file.exists(gdl <- system.file("gdal", package = "sf")[1]))
+			if_exists_replace("GDAL_DATA", gdl, .sf_cache)
 	}
 	CPL_gdal_init()
 	register_all_s3_methods() # dynamically registers non-imported pkgs (tidyverse)
@@ -92,19 +108,7 @@ load_gdal <- function() {
 
 unload_gdal <- function() {
 	CPL_gdal_cleanup_all()
-	if (file.exists(system.file("proj/nad.lst", package = "sf")[1])) {
-		# nocov start
-		if (! CPL_set_data_dir(system.file("proj", package = "sf")[1])) # set back:
-			Sys.setenv("PROJ_LIB"=get(".sf.PROJ_LIB", envir=.sf_cache))
-
-		Sys.setenv("GDAL_DATA"=get(".sf.GDAL_DATA", envir=.sf_cache))
-		# nocov end
-	}
-	#units::remove_symbolic_unit("link")
-	#units::remove_symbolic_unit("us_in")
-	#units::remove_symbolic_unit("ind_yd")
-	#units::remove_symbolic_unit("ind_ft")
-	#units::remove_symbolic_unit("ind_ch")
+	if_exists_restore(c("PROJ_LIB", "PROJ_DATA", "GDAL_DATA"), .sf_cache)
 }