* exec/configure.ac (USER_SWORD): New macro.
* exec/exec.c (format_pid): Export this function.
* exec/exec.h:
* exec/trace.c (canon_path): New function.
(handle_readlinkat, handle_openat): Test complete file name
against /proc/self/exe, and further check for /proc/pid/exe.
* exec/configure.ac (OPEN_SYSCALL, OPENAT_SYSCALL): Define new
macros.
* exec/exec.h (struct exec_tracee): New field `sp'.
* exec/trace.c (handle_openat): New function.
(process_system_call): If handle_openat executes successfully,
save the unmodified stack pointer within the tracee structure to
be restored once the system call completes.
* exec/trace.c (process_system_call) <READLINKAT_SYSCALL>:
Examine tracee->waiting_for_syscall and avoid rewriting user
arguments if a system call is presently being executed by the
kernel. Reported by Romário Rios <romariorios@protonmail.com>.
* exec/exec.h (struct exec_tracee): New field `new_child'.
Also, make `waiting_for_syscall' a bitfield.
* exec/trace.c (PTRACE_GETEVENTMSG): New declaration.
(MAX_TRACEES): Bump to 4096.
(handle_clone_prepare): New function.
(handle_clone): If required, set `new_child' and wait for a
ptrace event describing the parent to arrive.
(after_fork): Clear new field.
(exec_waitpid): Upon a ptrace event describing a clone, create
the child's tracee if it doesn't already exist. Otherwise, copy
over the parent's cmdline and start running it.
* exec/trace.c (check_signal): New function.
(handle_exec, process_system_call): Handle signal-delivery-stop
while waiting synchronously for syscall completion.
* exec/config.h.in: Autoheader.
* exec/configure.ac: Check for siginfo_t.si_syscall.
* exec/trace.c (exec_waitpid): If SIGSYS is received, and caused by
seccomp, drop it should the call number be the invalid system call
used by Emacs.
* exec/config.h.in: Autoheader.
* exec/configure.ac: Use system extensions.
(HAVE_PROCESS_VM): Define if process_vm_readv and
process_vm_writev are available.
* exec/trace.c (read_memory, user_copy): Implement in terms of
process_vm if possible.
* exec/config.h.in (__bool_true_false_are_defined):
* exec/configure.ac (REENTRANT): New definition.
(READLINKAT_SYSCALL, READLINK_SYSCALL): New defines. Set on all
hosts.
* exec/exec.c (MIN, MAX): Remove redundant declarations. Move
to config.h.
(exec_0): Copy name of executable into NAME when !REENTRANT.
* exec/exec.h (struct exec_tracee): New struct `exec_file'.
* exec/trace.c (remove_tracee, handle_exec, handle_readlinkat)
(process_system_call, after_fork): Handle readlinkat system
calls.
