1 files changed, 222 insertions, 0 deletions
diff --git a/sdn-mc-ext.cpp b/sdn-mc-ext.cpp
new file mode 100644
index 0000000..9e06760
--- /dev/null
+++ b/sdn-mc-ext.cpp
@@ -0,0 +1,222 @@
+//
+// sdn-mc-ext: Midnight Commander extension file processor
+//
+// Copyright (c) 2024, Přemysl Eric Janouch <p@janouch.name>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+//
+
+#include <cstdlib>
+#include <cctype>
+#include <iostream>
+#include <regex>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+// Trailing return types make C++ syntax suck considerably less
+#define fun static auto
+
+using namespace std;
+
+// It is completely fine if this only modifies ASCII letters.
+fun tolower (const string &s) -> string {
+    string result;
+	for (auto c : s) result += tolower (c);
+    return result;
+}
+
+fun shell_escape (const string &v) -> string {
+    return "'" + regex_replace (v, regex {"'"}, "'\\''") + "'";
+}
+
+string arg_type, arg_path, arg_basename, arg_dirname, arg_verb;
+unordered_map<string, unordered_map<string, string>> sections;
+
+fun expand_command (string command) -> pair<string, string> {
+	regex re_sequence {R"(%(%|[[:alpha:]]*\{([^}]*)\}|[[:alpha:]]+))"};
+	regex re_name {R"([^{}]*)"};
+	regex re_parameter {R"([^,]+")"};
+	string kind, out, pipe; smatch m;
+	while (regex_search (command, m, re_sequence)) {
+		out.append (m.prefix ());
+		auto seq = m.str (1);
+		command = m.suffix ();
+
+		string argument = m.str (2);
+		if (regex_search (seq, m, re_name))
+			seq = m.str ();
+
+		if (seq == "%") {
+			out += "%";
+		} else if (seq == "p") {
+			out += shell_escape (arg_basename);
+		} else if (seq == "f") {
+			out += shell_escape (arg_path);
+		} else if (seq == "d") {
+			out += shell_escape (arg_dirname);
+		} else if (seq == "var") {
+			string value;
+			if (auto colon = argument.find (':'); colon == argument.npos) {
+				if (auto v = getenv (argument.c_str ()))
+					value = v;
+			} else {
+				value = argument.substr (colon + 1);
+				if (auto v = getenv (argument.substr (0, colon).c_str ()))
+					value = v;
+			}
+			out += shell_escape (value);
+		} else if (seq == "cd") {
+			kind = seq;
+			command = regex_replace (command, regex {"^ +"}, "");
+		} else if (seq == "view") {
+			kind = seq;
+			command = regex_replace (command, regex {"^ +"}, "");
+
+			sregex_token_iterator it (argument.begin (), argument.end (),
+				re_parameter, 0), end;
+			for (; it != end; it++) {
+				if (*it == "hex")
+					pipe.append (" | od -t x1");
+
+				// more(1) and less(1) either ignore or display this:
+				//if (*it == "nroff")
+				//	pipe.append (" | col -b");
+			}
+		} else if (seq == "") {
+			cerr << "sdn-mc-ext: prompting not supported" << endl;
+			return {};
+		} else {
+			cerr << "sdn-mc-ext: unsupported: %" << seq << endl;
+			return {};
+		}
+	}
+	return {kind,
+		pipe.empty () ? out.append (command) : "(" + out + ")" + pipe};
+}
+
+fun print_command (string cmd) {
+	auto command = expand_command (cmd);
+	cout << get<0> (command) << endl << get<1> (command) << endl;
+}
+
+fun section_matches (const unordered_map<string, string> &section) -> bool {
+	if (section.count ("Directory"))
+		return false;
+
+	// The configuration went through some funky changes;
+	// unescape \\ but leave other escapes alone.
+	auto filter_re = [](const string &s) {
+		string result;
+		for (size_t i = 0; i < s.length (); ) {
+			auto c = s[i++];
+			if (c == '\\' && i < s.length ())
+				if (c = s[i++]; c != '\\')
+					result += '\\';
+			result += c;
+		}
+		return result;
+	};
+	auto is_true = [&](const string &name) {
+		auto value = section.find (name);
+		return value != section.end () && value->second == "true";
+	};
+	if (auto kv = section.find ("Type"); kv != section.end ()) {
+		auto flags = std::regex::ECMAScript;
+		if (is_true ("TypeIgnoreCase"))
+			flags |= regex_constants::icase;
+		if (!regex_search (arg_type, regex {filter_re (kv->second), flags}))
+			return false;
+	}
+	auto basename = arg_basename;
+	if (auto kv = section.find ("Regex"); kv != section.end ()) {
+		auto flags = std::regex::ECMAScript;
+		if (is_true ("RegexIgnoreCase"))
+			flags |= regex_constants::icase;
+		return regex_search (basename, regex {filter_re (kv->second), flags});
+	}
+	if (auto kv = section.find ("Shell"); kv != section.end ()) {
+		auto value = kv->second;
+		if (is_true ("ShellIgnoreCase")) {
+			value = tolower (value);
+			basename = tolower (arg_basename);
+		}
+		if (value.empty () || value[0] != '.')
+			return value == basename;
+		return basename.length () >= value.length () &&
+			basename.substr (basename.length () - value.length ()) == value;
+	}
+	return !arg_type.empty ();
+}
+
+fun process (const string &section) -> bool {
+	auto full = sections.at (section);
+	if (auto include = full.find ("Include"); include != full.end ()) {
+		full.erase ("Open");
+		full.erase ("View");
+		full.erase ("Edit");
+
+		if (auto included = sections.find ("Include/" + include->second);
+			included != sections.end ()) {
+			for (const auto &kv : included->second)
+				full[kv.first] = kv.second;
+		}
+	}
+	if (getenv ("SDN_MC_EXT_DEBUG")) {
+		cerr << "[" << section << "]" << endl;
+		for (const auto &kv : full)
+			cerr << "  " << kv.first << ": " << kv.second << endl;
+	}
+	if (full.count (arg_verb) && section_matches (full)) {
+		print_command (full[arg_verb]);
+		return true;
+	}
+	return false;
+}
+
+int main (int argc, char *argv[]) {
+	if (argc != 6) {
+		cerr << "Usage: " << argv[0]
+			<< " TYPE PATH BASENAME DIRNAME VERB < mc.ext.ini" << endl;
+		return 2;
+	}
+
+	arg_type = argv[1];
+	arg_path = argv[2], arg_basename = argv[3], arg_dirname = argv[4];
+	arg_verb = argv[5];
+
+	string line, section;
+	vector<string> order;
+	regex re_entry {R"(^([-\w]+) *= *(.*)$)"};
+	smatch m;
+	while (getline (cin, line)) {
+		if (line.empty () || line[0] == '#') {
+			continue;
+		} else if (auto length = line.length();
+			line.find_last_of ('[') == 0 &&
+			line.find_first_of (']') == length - 1) {
+			order.push_back ((section = line.substr (1, length - 2)));
+		} else if (regex_match (line, m, re_entry)) {
+			sections[section][m[1]] = m[2];
+		}
+	}
+	for (const auto &section : order) {
+		if (section == "mc.ext.ini" ||
+			section == "Default" ||
+			section.substr (0, 8) == "Include/")
+			continue;
+		if (process (section))
+			return 0;
+	}
+	print_command (sections["Default"][arg_verb]);
+	return 0;
+}