612 lines
15 KiB
C
612 lines
15 KiB
C
/* Dump an executable file.
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Copyright (C) 1985-1988, 1999, 2001-2024 Free Software Foundation,
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Inc.
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This file is part of GNU Emacs.
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GNU Emacs is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at
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your option) any later version.
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GNU Emacs is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
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/*
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In other words, you are welcome to use, share and improve this program.
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You are forbidden to forbid anyone else to use, share and improve
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what you give them. Help stamp out software-hoarding! */
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/* Originally based on the COFF unexec.c by Spencer W. Thomas.
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*
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* Subsequently hacked on by
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* Bill Mann <Bill_Man@praxisint.com>
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* Andrew Vignaux <Andrew.Vignaux@comp.vuw.ac.nz>
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* Mike Sperber <sperber@informatik.uni-tuebingen.de>
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*
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* Synopsis:
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* unexec (const char *new_name, const *old_name);
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*
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* Takes a snapshot of the program and makes an a.out format file in the
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* file named by the string argument new_name.
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* If a_name is non-NULL, the symbol table will be taken from the given file.
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* On some machines, an existing a_name file is required.
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*
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*/
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#include <config.h>
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#include "unexec.h"
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#include "lisp.h"
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#define PERROR(file) report_error (file, new)
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#include <a.out.h>
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/* Define getpagesize () if the system does not.
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Note that this may depend on symbols defined in a.out.h
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*/
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#include "getpagesize.h"
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#include <sys/types.h>
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#include <inttypes.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <errno.h>
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#include <unistd.h>
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#include <fcntl.h>
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extern char _data[];
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extern char _text[];
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#include <filehdr.h>
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#include <aouthdr.h>
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#include <scnhdr.h>
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#include <syms.h>
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static struct filehdr f_hdr; /* File header */
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static struct aouthdr f_ohdr; /* Optional file header (a.out) */
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static off_t bias; /* Bias to add for growth */
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static off_t lnnoptr; /* Pointer to line-number info within file */
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static off_t text_scnptr;
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static off_t data_scnptr;
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#define ALIGN(val, pwr) (((val) + ((1L<<(pwr))-1)) & ~((1L<<(pwr))-1))
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static off_t load_scnptr;
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static off_t orig_load_scnptr;
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static off_t orig_data_scnptr;
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static int unrelocate_symbols (int, int, const char *, const char *);
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#ifndef MAX_SECTIONS
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#define MAX_SECTIONS 10
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#endif
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static int adjust_lnnoptrs (int, int, const char *);
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static int pagemask;
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#include "lisp.h"
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static _Noreturn void
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report_error (const char *file, int fd)
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{
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int err = errno;
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if (fd)
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emacs_close (fd);
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report_file_errno ("Cannot unexec", build_string (file), err);
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}
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#define ERROR0(msg) report_error_1 (new, msg)
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#define ERROR1(msg,x) report_error_1 (new, msg, x)
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#define ERROR2(msg,x,y) report_error_1 (new, msg, x, y)
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static _Noreturn void ATTRIBUTE_FORMAT_PRINTF (2, 3)
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report_error_1 (int fd, const char *msg, ...)
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{
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va_list ap;
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emacs_close (fd);
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va_start (ap, msg);
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verror (msg, ap);
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va_end (ap);
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}
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static int make_hdr (int, int, const char *, const char *);
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static void mark_x (const char *);
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static int copy_text_and_data (int);
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static int copy_sym (int, int, const char *, const char *);
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static void write_segment (int, char *, char *);
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/* ****************************************************************
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* unexec
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*
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* driving logic.
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*/
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void
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unexec (const char *new_name, const char *a_name)
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{
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int new = -1, a_out = -1;
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if (a_name && (a_out = emacs_open (a_name, O_RDONLY, 0)) < 0)
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{
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PERROR (a_name);
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}
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if ((new = emacs_open (new_name, O_WRONLY | O_CREAT | O_TRUNC, 0777)) < 0)
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{
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PERROR (new_name);
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}
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if (make_hdr (new, a_out,
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a_name, new_name) < 0
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|| copy_text_and_data (new) < 0
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|| copy_sym (new, a_out, a_name, new_name) < 0
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|| adjust_lnnoptrs (new, a_out, new_name) < 0
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|| unrelocate_symbols (new, a_out, a_name, new_name) < 0)
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{
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emacs_close (new);
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return;
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}
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emacs_close (new);
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if (a_out >= 0)
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emacs_close (a_out);
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}
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/* ****************************************************************
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* make_hdr
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*
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* Make the header in the new a.out from the header in core.
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* Modify the text and data sizes.
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*/
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static int
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make_hdr (int new, int a_out,
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const char *a_name, const char *new_name)
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{
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int scns;
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uintptr_t bss_start;
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uintptr_t data_start;
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struct scnhdr section[MAX_SECTIONS];
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struct scnhdr * f_thdr; /* Text section header */
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struct scnhdr * f_dhdr; /* Data section header */
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struct scnhdr * f_bhdr; /* Bss section header */
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struct scnhdr * f_lhdr; /* Loader section header */
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struct scnhdr * f_tchdr; /* Typechk section header */
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struct scnhdr * f_dbhdr; /* Debug section header */
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struct scnhdr * f_xhdr; /* Except section header */
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load_scnptr = orig_load_scnptr = lnnoptr = 0;
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pagemask = getpagesize () - 1;
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/* Adjust text/data boundary. */
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data_start = (uintptr_t) _data;
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data_start = data_start & ~pagemask; /* (Down) to page boundary. */
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bss_start = (uintptr_t) sbrk (0) + pagemask;
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bss_start &= ~ pagemask;
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if (data_start > bss_start) /* Can't have negative data size. */
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{
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ERROR2 (("unexec: data_start (0x%"PRIxPTR
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") can't be greater than bss_start (0x%"PRIxPTR")"),
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data_start, bss_start);
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}
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/* Salvage as much info from the existing file as possible */
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f_thdr = NULL; f_dhdr = NULL; f_bhdr = NULL;
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f_lhdr = NULL; f_tchdr = NULL; f_dbhdr = NULL; f_xhdr = NULL;
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if (a_out >= 0)
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{
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if (read (a_out, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
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{
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PERROR (a_name);
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}
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if (f_hdr.f_opthdr > 0)
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{
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if (read (a_out, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
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{
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PERROR (a_name);
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}
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}
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if (f_hdr.f_nscns > MAX_SECTIONS)
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{
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ERROR0 ("unexec: too many section headers -- increase MAX_SECTIONS");
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}
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/* Loop through section headers */
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for (scns = 0; scns < f_hdr.f_nscns; scns++) {
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struct scnhdr *s = §ion[scns];
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if (read (a_out, s, sizeof (*s)) != sizeof (*s))
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{
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PERROR (a_name);
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}
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#define CHECK_SCNHDR(ptr, name, flags) \
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if (strcmp (s->s_name, name) == 0) { \
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if (s->s_flags != flags) { \
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fprintf (stderr, "unexec: %lx flags where %x expected in %s section.\n", \
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(unsigned long)s->s_flags, flags, name); \
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} \
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if (ptr) { \
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fprintf (stderr, "unexec: duplicate section header for section %s.\n", \
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name); \
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} \
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ptr = s; \
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}
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CHECK_SCNHDR (f_thdr, _TEXT, STYP_TEXT);
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CHECK_SCNHDR (f_dhdr, _DATA, STYP_DATA);
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CHECK_SCNHDR (f_bhdr, _BSS, STYP_BSS);
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CHECK_SCNHDR (f_lhdr, _LOADER, STYP_LOADER);
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CHECK_SCNHDR (f_dbhdr, _DEBUG, STYP_DEBUG);
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CHECK_SCNHDR (f_tchdr, _TYPCHK, STYP_TYPCHK);
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CHECK_SCNHDR (f_xhdr, _EXCEPT, STYP_EXCEPT);
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}
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if (f_thdr == 0)
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{
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ERROR1 ("unexec: couldn't find \"%s\" section", _TEXT);
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}
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if (f_dhdr == 0)
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{
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ERROR1 ("unexec: couldn't find \"%s\" section", _DATA);
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}
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if (f_bhdr == 0)
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{
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ERROR1 ("unexec: couldn't find \"%s\" section", _BSS);
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}
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}
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else
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{
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ERROR0 ("can't build a COFF file from scratch yet");
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}
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orig_data_scnptr = f_dhdr->s_scnptr;
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orig_load_scnptr = f_lhdr ? f_lhdr->s_scnptr : 0;
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/* Now we alter the contents of all the f_*hdr variables
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to correspond to what we want to dump. */
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/* Indicate that the reloc information is no longer valid for ld (bind);
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we only update it enough to fake out the exec-time loader. */
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f_hdr.f_flags |= (F_RELFLG | F_EXEC);
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f_ohdr.dsize = bss_start - f_ohdr.data_start;
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f_ohdr.bsize = 0;
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f_dhdr->s_size = f_ohdr.dsize;
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f_bhdr->s_size = f_ohdr.bsize;
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f_bhdr->s_paddr = f_ohdr.data_start + f_ohdr.dsize;
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f_bhdr->s_vaddr = f_ohdr.data_start + f_ohdr.dsize;
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/* fix scnptr's */
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{
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off_t ptr = section[0].s_scnptr;
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bias = -1;
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for (scns = 0; scns < f_hdr.f_nscns; scns++)
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{
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struct scnhdr *s = §ion[scns];
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if (s->s_flags & STYP_PAD) /* .pad sections omitted in AIX 4.1 */
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{
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/*
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* the text_start should probably be o_algntext but that doesn't
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* seem to change
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*/
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if (f_ohdr.text_start != 0) /* && scns != 0 */
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{
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s->s_size = 512 - (ptr % 512);
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if (s->s_size == 512)
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s->s_size = 0;
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}
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s->s_scnptr = ptr;
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}
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else if (s->s_flags & STYP_DATA)
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s->s_scnptr = ptr;
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else if (!(s->s_flags & (STYP_TEXT | STYP_BSS)))
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{
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if (bias == -1) /* if first section after bss */
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bias = ptr - s->s_scnptr;
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s->s_scnptr += bias;
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ptr = s->s_scnptr;
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}
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ptr = ptr + s->s_size;
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}
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}
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/* fix other pointers */
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for (scns = 0; scns < f_hdr.f_nscns; scns++)
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{
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struct scnhdr *s = §ion[scns];
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if (s->s_relptr != 0)
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{
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s->s_relptr += bias;
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}
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if (s->s_lnnoptr != 0)
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{
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if (lnnoptr == 0) lnnoptr = s->s_lnnoptr;
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s->s_lnnoptr += bias;
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}
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}
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if (f_hdr.f_symptr > 0L)
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{
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f_hdr.f_symptr += bias;
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}
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text_scnptr = f_thdr->s_scnptr;
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data_scnptr = f_dhdr->s_scnptr;
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load_scnptr = f_lhdr ? f_lhdr->s_scnptr : 0;
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if (write (new, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
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{
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PERROR (new_name);
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}
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if (f_hdr.f_opthdr > 0)
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{
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if (write (new, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
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{
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PERROR (new_name);
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}
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}
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for (scns = 0; scns < f_hdr.f_nscns; scns++) {
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struct scnhdr *s = §ion[scns];
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if (write (new, s, sizeof (*s)) != sizeof (*s))
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{
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PERROR (new_name);
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}
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}
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return (0);
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}
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/* ****************************************************************
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*
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* Copy the text and data segments from memory to the new a.out
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*/
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static int
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copy_text_and_data (int new)
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{
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char *end;
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char *ptr;
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lseek (new, text_scnptr, SEEK_SET);
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ptr = _text;
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end = ptr + f_ohdr.tsize;
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write_segment (new, ptr, end);
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lseek (new, data_scnptr, SEEK_SET);
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ptr = (char *) (ptrdiff_t) f_ohdr.data_start;
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end = ptr + f_ohdr.dsize;
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write_segment (new, ptr, end);
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return 0;
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}
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#define UnexBlockSz (1<<12) /* read/write block size */
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static void
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write_segment (int new, char *ptr, char *end)
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{
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int i, nwrite, ret;
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char zeros[UnexBlockSz];
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for (i = 0; ptr < end;)
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{
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/* distance to next block. */
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nwrite = (((ptrdiff_t) ptr + UnexBlockSz) & -UnexBlockSz) - (ptrdiff_t) ptr;
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/* But not beyond specified end. */
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if (nwrite > end - ptr) nwrite = end - ptr;
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ret = write (new, ptr, nwrite);
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/* If write gets a page fault, it means we reached
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a gap between the old text segment and the old data segment.
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This gap has probably been remapped into part of the text segment.
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So write zeros for it. */
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if (ret == -1 && errno == EFAULT)
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{
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memset (zeros, 0, nwrite);
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write (new, zeros, nwrite);
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}
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else if (nwrite != ret)
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{
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int write_errno = errno;
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char buf[1000];
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void *addr = ptr;
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sprintf (buf,
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"unexec write failure: addr %p, fileno %d, size 0x%x, wrote 0x%x, errno %d",
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addr, new, nwrite, ret, errno);
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errno = write_errno;
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PERROR (buf);
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}
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i += nwrite;
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ptr += nwrite;
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}
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}
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/* ****************************************************************
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* copy_sym
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*
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* Copy the relocation information and symbol table from the a.out to the new
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*/
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static int
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copy_sym (int new, int a_out, const char *a_name, const char *new_name)
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{
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char page[UnexBlockSz];
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int n;
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if (a_out < 0)
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return 0;
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if (orig_load_scnptr == 0L)
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return 0;
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if (lnnoptr && lnnoptr < orig_load_scnptr) /* if there is line number info */
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lseek (a_out, lnnoptr, SEEK_SET); /* start copying from there */
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else
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lseek (a_out, orig_load_scnptr, SEEK_SET); /* Position a.out to symtab. */
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while ((n = read (a_out, page, sizeof page)) > 0)
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{
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if (write (new, page, n) != n)
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{
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PERROR (new_name);
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}
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}
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if (n < 0)
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{
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PERROR (a_name);
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}
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return 0;
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}
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static int
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adjust_lnnoptrs (int writedesc, int readdesc, const char *new_name)
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{
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int nsyms;
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int naux;
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int new;
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struct syment symentry;
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union auxent auxentry;
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if (!lnnoptr || !f_hdr.f_symptr)
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return 0;
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if ((new = emacs_open (new_name, O_RDWR, 0)) < 0)
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{
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PERROR (new_name);
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return -1;
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}
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lseek (new, f_hdr.f_symptr, SEEK_SET);
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for (nsyms = 0; nsyms < f_hdr.f_nsyms; nsyms++)
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{
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read (new, &symentry, SYMESZ);
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if (symentry.n_sclass == C_BINCL || symentry.n_sclass == C_EINCL)
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{
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symentry.n_value += bias;
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lseek (new, -SYMESZ, SEEK_CUR);
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write (new, &symentry, SYMESZ);
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}
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for (naux = symentry.n_numaux; naux-- != 0; )
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{
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read (new, &auxentry, AUXESZ);
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nsyms++;
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if (naux != 0 /* skip csect auxentry (last entry) */
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&& (symentry.n_sclass == C_EXT || symentry.n_sclass == C_HIDEXT))
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{
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auxentry.x_sym.x_fcnary.x_fcn.x_lnnoptr += bias;
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lseek (new, -AUXESZ, SEEK_CUR);
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write (new, &auxentry, AUXESZ);
|
||
}
|
||
}
|
||
}
|
||
emacs_close (new);
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int
|
||
unrelocate_symbols (int new, int a_out,
|
||
const char *a_name, const char *new_name)
|
||
{
|
||
int i;
|
||
LDHDR ldhdr;
|
||
LDREL ldrel;
|
||
off_t t_reloc = (intptr_t) _text - f_ohdr.text_start;
|
||
#ifndef ALIGN_DATA_RELOC
|
||
off_t d_reloc = (intptr_t) _data - f_ohdr.data_start;
|
||
#else
|
||
/* This worked (and was needed) before AIX 4.2.
|
||
I have no idea why. -- Mike */
|
||
off_t d_reloc = (intptr_t) _data - ALIGN (f_ohdr.data_start, 2);
|
||
#endif
|
||
int * p;
|
||
|
||
if (load_scnptr == 0)
|
||
return 0;
|
||
|
||
lseek (a_out, orig_load_scnptr, SEEK_SET);
|
||
if (read (a_out, &ldhdr, sizeof (ldhdr)) != sizeof (ldhdr))
|
||
{
|
||
PERROR (new_name);
|
||
}
|
||
|
||
#define SYMNDX_TEXT 0
|
||
#define SYMNDX_DATA 1
|
||
#define SYMNDX_BSS 2
|
||
|
||
for (i = 0; i < ldhdr.l_nreloc; i++)
|
||
{
|
||
lseek (a_out,
|
||
orig_load_scnptr + LDHDRSZ + LDSYMSZ*ldhdr.l_nsyms + LDRELSZ*i,
|
||
SEEK_SET);
|
||
|
||
if (read (a_out, &ldrel, LDRELSZ) != LDRELSZ)
|
||
{
|
||
PERROR (a_name);
|
||
}
|
||
|
||
/* move the BSS loader symbols to the DATA segment */
|
||
if (ldrel.l_symndx == SYMNDX_BSS)
|
||
{
|
||
ldrel.l_symndx = SYMNDX_DATA;
|
||
|
||
lseek (new,
|
||
load_scnptr + LDHDRSZ + LDSYMSZ*ldhdr.l_nsyms + LDRELSZ*i,
|
||
SEEK_SET);
|
||
|
||
if (write (new, &ldrel, LDRELSZ) != LDRELSZ)
|
||
{
|
||
PERROR (new_name);
|
||
}
|
||
}
|
||
|
||
if (ldrel.l_rsecnm == f_ohdr.o_sndata)
|
||
{
|
||
int orig_int;
|
||
|
||
lseek (a_out,
|
||
orig_data_scnptr + (ldrel.l_vaddr - f_ohdr.data_start),
|
||
SEEK_SET);
|
||
|
||
if (read (a_out, (void *) &orig_int, sizeof (orig_int))
|
||
!= sizeof (orig_int))
|
||
{
|
||
PERROR (a_name);
|
||
}
|
||
|
||
p = (int *) (intptr_t) (ldrel.l_vaddr + d_reloc);
|
||
|
||
switch (ldrel.l_symndx) {
|
||
case SYMNDX_TEXT:
|
||
orig_int = * p - t_reloc;
|
||
break;
|
||
|
||
case SYMNDX_DATA:
|
||
case SYMNDX_BSS:
|
||
orig_int = * p - d_reloc;
|
||
break;
|
||
}
|
||
|
||
if (orig_int != * p)
|
||
{
|
||
lseek (new,
|
||
data_scnptr + (ldrel.l_vaddr - f_ohdr.data_start),
|
||
SEEK_SET);
|
||
if (write (new, (void *) &orig_int, sizeof (orig_int))
|
||
!= sizeof (orig_int))
|
||
{
|
||
PERROR (new_name);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
return 0;
|
||
}
|