From afe666fd6ed3232aee0bd8bf5fa062b980190ee8 Mon Sep 17 00:00:00 2001
From: Johan Malm <jgm323@gmail.com>
Date: Wed, 30 Jun 2021 19:56:31 +0100
Subject: [PATCH] action: expand shell variables before execvp()

Expanding shell variables, including tilde, enables the following type
of keybind:

<keyboard>
    <keybind key="XF86AudioMute">
      <action name="Execute">
        <command>bash ~/mute-script.sh</command>
      </action>
    </keybind>
</keyboard>

Fixes issue #32
---
 include/common/buf.h | 13 ++++++++++---
 src/action.c         |  7 ++++++-
 src/common/buf.c     | 44 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/include/common/buf.h b/include/common/buf.h
index 98be625d..bb18624d 100644
--- a/include/common/buf.h
+++ b/include/common/buf.h
@@ -17,17 +17,24 @@ struct buf {
 	int len;
 };
 
+/**
+ * buf_expand_shell_variables - expand $foo and ~ in buffer
+ * @s: buffer
+ * Note: ${foo} and $$ are not handled
+ */
+void buf_expand_shell_variables(struct buf *s);
+
 /**
  * buf_init - allocate NULL-terminated C string buffer
- * @s - buffer
+ * @s: buffer
  * Note: use free(s->buf) to free it.
  */
 void buf_init(struct buf *s);
 
 /**
  * buf_add - add data to C string buffer
- * @s - buffer
- * @data - data to be added
+ * @s: buffer
+ * @data: data to be added
  */
 void buf_add(struct buf *s, const char *data);
 
diff --git a/src/action.c b/src/action.c
index 5510dc85..3ac0633d 100644
--- a/src/action.c
+++ b/src/action.c
@@ -26,7 +26,12 @@ action(struct server *server, const char *action, const char *command)
 	if (!strcasecmp(action, "Debug")) {
 		/* nothing */
 	} else if (!strcasecmp(action, "Execute")) {
-		spawn_async_no_shell(command);
+		struct buf cmd;
+		buf_init(&cmd);
+		buf_add(&cmd, command);
+		buf_expand_shell_variables(&cmd);
+		spawn_async_no_shell(cmd.buf);
+		free(cmd.buf);
 	} else if (!strcasecmp(action, "Exit")) {
 		wl_display_terminate(server->wl_display);
 	} else if (!strcasecmp(action, "NextWindow")) {
diff --git a/src/common/buf.c b/src/common/buf.c
index 27081f01..abc2b877 100644
--- a/src/common/buf.c
+++ b/src/common/buf.c
@@ -1,5 +1,49 @@
+#include <ctype.h>
 #include "common/buf.h"
 
+void
+buf_expand_shell_variables(struct buf *s)
+{
+	struct buf new;
+	struct buf environment_variable;
+	buf_init(&new);
+	buf_init(&environment_variable);
+
+	for (int i = 0 ; i < s->len ; i++) {
+		if (s->buf[i] == '$') {
+			/* expand environment variable */
+			environment_variable.len = 0;
+			buf_add(&environment_variable, s->buf + i + 1);
+			char *p = environment_variable.buf;
+			while (isalnum(*p)) {
+				++p;
+			}
+			*p = '\0';
+			p = getenv(environment_variable.buf);
+			if (!p) {
+				goto out;
+			}
+			buf_add(&new, p);
+			i += strlen(environment_variable.buf);
+		} else if (s->buf[i] == '~') {
+			/* expand tilde */
+			buf_add(&new, getenv("HOME"));
+		} else {
+			/* just add one character at a time */
+			if (new.alloc <= new.len + 1) {
+				new.alloc = new.alloc * 3/2 + 16;
+				new.buf = realloc(new.buf, new.alloc);
+			}
+			new.buf[new.len++] = s->buf[i];
+			new.buf[new.len] = '\0';
+		}
+	}
+out:
+	free(environment_variable.buf);
+	free(s->buf);
+	s->buf = new.buf;
+}
+
 void
 buf_init(struct buf *s)
 {
-- 
2.52.0