X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/usb-driver/blobdiff_plain/765c485a06fd49d423277e37ba6562ad5b1d62b9..142aeb0f9295e4abf809b87bdd36dee049bc1c5e:/usb-driver.c

diff --git a/usb-driver.c b/usb-driver.c
index 252e327..3b8b51d 100644
--- a/usb-driver.c
+++ b/usb-driver.c
@@ -41,6 +41,7 @@
 #include <bits/wordsize.h>
 #include <sys/ipc.h>
 #include <sys/sem.h>
+#include <sys/mman.h>
 #include <syscall.h>
 #include <linux/personality.h>
 #include "usb-driver.h"
@@ -673,32 +674,88 @@ long int _Z14isModuleLoadedPci(char *module_name, int i) {
 	return 1;
 }
 
+void cpr_segv_handler(int sig, siginfo_t *info, void *context) {
+	void *newmem;
+
+	DPRINTF("SEGV at %p, mapping memory\n", info->si_addr);
+	errno = 0;
+	newmem = mmap(info->si_addr, 1, PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, -1, 0);
+	if (newmem != info->si_addr) {
+		perror("libusb-driver.so: Can't map memory, crashing now");
+		exit(EXIT_FAILURE);
+	}
+}
+
 /* XilCommNS::CPortResources::Instance() */
 void* _ZN9XilCommNS14CPortResources8InstanceEv() {
 	static void* (*func) (void) = NULL;
+	char *filename = NULL;
 	void *ret;
+	int i;
+
+	if (!func) {
+		struct sigaction act, oldact;
+		int sighand_installed = 0;
 
-	if (!func)
 		func = (void* (*) (void)) dlsym(RTLD_NEXT, "_ZN9XilCommNS14CPortResources8InstanceEv");
 
-	DPRINTF("-> XilCommNS::CPortResources::Instance()\n");
+		DPRINTF("Installing signal-handler for SIGSEGV\n");
+		bzero(&act, sizeof(struct sigaction));
+		act.sa_sigaction = cpr_segv_handler;
+		act.sa_flags = SA_SIGINFO;
+		if (sigaction(SIGSEGV, &act, &oldact) == 0) {
+			sighand_installed = 1;
+		}
 
-	ret = func();
+		DPRINTF("Searching for filename starting at %p\n", func);
+		for(i = 0; i < 32768; i++) {
+			if (!strcmp(((char*)func)+i, "/proc/sys/dev/parport/%s/base-addr")) {
+				filename = ((char*)func)+i;
+				DPRINTF("Filename found at offset %p\n", (void*)(filename - ((char*)func)));
+				break;
+			}
+		}
+		if (sighand_installed) {
+			DPRINTF("Restoring signal-handler for SIGSEGV\n");
+			sigaction(SIGSEGV, &oldact, NULL);
+		}
+		if (!filename)
+			fprintf(stderr, "libusb-driver.so: Can't find memory to patch, parallel cables will probably not work!\n");
+	}
 
-#ifdef DEBUG
-	hexdump(ret, 0x29, "<-");
-	#if 0
-	{
-		void *portinfo;
-		portinfo = ((unsigned char**)ret+0x00);
-		hexdump(portinfo, 256, "PI");
-		hexdump(portinfo+0x50, 4, "BS");
-		hexdump(portinfo+0x54, 4, "BE");
-		hexdump(portinfo+0x58, 4, "ES");
-		hexdump(portinfo+0x5c, 4, "EE");
+	if (filename) {
+		long pagesize;
+		size_t protectlen;
+		void *start;
+		int len = strlen(filename) + 1;
+		int ret;
+
+		pagesize = sysconf(_SC_PAGE_SIZE);
+		DPRINTF("You have %lu bytes sized pages!\n", pagesize);
+
+		start = (void*)((long)filename & (~(pagesize-1)));
+
+		protectlen = pagesize;
+		if ((long)(filename + len) > (long)(start + protectlen))
+			protectlen += pagesize;
+
+		DPRINTF("Unprotecting %zd bytes starting at %p\n", protectlen, start);
+		ret = mprotect(start, protectlen, PROT_READ|PROT_WRITE);
+		if (ret == -1)
+			perror("mprotect");
+
+		DPRINTF("Replacing %s with /dev/zero\n", filename);
+		strcpy(filename, "/dev/zero");
+
+		DPRINTF("Reprotecting %zd bytes starting at %p\n", protectlen, start);
+		ret = mprotect(start, protectlen, PROT_READ|PROT_EXEC);
+		if (ret == -1)
+			perror("mprotect");
 	}
-	#endif
-#endif
+
+	DPRINTF("-> XilCommNS::CPortResources::Instance()\n");
+
+	ret = func();
 
 	DPRINTF("<- XilCommNS::CPortResources::Instance()\n");