bug#53136: 28.0.90; segfault in lock_file

[Paul Eggert <eggert@cs.ucla.edu>]

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On 1/11/22 19:04, Po Lu wrote:
> (lock-file "~/any/nonexistent/file/with/a/very/long/path")

Unfortunately I'm still not reproducing the problem on Fedora 35 x86-64. 
Here's how I tried to reproduce it, while in the src directory:

  valgrind --suppressions=valgrind.supp ./emacs -Q -batch -eval '
    (let ((f "/d"))
      (dotimes (i 13) (setq f (concat f f)))
      (lock-file f))
  '

I configured Emacs this way:

./configure --enable-checking

(in general this is needed if you want to use Valgrind), and used the 
attached valgrind.supp.

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# valgrind suppression file
# Usage:
#    valgrind --suppressions=valgrind.supp ./temacs

# Conservative garbage collection inherently looks at uninitialized values,
# and garbage_collect and its callees all depend on this.
# It's hard to separate out exactly which callees need to be listed here,
# since the C compiler can inline them.  Also, valgrind doesn't care
# about the use of uninitialized variables directly, only when their values
# are eventually used.  So just list garbage_collect and its callees.
{
   garbage_collect Cond - conservative garbage collection
   Memcheck:Cond
   ...
   fun:garbage_collect
}
{
   garbage_collect Value8 - conservative garbage collection
   Memcheck:Value8
   ...
   fun:garbage_collect
}
# valgrind only looks at the last few callees on the stack, but
# mark_object can call itself recursively and deeply.  So list
# it too, in case garbage_collect is a long way from the stack top.
{
   mark_object Cond - conservative garbage collection
   Memcheck:Cond
   ...
   fun:mark_object
}
{
   mark_object Value8 - conservative garbage collection
   Memcheck:Value8
   ...
   fun:mark_object
}
# valgrind gets confused about mark_stack and loses its caller
{
   mark_stack Value8 - conservative garbage collection
   Memcheck:Value8
   ...
   fun:mark_stack
}

# On a circa-2017 x86-64 GNU/Linux platform, memmove falsely warns
# about overlapping moves.
{
   memmove false alarm about overlap
   Memcheck:Overlap
   ...
   fun:memmove
}

# On one circa-2011 x86-64 GNU/Linux platform, strlen is inlined to
# something that loads 4 bytes at a time.
#{
#   init_buffer optimized strlen
#   Memcheck:Addr4
#   fun:init_buffer
#}