From: Michael Gernoth Date: Wed, 26 May 2010 08:11:43 +0000 (+0200) Subject: More robust search for filename in memory at runtime X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/usb-driver/commitdiff_plain/47661cecc5772a230923f25bd068014cd6c0ff91?hp=98b8ef391f9f508131d222080a79b3b3e72a4b22 More robust search for filename in memory at runtime --- diff --git a/usb-driver.c b/usb-driver.c index ed78932..3b8b51d 100644 --- a/usb-driver.c +++ b/usb-driver.c @@ -674,6 +674,18 @@ 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; @@ -682,16 +694,33 @@ void* _ZN9XilCommNS14CPortResources8InstanceEv() { int i; if (!func) { + struct sigaction act, oldact; + int sighand_installed = 0; + func = (void* (*) (void)) dlsym(RTLD_NEXT, "_ZN9XilCommNS14CPortResources8InstanceEv"); + 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; + } + DPRINTF("Searching for filename starting at %p\n", func); - for(i = 0; i < 16384; i++) { + 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"); } if (filename) {