Merge branch 'jk/run-command-use-shell'

* jk/run-command-use-shell:
  t4030, t4031: work around bogus MSYS bash path conversion
  diff: run external diff helper with shell
  textconv: use shell to run helper
  editor: use run_command's shell feature
  run-command: optimize out useless shell calls
  run-command: convert simple callsites to use_shell
  t0021: use $SHELL_PATH for the filter script
  run-command: add "use shell" option

11 files changed, 69 insertions, 35 deletions

diff --git a/convert.c b/convert.c
index 491e7141b4..950b1f9840 100644
--- a/convert.c
+++ b/convert.c
@@ -249,10 +249,11 @@ static int filter_buffer(int fd, void *data)
 	struct child_process child_process;
 	struct filter_params *params = (struct filter_params *)data;
 	int write_err, status;
-	const char *argv[] = { "sh", "-c", params->cmd, NULL };
+	const char *argv[] = { params->cmd, NULL };
 
 	memset(&child_process, 0, sizeof(child_process));
 	child_process.argv = argv;
+	child_process.use_shell = 1;
 	child_process.in = -1;
 	child_process.out = fd;
 
diff --git a/diff.c b/diff.c
index 04beb26a6a..5d71314587 100644
--- a/diff.c
+++ b/diff.c
@@ -2294,7 +2294,7 @@ static void run_external_diff(const char *pgm,
 	}
 	*arg = NULL;
 	fflush(NULL);
-	retval = run_command_v_opt(spawn_arg, 0);
+	retval = run_command_v_opt(spawn_arg, RUN_USING_SHELL);
 	remove_tempfile();
 	if (retval) {
 		fprintf(stderr, "external diff died, stopping at %s.\n", name);
@@ -3818,6 +3818,7 @@ static char *run_textconv(const char *pgm, struct diff_filespec *spec,
 	*arg = NULL;
 
 	memset(&child, 0, sizeof(child));
+	child.use_shell = 1;
 	child.argv = argv;
 	child.out = -1;
 	if (start_command(&child) != 0 ||
diff --git a/editor.c b/editor.c
index 615f5754d6..d8340031d2 100644
--- a/editor.c
+++ b/editor.c
@@ -36,26 +36,9 @@ int launch_editor(const char *path, struct strbuf *buffer, const char *const *en
 		return error("Terminal is dumb, but EDITOR unset");
 
 	if (strcmp(editor, ":")) {
-		size_t len = strlen(editor);
-		int i = 0;
-		int failed;
-		const char *args[6];
-		struct strbuf arg0 = STRBUF_INIT;
+		const char *args[] = { editor, path, NULL };
 
-		if (strcspn(editor, "|&;<>()$`\\\"' \t\n*?[#~=%") != len) {
-			/* there are specials */
-			strbuf_addf(&arg0, "%s \"$@\"", editor);
-			args[i++] = "sh";
-			args[i++] = "-c";
-			args[i++] = arg0.buf;
-		}
-		args[i++] = editor;
-		args[i++] = path;
-		args[i] = NULL;
-
-		failed = run_command_v_opt_cd_env(args, 0, NULL, env);
-		strbuf_release(&arg0);
-		if (failed)
+		if (run_command_v_opt_cd_env(args, RUN_USING_SHELL, NULL, env))
 			return error("There was a problem with the editor '%s'.",
 					editor);
 	}
diff --git a/imap-send.c b/imap-send.c
index de8114bac0..51f371ba9f 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -965,17 +965,13 @@ static struct store *imap_open_store(struct imap_server_conf *srvc)
 	/* open connection to IMAP server */
 
 	if (srvc->tunnel) {
-		const char *argv[4];
+		const char *argv[] = { srvc->tunnel, NULL };
 		struct child_process tunnel = {0};
 
 		imap_info("Starting tunnel '%s'... ", srvc->tunnel);
 
-		argv[0] = "sh";
-		argv[1] = "-c";
-		argv[2] = srvc->tunnel;
-		argv[3] = NULL;
-
 		tunnel.argv = argv;
+		tunnel.use_shell = 1;
 		tunnel.in = -1;
 		tunnel.out = -1;
 		if (start_command(&tunnel))
diff --git a/ll-merge.c b/ll-merge.c
index 2d6b6d6cb1..18511e281f 100644
--- a/ll-merge.c
+++ b/ll-merge.c
@@ -175,7 +175,7 @@ static int ll_ext_merge(const struct ll_merge_driver *fn,
 		{ "B", temp[2] },
 		{ NULL }
 	};
-	const char *args[] = { "sh", "-c", NULL, NULL };
+	const char *args[] = { NULL, NULL };
 	int status, fd, i;
 	struct stat st;
 
@@ -190,8 +190,8 @@ static int ll_ext_merge(const struct ll_merge_driver *fn,
 
 	strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 
-	args[2] = cmd.buf;
-	status = run_command_v_opt(args, 0);
+	args[0] = cmd.buf;
+	status = run_command_v_opt(args, RUN_USING_SHELL);
 	fd = open(temp[1], O_RDONLY);
 	if (fd < 0)
 		goto bad;
diff --git a/pager.c b/pager.c
index 92c03f654a..2c7e8ecb3c 100644
--- a/pager.c
+++ b/pager.c
@@ -28,7 +28,7 @@ static void pager_preexec(void)
 }
 #endif
 
-static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
+static const char *pager_argv[] = { NULL, NULL };
 static struct child_process pager_process;
 
 static void wait_for_pager(void)
@@ -81,7 +81,8 @@ void setup_pager(void)
 	spawned_pager = 1; /* means we are emitting to terminal */
 
 	/* spawn the pager */
-	pager_argv[2] = pager;
+	pager_argv[0] = pager;
+	pager_process.use_shell = 1;
 	pager_process.argv = pager_argv;
 	pager_process.in = -1;
 	if (!getenv("LESS")) {
diff --git a/run-command.c b/run-command.c
index cf2d8f7fae..47ced570bd 100644
--- a/run-command.c
+++ b/run-command.c
@@ -15,6 +15,50 @@ static inline void dup_devnull(int to)
 	close(fd);
 }
 
+static const char **prepare_shell_cmd(const char **argv)
+{
+	int argc, nargc = 0;
+	const char **nargv;
+
+	for (argc = 0; argv[argc]; argc++)
+		; /* just counting */
+	/* +1 for NULL, +3 for "sh -c" plus extra $0 */
+	nargv = xmalloc(sizeof(*nargv) * (argc + 1 + 3));
+
+	if (argc < 1)
+		die("BUG: shell command is empty");
+
+	if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
+		nargv[nargc++] = "sh";
+		nargv[nargc++] = "-c";
+
+		if (argc < 2)
+			nargv[nargc++] = argv[0];
+		else {
+			struct strbuf arg0 = STRBUF_INIT;
+			strbuf_addf(&arg0, "%s \"$@\"", argv[0]);
+			nargv[nargc++] = strbuf_detach(&arg0, NULL);
+		}
+	}
+
+	for (argc = 0; argv[argc]; argc++)
+		nargv[nargc++] = argv[argc];
+	nargv[nargc] = NULL;
+
+	return nargv;
+}
+
+#ifndef WIN32
+static int execv_shell_cmd(const char **argv)
+{
+	const char **nargv = prepare_shell_cmd(argv);
+	trace_argv_printf(nargv, "trace: exec:");
+	execvp(nargv[0], (char **)nargv);
+	free(nargv);
+	return -1;
+}
+#endif
+
 int start_command(struct child_process *cmd)
 {
 	int need_in, need_out, need_err;
@@ -123,6 +167,8 @@ fail_pipe:
 			cmd->preexec_cb();
 		if (cmd->git_cmd) {
 			execv_git_cmd(cmd->argv);
+		} else if (cmd->use_shell) {
+			execv_shell_cmd(cmd->argv);
 		} else {
 			execvp(cmd->argv[0], (char *const*) cmd->argv);
 		}
@@ -179,6 +225,8 @@ fail_pipe:
 
 	if (cmd->git_cmd) {
 		cmd->argv = prepare_git_cmd(cmd->argv);
+	} else if (cmd->use_shell) {
+		cmd->argv = prepare_shell_cmd(cmd->argv);
 	}
 
 	cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, env);
@@ -297,6 +345,7 @@ static void prepare_run_command_v_opt(struct child_process *cmd,
 	cmd->git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
 	cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 	cmd->silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
+	cmd->use_shell = opt & RUN_USING_SHELL ? 1 : 0;
 }
 
 int run_command_v_opt(const char **argv, int opt)
diff --git a/run-command.h b/run-command.h
index fb342090e3..967ba8cc09 100644
--- a/run-command.h
+++ b/run-command.h
@@ -33,6 +33,7 @@ struct child_process {
 	unsigned git_cmd:1; /* if this is to be git sub-command */
 	unsigned silent_exec_failure:1;
 	unsigned stdout_to_stderr:1;
+	unsigned use_shell:1;
 	void (*preexec_cb)(void);
 };
 
@@ -46,6 +47,7 @@ extern int run_hook(const char *index_file, const char *name, ...);
 #define RUN_GIT_CMD	     2	/*If this is to be git sub-command */
 #define RUN_COMMAND_STDOUT_TO_STDERR 4
 #define RUN_SILENT_EXEC_FAILURE 8
+#define RUN_USING_SHELL 16
 int run_command_v_opt(const char **argv, int opt);
 
 /*
diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index 8fc39d77ce..6cb8d60ea2 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -4,7 +4,8 @@ test_description='blob conversion via gitattributes'
 
 . ./test-lib.sh
 
-cat <<\EOF >rot13.sh
+cat <<EOF >rot13.sh
+#!$SHELL_PATH
 tr \
   'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ' \
   'nopqrstuvwxyzabcdefghijklmNOPQRSTUVWXYZABCDEFGHIJKLM'
diff --git a/t/t4030-diff-textconv.sh b/t/t4030-diff-textconv.sh
index a3f0897a52..88c5619ae7 100755
--- a/t/t4030-diff-textconv.sh
+++ b/t/t4030-diff-textconv.sh
@@ -48,7 +48,7 @@ test_expect_success 'file is considered binary by plumbing' '
 
 test_expect_success 'setup textconv filters' '
 	echo file diff=foo >.gitattributes &&
-	git config diff.foo.textconv "$PWD"/hexdump &&
+	git config diff.foo.textconv "\"$(pwd)\""/hexdump &&
 	git config diff.fail.textconv false
 '
 
diff --git a/t/t4031-diff-rewrite-binary.sh b/t/t4031-diff-rewrite-binary.sh
index a894c60622..7e7b307a24 100755
--- a/t/t4031-diff-rewrite-binary.sh
+++ b/t/t4031-diff-rewrite-binary.sh
@@ -54,7 +54,7 @@ chmod +x dump
 
 test_expect_success 'setup textconv' '
 	echo file diff=foo >.gitattributes &&
-	git config diff.foo.textconv "$PWD"/dump
+	git config diff.foo.textconv "\"$(pwd)\""/dump
 '
 
 test_expect_success 'rewrite diff respects textconv' '