ipc: remove possible memory corruption due to strcat on provided pointer

[GovanifY]

I was using strcat on a getenv pointer which was reused by the system's lib instead of providing a new one.
Because of this behaviour and me mistakenly appending to this pointer, I ended up corrupting the stack if called enough times.
tl;dr: code bad

[GovanifY]

codacy's warning is stupid, getenv returns null terminated strings.

[Warepire]

I placed my comment in a bad spot, I meant like this (which also made me find that you forgot to free m_socket_name so you have a memory leak):

--- IPC.cpp.orig	2021-03-29 19:35:17.526725932 +0200
+++ IPC.cpp	2021-03-29 19:39:02.478163161 +0200
@@ -85,20 +85,16 @@
 	// fallback in case macOS or other OSes don't implement the XDG base
 	// spec
 	if (runtime_dir == nullptr)
-		m_socket_name = (char*)"/tmp/" IPC_EMULATOR_NAME ".sock";
+		m_socket_name = "/tmp/" IPC_EMULATOR_NAME ".sock";
 	else
 	{
-		m_socket_name = new char[strlen(runtime_dir) + strlen("/" IPC_EMULATOR_NAME ".sock") + 1];
-		strcpy(m_socket_name, runtime_dir);
-		strcat(m_socket_name, "/" IPC_EMULATOR_NAME ".sock");
+		m_socket_name = runtime_dir;
+		m_socket_name += "/" IPC_EMULATOR_NAME ".sock";
 	}
 
 	if (slot != IPC_DEFAULT_SLOT)
 	{
-		// maximum size of .%u
-		char slot_ending[34];
-		sprintf(slot_ending, ".%u", slot);
-		m_socket_name = strcat(m_socket_name, slot_ending);
+		m_socket_name += "." + std::to_string(slot);
 	}
 
 	struct sockaddr_un server;
@@ -110,11 +106,11 @@
 		return;
 	}
 	server.sun_family = AF_UNIX;
-	strcpy(server.sun_path, m_socket_name);
+	strcpy(server.sun_path, m_socket_name.c_str());
 
 	// we unlink the socket so that when releasing this thread the socket gets
 	// freed even if we didn't close correctly the loop
-	unlink(m_socket_name);
+	unlink(m_socket_name.c_str());
 	if (bind(m_sock, (struct sockaddr*)&server, sizeof(struct sockaddr_un)))
 	{
 		Console.WriteLn(Color_Red, "IPC: Error while binding to socket! Shutting down...");
@@ -250,7 +246,7 @@
 #ifdef _WIN32
 	WSACleanup();
 #else
-	unlink(m_socket_name);
+	unlink(m_socket_name.c_str());
 #endif
 	close_portable(m_sock);
 	close_portable(m_msgsock);

--- IPC.h.orig	2021-03-29 19:35:24.000005145 +0200
+++ IPC.h	2021-03-29 19:36:13.569589803 +0200
@@ -25,6 +25,8 @@
 #define IPC_DEFAULT_SLOT 28011
 #define IPC_EMULATOR_NAME "pcsx2"
 
+#include <string>
+
 #include "Utilities/PersistentThread.h"
 #include "System/SysThreads.h"
 #ifdef _WIN32
@@ -48,7 +50,7 @@
 	SOCKET m_msgsock = INVALID_SOCKET;
 #else
 	// absolute path of the socket. Stored in XDG_RUNTIME_DIR, if unset /tmp
-	char* m_socket_name;
+	std::string m_socket_name;
 	int m_sock = 0;
 	// the message socket used in thread's accept().
 	int m_msgsock = 0;

[GovanifY]

@Warepire good catch, thanks!
Indeed the code is more readable with std::string in that case and it does fix the free I forgot about :p

Thanks!

[Warepire]

Looks fine to me now.