Synchronize libiberty with gcc and add --no-recruse-limit option to tools that support name demangling.

This patch addresses the multitude of bug reports about resource exhaustion
in libiberty's name demangling code.  It adds a limit to the amount of
recursion that is allowed, before an error is triggered.  It also adds a
new demangling option to disable this limit.  (The limit is enabled by
default).

	PR 87681
	PR 87675
	PR 87636
	PR 87335
libiberty * cp-demangle.h (struct d_info): Add recursion_limit field.
	* cp-demangle.c (d_function_type): If the recursion limit is
	enabled and reached, return with a failure result.
        (d_demangle_callback): If the recursion limit is enabled, check
	for a mangled string that is so long that there is not enough
	stack space for the local arrays.
        * cplus-dem.c (struct work): Add recursion_level field.
	(demangle_nested_args): If the recursion limit is enabled and
	reached, return with a failure result.

include	* demangle.h (DMGL_RECURSE_LIMIT): Define.
        (DEMANGLE_RECURSION_LIMIT): Prototype.

binutuils * addr2line.c (demangle_flags): New static variable.
        (long_options): Add --recurse-limit and --no-recurse-limit.
        (translate_address): Pass demangle_flags to bfd_demangle.
        (main): Handle --recurse-limit and --no-recurse-limit options.
        * cxxfilt.c (flags): Add DMGL_RECURSE_LIMIT.
        (long_options): Add --recurse-limit and --no-recurse-limit.
        (main): Handle new options.
        * dlltool.c (gen_def_file): Include DMGL_RECURSE_LIMIT in flags
        passed to cplus_demangle.
        * nm.c (demangle_flags): New static variable.
        (long_options): Add --recurse-limit and --no-recurse-limit.
        (main): Handle new options.
        * objdump.c (demangle_flags): New static variable.
        (usage): Add --recurse-limit and --no-recurse-limit.
        (long_options): Likewise.
        (objdump_print_symname): Pass demangle_flags to bfd_demangle.
        (disassemble_section): Likewise.
        (dump_dymbols): Likewise.
        (main): Handle new options.
        * prdbg.c (demangle_flags): New static variable.
        (tg_variable): Pass demangle_flags to demangler.
        (tg_start_function): Likewise.
        * stabs.c (demangle_flags): New static variable.
        (stab_demangle_template): Pass demangle_flags to demangler.
        (stab_demangle_v3_argtypes): Likewise.
        (stab_demangle_v3_arg): Likewise.
	* doc/binutuls.texi: Document new command line options.
	* NEWS: Mention the new feature.
        * testsuite/config/default.exp (CXXFILT): Define if not already
        defined.
        (CXXFILTFLAGS): Likewise.
        * testsuite/binutils-all/cxxfilt.exp: New file.  Runs a few
        simple tests of the cxxfilt program.

binutils/ChangeLog

@@ -1,3 +1,37 @@
+2018-12-07  Nick Clifton  <nickc@redhat.com>
+
+	* addr2line.c (demangle_flags): New static variable.
+        (long_options): Add --recurse-limit and --no-recurse-limit.
+        (translate_address): Pass demangle_flags to bfd_demangle.
+        (main): Handle --recurse-limit and --no-recurse-limit options.
+        * cxxfilt.c: (long_options): Add --recurse-limit and
+	--no-recurse-limit.
+        (main): Handle new options.
+        * nm.c (demangle_flags): New static variable.
+        (long_options): Add --recurse-limit and --no-recurse-limit.
+        (main): Handle new options.
+        * objdump.c (demangle_flags): New static variable.
+        (usage): Add --recurse-limit and --no-recurse-limit.
+        (long_options): Likewise.
+        (objdump_print_symname): Pass demangle_flags to bfd_demangle.
+        (disassemble_section): Likewise.
+        (dump_dymbols): Likewise.
+        (main): Handle new options.
+        * prdbg.c (demangle_flags): New static variable.
+        (tg_variable): Pass demangle_flags to demangler.
+        (tg_start_function): Likewise.
+        * stabs.c (demangle_flags): New static variable.
+        (stab_demangle_template): Pass demangle_flags to demangler.
+        (stab_demangle_v3_argtypes): Likewise.
+        (stab_demangle_v3_arg): Likewise.
+	* doc/binutuls.texi: Document new command line options.
+	* NEWS: Mention the new feature.
+        * testsuite/config/default.exp (CXXFILT): Define if not already
+        defined.
+        (CXXFILTFLAGS): Likewise.
+        * testsuite/binutils-all/cxxfilt.exp: New file.  Runs a few
+        simple tests of the cxxfilt program.
+
 2018-12-03  Nick Clifton  <nickc@redhat.com>
 
 	PR 23941

binutils/NEWS

@@ -1,5 +1,16 @@
 -*- text -*-
 
+* The addr2line, c++filt, nm and objdump tools now have a limit on the
+  maximum amount of recursion that is allowed whilst demangling strings.
+  The value for this limit is defined by the DEMANGLE_RECRUSE_LIMIT
+  constant declared in the include/demangle.h header file.  At the time
+  of writing this constant has the value of 1024.
+
+  The --no-recurse-limit option can be used to remove the limit, restoring
+  the behaviour of earlier versions of these tools.  This may be needed in
+  order to dmangle truly complicated names, but it also leaves the tools
+  vulnerable to stack exhaustion from maliciously constructed mangled names.
+
 * Objdump's --disassemble option can now take a parameter, specifying the
   starting symbol for disassembly.  Disassembly will continue from this
   symbol up to the next symbol.

binutils/addr2line.c

@@ -45,6 +45,9 @@ static bfd_boolean do_demangle;		/* -C, demangle names.  */
 static bfd_boolean pretty_print;	/* -p, print on one line.  */
 static bfd_boolean base_names;		/* -s, strip directory names.  */
 
+/* Flags passed to the name demangler.  */
+static int demangle_flags = DMGL_PARAMS | DMGL_ANSI;
+
 static int naddr;		/* Number of addresses to process.  */
 static char **addr;		/* Hex addresses to process.  */
 
@@ -59,6 +62,10 @@ static struct option long_options[] =
   {"functions", no_argument, NULL, 'f'},
   {"inlines", no_argument, NULL, 'i'},
   {"pretty-print", no_argument, NULL, 'p'},
+  {"recurse-limit", no_argument, NULL, 'R'},
+  {"recursion-limit", no_argument, NULL, 'R'},  
+  {"no-recurse-limit", no_argument, NULL, 'r'},
+  {"no-recursion-limit", no_argument, NULL, 'r'},  
   {"section", required_argument, NULL, 'j'},
   {"target", required_argument, NULL, 'b'},
   {"help", no_argument, NULL, 'H'},
@@ -91,6 +98,8 @@ usage (FILE *stream, int status)
   -s --basenames         Strip directory names\n\
   -f --functions         Show function names\n\
   -C --demangle[=style]  Demangle function names\n\
+  -R --recurse-limit     Enable a limit on recursion whilst demangling.  [Default]\n\
+  -r --no-recurse-limit  Disable a limit on recursion whilst demangling\n\
   -h --help              Display this information\n\
   -v --version           Display the program's version\n\
 \n"));
@@ -289,7 +298,7 @@ translate_addresses (bfd *abfd, asection *section)
                     name = "??";
                   else if (do_demangle)
                     {
-                      alloc = bfd_demangle (abfd, name, DMGL_ANSI | DMGL_PARAMS);
+                      alloc = bfd_demangle (abfd, name, demangle_flags);
                       if (alloc != NULL)
                         name = alloc;
                     }
@@ -442,7 +451,7 @@ main (int argc, char **argv)
   file_name = NULL;
   section_name = NULL;
   target = NULL;
-  while ((c = getopt_long (argc, argv, "ab:Ce:sfHhij:pVv", long_options, (int *) 0))
+  while ((c = getopt_long (argc, argv, "ab:Ce:rRsfHhij:pVv", long_options, (int *) 0))
 	 != EOF)
     {
       switch (c)
@@ -469,6 +478,12 @@ main (int argc, char **argv)
 	      cplus_demangle_set_style (style);
 	    }
 	  break;
+	case 'r':
+	  demangle_flags |= DMGL_NO_RECURSE_LIMIT;
+	  break;
+	case 'R':
+	  demangle_flags &= ~ DMGL_NO_RECURSE_LIMIT;
+	  break;
 	case 'e':
 	  file_name = optarg;
 	  break;

binutils/cxxfilt.c

@@ -42,6 +42,10 @@ static const struct option long_options[] =
   {"no-verbose", no_argument, NULL, 'i'},
   {"types", no_argument, NULL, 't'},
   {"version", no_argument, NULL, 'v'},
+  {"recurse-limit", no_argument, NULL, 'R'},
+  {"recursion-limit", no_argument, NULL, 'R'},
+  {"no-recurse-limit", no_argument, NULL, 'r'},
+  {"no-recursion-limit", no_argument, NULL, 'r'},
   {NULL, no_argument, NULL, 0}
 };
 
@@ -102,6 +106,8 @@ Options are:\n\
   fprintf (stream, "\
   [-p|--no-params]            Do not display function arguments\n\
   [-i|--no-verbose]           Do not show implementation details (if any)\n\
+  [-R|--recurse-limit]        Enable a limit on recursion whilst demangling.  [Default]\n\
+  ]-r|--no-recurse-limit]     Disable a limit on recursion whilst demangling\n\
   [-t|--types]                Also attempt to demangle type encodings\n\
   [-s|--format ");
   print_demangler_list (stream);
@@ -180,7 +186,7 @@ main (int argc, char **argv)
 
   expandargv (&argc, &argv);
 
-  while ((c = getopt_long (argc, argv, "_hinps:tv", long_options, (int *) 0)) != EOF)
+  while ((c = getopt_long (argc, argv, "_hinprRs:tv", long_options, (int *) 0)) != EOF)
     {
       switch (c)
 	{
@@ -195,6 +201,12 @@ main (int argc, char **argv)
 	case 'p':
 	  flags &= ~ DMGL_PARAMS;
 	  break;
+	case 'r':
+	  flags |= DMGL_NO_RECURSE_LIMIT;
+	  break;
+	case 'R':
+	  flags &= ~ DMGL_NO_RECURSE_LIMIT;
+	  break;
 	case 't':
 	  flags |= DMGL_TYPES;
 	  break;

binutils/doc/binutils.texi

@@ -769,7 +769,9 @@ nm [@option{-A}|@option{-o}|@option{--print-file-name}] [@option{-a}|@option{--d
    [@option{-s}|@option{--print-armap}] [@option{-t} @var{radix}|@option{--radix=}@var{radix}]
    [@option{-u}|@option{--undefined-only}] [@option{-V}|@option{--version}]
    [@option{-X 32_64}] [@option{--defined-only}] [@option{--no-demangle}]
-   [@option{--plugin} @var{name}] [@option{--size-sort}] [@option{--special-syms}]
+   [@option{--plugin} @var{name}]
+   [@option{--no-recurse-limit}|@option{--recurse-limit}]]
+   [@option{--size-sort}] [@option{--special-syms}]
    [@option{--synthetic}] [@option{--with-symbol-versions}] [@option{--target=}@var{bfdname}]
    [@var{objfile}@dots{}]
 @c man end
@@ -939,6 +941,22 @@ for more information on demangling.
 @item --no-demangle
 Do not demangle low-level symbol names.  This is the default.
 
+@item --recurse-limit
+@itemx --no-recurse-limit
+@itemx --recursion-limit
+@itemx --no-recursion-limit
+Enables or disables a limit on the amount of recursion performed
+whilst demangling strings.  Since the name mangling formats allow for
+an inifinite level of recursion it is possible to create strings whose
+decoding will exhaust the amount of stack space available on the host
+machine, triggering a memory fault.  The limit tries to prevent this
+from happening by restricting recursion to 1024 levels of nesting.
+
+The default is for this limit to be enabled, but disabling it may be
+necessary in order to demangle truly complicated names.  Note however
+that if the recursion limit is disabled then stack exhaustion is
+possible and any bug reports about such an event will be rejected.
+
 @item -D
 @itemx --dynamic
 @cindex dynamic symbols
@@ -2098,6 +2116,7 @@ objdump [@option{-a}|@option{--archive-headers}]
         [@option{--adjust-vma=}@var{offset}]
         [@option{--dwarf-depth=@var{n}}]
         [@option{--dwarf-start=@var{n}}]
+        [@option{--no-recurse-limit}|@option{--recurse-limit}]
         [@option{--special-syms}]
         [@option{--prefix=}@var{prefix}]
         [@option{--prefix-strip=}@var{level}]
@@ -2174,6 +2193,22 @@ mangling styles. The optional demangling style argument can be used to
 choose an appropriate demangling style for your compiler. @xref{c++filt},
 for more information on demangling.
 
+@item --recurse-limit
+@itemx --no-recurse-limit
+@itemx --recursion-limit
+@itemx --no-recursion-limit
+Enables or disables a limit on the amount of recursion performed
+whilst demangling strings.  Since the name mangling formats allow for
+an inifinite level of recursion it is possible to create strings whose
+decoding will exhaust the amount of stack space available on the host
+machine, triggering a memory fault.  The limit tries to prevent this
+from happening by restricting recursion to 1024 levels of nesting.
+
+The default is for this limit to be enabled, but disabling it may be
+necessary in order to demangle truly complicated names.  Note however
+that if the recursion limit is disabled then stack exhaustion is
+possible and any bug reports about such an event will be rejected.
+
 @item -g
 @itemx --debugging
 Display debugging information.  This attempts to parse STABS
@@ -3403,6 +3438,8 @@ c++filt [@option{-_}|@option{--strip-underscore}]
         [@option{-p}|@option{--no-params}]
         [@option{-t}|@option{--types}]
         [@option{-i}|@option{--no-verbose}]
+        [@option{-r}|@option{--no-recurse-limit}]
+        [@option{-R}|@option{--recurse-limit}]
         [@option{-s} @var{format}|@option{--format=}@var{format}]
         [@option{--help}]  [@option{--version}]  [@var{symbol}@dots{}]
 @c man end
@@ -3507,6 +3544,28 @@ demangled to ``signed char''.
 Do not include implementation details (if any) in the demangled
 output.
 
+@item -r
+@itemx -R
+@itemx --recurse-limit
+@itemx --no-recurse-limit
+@itemx --recursion-limit
+@itemx --no-recursion-limit
+Enables or disables a limit on the amount of recursion performed
+whilst demangling strings.  Since the name mangling formats allow for
+an inifinite level of recursion it is possible to create strings whose
+decoding will exhaust the amount of stack space available on the host
+machine, triggering a memory fault.  The limit tries to prevent this
+from happening by restricting recursion to 1024 levels of nesting.
+
+The default is for this limit to be enabled, but disabling it may be
+necessary in order to demangle truly complicated names.  Note however
+that if the recursion limit is disabled then stack exhaustion is
+possible and any bug reports about such an event will be rejected.
+
+The @option{-r} option is a synonym for the
+@option{--no-recurse-limit} option.  The @option{-R} option is a
+synonym for the @option{--recurse-limit} option.
+
 @item -s @var{format}
 @itemx --format=@var{format}
 @command{c++filt} can decode various methods of mangling, used by
@@ -3580,6 +3639,8 @@ c++filt @var{option} @var{symbol}
 addr2line [@option{-a}|@option{--addresses}]
           [@option{-b} @var{bfdname}|@option{--target=}@var{bfdname}]
           [@option{-C}|@option{--demangle}[=@var{style}]]
+          [@option{-r}|@option{--no-recurse-limit}]
+          [@option{-R}|@option{--recurse-limit}]
           [@option{-e} @var{filename}|@option{--exe=}@var{filename}]
           [@option{-f}|@option{--functions}] [@option{-s}|@option{--basename}]
           [@option{-i}|@option{--inlines}]
@@ -3705,6 +3766,32 @@ Read offsets relative to the specified section instead of absolute addresses.
 Make the output more human friendly: each location are printed on one line.
 If option @option{-i} is specified, lines for all enclosing scopes are
 prefixed with @samp{(inlined by)}.
+
+@item -r
+@itemx -R
+@itemx --recurse-limit
+@itemx --no-recurse-limit
+@itemx --recursion-limit
+@itemx --no-recursion-limit
+Enables or disables a limit on the amount of recursion performed
+whilst demangling strings.  Since the name mangling formats allow for
+an inifinite level of recursion it is possible to create strings whose
+decoding will exhaust the amount of stack space available on the host
+machine, triggering a memory fault.  The limit tries to prevent this
+from happening by restricting recursion to 1024 levels of nesting.
+
+The default is for this limit to be enabled, but disabling it may be
+necessary in order to demangle truly complicated names.  Note however
+that if the recursion limit is disabled then stack exhaustion is
+possible and any bug reports about such an event will be rejected.
+
+The @option{-r} option is a synonym for the
+@option{--no-recurse-limit} option.  The @option{-R} option is a
+synonym for the @option{--recurse-limit} option.
+
+Note this option is only effective if the @option{-C} or
+@option{--demangle} option has been enabled.
+
 @end table
 
 @c man end

binutils/nm.c

@@ -162,6 +162,8 @@ static int line_numbers = 0;	/* Print line numbers for symbols.  */
 static int allow_special_symbols = 0;  /* Allow special symbols.  */
 static int with_symbol_versions = 0; /* Include symbol version information in the output.  */
 
+static int demangle_flags = DMGL_ANSI | DMGL_PARAMS;
+
 /* When to print the names of files.  Not mutually exclusive in SYSV format.  */
 static int filename_per_file = 0;	/* Once per file, on its own line.  */
 static int filename_per_symbol = 0;	/* Once per symbol, at start of line.  */
@@ -194,9 +196,14 @@ static const char *plugin_target = NULL;
 static bfd *lineno_cache_bfd;
 static bfd *lineno_cache_rel_bfd;
 
-#define OPTION_TARGET 200
+enum long_option_values
-#define OPTION_PLUGIN (OPTION_TARGET + 1)
+{
-#define OPTION_SIZE_SORT (OPTION_PLUGIN + 1)
+  OPTION_TARGET = 200,
+  OPTION_PLUGIN,
+  OPTION_SIZE_SORT,
+  OPTION_RECURSE_LIMIT,
+  OPTION_NO_RECURSE_LIMIT
+};
 
 static struct option long_options[] =
 {
@@ -209,6 +216,8 @@ static struct option long_options[] =
   {"line-numbers", no_argument, 0, 'l'},
   {"no-cplus", no_argument, &do_demangle, 0},  /* Linux compatibility.  */
   {"no-demangle", no_argument, &do_demangle, 0},
+  {"no-recurse-limit", no_argument, NULL, OPTION_NO_RECURSE_LIMIT},
+  {"no-recursion-limit", no_argument, NULL, OPTION_NO_RECURSE_LIMIT},
   {"no-sort", no_argument, 0, 'p'},
   {"numeric-sort", no_argument, 0, 'n'},
   {"plugin", required_argument, 0, OPTION_PLUGIN},
@@ -217,6 +226,8 @@ static struct option long_options[] =
   {"print-file-name", no_argument, 0, 'o'},
   {"print-size", no_argument, 0, 'S'},
   {"radix", required_argument, 0, 't'},
+  {"recurse-limit", no_argument, NULL, OPTION_RECURSE_LIMIT},
+  {"recursion-limit", no_argument, NULL, OPTION_RECURSE_LIMIT},
   {"reverse-sort", no_argument, &reverse_sort, 1},
   {"size-sort", no_argument, 0, OPTION_SIZE_SORT},
   {"special-syms", no_argument, &allow_special_symbols, 1},
@@ -245,6 +256,8 @@ usage (FILE *stream, int status)
                           `gnu', `lucid', `arm', `hp', `edg', `gnu-v3', `java'\n\
                           or `gnat'\n\
       --no-demangle      Do not demangle low-level symbol names\n\
+      --recurse-limit    Enable a demangling recursion limit.  This is the default.\n\
+      --no-recurse-limit Disable a demangling recursion limit.\n\
   -D, --dynamic          Display dynamic symbols instead of normal symbols\n\
       --defined-only     Display only defined symbols\n\
   -e                     (ignored)\n\
@@ -407,7 +420,7 @@ print_symname (const char *form, const char *name, bfd *abfd)
 {
   if (do_demangle && *name)
     {
-      char *res = bfd_demangle (abfd, name, DMGL_ANSI | DMGL_PARAMS);
+      char *res = bfd_demangle (abfd, name, demangle_flags);
 
       if (res != NULL)
 	{
@@ -1687,6 +1700,12 @@ main (int argc, char **argv)
 	      cplus_demangle_set_style (style);
 	    }
 	  break;
+	case OPTION_RECURSE_LIMIT:
+	  demangle_flags &= ~ DMGL_NO_RECURSE_LIMIT;
+	  break;
+	case OPTION_NO_RECURSE_LIMIT:
+	  demangle_flags |= DMGL_NO_RECURSE_LIMIT;
+	  break;
 	case 'D':
 	  dynamic = 1;
 	  break;

binutils/objdump.c

@@ -120,6 +120,8 @@ static size_t prefix_length;
 static bfd_boolean unwind_inlines;	/* --inlines.  */
 static const char * disasm_sym;		/* Disassembly start symbol.  */
 
+static int demangle_flags = DMGL_ANSI | DMGL_PARAMS;
+
 /* A structure to record the sections mentioned in -j switches.  */
 struct only
 {
@@ -252,6 +254,8 @@ usage (FILE *stream, int status)
                                   The STYLE, if specified, can be `auto', `gnu',\n\
                                   `lucid', `arm', `hp', `edg', `gnu-v3', `java'\n\
                                   or `gnat'\n\
+      --recurse-limit            Enable a limit on recursion whilst demangling.  [Default]\n\
+      --no-recurse-limit         Disable a limit on recursion whilst demangling\n\
   -w, --wide                     Format output for more than 80 columns\n\
   -z, --disassemble-zeroes       Do not skip blocks of zeroes when disassembling\n\
       --start-address=ADDR       Only process data whose address is >= ADDR\n\
@@ -302,6 +306,8 @@ enum option_values
     OPTION_DWARF_DEPTH,
     OPTION_DWARF_CHECK,
     OPTION_DWARF_START,
+    OPTION_RECURSE_LIMIT,
+    OPTION_NO_RECURSE_LIMIT,
     OPTION_INLINES
   };
 
@@ -333,6 +339,10 @@ static struct option long_options[]=
   {"line-numbers", no_argument, NULL, 'l'},
   {"no-show-raw-insn", no_argument, &show_raw_insn, -1},
   {"prefix-addresses", no_argument, &prefix_addresses, 1},
+  {"recurse-limit", no_argument, NULL, OPTION_RECURSE_LIMIT},
+  {"recursion-limit", no_argument, NULL, OPTION_RECURSE_LIMIT},
+  {"no-recurse-limit", no_argument, NULL, OPTION_NO_RECURSE_LIMIT},
+  {"no-recursion-limit", no_argument, NULL, OPTION_NO_RECURSE_LIMIT},
   {"reloc", no_argument, NULL, 'r'},
   {"section", required_argument, NULL, 'j'},
   {"section-headers", no_argument, NULL, 'h'},
@@ -884,7 +894,7 @@ objdump_print_symname (bfd *abfd, struct disassemble_info *inf,
   if (do_demangle && name[0] != '\0')
     {
       /* Demangle the name.  */
-      alloc = bfd_demangle (abfd, name, DMGL_ANSI | DMGL_PARAMS);
+      alloc = bfd_demangle (abfd, name, demangle_flags);
       if (alloc != NULL)
 	name = alloc;
     }
@@ -2290,7 +2300,7 @@ disassemble_section (bfd *abfd, asection *section, void *inf)
 	  if (do_demangle && name[0] != '\0')
 	    {
 	      /* Demangle the name.  */
-	      alloc = bfd_demangle (abfd, name, DMGL_ANSI | DMGL_PARAMS);
+	      alloc = bfd_demangle (abfd, name, demangle_flags);
 	      if (alloc != NULL)
 		name = alloc;
 	    }
@@ -3268,7 +3278,7 @@ dump_symbols (bfd *abfd ATTRIBUTE_UNUSED, bfd_boolean dynamic)
 	      /* If we want to demangle the name, we demangle it
 		 here, and temporarily clobber it while calling
 		 bfd_print_symbol.  FIXME: This is a gross hack.  */
-	      alloc = bfd_demangle (cur_bfd, name, DMGL_ANSI | DMGL_PARAMS);
+	      alloc = bfd_demangle (cur_bfd, name, demangle_flags);
 	      if (alloc != NULL)
 		(*current)->name = alloc;
 	      bfd_print_symbol (cur_bfd, stdout, *current,
@@ -3927,6 +3937,12 @@ main (int argc, char **argv)
 	      cplus_demangle_set_style (style);
 	    }
 	  break;
+	case OPTION_RECURSE_LIMIT:
+	  demangle_flags &= ~ DMGL_NO_RECURSE_LIMIT;
+	  break;
+	case OPTION_NO_RECURSE_LIMIT:
+	  demangle_flags |= DMGL_NO_RECURSE_LIMIT;
+	  break;
 	case 'w':
 	  do_wide = wide_output = TRUE;
 	  break;

binutils/prdbg.c

@@ -286,6 +286,8 @@ static const struct debug_write_fns tg_fns =
   pr_end_function,		/* Same, does nothing.  */
   tg_lineno
 };
+
+static int demangle_flags = DMGL_ANSI | DMGL_PARAMS;
 
 /* Print out the generic debugging information recorded in dhandle.  */
 
@@ -2600,7 +2602,7 @@ tg_variable (void *p, const char *name, enum debug_var_kind kind,
 
   dname = NULL;
   if (info->demangler)
-    dname = info->demangler (info->abfd, name, DMGL_ANSI | DMGL_PARAMS);
+    dname = info->demangler (info->abfd, name, demangle_flags);
 
   from_class = NULL;
   if (dname != NULL)
@@ -2661,7 +2663,7 @@ tg_start_function (void *p, const char *name, bfd_boolean global)
 
   dname = NULL;
   if (info->demangler)
-    dname = info->demangler (info->abfd, name, DMGL_ANSI | DMGL_PARAMS);
+    dname = info->demangler (info->abfd, name, demangle_flags);
 
   if (! substitute_type (info, dname ? dname : name))
     return FALSE;

binutils/stabs.c

@@ -215,6 +215,8 @@ static debug_type stab_demangle_v3_arg
   (void *, struct stab_handle *, struct demangle_component *, debug_type,
    bfd_boolean *);
 
+static int demangle_flags = DMGL_ANSI;
+
 /* Save a string in memory.  */
 
 static char *
@@ -4517,7 +4519,7 @@ stab_demangle_template (struct stab_demangle_info *minfo, const char **pp,
 
       free (s1);
 
-      s3 = cplus_demangle (s2, DMGL_ANSI);
+      s3 = cplus_demangle (s2, demangle_flags);
 
       free (s2);
 
@@ -5243,7 +5245,7 @@ stab_demangle_v3_argtypes (void *dhandle, struct stab_handle *info,
   void *mem;
   debug_type *pargs;
 
-  dc = cplus_demangle_v3_components (physname, DMGL_PARAMS | DMGL_ANSI, &mem);
+  dc = cplus_demangle_v3_components (physname, DMGL_PARAMS | demangle_flags, &mem);
   if (dc == NULL)
     {
       stab_bad_demangle (physname);
@@ -5418,7 +5420,7 @@ stab_demangle_v3_arg (void *dhandle, struct stab_handle *info,
 	/* We print this component to get a class name which we can
 	   use.  FIXME: This probably won't work if the template uses
 	   template parameters which refer to an outer template.  */
-	p = cplus_demangle_print (DMGL_PARAMS | DMGL_ANSI, dc, 20, &alc);
+	p = cplus_demangle_print (DMGL_PARAMS | demangle_flags, dc, 20, &alc);
 	if (p == NULL)
 	  {
 	    fprintf (stderr, _("Failed to print demangled template\n"));
@@ -5498,7 +5500,7 @@ stab_demangle_v3_arg (void *dhandle, struct stab_handle *info,
 	/* We print this component in order to find out the type name.
 	   FIXME: Should we instead expose the
 	   demangle_builtin_type_info structure?  */
-	p = cplus_demangle_print (DMGL_PARAMS | DMGL_ANSI, dc, 20, &alc);
+	p = cplus_demangle_print (DMGL_PARAMS | demangle_flags, dc, 20, &alc);
 	if (p == NULL)
 	  {
 	    fprintf (stderr, _("Couldn't get demangled builtin type\n"));

binutils/testsuite/binutils-all/cxxfilt.exp

@@ -0,0 +1,44 @@
+#   Copyright (C) 2018 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+# 
+# This program 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 General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
+
+proc test_cxxfilt {options mangled_string demangled_string} {
+    global CXXFILT
+    global CXXFILTFLAGS
+    
+    set testname "cxxfilt: demangling $mangled_string"
+    set got [binutils_run $CXXFILT "$options $CXXFILTFLAGS $mangled_string"]
+
+    if ![regexp $demangled_string $got] then {
+	fail "$testname"
+	verbose 0 "expected: $demangled_string"
+	return
+    }
+
+    pass $testname
+}
+
+# Mangled and demangled strings stolen from libiberty/testsuite/demangle-expected.
+test_cxxfilt {} \
+    "AddAlignment__9ivTSolverUiP12ivInteractorP7ivTGlue" \
+    "ivTSolver::AddAlignment(unsigned int, ivInteractor ., ivTGlue .)*"
+
+test_cxxfilt {--format=lucid} \
+    "__ct__12strstreambufFPFl_PvPFPv_v" \
+    "strstreambuf..(strstreambuf|_ct)(void .(.)(long), void (.)(void .))*"
+
+test_cxxfilt {--no-recurse-limit} \
+    "Z3fooiPiPS_PS0_PS1_PS2_PS3_PS4_PS5_PS6_PS7_PS8_PS9_PSA_PSB_PSC_" \
+    "foo(int, int., int.., int..., int...., int....., int......, int......., int........, int........., int.........., int..........., int............, int............., int.............., int...............)*"

binutils/testsuite/config/default.exp

@@ -93,6 +93,12 @@ if ![info exists WINDRES] then {
 if ![info exists DLLTOOL] then {
     set DLLTOOL [findfile $base_dir/dlltool]
 }
+if ![info exists CXXFILT] then {
+    set CXXFILT [findfile $base_dir/cxxfilt]
+}
+if ![info exists CXXFILTFLAGS] then {
+    set CXXFILTFLAGS ""
+}
 
 if ![file isdirectory tmpdir] {catch "exec mkdir tmpdir" status}
 

include/ChangeLog

@@ -1,3 +1,8 @@
+2018-12-07  Nick Clifton  <nickc@redhat.com>
+
+	* demangle.h (DMGL_NO_RECURSE_LIMIT): Define.
+        (DEMANGLE_RECURSION_LIMIT): Define
+
 2018-12-06  Alan Modra  <amodra@gmail.com>
 
 	* opcode/ppc.h (E_OPCODE_MASK, E_LI_MASK, E_LI_INSN): Define.

include/demangle.h

@@ -68,6 +68,17 @@ extern "C" {
 /* If none of these are set, use 'current_demangling_style' as the default. */
 #define DMGL_STYLE_MASK (DMGL_AUTO|DMGL_GNU|DMGL_LUCID|DMGL_ARM|DMGL_HP|DMGL_EDG|DMGL_GNU_V3|DMGL_JAVA|DMGL_GNAT|DMGL_DLANG|DMGL_RUST)
 
+/* Disable a limit on the depth of recursion in mangled strings.
+   Note if this limit is disabled then stack exhaustion is possible when
+   demangling pathologically complicated strings.  Bug reports about stack
+   exhaustion when the option is enabled will be rejected.  */  
+#define DMGL_NO_RECURSE_LIMIT (1 << 18)	
+
+/* If DMGL_NO_RECURSE_LIMIT is not enabled, then this is the value used as
+   the maximum depth of recursion allowed.  It should be enough for any
+   real-world mangled name.  */
+#define DEMANGLE_RECURSION_LIMIT 1024
+  
 /* Enumeration of possible demangling styles.
 
    Lucid and ARM styles are still kept logically distinct, even though
@@ -392,6 +403,9 @@ enum demangle_component_type
      template argument, and the right subtree is either NULL or
      another TEMPLATE_ARGLIST node.  */
   DEMANGLE_COMPONENT_TEMPLATE_ARGLIST,
+  /* A template parameter object (C++20).  The left subtree is the
+     corresponding template argument.  */
+  DEMANGLE_COMPONENT_TPARM_OBJ,
   /* An initializer list.  The left subtree is either an explicit type or
      NULL, and the right subtree is a DEMANGLE_COMPONENT_ARGLIST.  */
   DEMANGLE_COMPONENT_INITIALIZER_LIST,

libiberty/ChangeLog

@@ -1,3 +1,68 @@
+2018-12-07  Nick Clifton  <nickc@redhat.com>
+
+	PR 87681
+	PR 87675
+	PR 87636
+	PR 87350
+	PR 87335
+	* cp-demangle.h (struct d_info): Add recursion_level field.
+	* cp-demangle.c (d_function_type): Add recursion counter.
+	If the recursion limit is reached and the check is not disabled,
+	then return with a failure result.
+	(cplus_demangle_init_info): Initialise the recursion_level field.
+        (d_demangle_callback): If the recursion limit is enabled, check
+	for a mangled string that is so long that there is not enough
+	stack space for the local arrays.
+        * cplus-dem.c (struct work): Add recursion_level field.
+	(squangle_mop_up): Set the numb and numk fields to zero.
+	(work_stuff_copy_to_from): Handle the case where a btypevec or
+	ktypevec field is NULL.
+	(demangle_nested_args): Add recursion counter.  If
+	the recursion limit is not disabled and reached, return with a
+	failure result.
+
+2018-10-23  Jason Merrill  <jason@redhat.com>
+
+	Implement P0732R2, class types in non-type template parameters.
+	* cp-demangle.c (d_dump, d_make_comp, d_count_templates_scopes)
+	(d_print_comp_inner): Handle DEMANGLE_COMPONENT_TPARM_OBJ.
+	(d_special_name): Handle TA.
+	(d_expresion_1): Fix demangling of brace-enclosed initializer list.
+
+2018-10-31  Joseph Myers  <joseph@codesourcery.com>
+
+	PR bootstrap/82856
+	Merge from binutils-gdb:
+	2018-06-19  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* configure.ac: Remove AC_PREREQ.
+	* configure: Re-generate.
+	* config.in: Re-generate.
+
+2018-10-01  Nathan Sidwell  <nathan@acm.org>
+
+	* configure.ac (checkfuncs): Add pipe2.
+	* config.in, configure: Rebuilt.
+	* pex-unix.c (pex_unix_exec_child): Comminicate errors from child
+	to parent with a pipe, when possible.
+
+2018-08-23  Nathan Sidwell  <nathan@acm.org>
+	    Martin Liska  <mliska@suse.cz>
+
+	PR driver/87056
+	* pex-unix.c (pex_unix_exec_child): Duplicate bad_fn into local
+	scopes to avoid potential clobber.
+
+2018-08-20  Nathan Sidwell  <nathan@acm.org>
+
+	* pex-unix.c (pex_child_error): Delete.
+	(pex_unix_exec_child): Commonize error paths to single message &
+	exit.
+
+2018-07-30  Tom Tromey  <tom@tromey.com>
+
+	* cplus-dem.c (remember_Btype): Don't call memcpy with LEN==0.
+
 2018-08-01  Richard Earnshaw  <rearnsha@arm.com>
 
 	Copy over from GCC

libiberty/config.in

@@ -195,6 +195,9 @@
 /* Define to 1 if you have the `on_exit' function. */
 #undef HAVE_ON_EXIT
 
+/* Define to 1 if you have the `pipe2' function. */
+#undef HAVE_PIPE2
+
 /* Define to 1 if you have the <process.h> header file. */
 #undef HAVE_PROCESS_H
 

libiberty/configure

@@ -5797,7 +5797,7 @@ funcs="$funcs setproctitle"
 vars="sys_errlist sys_nerr sys_siglist"
 
 checkfuncs="__fsetlocking canonicalize_file_name dup3 getrlimit getrusage \
- getsysinfo gettimeofday on_exit psignal pstat_getdynamic pstat_getstatic \
+ getsysinfo gettimeofday on_exit pipe2 psignal pstat_getdynamic pstat_getstatic \
  realpath setrlimit sbrk spawnve spawnvpe strerror strsignal sysconf sysctl \
  sysmp table times wait3 wait4"
 
@@ -5813,7 +5813,7 @@ if test "x" = "y"; then
     index insque \
     memchr memcmp memcpy memmem memmove memset mkstemps \
     on_exit \
-    psignal pstat_getdynamic pstat_getstatic putenv \
+    pipe2 psignal pstat_getdynamic pstat_getstatic putenv \
     random realpath rename rindex \
     sbrk setenv setproctitle setrlimit sigsetmask snprintf spawnve spawnvpe \
      stpcpy stpncpy strcasecmp strchr strdup \

libiberty/configure.ac

@@ -390,7 +390,7 @@ funcs="$funcs setproctitle"
 vars="sys_errlist sys_nerr sys_siglist"
 
 checkfuncs="__fsetlocking canonicalize_file_name dup3 getrlimit getrusage \
- getsysinfo gettimeofday on_exit psignal pstat_getdynamic pstat_getstatic \
+ getsysinfo gettimeofday on_exit pipe2 psignal pstat_getdynamic pstat_getstatic \
  realpath setrlimit sbrk spawnve spawnvpe strerror strsignal sysconf sysctl \
  sysmp table times wait3 wait4"
 
@@ -406,7 +406,7 @@ if test "x" = "y"; then
     index insque \
     memchr memcmp memcpy memmem memmove memset mkstemps \
     on_exit \
-    psignal pstat_getdynamic pstat_getstatic putenv \
+    pipe2 psignal pstat_getdynamic pstat_getstatic putenv \
     random realpath rename rindex \
     sbrk setenv setproctitle setrlimit sigsetmask snprintf spawnve spawnvpe \
      stpcpy stpncpy strcasecmp strchr strdup \

libiberty/cp-demangle.c

@@ -625,6 +625,9 @@ d_dump (struct demangle_component *dc, int indent)
     case DEMANGLE_COMPONENT_TEMPLATE_PARAM:
       printf ("template parameter %ld\n", dc->u.s_number.number);
       return;
+    case DEMANGLE_COMPONENT_TPARM_OBJ:
+      printf ("template parameter object\n");
+      break;
     case DEMANGLE_COMPONENT_FUNCTION_PARAM:
       printf ("function parameter %ld\n", dc->u.s_number.number);
       return;
@@ -1007,6 +1010,7 @@ d_make_comp (struct d_info *di, enum demangle_component_type type,
     case DEMANGLE_COMPONENT_GLOBAL_DESTRUCTORS:
     case DEMANGLE_COMPONENT_NULLARY:
     case DEMANGLE_COMPONENT_TRINARY_ARG2:
+    case DEMANGLE_COMPONENT_TPARM_OBJ:
       if (left == NULL)
 	return NULL;
       break;
@@ -2007,6 +2011,7 @@ d_java_resource (struct d_info *di)
                   ::= TT <type>
                   ::= TI <type>
                   ::= TS <type>
+		  ::= TA <template-arg>
                   ::= GV <(object) name>
                   ::= T <call-offset> <(base) encoding>
                   ::= Tc <call-offset> <call-offset> <(base) encoding>
@@ -2099,6 +2104,10 @@ d_special_name (struct d_info *di)
 	  return d_make_comp (di, DEMANGLE_COMPONENT_TLS_WRAPPER,
 			      d_name (di), NULL);
 
+	case 'A':
+	  return d_make_comp (di, DEMANGLE_COMPONENT_TPARM_OBJ,
+			      d_template_arg (di), NULL);
+
 	default:
 	  return NULL;
 	}
@@ -2843,10 +2852,20 @@ d_ref_qualifier (struct d_info *di, struct demangle_component *sub)
 static struct demangle_component *
 d_function_type (struct d_info *di)
 {
-  struct demangle_component *ret;
+  struct demangle_component *ret = NULL;
 
-  if (! d_check_char (di, 'F'))
+  if ((di->options & DMGL_NO_RECURSE_LIMIT) == 0)
+    {
+      if (di->recursion_level > DEMANGLE_RECURSION_LIMIT)
+	/* FIXME: There ought to be a way to report
+	   that the recursion limit has been reached.  */
 	return NULL;
+
+      di->recursion_level ++;
+    }
+
+  if (d_check_char (di, 'F'))
+    {
       if (d_peek_char (di) == 'Y')
 	{
 	  /* Function has C linkage.  We don't print this information.
@@ -2857,7 +2876,11 @@ d_function_type (struct d_info *di)
       ret = d_ref_qualifier (di, ret);
       
       if (! d_check_char (di, 'E'))
-    return NULL;
+	ret = NULL;
+    }
+
+  if ((di->options & DMGL_NO_RECURSE_LIMIT) == 0)
+    di->recursion_level --;
   return ret;
 }
 
@@ -3327,11 +3350,11 @@ d_expression_1 (struct d_info *di)
     {
       /* Brace-enclosed initializer list, untyped or typed.  */
       struct demangle_component *type = NULL;
+      d_advance (di, 2);
       if (peek == 't')
 	type = cplus_demangle_type (di);
       if (!d_peek_next_char (di))
 	return NULL;
-      d_advance (di, 2);
       return d_make_comp (di, DEMANGLE_COMPONENT_INITIALIZER_LIST,
 			  type, d_exprlist (di, 'E'));
     }
@@ -4101,6 +4124,7 @@ d_count_templates_scopes (int *num_templates, int *num_scopes,
     case DEMANGLE_COMPONENT_VECTOR_TYPE:
     case DEMANGLE_COMPONENT_ARGLIST:
     case DEMANGLE_COMPONENT_TEMPLATE_ARGLIST:
+    case DEMANGLE_COMPONENT_TPARM_OBJ:
     case DEMANGLE_COMPONENT_INITIALIZER_LIST:
     case DEMANGLE_COMPONENT_CAST:
     case DEMANGLE_COMPONENT_CONVERSION:
@@ -4872,6 +4896,11 @@ d_print_comp_inner (struct d_print_info *dpi, int options,
 	}
       return;
 
+    case DEMANGLE_COMPONENT_TPARM_OBJ:
+      d_append_string (dpi, "template parameter object for ");
+      d_print_comp (dpi, options, d_left (dc));
+      return;
+
     case DEMANGLE_COMPONENT_CTOR:
       d_print_comp (dpi, options, dc->u.s_ctor.name);
       return;
@@ -6188,6 +6217,7 @@ cplus_demangle_init_info (const char *mangled, int options, size_t len,
   di->expansion = 0;
   di->is_expression = 0;
   di->is_conversion = 0;
+  di->recursion_level = 0;
 }
 
 /* Internal implementation for the demangler.  If MANGLED is a g++ v3 ABI
@@ -6227,6 +6257,20 @@ d_demangle_callback (const char *mangled, int options,
 
   cplus_demangle_init_info (mangled, options, strlen (mangled), &di);
 
+  /* PR 87675 - Check for a mangled string that is so long
+     that we do not have enough stack space to demangle it.  */
+  if (((options & DMGL_NO_RECURSE_LIMIT) == 0)
+      /* This check is a bit arbitrary, since what we really want to do is to
+	 compare the sizes of the di.comps and di.subs arrays against the
+	 amount of stack space remaining.  But there is no portable way to do
+	 this, so instead we use the recursion limit as a guide to the maximum
+	 size of the arrays.  */
+      && (unsigned long) di.num_comps > DEMANGLE_RECURSION_LIMIT)
+    {
+      /* FIXME: We need a way to indicate that a stack limit has been reached.  */
+      return 0;
+    }
+
   {
 #ifdef CP_DYNAMIC_ARRAYS
     __extension__ struct demangle_component comps[di.num_comps];

libiberty/cp-demangle.h

@@ -122,6 +122,9 @@ struct d_info
   /* Non-zero if we are parsing the type operand of a conversion
      operator, but not when in an expression.  */
   int is_conversion;
+  /* If DMGL_NO_RECURSE_LIMIT is not active then this is set to
+     the current recursion level.  */
+  unsigned int recursion_level;
 };
 
 /* To avoid running past the ending '\0', don't:

libiberty/cplus-dem.c

@@ -146,6 +146,7 @@ struct work_stuff
   int *proctypevec;     /* Indices of currently processed remembered typevecs.  */
   int proctypevec_size;
   int nproctypes;
+  unsigned int recursion_level;
 };
 
 #define PRINT_ANSI_QUALIFIERS (work -> options & DMGL_ANSI)
@@ -1292,12 +1293,14 @@ squangle_mop_up (struct work_stuff *work)
       free ((char *) work -> btypevec);
       work->btypevec = NULL;
       work->bsize = 0;
+      work->numb = 0;
     }
   if (work -> ktypevec != NULL)
     {
       free ((char *) work -> ktypevec);
       work->ktypevec = NULL;
       work->ksize = 0;
+      work->numk = 0;
     }
 }
 
@@ -1331,8 +1334,15 @@ work_stuff_copy_to_from (struct work_stuff *to, struct work_stuff *from)
 
   for (i = 0; i < from->numk; i++)
     {
-      int len = strlen (from->ktypevec[i]) + 1;
+      int len;
 
+      if (from->ktypevec[i] == NULL)
+	{
+	  to->ktypevec[i] = NULL;
+	  continue;
+	}
+
+      len = strlen (from->ktypevec[i]) + 1;
       to->ktypevec[i] = XNEWVEC (char, len);
       memcpy (to->ktypevec[i], from->ktypevec[i], len);
     }
@@ -1342,8 +1352,15 @@ work_stuff_copy_to_from (struct work_stuff *to, struct work_stuff *from)
 
   for (i = 0; i < from->numb; i++)
     {
-      int len = strlen (from->btypevec[i]) + 1;
+      int len;
 
+      if (from->btypevec[i] == NULL)
+	{
+	  to->btypevec[i] = NULL;
+	  continue;
+	}
+
+      len = strlen (from->btypevec[i]) + 1;
       to->btypevec[i] = XNEWVEC (char , len);
       memcpy (to->btypevec[i], from->btypevec[i], len);
     }
@@ -1401,6 +1418,7 @@ delete_non_B_K_work_stuff (struct work_stuff *work)
 
       free ((char*) work->tmpl_argvec);
       work->tmpl_argvec = NULL;
+      work->ntmpl_args = 0;
     }
   if (work->previous_argument)
     {
@@ -4471,12 +4489,14 @@ remember_Btype (struct work_stuff *work, const char *start,
   char *tem;
 
   tem = XNEWVEC (char, len + 1);
+  if (len > 0)
     memcpy (tem, start, len);
   tem[len] = '\0';
   work -> btypevec[index] = tem;
 }
 
 /* Lose all the info related to B and K type codes. */
+
 static void
 forget_B_and_K_types (struct work_stuff *work)
 {
@@ -4502,6 +4522,7 @@ forget_B_and_K_types (struct work_stuff *work)
 	}
     }
 }
+
 /* Forget the remembered types, but not the type vector itself.  */
 
 static void
@@ -4696,6 +4717,16 @@ demangle_nested_args (struct work_stuff *work, const char **mangled,
   int result;
   int saved_nrepeats;
 
+  if ((work->options & DMGL_NO_RECURSE_LIMIT) == 0)
+    {
+      if (work->recursion_level > DEMANGLE_RECURSION_LIMIT)
+	/* FIXME: There ought to be a way to report
+	   that the recursion limit has been reached.  */
+	return 0;
+
+      work->recursion_level ++;
+    }
+
   /* The G++ name-mangling algorithm does not remember types on nested
      argument lists, unless -fsquangling is used, and in that case the
      type vector updated by remember_type is not used.  So, we turn
@@ -4722,6 +4753,9 @@ demangle_nested_args (struct work_stuff *work, const char **mangled,
   --work->forgetting_types;
   work->nrepeats = saved_nrepeats;
 
+  if ((work->options & DMGL_NO_RECURSE_LIMIT) == 0)
+    --work->recursion_level;
+
   return result;
 }
 

libiberty/pex-unix.c

@@ -298,8 +298,6 @@ pex_wait (struct pex_obj *obj, pid_t pid, int *status, struct pex_time *time)
 #endif /* ! defined (HAVE_WAITPID) */
 #endif /* ! defined (HAVE_WAIT4) */
 
-static void pex_child_error (struct pex_obj *, const char *, const char *, int)
-     ATTRIBUTE_NORETURN;
 static int pex_unix_open_read (struct pex_obj *, const char *, int);
 static int pex_unix_open_write (struct pex_obj *, const char *, int, int);
 static pid_t pex_unix_exec_child (struct pex_obj *, int, const char *,
@@ -366,28 +364,6 @@ pex_unix_close (struct pex_obj *obj ATTRIBUTE_UNUSED, int fd)
   return close (fd);
 }
 
-/* Report an error from a child process.  We don't use stdio routines,
-   because we might be here due to a vfork call.  */
-
-static void
-pex_child_error (struct pex_obj *obj, const char *executable,
-		 const char *errmsg, int err)
-{
-  int retval = 0;
-#define writeerr(s) retval |= (write (STDERR_FILE_NO, s, strlen (s)) < 0)
-  writeerr (obj->pname);
-  writeerr (": error trying to exec '");
-  writeerr (executable);
-  writeerr ("': ");
-  writeerr (errmsg);
-  writeerr (": ");
-  writeerr (xstrerror (err));
-  writeerr ("\n");
-#undef writeerr
-  /* Exit with -2 if the error output failed, too.  */
-  _exit (retval == 0 ? -1 : -2);
-}
-
 /* Execute a child.  */
 
 #if defined(HAVE_SPAWNVE) && defined(HAVE_SPAWNVPE)
@@ -592,21 +568,53 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
                      int in, int out, int errdes,
 		     int toclose, const char **errmsg, int *err)
 {
-  pid_t pid;
+  pid_t pid = -1;
+  /* Tuple to communicate error from child to parent.  We can safely
+     transfer string literal pointers as both run with identical
+     address mappings.  */
+  struct fn_err 
+  {
+    const char *fn;
+    int err;
+  };
+  volatile int do_pipe = 0;
+  volatile int pipes[2]; /* [0]:reader,[1]:writer.  */
+#ifdef O_CLOEXEC
+  do_pipe = 1;
+#endif
+  if (do_pipe)
+    {
+#ifdef HAVE_PIPE2
+      if (pipe2 ((int *)pipes, O_CLOEXEC))
+	do_pipe = 0;
+#else
+      if (pipe ((int *)pipes))
+	do_pipe = 0;
+      else
+	{
+	  if (fcntl (pipes[1], F_SETFD, FD_CLOEXEC) == -1)
+	    {
+	      close (pipes[0]);
+	      close (pipes[1]);
+	      do_pipe = 0;
+	    }
+	}
+#endif
+    }
 
   /* We declare these to be volatile to avoid warnings from gcc about
      them being clobbered by vfork.  */
-  volatile int sleep_interval;
+  volatile int sleep_interval = 1;
   volatile int retries;
 
   /* We vfork and then set environ in the child before calling execvp.
      This clobbers the parent's environ so we need to restore it.
      It would be nice to use one of the exec* functions that takes an
-     environment as a parameter, but that may have portability issues.  */
+     environment as a parameter, but that may have portability
-  char **save_environ = environ;
+     issues.  It is marked volatile so the child doesn't consider it a
+     dead variable and therefore clobber where ever it is stored.  */
+  char **volatile save_environ = environ;
 
-  sleep_interval = 1;
-  pid = -1;
   for (retries = 0; retries < 4; ++retries)
     {
       pid = vfork ();
@@ -619,104 +627,138 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
   switch (pid)
     {
     case -1:
+      if (do_pipe)
+	{
+	  close (pipes[0]);
+	  close (pipes[1]);
+	}
       *err = errno;
       *errmsg = VFORK_STRING;
       return (pid_t) -1;
 
     case 0:
       /* Child process.  */
-      if (in != STDIN_FILE_NO)
+      {
+	struct fn_err failed;
+	failed.fn = NULL;
+
+	if (do_pipe)
+	  close (pipes[0]);
+	if (!failed.fn && in != STDIN_FILE_NO)
 	  {
 	    if (dup2 (in, STDIN_FILE_NO) < 0)
-	    pex_child_error (obj, executable, "dup2", errno);
+	      failed.fn = "dup2", failed.err = errno;
-	  if (close (in) < 0)
+	    else if (close (in) < 0)
-	    pex_child_error (obj, executable, "close", errno);
+	      failed.fn = "close", failed.err = errno;
 	  }
-      if (out != STDOUT_FILE_NO)
+	if (!failed.fn && out != STDOUT_FILE_NO)
 	  {
 	    if (dup2 (out, STDOUT_FILE_NO) < 0)
-	    pex_child_error (obj, executable, "dup2", errno);
+	      failed.fn = "dup2", failed.err = errno;
-	  if (close (out) < 0)
+	    else if (close (out) < 0)
-	    pex_child_error (obj, executable, "close", errno);
+	      failed.fn = "close", failed.err = errno;
 	  }
-      if (errdes != STDERR_FILE_NO)
+	if (!failed.fn && errdes != STDERR_FILE_NO)
 	  {
 	    if (dup2 (errdes, STDERR_FILE_NO) < 0)
-	    pex_child_error (obj, executable, "dup2", errno);
+	      failed.fn = "dup2", failed.err = errno;
-	  if (close (errdes) < 0)
+	    else if (close (errdes) < 0)
-	    pex_child_error (obj, executable, "close", errno);
+	      failed.fn = "close", failed.err = errno;
 	  }
-      if (toclose >= 0)
+	if (!failed.fn && toclose >= 0)
 	  {
 	    if (close (toclose) < 0)
-	    pex_child_error (obj, executable, "close", errno);
+	      failed.fn = "close", failed.err = errno;
 	  }
-      if ((flags & PEX_STDERR_TO_STDOUT) != 0)
+	if (!failed.fn && (flags & PEX_STDERR_TO_STDOUT) != 0)
 	  {
 	    if (dup2 (STDOUT_FILE_NO, STDERR_FILE_NO) < 0)
-	    pex_child_error (obj, executable, "dup2", errno);
+	      failed.fn = "dup2", failed.err = errno;
 	  }
-
+	if (!failed.fn)
-      if (env)
 	  {
-	  /* NOTE: In a standard vfork implementation this clobbers the
+	    if (env)
-	     parent's copy of environ "too" (in reality there's only one copy).
+	      /* NOTE: In a standard vfork implementation this clobbers
-	     This is ok as we restore it below.  */
+		 the parent's copy of environ "too" (in reality there's
+		 only one copy).  This is ok as we restore it below.  */
 	      environ = (char**) env;
-	}
-
 	    if ((flags & PEX_SEARCH) != 0)
 	      {
 		execvp (executable, to_ptr32 (argv));
-	  pex_child_error (obj, executable, "execvp", errno);
+		failed.fn = "execvp", failed.err = errno;
 	      }
 	    else
 	      {
 		execv (executable, to_ptr32 (argv));
-	  pex_child_error (obj, executable, "execv", errno);
+		failed.fn = "execv", failed.err = errno;
+	      }
 	  }
 
+	/* Something failed, report an error.  We don't use stdio
+	   routines, because we might be here due to a vfork call.  */
+	ssize_t retval = 0;
+
+	if (!do_pipe
+	    || write (pipes[1], &failed, sizeof (failed)) != sizeof (failed))
+	  {
+	    /* The parent will not see our scream above, so write to
+	       stdout.  */
+#define writeerr(s) (retval |= write (STDERR_FILE_NO, s, strlen (s)))
+	    writeerr (obj->pname);
+	    writeerr (": error trying to exec '");
+	    writeerr (executable);
+	    writeerr ("': ");
+	    writeerr (failed.fn);
+	    writeerr (": ");
+	    writeerr (xstrerror (failed.err));
+	    writeerr ("\n");
+#undef writeerr
+	  }
+
+	/* Exit with -2 if the error output failed, too.  */
+	_exit (retval < 0 ? -2 : -1);
+      }
       /* NOTREACHED */
       return (pid_t) -1;
 
     default:
       /* Parent process.  */
-
+      {
-      /* Restore environ.
+	/* Restore environ.  Note that the parent either doesn't run
-	 Note that the parent either doesn't run until the child execs/exits
+	   until the child execs/exits (standard vfork behaviour), or
-	 (standard vfork behaviour), or if it does run then vfork is behaving
+	   if it does run then vfork is behaving more like fork.  In
-	 more like fork.  In either case we needn't worry about clobbering
+	   either case we needn't worry about clobbering the child's
-	 the child's copy of environ.  */
+	   copy of environ.  */
 	environ = save_environ;
 
-      if (in != STDIN_FILE_NO)
+	struct fn_err failed;
+	failed.fn = NULL;
+	if (do_pipe)
 	  {
-	  if (close (in) < 0)
+	    close (pipes[1]);
-	    {
+	    ssize_t len = read (pipes[0], &failed, sizeof (failed));
-	      *err = errno;
+	    if (len < 0)
-	      *errmsg = "close";
+	      failed.fn = NULL;
-	      return (pid_t) -1;
+	    close (pipes[0]);
-	    }
-	}
-      if (out != STDOUT_FILE_NO)
-	{
-	  if (close (out) < 0)
-	    {
-	      *err = errno;
-	      *errmsg = "close";
-	      return (pid_t) -1;
-	    }
-	}
-      if (errdes != STDERR_FILE_NO)
-	{
-	  if (close (errdes) < 0)
-	    {
-	      *err = errno;
-	      *errmsg = "close";
-	      return (pid_t) -1;
-	    }
 	  }
 
+	if (!failed.fn && in != STDIN_FILE_NO)
+	  if (close (in) < 0)
+	    failed.fn = "close", failed.err = errno;
+	if (!failed.fn && out != STDOUT_FILE_NO)
+	  if (close (out) < 0)
+	    failed.fn = "close", failed.err = errno;
+	if (!failed.fn && errdes != STDERR_FILE_NO)
+	  if (close (errdes) < 0)
+	    failed.fn = "close", failed.err = errno;
+
+	if (failed.fn)
+	  {
+	    *err = failed.err;
+	    *errmsg = failed.fn;
+	    return (pid_t) -1;
+	  }
+      }
       return pid;
     }
 }