Add helper binary `exec1'

* .gitignore: New files.
* Makefile.in (mostlyclean_dirs): Add libexec, if its Makefile
exists.
* autogen.sh (do_git): Autoreconf in exec as well.
* configure.ac: Configure libexec on Android.
* exec/Makefile.in:
* exec/README:
* exec/config-mips.m4.in:
* exec/config.guess:
* exec/config.h.in:
* exec/config.sub:
* exec/configure:
* exec/configure.ac:
* exec/deps.mk:
* exec/exec.c (MIN, struct exec_open_command)
(struct exec_map_command, struct exec_jump_command)
(write_open_command, write_load_command, process_interpreter_1)
(process_interpreter, process_program_header, insert_args)
(exec_0):
* exec/exec.h (_EXEC_H_, struct elf_header_32)
(struct program_header_32, struct dt_entry_32)
(struct elf_header_64, struct program_header_64)
(struct dt_entry_64, struct exec_tracee):
* exec/exec1.c (main):
* exec/install-sh (scriptversion):
* exec/loader-aarch64.s (_start):
* exec/loader-armeabi.s (_start):
* exec/loader-mips64el.s (__start):
* exec/loader-mipsel.s (__start):
* exec/loader-x86.s (_start):
* exec/loader-x86_64.s (_start):
* exec/mipsel-user.h (_MIPSEL_USER_H_):
* exec/mipsfpu.c (MIPS_ABI_FP_ANY, fpu_reqs, valid_abi_p)
(fp_mode_for_abi, cpu_supports_fr0_p, determine_fpu_mode):
* exec/mipsfpu.h (_MIPSFPU_H_, FP_FR0):
* exec/test.c (print_usage, main):
* exec/trace.c (MAX_TRACEES, aarch64_set_regs, read_memory)
(user_alloca, user_copy, remove_tracee, handle_clone)
(syscall_trap_p, handle_exec, process_system_call, tracing_execve)
(after_fork, find_tracee, exec_waitpid, exec_init): New files.
* java/Makefile.in (CROSS_EXEC_BINS): Add exec1 and
loader.
($(CROSS_EXEC_BINS) &): New target.

exec/exec.h

@@ -0,0 +1,192 @@
+/* Program execution for Emacs.
+
+Copyright (C) 2023 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs 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.
+
+GNU Emacs 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 GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
+
+
+
+#ifndef _EXEC_H_
+#define _EXEC_H_
+
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#endif /* HAVE_STDINT_H */
+
+#include <sys/types.h>
+
+#include USER_HEADER
+
+/* Define a replacement for `uint64_t' if it's not present in the C
+   library.  */
+
+#ifndef UINT64_MAX
+
+typedef struct
+{
+  uint32_t word1;
+  uint32_t word2;
+} xint64_t;
+
+#else /* UINT64_MAX */
+typedef uint64_t xint64_t;
+#endif /* !UINT64_MAX */
+
+
+
+/* 32-bit ELF headers.  */
+
+struct elf_header_32
+{
+  unsigned char e_ident[16];
+  uint16_t      e_type;
+  uint16_t      e_machine;
+  uint32_t      e_version;
+  uint32_t      e_entry;
+  uint32_t      e_phoff;
+  uint32_t      e_shoff;
+  uint32_t      e_flags;
+  uint16_t      e_ehsize;
+  uint16_t      e_phentsize;
+  uint16_t      e_phnum;
+  uint16_t      e_shentsize;
+  uint16_t      e_shnum;
+  uint16_t      e_shstrndx;
+};
+
+struct program_header_32
+{
+  uint32_t p_type;
+  uint32_t p_offset;
+  uint32_t p_vaddr;
+  uint32_t p_paddr;
+  uint32_t p_filesz;
+  uint32_t p_memsz;
+  uint32_t p_flags;
+  uint32_t p_align;
+};
+
+struct dt_entry_32
+{
+  uint32_t d_tag;
+  uint32_t d_val;
+};
+
+
+
+struct elf_header_64
+{
+  unsigned char e_ident[16];
+  uint16_t      e_type;
+  uint16_t      e_machine;
+  uint32_t      e_version;
+  xint64_t      e_entry;
+  xint64_t      e_phoff;
+  xint64_t      e_shoff;
+  uint32_t      e_flags;
+  uint16_t      e_ehsize;
+  uint16_t      e_phentsize;
+  uint16_t      e_phnum;
+  uint16_t      e_shentsize;
+  uint16_t      e_shnum;
+  uint16_t      e_shstrndx;
+};
+
+struct program_header_64
+{
+  uint32_t p_type;
+  uint32_t p_flags;
+  xint64_t p_offset;
+  xint64_t p_vaddr;
+  xint64_t p_paddr;
+  xint64_t p_filesz;
+  xint64_t p_memsz;
+  xint64_t p_align;
+};
+
+struct dt_entry_64
+{
+  xint64_t d_tag;
+  xint64_t d_val;
+};
+
+
+
+/* Define some types to the correct values.  */
+
+#ifdef EXEC_64
+typedef struct elf_header_64 elf_header;
+typedef struct program_header_64 program_header;
+typedef struct dt_entry_64 dt_entry;
+#else /* !EXEC_64 */
+typedef struct elf_header_32 elf_header;
+typedef struct program_header_32 program_header;
+typedef struct dt_entry_32 dt_entry;
+#endif /* EXEC_64 */
+
+
+
+/* Defined in trace.c.  */
+
+/* Structure describing a process being traced.  */
+
+struct exec_tracee
+{
+  /* The next process being traced.  */
+  struct exec_tracee *next;
+
+  /* The thread ID of this process.  */
+  pid_t pid;
+
+  /* Whether or not the tracee is currently waiting for a system call
+     to complete.  */
+  bool waiting_for_syscall;
+};
+
+
+
+#ifdef __aarch64__
+
+extern int aarch64_get_regs (pid_t, USER_REGS_STRUCT *);
+extern int aarch64_set_regs (pid_t, USER_REGS_STRUCT *, bool);
+
+#endif /* __aarch64__ */
+
+
+
+extern USER_WORD user_alloca (struct exec_tracee *, USER_REGS_STRUCT *,
+			      USER_REGS_STRUCT *, USER_WORD);
+extern int user_copy (struct exec_tracee *, const unsigned char *,
+		      USER_WORD, USER_WORD);
+extern void exec_init (const char *);
+
+
+
+extern int tracing_execve (const char *, char *const *,
+			   char *const *);
+extern int after_fork (pid_t);
+extern pid_t exec_waitpid (pid_t, int *, int);
+
+
+
+/* Defined in exec.c.  */
+
+extern char *exec_0 (const char *, struct exec_tracee *,
+		     size_t *, USER_REGS_STRUCT *);
+
+
+
+#endif /* _EXEC_H_ */