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/* Copyright (C) 1985,86,87,88,92,93,94 Free Software Foundation, 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 2, or (at your option)
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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; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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* unexec.c - Convert a running program into an a.out file.
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* Author: Spencer W. Thomas
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* Computer Science Dept.
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* Date: Tue Mar 2 1982
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* Modified heavily since then.
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* unexec (new_name, a_name, data_start, bss_start, entry_address)
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* char *new_name, *a_name;
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* unsigned data_start, bss_start, entry_address;
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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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* The boundaries within the a.out file may be adjusted with the data_start
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* and bss_start arguments. Either or both may be given as 0 for defaults.
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* Data_start gives the boundary between the text segment and the data
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* segment of the program. The text segment can contain shared, read-only
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* program code and literal data, while the data segment is always unshared
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* and unprotected. Data_start gives the lowest unprotected address.
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* The value you specify may be rounded down to a suitable boundary
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* as required by the machine you are using.
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* Specifying zero for data_start means the boundary between text and data
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* should not be the same as when the program was loaded.
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* If NO_REMAP is defined, the argument data_start is ignored and the
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* segment boundaries are never changed.
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* Bss_start indicates how much of the data segment is to be saved in the
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* a.out file and restored when the program is executed. It gives the lowest
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* unsaved address, and is rounded up to a page boundary. The default when 0
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* is given assumes that the entire data segment is to be stored, including
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* the previous data and bss as well as any additional storage allocated with
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* The new file is set up to start at entry_address.
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* If you make improvements I'd like to get them too.
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* harpo!utah-cs!thomas, thomas@Utah-20
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/* Modified to support SysVr3 shared libraries by James Van Artsdalen
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* of Dell Computer Corporation. james@bigtex.cactus.org.
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/* There are several compilation parameters affecting unexec:
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Define this if your system uses COFF for executables.
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Define this if you are using the GNU coff encapsulated a.out format.
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This is closer to a.out than COFF. You should *not* define COFF if
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you define COFF_ENCAPSULATE
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Otherwise we assume you use Berkeley format.
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Define this if you do not want to try to save Emacs's pure data areas
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as part of the text segment.
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Saving them as text is good because it allows users to share more.
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However, on machines that locate the text area far from the data area,
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the boundary cannot feasibly be moved. Such machines require
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Also, remapping can cause trouble with the built-in startup routine
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/lib/crt0.o, which defines `environ' as an initialized variable.
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Dumping `environ' as pure does not work! So, to use remapping,
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you must write a startup routine for your machine in Emacs's crt0.c.
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If NO_REMAP is defined, Emacs uses the system's crt0.o.
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Some machines that use COFF executables require that each section
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start on a certain boundary *in the COFF file*. Such machines should
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define SECTION_ALIGNMENT to a mask of the low-order bits that must be
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zero on such a boundary. This mask is used to control padding between
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segments in the COFF file.
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If SECTION_ALIGNMENT is not defined, the segments are written
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consecutively with no attempt at alignment. This is right for
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Some machines require that the beginnings and ends of segments
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*in core* be on certain boundaries. For most machines, a page
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boundary is sufficient. That is the default. When a larger
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boundary is needed, define SEGMENT_MASK to a mask of
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the bits that must be zero on such a boundary.
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Some machines count the a.out header as part of the size of the text
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segment (a_text); they may actually load the header into core as the
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first data in the text segment. Some have additional padding between
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the header and the real text of the program that is counted in a_text.
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For these machines, define A_TEXT_OFFSET(HDR) to examine the header
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structure HDR and return the number of bytes to add to `a_text'
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before writing it (above and beyond the number of bytes of actual
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program text). HDR's standard fields are already correct, except that
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this adjustment to the `a_text' field has not yet been made;
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thus, the amount of offset can depend on the data in the file.
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If defined, this macro specifies the number of bytes to seek into the
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a.out file before starting to write the text segment.
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For machines using COFF, this macro, if defined, is a value stored
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into the magic number field of the output file.
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This macro can be used to generate statements to adjust or
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initialize nonstandard fields in the file header
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Macro to correct an int which is the bit pattern of a pointer to a byte
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into an int which is the number of a byte.
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This macro has a default definition which is usually right.
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This default definition is a no-op on most machines (where a
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pointer looks like an int) but not on all machines.
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#define PERROR(arg) perror (arg); return -1
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#define PERROR(file) report_error (file, new)
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#ifndef CANNOT_DUMP /* all rest of file! */
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#ifdef COFF_ENCAPSULATE
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int need_coff_header = 1;
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#include <coff-encap/a.out.encap.h> /* The location might be a poor assumption */
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#define filehdr external_filehdr
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#define scnhdr external_scnhdr
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#define syment external_syment
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#define auxent external_auxent
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#define n_numaux e_numaux
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#define n_type e_type
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unsigned short magic; /* type of file */
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unsigned short vstamp; /* version stamp */
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unsigned long tsize; /* text size in bytes, padded to FW bdry*/
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unsigned long dsize; /* initialized data " " */
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unsigned long bsize; /* uninitialized data " " */
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unsigned long entry; /* entry pt. */
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unsigned long text_start;/* base of text used for this file */
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unsigned long data_start;/* base of data used for this file */
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#else /* not MSDOS */
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#endif /* not MSDOS */
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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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#include "getpagesize.h"
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#ifndef makedev /* Try to detect types.h already loaded */
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/file.h> /* Must be after sys/types.h for USG and BSD4_1*/
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#ifndef start_of_data
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extern char *start_of_text (); /* Start of text */
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extern char *start_of_data (); /* Start of initialized data */
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static long block_copy_start; /* Old executable start point */
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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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long bias; /* Bias to add for growth */
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long lnnoptr; /* Pointer to line-number info within file */
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#define SYMS_START block_copy_start
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static long text_scnptr;
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static long data_scnptr;
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extern void *sbrk ();
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/* Some systems with __STDC__ compilers still declare this `char *' in some
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header file, and our declaration conflicts. The return value is always
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cast, so it should be harmless to leave it undefined. Hopefully
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machines with different size pointers and ints declare sbrk in a header
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extern void *sbrk ();
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extern char *sbrk ();
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#endif /* __STDC__ */
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#define SYMS_START ((long) N_SYMOFF (ohdr))
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/* Some machines override the structure name for an a.out header. */
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#ifndef EXEC_HDR_TYPE
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#define EXEC_HDR_TYPE struct exec
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#define MY_ID HP9000S200_ID
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#endif /* no HP9000S200_ID */
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static MAGIC OLDMAGIC = {MY_ID, SHARE_MAGIC};
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static MAGIC NEWMAGIC = {MY_ID, DEMAND_MAGIC};
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#define N_TXTOFF(x) TEXT_OFFSET(x)
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#define N_SYMOFF(x) LESYM_OFFSET(x)
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static EXEC_HDR_TYPE hdr, ohdr;
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#if defined (USG) && !defined (IBMAIX) && !defined (IRIS) && !defined (COFF_ENCAPSULATE) && !defined (LINUX)
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static struct bhdr hdr, ohdr;
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#define a_magic fmagic
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#define a_trsize rtsize
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#define a_drsize rdsize
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#define a_entry entry
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#define N_BADMAG(x) \
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(((x).fmagic)!=OMAGIC && ((x).fmagic)!=NMAGIC &&\
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((x).fmagic)!=FMAGIC && ((x).fmagic)!=IMAGIC)
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#define NEWMAGIC FMAGIC
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#else /* IRIS or IBMAIX or not USG */
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static EXEC_HDR_TYPE hdr, ohdr;
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#define NEWMAGIC ZMAGIC
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#endif /* IRIS or IBMAIX not USG */
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#endif /* not HPUX */
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static int unexec_text_start;
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static int unexec_data_start;
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#ifdef COFF_ENCAPSULATE
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/* coffheader is defined in the GNU a.out.encap.h file. */
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struct coffheader coffheader;
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#endif /* not COFF */
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/* Correct an int which is the bit pattern of a pointer to a byte
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into an int which is the number of a byte.
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This is a no-op on ordinary machines, but not on all. */
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#ifndef ADDR_CORRECT /* Let m-*.h files override this definition */
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#define ADDR_CORRECT(x) ((char *)(x) - (char*)0)
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report_error (file, fd)
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report_file_error ("Cannot unexec", Fcons (build_string (file), Qnil));
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#define ERROR0(msg) report_error_1 (new, msg, 0, 0); return -1
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#define ERROR1(msg,x) report_error_1 (new, msg, x, 0); return -1
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#define ERROR2(msg,x,y) report_error_1 (new, msg, x, y); return -1
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report_error_1 (fd, msg, a1, a2)
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fprintf (stderr, msg, a1, a2);
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fprintf (stderr, "\n");
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static int make_hdr ();
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static int copy_text_and_data ();
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static int copy_sym ();
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static void mark_x ();
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/* ****************************************************************
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unexec (new_name, a_name, data_start, bss_start, entry_address)
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char *new_name, *a_name;
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unsigned data_start, bss_start, entry_address;
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if (a_name && (a_out = open (a_name, O_RDONLY)) < 0)
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if ((new = creat (new_name, 0666)) < 0)
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if (make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name) < 0
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|| copy_text_and_data (new, a_out) < 0
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|| copy_sym (new, a_out, a_name, new_name) < 0
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#ifndef COFF_BSD_SYMBOLS
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|| adjust_lnnoptrs (new, a_out, new_name) < 0
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/* unlink (new_name); /* Failed, unlink new a.out */
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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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make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name)
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unsigned data_start, bss_start, entry_address;
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auto struct scnhdr f_thdr; /* Text section header */
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auto struct scnhdr f_dhdr; /* Data section header */
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auto struct scnhdr f_bhdr; /* Bss section header */
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auto struct scnhdr scntemp; /* Temporary section header */
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#ifdef USG_SHARED_LIBRARIES
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extern unsigned int bss_end;
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unsigned int bss_end;
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pagemask = getpagesize () - 1;
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/* Adjust text/data boundary. */
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data_start = (int) start_of_data ();
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#else /* not NO_REMAP */
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data_start = (int) start_of_data ();
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#endif /* not NO_REMAP */
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data_start = ADDR_CORRECT (data_start);
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data_start = data_start & ~SEGMENT_MASK; /* (Down) to segment boundary. */
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data_start = data_start & ~pagemask; /* (Down) to page boundary. */
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bss_end = ADDR_CORRECT (sbrk (0)) + pagemask;
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bss_end &= ~ pagemask;
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/* Adjust data/bss boundary. */
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bss_start = (ADDR_CORRECT (bss_start) + pagemask);
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/* (Up) to page bdry. */
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bss_start &= ~ pagemask;
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if (bss_start > bss_end)
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ERROR1 ("unexec: Specified bss_start (%u) is past end of program",
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if (data_start > bss_start) /* Can't have negative data size. */
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ERROR2 ("unexec: data_start (%u) can't be greater than bss_start (%u)",
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data_start, bss_start);
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/* Salvage as much info from the existing file as possible */
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if (read (a_out, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
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block_copy_start += sizeof (f_hdr);
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if (f_hdr.f_opthdr > 0)
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if (read (a_out, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
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block_copy_start += sizeof (f_ohdr);
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/* Loop through section headers, copying them in */
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lseek (a_out, sizeof (f_hdr) + f_hdr.f_opthdr, 0);
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for (scns = f_hdr.f_nscns; scns > 0; scns--) {
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if (read (a_out, &scntemp, sizeof (scntemp)) != sizeof (scntemp))
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if (scntemp.s_scnptr > 0L)
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if (block_copy_start < scntemp.s_scnptr + scntemp.s_size)
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block_copy_start = scntemp.s_scnptr + scntemp.s_size;
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if (strcmp (scntemp.s_name, ".text") == 0)
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else if (strcmp (scntemp.s_name, ".data") == 0)
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else if (strcmp (scntemp.s_name, ".bss") == 0)
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ERROR0 ("can't build a COFF file from scratch yet");
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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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#ifdef USG_SHARED_LIBRARIES
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/* The amount of data we're adding to the file is distance from the
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* end of the original .data space to the current end of the .data
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bias = bss_start - (f_ohdr.data_start + f_dhdr.s_size);
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f_hdr.f_flags |= (F_RELFLG | F_EXEC);
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f_ohdr.magic = EXEC_MAGIC;
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f_ohdr.text_start = (long) start_of_text ();
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f_ohdr.tsize = data_start - f_ohdr.text_start;
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f_ohdr.data_start = data_start;
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#endif /* NO_REMAP */
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f_ohdr.dsize = bss_start - f_ohdr.data_start;
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f_ohdr.bsize = bss_end - bss_start;
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#ifndef KEEP_OLD_TEXT_SCNPTR
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/* On some machines, the old values are right.
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??? Maybe on all machines with NO_REMAP. */
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f_thdr.s_size = f_ohdr.tsize;
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f_thdr.s_scnptr = sizeof (f_hdr) + sizeof (f_ohdr);
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f_thdr.s_scnptr += (f_hdr.f_nscns) * (sizeof (f_thdr));
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#endif /* KEEP_OLD_TEXT_SCNPTR */
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#ifdef ADJUST_TEXT_SCNHDR_SIZE
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/* On some machines, `text size' includes all headers. */
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f_thdr.s_size -= f_thdr.s_scnptr;
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#endif /* ADJUST_TEST_SCNHDR_SIZE */
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lnnoptr = f_thdr.s_lnnoptr;
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#ifdef SECTION_ALIGNMENT
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/* Some systems require special alignment
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of the sections in the file itself. */
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= (f_thdr.s_scnptr + SECTION_ALIGNMENT) & ~SECTION_ALIGNMENT;
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#endif /* SECTION_ALIGNMENT */
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f_thdr.s_scnptr = 0xd0;
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text_scnptr = f_thdr.s_scnptr;
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#ifdef ADJUST_TEXTBASE
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text_scnptr = sizeof (f_hdr) + sizeof (f_ohdr) + (f_hdr.f_nscns) * (sizeof (f_thdr));
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#ifndef KEEP_OLD_PADDR
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f_dhdr.s_paddr = f_ohdr.data_start;
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#endif /* KEEP_OLD_PADDR */
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f_dhdr.s_vaddr = f_ohdr.data_start;
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f_dhdr.s_size = f_ohdr.dsize;
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f_dhdr.s_scnptr = f_thdr.s_scnptr + f_thdr.s_size;
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#ifdef SECTION_ALIGNMENT
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/* Some systems require special alignment
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of the sections in the file itself. */
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= (f_dhdr.s_scnptr + SECTION_ALIGNMENT) & ~SECTION_ALIGNMENT;
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#endif /* SECTION_ALIGNMENT */
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#ifdef DATA_SECTION_ALIGNMENT
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/* Some systems require special alignment
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of the data section only. */
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= (f_dhdr.s_scnptr + DATA_SECTION_ALIGNMENT) & ~DATA_SECTION_ALIGNMENT;
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#endif /* DATA_SECTION_ALIGNMENT */
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data_scnptr = f_dhdr.s_scnptr;
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#ifndef KEEP_OLD_PADDR
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f_bhdr.s_paddr = f_ohdr.data_start + f_ohdr.dsize;
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#endif /* KEEP_OLD_PADDR */
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f_bhdr.s_vaddr = f_ohdr.data_start + f_ohdr.dsize;
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f_bhdr.s_size = f_ohdr.bsize;
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f_bhdr.s_scnptr = 0L;
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#ifndef USG_SHARED_LIBRARIES
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bias = f_dhdr.s_scnptr + f_dhdr.s_size - block_copy_start;
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if (f_hdr.f_symptr > 0L)
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f_hdr.f_symptr += bias;
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if (f_thdr.s_lnnoptr > 0L)
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f_thdr.s_lnnoptr += bias;
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#ifdef ADJUST_EXEC_HEADER
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#endif /* ADJUST_EXEC_HEADER */
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if (write (new, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
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if (write (new, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
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#ifndef USG_SHARED_LIBRARIES
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if (write (new, &f_thdr, sizeof (f_thdr)) != sizeof (f_thdr))
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if (write (new, &f_dhdr, sizeof (f_dhdr)) != sizeof (f_dhdr))
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if (write (new, &f_bhdr, sizeof (f_bhdr)) != sizeof (f_bhdr))
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#else /* USG_SHARED_LIBRARIES */
650
/* The purpose of this code is to write out the new file's section
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* Scan through the original file's sections. If the encountered
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* section is one we know (.text, .data or .bss), write out the
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* correct header. If it is a section we do not know (such as
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* .lib), adjust the address of where the section data is in the
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* file, and write out the header.
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* If any section precedes .text or .data in the file, this code
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* will not adjust the file pointer for that section correctly.
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/* This used to use sizeof (f_ohdr) instead of .f_opthdr.
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.f_opthdr is said to be right when there is no optional header. */
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lseek (a_out, sizeof (f_hdr) + f_hdr.f_opthdr, 0);
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for (scns = f_hdr.f_nscns; scns > 0; scns--)
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if (read (a_out, &scntemp, sizeof (scntemp)) != sizeof (scntemp))
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if (!strcmp (scntemp.s_name, f_thdr.s_name)) /* .text */
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if (write (new, &f_thdr, sizeof (f_thdr)) != sizeof (f_thdr))
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else if (!strcmp (scntemp.s_name, f_dhdr.s_name)) /* .data */
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if (write (new, &f_dhdr, sizeof (f_dhdr)) != sizeof (f_dhdr))
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else if (!strcmp (scntemp.s_name, f_bhdr.s_name)) /* .bss */
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if (write (new, &f_bhdr, sizeof (f_bhdr)) != sizeof (f_bhdr))
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if (scntemp.s_scnptr)
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scntemp.s_scnptr += bias;
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if (write (new, &scntemp, sizeof (scntemp)) != sizeof (scntemp))
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#endif /* USG_SHARED_LIBRARIES */
699
#else /* if not COFF */
701
/* Get symbol table info from header of a.out file if given one. */
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#ifdef COFF_ENCAPSULATE
705
if (read (a_out, &coffheader, sizeof coffheader) != sizeof coffheader)
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if (coffheader.f_magic != COFF_MAGIC)
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ERROR1("%s doesn't have legal coff magic number\n", a_name);
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if (read (a_out, &ohdr, sizeof hdr) != sizeof hdr)
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ERROR1 ("invalid magic number in %s", a_name);
727
#ifdef COFF_ENCAPSULATE
728
/* We probably could without too much trouble. The code is in gld
729
* but I don't have that much time or incentive.
731
ERROR0 ("can't build a COFF file from scratch yet");
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#ifdef MSDOS /* Demacs 1.1.1 91/10/16 HIRANO Satoshi */
734
bzero ((void *)&hdr, sizeof hdr);
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bzero (&hdr, sizeof hdr);
741
unexec_text_start = (long) start_of_text ();
742
unexec_data_start = data_start;
744
/* Machine-dependent fixup for header, or maybe for unexec_text_start */
745
#ifdef ADJUST_EXEC_HEADER
747
#endif /* ADJUST_EXEC_HEADER */
751
if (entry_address != 0)
752
hdr.a_entry = entry_address;
754
hdr.a_bss = bss_end - bss_start;
755
hdr.a_data = bss_start - data_start;
757
hdr.a_text = ohdr.a_text;
758
#else /* not NO_REMAP */
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hdr.a_text = data_start - unexec_text_start;
762
hdr.a_text += A_TEXT_OFFSET (ohdr);
765
#endif /* not NO_REMAP */
767
#ifdef COFF_ENCAPSULATE
768
/* We are encapsulating BSD format within COFF format. */
770
struct coffscn *tp, *dp, *bp;
771
tp = &coffheader.scns[0];
772
dp = &coffheader.scns[1];
773
bp = &coffheader.scns[2];
774
tp->s_size = hdr.a_text + sizeof(struct exec);
775
dp->s_paddr = data_start;
776
dp->s_vaddr = data_start;
777
dp->s_size = hdr.a_data;
778
bp->s_paddr = dp->s_vaddr + dp->s_size;
779
bp->s_vaddr = bp->s_paddr;
780
bp->s_size = hdr.a_bss;
781
coffheader.tsize = tp->s_size;
782
coffheader.dsize = dp->s_size;
783
coffheader.bsize = bp->s_size;
784
coffheader.text_start = tp->s_vaddr;
785
coffheader.data_start = dp->s_vaddr;
787
if (write (new, &coffheader, sizeof coffheader) != sizeof coffheader)
791
#endif /* COFF_ENCAPSULATE */
793
if (write (new, &hdr, sizeof hdr) != sizeof hdr)
798
#if 0 /* This #ifndef caused a bug on Linux when using QMAGIC. */
799
/* This adjustment was done above only #ifndef NO_REMAP,
800
so only undo it now #ifndef NO_REMAP. */
801
/* #ifndef NO_REMAP */
804
hdr.a_text -= A_TEXT_OFFSET (ohdr);
809
#endif /* not COFF */
812
/* ****************************************************************
815
* Copy the text and data segments from memory to the new a.out
818
copy_text_and_data (new, a_out)
826
#ifdef USG_SHARED_LIBRARIES
829
struct scnhdr scntemp; /* Temporary section header */
831
/* The purpose of this code is to write out the new file's section
834
* Step through the section table. If we know the section (.text,
835
* .data) do the appropriate thing. Otherwise, if the section has
836
* no allocated space in the file (.bss), do nothing. Otherwise,
837
* the section has space allocated in the file, and is not a section
838
* we know. So just copy it.
841
lseek (a_out, sizeof (struct filehdr) + sizeof (struct aouthdr), 0);
843
for (scns = f_hdr.f_nscns; scns > 0; scns--)
845
if (read (a_out, &scntemp, sizeof (scntemp)) != sizeof (scntemp))
848
if (!strcmp (scntemp.s_name, ".text"))
850
lseek (new, (long) text_scnptr, 0);
851
ptr = (char *) f_ohdr.text_start;
852
end = ptr + f_ohdr.tsize;
853
write_segment (new, ptr, end);
855
else if (!strcmp (scntemp.s_name, ".data"))
857
lseek (new, (long) data_scnptr, 0);
858
ptr = (char *) f_ohdr.data_start;
859
end = ptr + f_ohdr.dsize;
860
write_segment (new, ptr, end);
862
else if (!scntemp.s_scnptr)
863
; /* do nothing - no data for this section */
868
long old_a_out_ptr = lseek (a_out, 0, 1);
870
lseek (a_out, scntemp.s_scnptr, 0);
871
for (size = scntemp.s_size; size > 0; size -= sizeof (page))
873
n = size > sizeof (page) ? sizeof (page) : size;
874
if (read (a_out, page, n) != n || write (new, page, n) != n)
877
lseek (a_out, old_a_out_ptr, 0);
881
#else /* COFF, but not USG_SHARED_LIBRARIES */
883
lseek (new, (long) text_scnptr, 0);
884
ptr = (char *) f_ohdr.text_start;
885
#ifdef HEADER_INCL_IN_TEXT
886
/* For Gould UTX/32, text starts after headers */
887
ptr = (char *) (ptr + text_scnptr);
888
#endif /* HEADER_INCL_IN_TEXT */
889
end = ptr + f_ohdr.tsize;
890
write_segment (new, ptr, end);
892
lseek (new, (long) data_scnptr, 0);
893
ptr = (char *) f_ohdr.data_start;
894
end = ptr + f_ohdr.dsize;
895
write_segment (new, ptr, end);
897
#endif /* USG_SHARED_LIBRARIES */
899
#else /* if not COFF */
901
/* Some machines count the header as part of the text segment.
902
That is to say, the header appears in core
903
just before the address that start_of_text returns.
904
For them, N_TXTOFF is the place where the header goes.
905
We must adjust the seek to the place after the header.
906
Note that at this point hdr.a_text does *not* count
907
the extra A_TEXT_OFFSET bytes, only the actual bytes of code. */
910
lseek (new, (long) A_TEXT_SEEK (hdr), 0);
912
lseek (new, (long) N_TXTOFF (hdr), 0);
913
#endif /* no A_TEXT_SEEK */
917
/* Acorn's RISC-iX has a wacky way of initialising the position of the heap.
918
* There is a little table in crt0.o that is filled at link time with
919
* the min and current brk positions, among other things. When start
920
* runs, it copies the table to where these parameters live during
921
* execution. This data is in text space, so it cannot be modified here
922
* before saving the executable, so the data is written manually. In
923
* addition, the table does not have a label, and the nearest accessable
924
* label (mcount) is not prefixed with a '_', thus making it inaccessable
925
* from within C programs. To overcome this, emacs's executable is passed
926
* through the command 'nm %s | fgrep mcount' into a pipe, and the
927
* resultant output is then used to find the address of 'mcount'. As far as
928
* is possible to determine, in RISC-iX releases prior to 1.2, the negative
929
* offset of the table from mcount is 0x2c, whereas from 1.2 onwards it is
930
* 0x30. bss_end has been rounded up to page boundary. This solution is
931
* based on suggestions made by Kevin Welton and Steve Hunt of Acorn, and
932
* avoids the need for a custom version of crt0.o for emacs which has its
933
* table in data space.
939
char address_text[32];
944
int mcount_address, mcount_offset, count;
945
extern char *_execname;
948
/* The use of _execname is incompatible with RISCiX 1.1 */
949
sprintf (command, "nm %s | fgrep mcount", _execname);
951
if ( (pfile = popen(command, "r")) == NULL)
953
sprintf (errbuf, "Could not open pipe");
958
while ( ((c=getc(pfile)) != EOF) && (c != ' ') && (count < 31))
959
address_text[count++]=c;
960
address_text[count]=0;
962
if ((count == 0) || pclose(pfile) != NULL)
964
sprintf (errbuf, "Failed to execute the command '%s'\n", command);
968
sscanf(address_text, "%x", &mcount_address);
969
ptr = (char *) unexec_text_start;
970
mcount_offset = (char *)mcount_address - ptr;
973
#define EDATA_OFFSET 0x2c
975
#define EDATA_OFFSET 0x30
978
end = ptr + mcount_offset - EDATA_OFFSET;
980
write_segment (new, ptr, end);
982
proforma[0] = bss_end; /* becomes _edata */
983
proforma[1] = bss_end; /* becomes _end */
984
proforma[2] = bss_end; /* becomes _minbrk */
985
proforma[3] = bss_end; /* becomes _curbrk */
987
write (new, proforma, 16);
991
end = temp_ptr + hdr.a_text;
993
write_segment (new, ptr, end);
997
ptr = (char *) unexec_text_start;
998
end = ptr + hdr.a_text;
999
write_segment (new, ptr, end);
1002
ptr = (char *) unexec_data_start;
1003
end = ptr + hdr.a_data;
1004
/* This lseek is certainly incorrect when A_TEXT_OFFSET
1005
and I believe it is a no-op otherwise.
1006
Let's see if its absence ever fails. */
1007
/* lseek (new, (long) N_TXTOFF (hdr) + hdr.a_text, 0); */
1008
write_segment (new, ptr, end);
1010
#endif /* not COFF */
1015
write_segment (new, ptr, end)
1017
register char *ptr, *end;
1019
register int i, nwrite, ret;
1023
int amt_to_write = (1 << 13);
1025
bzero (zeros, sizeof zeros);
1027
for (i = 0; ptr < end;)
1029
/* distance to next multiple of amt_to_write . */
1031
nwrite = (((int) ptr + amt_to_write) & -amt_to_write) - (int) ptr;
1032
/* But not beyond specified end. */
1033
if (nwrite > end - ptr) nwrite = end - ptr;
1034
ret = write (new, ptr, nwrite);
1035
/* If write gets a page fault, it means we reached
1036
a gap between the old text segment and the old data segment.
1037
This gap has probably been remapped into part of the text segment.
1038
So write zeros for it. */
1044
{ if (amt_to_write > sizeof(zeros))
1045
{ amt_to_write = sizeof(zeros);
1048
write (new, zeros, nwrite);
1050
else if (nwrite != ret)
1053
"unexec write failure: addr 0x%x, fileno %d, size 0x%x, wrote 0x%x, errno %d",
1054
ptr, new, nwrite, ret, errno);
1062
/* ****************************************************************
1065
* Copy the relocation information and symbol table from the a.out to the new
1068
copy_sym (new, a_out, a_name, new_name)
1070
char *a_name, *new_name;
1079
if (SYMS_START == 0L)
1084
if (lnnoptr) /* if there is line number info */
1085
lseek (a_out, lnnoptr, 0); /* start copying from there */
1088
lseek (a_out, SYMS_START, 0); /* Position a.out to symtab. */
1090
while ((n = read (a_out, page, sizeof page)) > 0)
1092
if (write (new, page, n) != n)
1104
/* ****************************************************************
1107
* After successfully building the new a.out, mark it executable
1115
int new = 0; /* for PERROR */
1119
if (stat (name, &sbuf) == -1)
1123
sbuf.st_mode |= 0111 & ~um;
1124
if (chmod (name, sbuf.st_mode) == -1)
1129
#ifndef COFF_BSD_SYMBOLS
1132
* If the COFF file contains a symbol table and a line number section,
1133
* then any auxiliary entries that have values for x_lnnoptr must
1134
* be adjusted by the amount that the line number section has moved
1135
* in the file (bias computed in make_hdr). The #@$%&* designers of
1136
* the auxiliary entry structures used the absolute file offsets for
1137
* the line number entry rather than an offset from the start of the
1138
* line number section!
1140
* When I figure out how to scan through the symbol table and pick out
1141
* the auxiliary entries that need adjustment, this routine will
1142
* be fixed. As it is now, all such entries are wrong and sdb
1143
* will complain. Fred Fish, UniSoft Systems Inc.
1146
/* This function is probably very slow. Instead of reopening the new
1147
file for input and output it should copy from the old to the new
1148
using the two descriptors already open (WRITEDESC and READDESC).
1149
Instead of reading one small structure at a time it should use
1150
a reasonable size buffer. But I don't have time to work on such
1151
things, so I am installing it as submitted to me. -- RMS. */
1153
adjust_lnnoptrs (writedesc, readdesc, new_name)
1160
#if defined (amdahl_uts) || defined (pfa)
1164
struct syment symentry;
1165
union auxent auxentry;
1168
if (!lnnoptr || !f_hdr.f_symptr)
1172
if ((new = writedesc) < 0)
1174
if ((new = open (new_name, O_RDWR)) < 0)
1181
lseek (new, f_hdr.f_symptr, 0);
1182
for (nsyms = 0; nsyms < f_hdr.f_nsyms; nsyms++)
1184
read (new, &symentry, SYMESZ);
1185
if (symentry.n_numaux)
1187
read (new, &auxentry, AUXESZ);
1189
if (ISFCN (symentry.n_type) || symentry.n_type == 0x2400)
1191
auxentry.x_sym.x_fcnary.x_fcn.x_lnnoptr += bias;
1192
lseek (new, -AUXESZ, 1);
1193
write (new, &auxentry, AUXESZ);
1203
#endif /* COFF_BSD_SYMBOLS */
1207
#endif /* not CANNOT_DUMP */
added
removed
o/unexec.c
