debug: Remove catchsegv and libSegfault (BZ #14913)

Trapping SIGSEGV within the process is error-prone, adds security
issues, and modern analysis design tends to happen out of the
process (either by attaching a debugger or by post-mortem analysis).

The libSegfault also has some design problems, it uses non
async-signal-safe function (backtrace) on signal handler.

There are multiple alternatives if users do want to use similar
functionality, such as sigsegv gnulib module or libsegfault.

3 files changed, 2 insertions, 338 deletions

diff --git a/debug/Makefile b/debug/Makefile
index 9c2ce61..5818d75 100644
--- a/debug/Makefile
+++ b/debug/Makefile
@@ -167,12 +167,9 @@ tests-unsupported = tst-chk4 tst-chk5 tst-chk6 tst-chk8 \
 		    tst-lfschk4 tst-lfschk5 tst-lfschk6
 endif
 
-extra-libs = libSegFault libpcprofile
+extra-libs = libpcprofile
 extra-libs-others = $(extra-libs)
 
-libSegFault-routines = segfault
-libSegFault-inhibit-o = $(filter-out .os,$(object-suffixes))
-
 libpcprofile-routines = pcprofile
 libpcprofile-inhibit-o = $(filter-out .os,$(object-suffixes))
 
@@ -180,10 +177,7 @@ others = pcprofiledump
 install-bin = pcprofiledump
 install-bin-script = xtrace
 
-ifeq ($(build-shared),yes)
-install-bin-script += catchsegv
-endif
-generated += catchsegv xtrace
+generated += xtrace
 
 include ../Rules
 
@@ -209,15 +203,6 @@ endif
 
 sLIBdir := $(shell echo $(slibdir) | sed 's,lib\(\|64\)$$,\\\\$$LIB,')
 
-$(objpfx)catchsegv: catchsegv.sh $(common-objpfx)soversions.mk \
-		    $(common-objpfx)config.make
-	slibpfx=`echo $(slibdir)|sed 's/lib\(64\|\)$$/\\\\\\\\$$LIB/'`; \
-	sed -e 's|@VERSION@|$(version)|' -e "s|@SLIB@|$$slibpfx|" \
-	    -e 's|@PKGVERSION@|$(PKGVERSION)|' \
-	    -e 's|@REPORT_BUGS_TO@|$(REPORT_BUGS_TO)|' $< > $@.new
-	chmod 555 $@.new
-	mv -f $@.new $@
-
 $(objpfx)pcprofiledump: $(objpfx)pcprofiledump.o
 
 $(objpfx)xtrace: xtrace.sh
diff --git a/debug/catchsegv.sh b/debug/catchsegv.sh
deleted file mode 100755
index f8328ee..0000000
--- a/debug/catchsegv.sh
+++ /dev/null
@@ -1,106 +0,0 @@
-#!/bin/sh
-# Copyright (C) 1998-2022 Free Software Foundation, Inc.
-# This file is part of the GNU C Library.
-
-# The GNU C Library is free software; you can redistribute it and/or
-# modify it under the terms of the GNU Lesser General Public
-# License as published by the Free Software Foundation; either
-# version 2.1 of the License, or (at your option) any later version.
-
-# The GNU C Library is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-# Lesser General Public License for more details.
-
-# You should have received a copy of the GNU Lesser General Public
-# License along with the GNU C Library; if not, see
-# <https://www.gnu.org/licenses/>.
-
-if test $# -eq 0; then
-  echo "$0: missing program name" >&2
-  echo "Try \`$0 --help' for more information." >&2
-  exit 1
-fi
-
-prog="$1"
-shift
-
-if test $# -eq 0; then
-  case "$prog" in
-    --h | --he | --hel | --help)
-      echo 'Usage: catchsegv PROGRAM ARGS...'
-      echo '  --help      print this help, then exit'
-      echo '  --version   print version number, then exit'
-      echo 'For bug reporting instructions, please see:'
-      cat <<\EOF
-@REPORT_BUGS_TO@.
-EOF
-      exit 0
-      ;;
-    --v | --ve | --ver | --vers | --versi | --versio | --version)
-      echo 'catchsegv @PKGVERSION@@VERSION@'
-      echo 'Copyright (C) 2022 Free Software Foundation, Inc.
-This is free software; see the source for copying conditions.  There is NO
-warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-Written by Ulrich Drepper.'
-      exit 0
-      ;;
-    *)
-      ;;
-  esac
-fi
-
-segv_output=`mktemp ${TMPDIR:-/tmp}/segv_output.XXXXXX` || exit
-
-# Redirect stderr to avoid termination message from shell.
-(exec 3>&2 2>/dev/null
-LD_PRELOAD=${LD_PRELOAD:+${LD_PRELOAD}:}@SLIB@/libSegFault.so \
-SEGFAULT_USE_ALTSTACK=1 \
-SEGFAULT_OUTPUT_NAME=$segv_output \
-"$prog" ${1+"$@"} 2>&3 3>&-)
-exval=$?
-
-# Check for output.  Even if the program terminated correctly it might
-# be that a minor process (clone) failed.  Therefore we do not check the
-# exit code.
-if test -s "$segv_output"; then
-  # The program caught a signal.  The output is in the file with the
-  # name we have in SEGFAULT_OUTPUT_NAME.  In the output the names of
-  # functions in shared objects are available, but names in the static
-  # part of the program are not.  We use addr2line to get this information.
-  case $prog in
-  */*) ;;
-  *)
-    old_IFS=$IFS
-    IFS=:
-    for p in $PATH; do
-      test -n "$p" || p=.
-      if test -f "$p/$prog"; then
-	prog=$p/$prog
-      break
-      fi
-    done
-    IFS=$old_IFS
-    ;;
-  esac
-  sed '/Backtrace/q' "$segv_output"
-  sed '1,/Backtrace/d' "$segv_output" |
-  (while read line; do
-     line=`echo $line | sed "s@^$prog\\(\\[.*\\)@\1@"`
-     case "$line" in
-       \[*) addr=`echo "$line" | sed 's/^\[\(.*\)\]$/\1/'`
-	    complete=`addr2line -f -e "$prog" $addr 2>/dev/null`
-	    if test $? -eq 0; then
-	      echo "`echo "$complete"|sed 'N;s/\(.*\)\n\(.*\)/\2(\1)/;'`$line"
-	    else
-	      echo "$line"
-	    fi
-	    ;;
-	 *) echo "$line"
-	    ;;
-     esac
-   done)
-fi
-rm -f "$segv_output"
-
-exit $exval
diff --git a/debug/segfault.c b/debug/segfault.c
deleted file mode 100644
index 55801d1..0000000
--- a/debug/segfault.c
+++ /dev/null
@@ -1,215 +0,0 @@
-/* Catch segmentation faults and print backtrace.
-   Copyright (C) 1998-2022 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <alloca.h>
-#include <ctype.h>
-#include <errno.h>
-#include <execinfo.h>
-#include <fcntl.h>
-#include <signal.h>
-#include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <_itoa.h>
-#include <ldsodefs.h>
-
-/* This file defines macros to access the content of the sigcontext element
-   passed up by the signal handler.  */
-#include <sigcontextinfo.h>
-
-#ifdef SA_SIGINFO
-# define SIGCONTEXT siginfo_t *info, void *
-#endif
-
-/* Get code to possibly dump the content of all registers.  */
-#include <register-dump.h>
-
-/* We'll use this a lot.  */
-#define WRITE_STRING(s) write (fd, s, strlen (s))
-
-/* Name of the output file.  */
-static const char *fname;
-
-
-/* Print the signal number SIGNAL.  Either strerror or strsignal might
-   call local internal functions and these in turn call far too many
-   other functions and might even allocate memory which might fail.  */
-static void
-write_strsignal (int fd, int signal)
-{
-  char buf[30];
-  char *ptr = _itoa_word (signal, &buf[sizeof (buf)], 10, 0);
-  WRITE_STRING ("signal ");
-  write (fd, ptr, &buf[sizeof (buf)] - ptr);
-}
-
-
-/* This function is called when a segmentation fault is caught.  The system
-   is in an unstable state now.  This means especially that malloc() might
-   not work anymore.  */
-static void
-catch_segfault (int signal, SIGCONTEXT ctx)
-{
-  int fd, cnt, i;
-  void **arr;
-  struct sigaction sa;
-  uintptr_t pc;
-
-  /* This is the name of the file we are writing to.  If none is given
-     or we cannot write to this file write to stderr.  */
-  fd = 2;
-  if (fname != NULL)
-    {
-      fd = open (fname, O_TRUNC | O_WRONLY | O_CREAT, 0666);
-      if (fd == -1)
-	fd = 2;
-    }
-
-  WRITE_STRING ("*** ");
-  write_strsignal (fd, signal);
-  WRITE_STRING ("\n");
-
-#ifdef REGISTER_DUMP
-  REGISTER_DUMP;
-#endif
-
-  WRITE_STRING ("\nBacktrace:\n");
-
-  /* Get the backtrace.  */
-  arr = alloca (256 * sizeof (void *));
-  cnt = backtrace (arr, 256);
-
-  /* Now try to locate the PC from signal context in the backtrace.
-     Normally it will be found at arr[2], but it might appear later
-     if there were some signal handler wrappers.  Allow a few bytes
-     difference to cope with as many arches as possible.  */
-  pc = sigcontext_get_pc (ctx);
-  for (i = 0; i < cnt; ++i)
-    if ((uintptr_t) arr[i] >= pc - 16 && (uintptr_t) arr[i] <= pc + 16)
-      break;
-
-  /* If we haven't found it, better dump full backtrace even including
-     the signal handler frames instead of not dumping anything.  */
-  if (i == cnt)
-    i = 0;
-
-  /* Now generate nicely formatted output.  */
-  __backtrace_symbols_fd (arr + i, cnt - i, fd);
-
-#ifdef HAVE_PROC_SELF
-  /* Now the link map.  */
-  int mapfd = open ("/proc/self/maps", O_RDONLY);
-  if (mapfd != -1)
-    {
-      write (fd, "\nMemory map:\n\n", 14);
-
-      char buf[256];
-      ssize_t n;
-
-      while ((n = TEMP_FAILURE_RETRY (read (mapfd, buf, sizeof (buf)))) > 0)
-	TEMP_FAILURE_RETRY (write (fd, buf, n));
-
-      close (mapfd);
-    }
-#endif
-
-  /* Pass on the signal (so that a core file is produced).  */
-  sa.sa_handler = SIG_DFL;
-  sigemptyset (&sa.sa_mask);
-  sa.sa_flags = 0;
-  sigaction (signal, &sa, NULL);
-  raise (signal);
-}
-
-
-static void
-__attribute__ ((constructor))
-install_handler (void)
-{
-  struct sigaction sa;
-  const char *sigs = getenv ("SEGFAULT_SIGNALS");
-  const char *name;
-
-#ifdef SA_SIGINFO
-  sa.sa_sigaction = catch_segfault;
-  sa.sa_flags = SA_SIGINFO;
-#else
-  sa.sa_handler = (void*) catch_segfault;
-  sa.sa_flags = 0;
-#endif
-  sigemptyset (&sa.sa_mask);
-  sa.sa_flags |= SA_RESTART;
-
-  /* Maybe we are expected to use an alternative stack.  */
-  if (getenv ("SEGFAULT_USE_ALTSTACK") != 0)
-    {
-      void *stack_mem = malloc (2 * SIGSTKSZ);
-      stack_t ss;
-
-      if (stack_mem != NULL)
-	{
-	  ss.ss_sp = stack_mem;
-	  ss.ss_flags = 0;
-	  ss.ss_size = 2 * SIGSTKSZ;
-
-	  if (sigaltstack (&ss, NULL) == 0)
-	    sa.sa_flags |= SA_ONSTACK;
-	}
-    }
-
-  if (sigs == NULL)
-    sigaction (SIGSEGV, &sa, NULL);
-  else if (sigs[0] == '\0')
-    /* Do not do anything.  */
-    return;
-  else
-    {
-      const char *where;
-      int all = __strcasecmp (sigs, "all") == 0;
-
-#define INSTALL_FOR_SIG(sig, name) \
-      where = __strcasestr (sigs, name);				      \
-      if (all || (where != NULL						      \
-		  && (where == sigs || !isalnum (where[-1]))		      \
-		  && !isalnum (where[sizeof (name) - 1])))		      \
-	sigaction (sig, &sa, NULL);
-
-      INSTALL_FOR_SIG (SIGSEGV, "segv");
-      INSTALL_FOR_SIG (SIGILL, "ill");
-#ifdef SIGBUS
-      INSTALL_FOR_SIG (SIGBUS, "bus");
-#endif
-#ifdef SIGSTKFLT
-      INSTALL_FOR_SIG (SIGSTKFLT, "stkflt");
-#endif
-      INSTALL_FOR_SIG (SIGABRT, "abrt");
-      INSTALL_FOR_SIG (SIGFPE, "fpe");
-    }
-
-  /* Preserve the output file name if there is any given.  */
-  name = getenv ("SEGFAULT_OUTPUT_NAME");
-  if (name != NULL && name[0] != '\0')
-    {
-      int ret = access (name, R_OK | W_OK);
-
-      if (ret == 0 || (ret == -1 && errno == ENOENT))
-	fname = __strdup (name);
-    }
-}