3 files changed, 109 insertions, 0 deletions
diff --git a/src/libutil/meson.build b/src/libutil/meson.build
index 66eba9d85..8e4b5211d 100644
--- a/src/libutil/meson.build
+++ b/src/libutil/meson.build
@@ -20,6 +20,7 @@ libutil_sources = files(
   'position.cc',
   'references.cc',
   'serialise.cc',
+  'shlex.cc',
   'signals.cc',
   'source-path.cc',
   'suggestions.cc',
@@ -71,6 +72,7 @@ libutil_headers = files(
   'regex-combinators.hh',
   'repair-flag.hh',
   'serialise.hh',
+  'shlex.hh',
   'signals.hh',
   'source-path.hh',
   'split.hh',
diff --git a/src/libutil/shlex.cc b/src/libutil/shlex.cc
new file mode 100644
index 000000000..b5f340251
--- /dev/null
+++ b/src/libutil/shlex.cc
@@ -0,0 +1,77 @@
+#include "shlex.hh"
+#include "util.hh"
+
+namespace nix {
+
+std::vector<std::string> shell_split(const std::string & input)
+{
+    std::vector<std::string> result;
+
+    // Hack: `shell_split` is janky and parses ` a` as `{"", "a"}`, so we trim
+    // whitespace before starting.
+    auto inputTrimmed = trim(input);
+
+    if (inputTrimmed.empty()) {
+        return result;
+    }
+
+    std::regex whitespace("^\\s+");
+    auto begin = inputTrimmed.cbegin();
+    std::string currentToken;
+    enum State { sBegin, sSingleQuote, sDoubleQuote };
+    State state = sBegin;
+    auto iterator = begin;
+
+    for (; iterator != inputTrimmed.cend(); ++iterator) {
+        if (state == sBegin) {
+            std::smatch match;
+            if (regex_search(iterator, inputTrimmed.cend(), match, whitespace)) {
+                currentToken.append(begin, iterator);
+                result.push_back(currentToken);
+                iterator = match[0].second;
+                if (iterator == inputTrimmed.cend()) {
+                    return result;
+                }
+                begin = iterator;
+                currentToken.clear();
+            }
+        }
+
+        switch (*iterator) {
+        case '\'':
+            if (state != sDoubleQuote) {
+                currentToken.append(begin, iterator);
+                begin = iterator + 1;
+                state = state == sBegin ? sSingleQuote : sBegin;
+            }
+            break;
+
+        case '"':
+            if (state != sSingleQuote) {
+                currentToken.append(begin, iterator);
+                begin = iterator + 1;
+                state = state == sBegin ? sDoubleQuote : sBegin;
+            }
+            break;
+
+        case '\\':
+            if (state != sSingleQuote) {
+                // perl shellwords mostly just treats the next char as part
+                // of the string with no special processing
+                currentToken.append(begin, iterator);
+                begin = ++iterator;
+            }
+            break;
+        }
+    }
+
+    if (state != sBegin) {
+        throw ShlexError(input);
+    }
+
+    currentToken.append(begin, iterator);
+    result.push_back(currentToken);
+    return result;
+}
+
+}
diff --git a/src/libutil/shlex.hh b/src/libutil/shlex.hh
new file mode 100644
index 000000000..4e7a48597
--- /dev/null
+++ b/src/libutil/shlex.hh
@@ -0,0 +1,30 @@
+#pragma once
+
+#include <regex>
+#include <string>
+#include <vector>
+
+#include "error.hh"
+
+namespace nix {
+
+class ShlexError : public Error
+{
+public:
+    const std::string input;
+
+    ShlexError(const std::string input)
+        : Error("Failed to parse shell arguments (unterminated quote?): %1%", input)
+        , input(input)
+    {
+    }
+};
+
+/**
+ * Parse a string into shell arguments.
+ *
+ * Takes care of whitespace, quotes, and backslashes (at least a bit).
+ */
+std::vector<std::string> shell_split(const std::string & input);
+
+} // namespace nix