run_editor: Pass the editor command through the shell

wordexp doesn’t work on OpenBSD, and escaping the path ourselves then
calling system() is actually easier than using wordexp.

opustags.1

@@ -103,7 +103,6 @@ Blank lines and lines starting with \fI#\fP are ignored.
 Edit tags interactively by spawning the program specified by the EDITOR
 environment variable. The allowed format is the same as \fB--set-all\fP.
 If TERM and VISUAL are set, VISUAL takes precedence over EDITOR.
-Both variables are expanded with wordexp(3).
 .SH EXAMPLES
 .PP
 List all the tags in file foo.opus:

src/cli.cc

@@ -302,7 +302,7 @@ static ot::status edit_tags_interactively(ot::opus_tags& tags, const std::option
 	timespec before, after;
 	if ((rc = ot::get_file_timestamp(tags_path.c_str(), before)) != ot::st::ok)
 		return rc;
-	ot::status editor_rc = ot::run_editor(editor, tags_path.c_str());
+	ot::status editor_rc = ot::run_editor(editor, tags_path);
 	if ((rc = ot::get_file_timestamp(tags_path.c_str(), after)) != ot::st::ok)
 		return rc; // probably because the file was deleted
 	bool modified = (before.tv_sec != after.tv_sec || before.tv_nsec != after.tv_nsec);

src/opustags.h

@@ -170,13 +170,13 @@ private:
 std::string shell_escape(std::string_view word);
 
 /**
- * Execute the editor process specified in editor using execlp. Wait for the process to exit and
+ * Execute the editor process specified in editor. Wait for the process to exit and
  * return st::ok on success, or st::child_process_failed if it did not exit with 0.
  *
- * editor may contain options, which will be expanded using wordexp(3).
+ * editor is passed unescaped to the shell, and may contain CLI options.
  * path is the name of the file to edit, which will be passed as the last argument to editor.
  */
-ot::status run_editor(const char* editor, const char* path);
+ot::status run_editor(std::string_view editor, std::string_view path);
 
 /**
  * Return the specified path’s mtime, i.e. the last data modification

src/system.cc

@@ -12,11 +12,11 @@
 #include <opustags.h>
 
 #include <errno.h>
+#include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <unistd.h>
-#include <wordexp.h>
 
 using namespace std::string_literals;
 
@@ -157,36 +157,12 @@ std::string ot::shell_escape(std::string_view word)
 	return escaped_word;
 }
 
-ot::status ot::run_editor(const char* editor, const char* path)
+ot::status ot::run_editor(std::string_view editor, std::string_view path)
 {
-	pid_t pid = fork();
-	if (pid == -1) {
-		return {st::standard_error, "Could not fork: "s + strerror(errno)};
-	} else if (pid == 0) {
-		wordexp_t p;
-		if (wordexp(editor, &p, WRDE_SHOWERR) != 0) {
-			fprintf(stderr, "error: wordexp failed while expanding %s\n", editor);
-			exit(1);
-		}
-		// After expansion of editor into an array of words by wordexp, append the file path
-		// and a sentinel nullptr for execvp.
-		std::vector<char*> argv;
-		argv.reserve(p.we_wordc + 2);
-		for (size_t i = 0; i < p.we_wordc; ++i)
-			argv.push_back(p.we_wordv[i]);
-		std::string path_copy = path; // execvp wants a char* and not a const char*
-		argv.push_back(path_copy.data());
-		argv.push_back(nullptr);
+	std::string command = std::string(editor) + " " + shell_escape(path);
+	int status = system(command.c_str());
 
-		execvp(argv[0], argv.data());
-		// execvp only returns on error. Let’s not have a runaway child process and kill it.
-		fprintf(stderr, "error: execvp %s failed: %s\n", argv[0], strerror(errno));
-		wordfree(&p);
-		exit(1);
-	}
-
-	int status = 0;
-	if (waitpid(pid, &status, 0) == -1)
+	if (status == -1)
 		return {st::standard_error, "waitpid error: "s + strerror(errno)};
 	else if (!WIFEXITED(status))
 		return {st::child_process_failed,

t/opustags.t

@@ -227,18 +227,18 @@ unlink('out2.opus');
 # Interactive edition
 
 $ENV{EDITOR} = 'sed -i -e y/aeiou/AEIOU/ `sleep 0.1`';
-is_deeply(opustags(qw(gobble.opus -o screaming.opus -e)), ['', '', 0], 'edit a file with EDITOR');
-is(md5('screaming.opus'), '56e85ccaa83a13c15576d75bbd6d835f', 'the tags were modified');
+is_deeply(opustags('gobble.opus', '-eo', "'screaming !'.opus"), ['', '', 0], 'edit a file with EDITOR');
+is(md5("'screaming !'.opus"), '56e85ccaa83a13c15576d75bbd6d835f', 'the tags were modified');
 
 $ENV{EDITOR} = 'true';
-is_deeply(opustags(qw(-i screaming.opus -e)), ['', "Cancelling edition because the tags file was not modified.\n", 256], 'close -e without saving');
-is(md5('screaming.opus'), '56e85ccaa83a13c15576d75bbd6d835f', 'the tags were not modified');
+is_deeply(opustags('-ie', "'screaming !'.opus"), ['', "Cancelling edition because the tags file was not modified.\n", 256], 'close -e without saving');
+is(md5("'screaming !'.opus"), '56e85ccaa83a13c15576d75bbd6d835f', 'the tags were not modified');
 
 $ENV{EDITOR} = 'false';
-is_deeply(opustags(qw(-i screaming.opus -e)), ['', "screaming.opus: error: Child process exited with 1\n", 256], 'editor exiting with an error');
-is(md5('screaming.opus'), '56e85ccaa83a13c15576d75bbd6d835f', 'the tags were not modified');
+is_deeply(opustags('-ie', "'screaming !'.opus"), ['', "'screaming !'.opus: error: Child process exited with 1\n", 256], 'editor exiting with an error');
+is(md5("'screaming !'.opus"), '56e85ccaa83a13c15576d75bbd6d835f', 'the tags were not modified');
 
-unlink('screaming.opus');
+unlink("'screaming !'.opus");
 
 ####################################################################################################
 # Test muxed streams