nix-shell: Fix $PATH handling in the impure case

We were passing "p=$PATH" rather than "p=$PATH;", resulting in some
invalid shell code.

Also, construct a separate environment for the child rather than
overwriting the parent's.

2 files changed, 20 insertions, 0 deletions

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 1750e03737b7..c95a713fa112 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -59,6 +59,21 @@ string getEnv(const string & key, const string & def)
 }
 
 
+std::map<std::string, std::string> getEnv()
+{
+    std::map<std::string, std::string> env;
+    for (size_t i = 0; environ[i]; ++i) {
+        auto s = environ[i];
+        auto eq = strchr(s, '=');
+        if (!eq)
+            // invalid env, just keep going
+            continue;
+        env.emplace(std::string(s, eq), std::string(eq + 1));
+    }
+    return env;
+}
+
+
 Path absPath(Path path, Path dir)
 {
     if (path[0] != '/') {
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 182a38fb3928..221165780a37 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -8,9 +8,11 @@
 #include <dirent.h>
 #include <unistd.h>
 #include <signal.h>
+
 #include <functional>
 #include <limits>
 #include <cstdio>
+#include <map>
 
 #ifndef HAVE_STRUCT_DIRENT_D_TYPE
 #define DT_UNKNOWN 0
@@ -25,6 +27,9 @@ namespace nix {
 /* Return an environment variable. */
 string getEnv(const string & key, const string & def = "");
 
+/* Get the entire environment. */
+std::map<std::string, std::string> getEnv();
+
 /* Return an absolutized path, resolving paths relative to the
    specified directory, or the current directory otherwise.  The path
    is also canonicalised. */