X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/63efa6c6a559a23be863cad0c08457a2d29a0a67..e6013e8c8f3de0ca39c17a2da95346b4a320e6d0:/src/sysdep.c
diff --git a/src/sysdep.c b/src/sysdep.c
index a2bda96192..836cc271b1 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -79,9 +79,6 @@ along with GNU Emacs. If not, see . */
#include "msdos.h"
#endif
-#ifdef HAVE_SYS_RESOURCE_H
-#include
-#endif
#include
#include
#include
@@ -662,14 +659,6 @@ unrequest_sigio (void)
interrupts_deferred = 1;
#endif
}
-
-void
-ignore_sigio (void)
-{
-#ifdef USABLE_SIGIO
- signal (SIGIO, SIG_IGN);
-#endif
-}
#ifndef MSDOS
/* Block SIGCHLD. */
@@ -1623,16 +1612,60 @@ handle_arith_signal (int sig)
xsignal0 (Qarith_error);
}
-#ifdef HAVE_STACK_OVERFLOW_HANDLING
-
-/* -1 if stack grows down as expected on most OS/ABI variants, 1 otherwise. */
-
-static int stack_direction;
+#if defined HAVE_STACK_OVERFLOW_HANDLING && !defined WINDOWSNT
/* Alternate stack used by SIGSEGV handler below. */
static unsigned char sigsegv_stack[SIGSTKSZ];
+
+/* Return true if SIGINFO indicates a stack overflow. */
+
+static bool
+stack_overflow (siginfo_t *siginfo)
+{
+ /* In theory, a more-accurate heuristic can be obtained by using
+ GNU/Linux pthread_getattr_np along with POSIX pthread_attr_getstack
+ and pthread_attr_getguardsize to find the location and size of the
+ guard area. In practice, though, these functions are so hard to
+ use reliably that they're not worth bothering with. E.g., see:
+ https://sourceware.org/bugzilla/show_bug.cgi?id=16291
+ Other operating systems also have problems, e.g., Solaris's
+ stack_violation function is tailor-made for this problem, but it
+ doesn't work on Solaris 11.2 x86-64 with a 32-bit executable.
+
+ GNU libsigsegv is overkill for Emacs; otherwise it might be a
+ candidate here. */
+
+ if (!siginfo)
+ return false;
+
+ /* The faulting address. */
+ char *addr = siginfo->si_addr;
+ if (!addr)
+ return false;
+
+ /* The known top and bottom of the stack. The actual stack may
+ extend a bit beyond these boundaries. */
+ char *bot = stack_bottom;
+ char *top = near_C_stack_top ();
+
+ /* Log base 2 of the stack heuristic ratio. This ratio is the size
+ of the known stack divided by the size of the guard area past the
+ end of the stack top. The heuristic is that a bad address is
+ considered to be a stack overflow if it occurs within
+ stacksize>>LG_STACK_HEURISTIC bytes above the top of the known
+ stack. This heuristic is not exactly correct but it's good
+ enough in practice. */
+ enum { LG_STACK_HEURISTIC = 8 };
+
+ if (bot < top)
+ return 0 <= addr - top && addr - top < (top - bot) >> LG_STACK_HEURISTIC;
+ else
+ return 0 <= top - addr && top - addr < (bot - top) >> LG_STACK_HEURISTIC;
+}
+
+
/* Attempt to recover from SIGSEGV caused by C stack overflow. */
static void
@@ -1640,28 +1673,15 @@ handle_sigsegv (int sig, siginfo_t *siginfo, void *arg)
{
/* Hard GC error may lead to stack overflow caused by
too nested calls to mark_object. No way to survive. */
- if (!gc_in_progress)
- {
- struct rlimit rlim;
+ bool fatal = gc_in_progress;
- if (!getrlimit (RLIMIT_STACK, &rlim))
- {
- enum { STACK_DANGER_ZONE = 16 * 1024 };
- char *beg, *end, *addr;
-
- beg = stack_bottom;
- end = stack_bottom + stack_direction * rlim.rlim_cur;
- if (beg > end)
- addr = beg, beg = end, end = addr;
- addr = (char *) siginfo->si_addr;
- /* If we're somewhere on stack and too close to
- one of its boundaries, most likely this is it. */
- if (beg < addr && addr < end
- && (addr - beg < STACK_DANGER_ZONE
- || end - addr < STACK_DANGER_ZONE))
- siglongjmp (return_to_command_loop, 1);
- }
- }
+#ifdef FORWARD_SIGNAL_TO_MAIN_THREAD
+ if (!fatal && !pthread_equal (pthread_self (), main_thread))
+ fatal = true;
+#endif
+
+ if (!fatal && stack_overflow (siginfo))
+ siglongjmp (return_to_command_loop, 1);
/* Otherwise we can't do anything with this. */
deliver_fatal_thread_signal (sig);
@@ -1676,8 +1696,6 @@ init_sigsegv (void)
struct sigaction sa;
stack_t ss;
- stack_direction = ((char *) &ss < stack_bottom) ? -1 : 1;
-
ss.ss_sp = sigsegv_stack;
ss.ss_size = sizeof (sigsegv_stack);
ss.ss_flags = 0;
@@ -1690,7 +1708,7 @@ init_sigsegv (void)
return sigaction (SIGSEGV, &sa, NULL) < 0 ? 0 : 1;
}
-#else /* not HAVE_STACK_OVERFLOW_HANDLING */
+#else /* not HAVE_STACK_OVERFLOW_HANDLING or WINDOWSNT */
static bool
init_sigsegv (void)
@@ -1698,7 +1716,7 @@ init_sigsegv (void)
return 0;
}
-#endif /* HAVE_STACK_OVERFLOW_HANDLING */
+#endif /* HAVE_STACK_OVERFLOW_HANDLING && !WINDOWSNT */
static void
deliver_arith_signal (int sig)
@@ -2147,7 +2165,17 @@ snprintf (char *buf, size_t bufsize, char const *format, ...)
/* If a backtrace is available, output the top lines of it to stderr.
Do not output more than BACKTRACE_LIMIT or BACKTRACE_LIMIT_MAX lines.
This function may be called from a signal handler, so it should
- not invoke async-unsafe functions like malloc. */
+ not invoke async-unsafe functions like malloc.
+
+ If BACKTRACE_LIMIT is -1, initialize tables that 'backtrace' uses
+ but do not output anything. This avoids some problems that can
+ otherwise occur if the malloc arena is corrupted before 'backtrace'
+ is called, since 'backtrace' may call malloc if the tables are not
+ initialized.
+
+ If the static variable THREAD_BACKTRACE_NPOINTERS is nonzero, a
+ fatal error has occurred in some other thread; generate a thread
+ backtrace instead, ignoring BACKTRACE_LIMIT. */
void
emacs_backtrace (int backtrace_limit)
{
@@ -2164,6 +2192,14 @@ emacs_backtrace (int backtrace_limit)
else
{
buffer = main_backtrace_buffer;
+
+ /* Work around 'backtrace' bug; see Bug#19959 and glibc bug#18084. */
+ if (bounded_limit < 0)
+ {
+ backtrace (buffer, 1);
+ return;
+ }
+
npointers = backtrace (buffer, bounded_limit + 1);
}
@@ -2683,10 +2719,8 @@ Lisp_Object
list_system_processes (void)
{
Lisp_Object procdir, match, proclist, next;
- struct gcpro gcpro1, gcpro2;
- register Lisp_Object tail;
+ Lisp_Object tail;
- GCPRO2 (procdir, match);
/* For every process on the system, there's a directory in the
"/proc" pseudo-directory whose name is the numeric ID of that
process. */
@@ -2701,7 +2735,6 @@ list_system_processes (void)
next = XCDR (tail);
XSETCAR (tail, Fstring_to_number (XCAR (tail), Qnil));
}
- UNGCPRO;
/* directory_files_internal returns the files in reverse order; undo
that. */
@@ -2723,7 +2756,6 @@ list_system_processes (void)
struct kinfo_proc *procs;
size_t i;
- struct gcpro gcpro1;
Lisp_Object proclist = Qnil;
if (sysctl (mib, 3, NULL, &len, NULL, 0) != 0)
@@ -2736,7 +2768,6 @@ list_system_processes (void)
return proclist;
}
- GCPRO1 (proclist);
len /= sizeof (struct kinfo_proc);
for (i = 0; i < len; i++)
{
@@ -2746,7 +2777,6 @@ list_system_processes (void)
proclist = Fcons (make_fixnum_or_float (procs[i].ki_pid), proclist);
#endif
}
- UNGCPRO;
xfree (procs);
@@ -2957,7 +2987,6 @@ system_process_attributes (Lisp_Object pid)
Lisp_Object attrs = Qnil;
Lisp_Object cmd_str, decoded_cmd;
ptrdiff_t count;
- struct gcpro gcpro1, gcpro2;
CHECK_NUMBER_OR_FLOAT (pid);
CONS_TO_INTEGER (pid, pid_t, proc_id);
@@ -2965,8 +2994,6 @@ system_process_attributes (Lisp_Object pid)
if (stat (procfn, &st) < 0)
return attrs;
- GCPRO2 (attrs, decoded_cmd);
-
/* euid egid */
uid = st.st_uid;
attrs = Fcons (Fcons (Qeuid, make_fixnum_or_float (uid)), attrs);
@@ -3155,7 +3182,6 @@ system_process_attributes (Lisp_Object pid)
attrs = Fcons (Fcons (Qargs, decoded_cmd), attrs);
}
- UNGCPRO;
return attrs;
}
@@ -3194,7 +3220,6 @@ system_process_attributes (Lisp_Object pid)
gid_t gid;
Lisp_Object attrs = Qnil;
Lisp_Object decoded_cmd;
- struct gcpro gcpro1, gcpro2;
ptrdiff_t count;
CHECK_NUMBER_OR_FLOAT (pid);
@@ -3203,8 +3228,6 @@ system_process_attributes (Lisp_Object pid)
if (stat (procfn, &st) < 0)
return attrs;
- GCPRO2 (attrs, decoded_cmd);
-
/* euid egid */
uid = st.st_uid;
attrs = Fcons (Fcons (Qeuid, make_fixnum_or_float (uid)), attrs);
@@ -3297,7 +3320,6 @@ system_process_attributes (Lisp_Object pid)
attrs = Fcons (Fcons (Qargs, decoded_cmd), attrs);
}
unbind_to (count, Qnil);
- UNGCPRO;
return attrs;
}
@@ -3333,7 +3355,6 @@ system_process_attributes (Lisp_Object pid)
struct kinfo_proc proc;
size_t proclen = sizeof proc;
- struct gcpro gcpro1, gcpro2;
Lisp_Object attrs = Qnil;
Lisp_Object decoded_comm;
@@ -3344,8 +3365,6 @@ system_process_attributes (Lisp_Object pid)
if (sysctl (mib, 4, &proc, &proclen, NULL, 0) != 0)
return attrs;
- GCPRO2 (attrs, decoded_comm);
-
attrs = Fcons (Fcons (Qeuid, make_fixnum_or_float (proc.ki_uid)), attrs);
block_input ();
@@ -3483,7 +3502,6 @@ system_process_attributes (Lisp_Object pid)
attrs = Fcons (Fcons (Qargs, decoded_comm), attrs);
}
- UNGCPRO;
return attrs;
}