From 6a3c94a9d0a33887cb5a746d304b65b26f39c389 Mon Sep 17 00:00:00 2001
From: David Given <dg@cowlark.com>
Date: Wed, 20 Jul 2022 00:24:20 +0200
Subject: [PATCH] Better string escaping, but it's still not good enough to
 support paths with spaces.

---
 modules/src/system/syssystem.c | 69 ++++++++++++++++++++++++++++------
 1 file changed, 57 insertions(+), 12 deletions(-)

diff --git a/modules/src/system/syssystem.c b/modules/src/system/syssystem.c
index c86b0be65..6013ade8d 100644
--- a/modules/src/system/syssystem.c
+++ b/modules/src/system/syssystem.c
@@ -2,34 +2,79 @@
 #include <string.h>
 #include "system.h"
 
+#if defined WIN32
+	#define ESCAPECHAR '^'
+
+	static int needs_escaping(char c)
+	{
+		switch (c)
+		{
+			case ' ':
+			case '"':
+			case '\'':
+			case '(':
+			case ')':
+			case '^':
+				return 1;
+
+			default:
+				return 0;
+		}
+	}
+#else
+	#define ESCAPECHAR '\\'
+
+	static int needs_escaping(char c)
+	{
+		switch (c)
+		{
+			case ' ':
+			case '"':
+			case '\'':
+			case '\\':
+			case '(':
+			case ')':
+				return 1;
+
+			default:
+				return 0;
+		}
+	}
+#endif
+
+static char* append_escaped(char* buffer, const char* word)
+{
+	for (;;)
+	{
+		char c = *word++;
+		if (!c)
+			break;
+		if (needs_escaping(c))
+			*buffer++ = ESCAPECHAR;
+		*buffer++ = c;
+	}
+	return buffer;
+}
+
 int sys_system(const char* prog, const char* const* arglist)
 {
 	/* Calculate the maximum length of the command line. */
 
-	int len = strlen(prog);
+	int len = strlen(prog) * 2 + 1;
 	for (const char* const* arg = arglist+1; *arg; arg++)
 		len += strlen(*arg) * 2 + 1;
 
 	/* Now actually build the command line. */
 
 	char* cmdline = malloc(len + 1);
-	strcpy(cmdline, prog);
-	char* p = cmdline + strlen(prog);
+	char* p = append_escaped(cmdline, prog);
 
 	for (const char* const* arg = arglist+1; *arg; arg++)
 	{
 		const char* word = *arg;
 		*p++ = ' ';
 
-		for (;;)
-		{
-			char c = *word++;
-			if (!c)
-				break;
-			if ((c == ' ') || (c == '\"') || (c == '\''))
-				*p++ = '\\';
-			*p++ = c;
-		}
+		p = append_escaped(p, word);
 	}
 
 	*p = 0;