diff options
Diffstat (limited to 'src/base/linuxthreads.c')
| -rw-r--r-- | src/base/linuxthreads.c | 37 |
1 files changed, 33 insertions, 4 deletions
diff --git a/src/base/linuxthreads.c b/src/base/linuxthreads.c index e721582..3696987 100644 --- a/src/base/linuxthreads.c +++ b/src/base/linuxthreads.c @@ -51,6 +51,10 @@ #include "base/linux_syscall_support.h" #include "base/thread_lister.h" +#ifndef CLONE_UNTRACED +#define CLONE_UNTRACED 0x00800000 +#endif + /* itoa() is not a standard function, and we cannot safely call printf() * after suspending threads. So, we just implement our own copy. A @@ -97,8 +101,19 @@ static int local_clone (int (*fn)(void *), void *arg, ...) { * Leave 4kB of gap between the callers stack and the new clone. This * should be more than sufficient for the caller to call waitpid() until * the cloned thread terminates. + * + * It is important that we set the CLONE_UNTRACED flag, because newer + * versions of "gdb" otherwise attempt to attach to our thread, and will + * attempt to reap its status codes. This subsequently results in the + * caller hanging indefinitely in waitpid(), waiting for a change in + * status that will never happen. By setting the CLONE_UNTRACED flag, we + * prevent "gdb" from stealing events, but we still expect the thread + * lister to fail, because it cannot PTRACE_ATTACH to the process that + * is being debugged. This is OK and the error code will be reported + * correctly. */ - return clone(fn, (char *)&arg - 4096, CLONE_VM|CLONE_FS|CLONE_FILES, arg); + return clone(fn, (char *)&arg - 4096, + CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_UNTRACED, arg); } @@ -209,7 +224,8 @@ struct ListerParams { static void ListerThread(struct ListerParams *args) { static const int signals[] = { SIGABRT, SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGXCPU, SIGXFSZ }; - pid_t clone_pid = sys_gettid(); + int found_parent = 0; + pid_t clone_pid = sys_gettid(), ppid = sys_getppid(); char proc_self_task[80], marker_name[48], *marker_path; const char *proc_paths[3]; const char *const *proc_path = proc_paths; @@ -239,8 +255,7 @@ static void ListerThread(struct ListerParams *args) { } /* Compute search paths for finding thread directories in /proc */ - local_itoa(strrchr(strcpy(proc_self_task, "/proc/"), '\000'), - sys_getppid()); + local_itoa(strrchr(strcpy(proc_self_task, "/proc/"), '\000'), ppid); marker_path = strrchr(strcpy(marker_name, proc_self_task), '\000'); strcat(proc_self_task, "/task/"); proc_paths[0] = proc_self_task; /* /proc/$$/task/ */ @@ -417,6 +432,7 @@ static void ListerThread(struct ListerParams *args) { num_threads--; sig_num_threads = num_threads; } else { + found_parent |= pid == ppid; added_entries++; } } @@ -435,6 +451,16 @@ static void ListerThread(struct ListerParams *args) { NO_INTR(sys_close(marker)); sig_marker = marker = -1; + /* If we never found the parent process, something is very wrong. + * Most likely, we are running in debugger. Any attempt to operate + * on the threads would be very incomplete. Let's just report an + * error to the caller. + */ + if (!found_parent) { + ResumeAllProcessThreads(num_threads, pids); + sys__exit(3); + } + /* Now we are ready to call the callback, * which takes care of resuming the threads for us. */ @@ -530,6 +556,9 @@ int ListAllProcessThreads(void *parameter, case 2: args.err = EFAULT; /* Some fault (e.g. SIGSEGV) detected */ args.result = -1; break; + case 3: args.err = EPERM; /* Process is already being traced */ + args.result = -1; + break; default:args.err = ECHILD; /* Child died unexpectedly */ args.result = -1; break; |