Initial revision

3 files changed, 1024 insertions, 0 deletions

diff --git a/src/m/iris5d.h b/src/m/iris5d.h
new file mode 100644
index 00000000000..1b9cfdfc8f6
--- /dev/null
+++ b/src/m/iris5d.h
@@ -0,0 +1,192 @@
+/* machine description file for Iris-4D machines.  Use with s-iris3-6.h
+   Copyright (C) 1987 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 1, 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; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+
+/* The following line tells the configuration script what sort of 
+   operating system this machine is likely to run.
+   USUAL-OPSYS="irix3-3"  */
+
+/* The following three symbols give information on
+ the size of various data types.  */
+
+#define SHORTBITS 16            /* Number of bits in a short */
+
+#define INTBITS 32              /* Number of bits in an int */
+
+#define LONGBITS 32             /* Number of bits in a long */
+
+/* Define BIG_ENDIAN iff lowest-numbered byte in a word
+   is the most significant byte.  */
+
+#define BIG_ENDIAN
+
+/* Define NO_ARG_ARRAY if you cannot take the address of the first of a
+ * group of arguments and treat it as an array of the arguments.  */
+
+#define NO_ARG_ARRAY
+
+/* Define WORD_MACHINE if addresses and such have
+ * to be corrected before they can be used as byte counts.  */
+
+#undef WORD_MACHINE
+
+/* Now define a symbol for the cpu type, if your compiler
+   does not define it automatically:
+   Ones defined so far include vax, m68000, ns16000, pyramid,
+   orion, tahoe, APOLLO and many others */
+
+#ifndef mips
+#define mips
+#endif
+
+#ifndef IRIS_4D
+#define IRIS_4D
+#endif
+
+/* Use type int rather than a union, to represent Lisp_Object */
+/* This is desirable for most machines.  */
+
+#define NO_UNION_TYPE
+
+/* Define EXPLICIT_SIGN_EXTEND if XINT must explicitly sign-extend
+   the 24-bit bit field into an int.  In other words, if bit fields
+   are always unsigned.
+
+   If you use NO_UNION_TYPE, this flag does not matter.  */
+
+#define EXPLICIT_SIGN_EXTEND
+
+/* Data type of load average, as read out of kmem.  */
+
+#define LOAD_AVE_TYPE long      /* This doesn't quite work on the 4D */
+
+/* Convert that into an integer that is 100 for a load average of 1.0  */
+
+#define LOAD_AVE_CVT(x) (int)(((double)(x)*100)/1024.0)
+
+/* s-iris3-6.h uses /vmunix */
+
+#undef KERNEL_FILE
+#define KERNEL_FILE "/unix"
+
+/* Define CANNOT_DUMP on machines where unexec does not work.
+   Then the function dump-emacs will not be defined
+   and temacs will do (load "loadup") automatically unless told otherwise.  */
+
+#undef CANNOT_DUMP
+
+/* Define VIRT_ADDR_VARIES if the virtual addresses of
+   pure and impure space as loaded can vary, and even their
+   relative order cannot be relied on.
+
+   Otherwise Emacs assumes that text space precedes data space,
+   numerically.  */
+
+/* #define VIRT_ADDR_VARIES */
+
+/* Define C_ALLOCA if this machine does not support a true alloca
+   and the one written in C should be used instead.
+   Define HAVE_ALLOCA to say that the system provides a properly
+   working alloca function and it should be used.
+   Define neither one if an assembler-language alloca
+   in the file alloca.s should be used.  */
+
+#define C_ALLOCA
+/* #define HAVE_ALLOCA */
+
+/* Define NO_REMAP if memory segmentation makes it not work well
+   to change the boundary between the text section and data section
+   when Emacs is dumped.  If you define this, the preloaded Lisp
+   code will not be sharable; but that's better than failing completely.  */
+
+#define NO_REMAP
+
+/* This machine requires completely different unexec code
+   which lives in a separate file.  Specify the file name.  */
+
+#define UNEXEC unexmips.o
+
+#define TEXT_START 0x400000
+
+/*
+ * DATA_SEG_BITS forces that bit to be or'd in with any pointers which
+ * are trying to access pure strings (as gnu-emacs only allows 24 bits
+ * for the value field of a LISP_OBJECT).
+ */
+
+#define DATA_START 0x10000000
+#define DATA_SEG_BITS   0x10000000
+
+#undef LIBS_MACHINE
+/* -lsun in case using Yellow Pages for passwords.  */
+#define LIBS_MACHINE -lsun -lmld
+#define LIBS_DEBUG
+
+/* Define this if you have a fairly recent system,
+   in which crt1.o and crt1.n should be used.  */
+#define HAVE_CRTN
+
+#ifdef HAVE_CRTN
+/* Must define START-FILES so that the linker can find /usr/lib/crt0.o.  */
+#define START_FILES pre-crt0.o /usr/lib/crt1.o
+#define LIB_STANDARD -lbsd -lc /usr/lib/crtn.o
+#else
+#define START_FILES pre-crt0.o /usr/lib/crt0.o
+/* The entry-point label (start of text segment) is `start', not `__start'.  */
+#define DEFAULT_ENTRY_ADDRESS start
+#define LIB_STANDARD -lbsd -lc
+#endif
+
+/* Use terminfo instead of termcap.  */
+
+#define TERMINFO
+
+/* sioctl.h should be included where appropriate.  */
+
+#define NEED_SIOCTL
+
+/* Letter to use in finding device name of first pty,
+  if system supports pty's.  'a' means it is /dev/ptya0  */
+
+#undef FIRST_PTY_LETTER
+#define FIRST_PTY_LETTER 'q'
+
+/* Define STACK_DIRECTION for alloca.c */
+
+#define STACK_DIRECTION -1
+
+/* The standard definitions of these macros would work ok,
+   but these are faster because the constants are short.  */
+
+#define XUINT(a) (((unsigned)(a) << INTBITS-VALBITS) >> INTBITS-VALBITS)
+
+#define XSET(var, type, ptr) \
+   ((var) = ((int)(type) << VALBITS) + (((unsigned) (ptr) << INTBITS-VALBITS) >> INTBITS-VALBITS))
+
+#define XSETINT(a, b)  XSET(a, XTYPE(a), b)
+#define XSETUINT(a, b) XSET(a, XTYPE(a), b)
+#define XSETPNTR(a, b) XSET(a, XTYPE(a), b)
+
+#define XMARKBIT(a) ((a) < 0)
+#define XSETMARKBIT(a,b) ((a) = ((a) & ~MARKBIT) | ((b) ? MARKBIT : 0))
+#define XUNMARK(a) ((a) = (((unsigned)(a) << INTBITS-GCTYPEBITS-VALBITS) >> INTBITS-GCTYPEBITS-VALBITS))
+
+/* Turn off some "helpful" error checks for type mismatches
+   that we can't fix without breaking other machines.  */
+#define C_SWITCH_MACHINE -cckr
diff --git a/src/s/irix5-0.h b/src/s/irix5-0.h
new file mode 100644
index 00000000000..7f8cb356ee6
--- /dev/null
+++ b/src/s/irix5-0.h
@@ -0,0 +1,47 @@
+#include "irix3-3.h"
+
+#define USG5_3
+
+/* Define HAVE_ALLOCA to say that the system provides a properly
+   working alloca function and it should be used. */
+#define HAVE_ALLOCA
+#undef C_ALLOCA
+#define alloca __builtin_alloca
+
+/* use K&R C */
+#ifndef __GNUC__
+#define C_SWITCH_MACHINE -cckr
+#endif
+
+/* SGI has all the fancy wait stuff, but we can't include sys/wait.h
+   because it defines BIG_ENDIAN and LITTLE_ENDIAN (ugh!.)  Instead
+   we'll just define WNOHANG right here.
+   (An implicit decl is good enough for wait3.)  */
+
+#define WNOHANG         0x1
+
+/* No need to use sprintf to get the tty name--we get that from _getpty.  */
+#define PTY_TTY_NAME_SPRINTF
+/* No need to get the pty name at all.  */
+#define PTY_NAME_SPRINTF
+#ifdef emacs
+char *_getpty();
+#endif
+/* We need only try once to open a pty.  */
+#define PTY_ITERATION
+/* Here is how to do it.  */
+/* It is necessary to prevent SIGCHLD signals within _getpty.
+   So we block them. */
+#define PTY_OPEN                                                \
+{                                                               \
+  int mask = sigblock (sigmask (SIGCHLD));                      \
+  char *name = _getpty (&fd, O_RDWR | O_NDELAY, 0600, 0);       \
+  sigsetmask(mask);                                             \
+  if (name == 0)                                                \
+    return -1;                                                  \
+  if (fd < 0)                                                   \
+    return -1;                                                  \
+  if (fstat (fd, &stb) < 0)                                     \
+    return -1;                                                  \
+  strcpy (pty_name, name);                                      \
+}
diff --git a/src/unexsgi.c b/src/unexsgi.c
new file mode 100644
index 00000000000..b37e09da2f9
--- /dev/null
+++ b/src/unexsgi.c
@@ -0,0 +1,785 @@
+/* Copyright (C) 1985, 1986, 1987, 1988, 1990, 1992
+   Free Software Foundation, Inc.
+
+    This program 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 2, or (at your option)
+    any later version.
+
+    This program 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 this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+In other words, you are welcome to use, share and improve this program.
+You are forbidden to forbid anyone else to use, share and improve
+what you give them.   Help stamp out software-hoarding!  */
+
+
+/*
+ * unexec.c - Convert a running program into an a.out file.
+ *
+ * Author:      Spencer W. Thomas
+ *              Computer Science Dept.
+ *              University of Utah
+ * Date:        Tue Mar  2 1982
+ * Modified heavily since then.
+ *
+ * Synopsis:
+ *      unexec (new_name, a_name, data_start, bss_start, entry_address)
+ *      char *new_name, *a_name;
+ *      unsigned data_start, bss_start, entry_address;
+ *
+ * Takes a snapshot of the program and makes an a.out format file in the
+ * file named by the string argument new_name.
+ * If a_name is non-NULL, the symbol table will be taken from the given file.
+ * On some machines, an existing a_name file is required.
+ *
+ * The boundaries within the a.out file may be adjusted with the data_start
+ * and bss_start arguments.  Either or both may be given as 0 for defaults.
+ *
+ * Data_start gives the boundary between the text segment and the data
+ * segment of the program.  The text segment can contain shared, read-only
+ * program code and literal data, while the data segment is always unshared
+ * and unprotected.  Data_start gives the lowest unprotected address.
+ * The value you specify may be rounded down to a suitable boundary
+ * as required by the machine you are using.
+ *
+ * Specifying zero for data_start means the boundary between text and data
+ * should not be the same as when the program was loaded.
+ * If NO_REMAP is defined, the argument data_start is ignored and the
+ * segment boundaries are never changed.
+ *
+ * Bss_start indicates how much of the data segment is to be saved in the
+ * a.out file and restored when the program is executed.  It gives the lowest
+ * unsaved address, and is rounded up to a page boundary.  The default when 0
+ * is given assumes that the entire data segment is to be stored, including
+ * the previous data and bss as well as any additional storage allocated with
+ * break (2).
+ *
+ * The new file is set up to start at entry_address.
+ *
+ * If you make improvements I'd like to get them too.
+ * harpo!utah-cs!thomas, thomas@Utah-20
+ *
+ */
+
+/* Even more heavily modified by james@bigtex.cactus.org of Dell Computer Co.
+ * ELF support added.
+ *
+ * Basic theory: the data space of the running process needs to be
+ * dumped to the output file.  Normally we would just enlarge the size
+ * of .data, scooting everything down.  But we can't do that in ELF,
+ * because there is often something between the .data space and the
+ * .bss space.
+ *
+ * In the temacs dump below, notice that the Global Offset Table
+ * (.got) and the Dynamic link data (.dynamic) come between .data1 and
+ * .bss.  It does not work to overlap .data with these fields.
+ *
+ * The solution is to create a new .data segment.  This segment is
+ * filled with data from the current process.  Since the contents of
+ * various sections refer to sections by index, the new .data segment
+ * is made the last in the table to avoid changing any existing index.
+
+ * This is an example of how the section headers are changed.  "Addr"
+ * is a process virtual address.  "Offset" is a file offset.
+
+raid:/nfs/raid/src/dist-18.56/src> dump -h temacs
+
+temacs:
+
+           **** SECTION HEADER TABLE ****
+[No]    Type    Flags   Addr         Offset       Size          Name
+        Link    Info    Adralgn      Entsize
+
+[1]     1       2       0x80480d4    0xd4         0x13          .interp
+        0       0       0x1          0            
+
+[2]     5       2       0x80480e8    0xe8         0x388         .hash
+        3       0       0x4          0x4          
+
+[3]     11      2       0x8048470    0x470        0x7f0         .dynsym
+        4       1       0x4          0x10         
+
+[4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
+        0       0       0x1          0            
+
+[5]     9       2       0x8049010    0x1010       0x338         .rel.plt
+        3       7       0x4          0x8          
+
+[6]     1       6       0x8049348    0x1348       0x3           .init
+        0       0       0x4          0            
+
+[7]     1       6       0x804934c    0x134c       0x680         .plt
+        0       0       0x4          0x4          
+
+[8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
+        0       0       0x4          0            
+
+[9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
+        0       0       0x4          0            
+
+[10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
+        0       0       0x4          0            
+
+[11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
+        0       0       0x4          0            
+
+[12]    1       3       0x8088330    0x3f330      0x20afc       .data
+        0       0       0x4          0            
+
+[13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
+        0       0       0x4          0            
+
+[14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
+        0       0       0x4          0x4          
+
+[15]    6       3       0x80a9874    0x60874      0x80          .dynamic
+        4       0       0x4          0x8          
+
+[16]    8       3       0x80a98f4    0x608f4      0x449c        .bss
+        0       0       0x4          0            
+
+[17]    2       0       0            0x608f4      0x9b90        .symtab
+        18      371     0x4          0x10         
+
+[18]    3       0       0            0x6a484      0x8526        .strtab
+        0       0       0x1          0            
+
+[19]    3       0       0            0x729aa      0x93          .shstrtab
+        0       0       0x1          0            
+
+[20]    1       0       0            0x72a3d      0x68b7        .comment
+        0       0       0x1          0            
+
+raid:/nfs/raid/src/dist-18.56/src> dump -h xemacs
+
+xemacs:
+
+           **** SECTION HEADER TABLE ****
+[No]    Type    Flags   Addr         Offset       Size          Name
+        Link    Info    Adralgn      Entsize
+
+[1]     1       2       0x80480d4    0xd4         0x13          .interp
+        0       0       0x1          0            
+
+[2]     5       2       0x80480e8    0xe8         0x388         .hash
+        3       0       0x4          0x4          
+
+[3]     11      2       0x8048470    0x470        0x7f0         .dynsym
+        4       1       0x4          0x10         
+
+[4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
+        0       0       0x1          0            
+
+[5]     9       2       0x8049010    0x1010       0x338         .rel.plt
+        3       7       0x4          0x8          
+
+[6]     1       6       0x8049348    0x1348       0x3           .init
+        0       0       0x4          0            
+
+[7]     1       6       0x804934c    0x134c       0x680         .plt
+        0       0       0x4          0x4          
+
+[8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
+        0       0       0x4          0            
+
+[9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
+        0       0       0x4          0            
+
+[10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
+        0       0       0x4          0            
+
+[11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
+        0       0       0x4          0            
+
+[12]    1       3       0x8088330    0x3f330      0x20afc       .data
+        0       0       0x4          0            
+
+[13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
+        0       0       0x4          0            
+
+[14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
+        0       0       0x4          0x4          
+
+[15]    6       3       0x80a9874    0x60874      0x80          .dynamic
+        4       0       0x4          0x8          
+
+[16]    8       3       0x80c6800    0x7d800      0             .bss
+        0       0       0x4          0            
+
+[17]    2       0       0            0x7d800      0x9b90        .symtab
+        18      371     0x4          0x10         
+
+[18]    3       0       0            0x87390      0x8526        .strtab
+        0       0       0x1          0            
+
+[19]    3       0       0            0x8f8b6      0x93          .shstrtab
+        0       0       0x1          0            
+
+[20]    1       0       0            0x8f949      0x68b7        .comment
+        0       0       0x1          0            
+
+[21]    1       3       0x80a98f4    0x608f4      0x1cf0c       .data
+        0       0       0x4          0            
+
+ * This is an example of how the file header is changed.  "Shoff" is
+ * the section header offset within the file.  Since that table is
+ * after the new .data section, it is moved.  "Shnum" is the number of
+ * sections, which we increment.
+ *
+ * "Phoff" is the file offset to the program header.  "Phentsize" and
+ * "Shentsz" are the program and section header entries sizes respectively.
+ * These can be larger than the apparent struct sizes.
+
+raid:/nfs/raid/src/dist-18.56/src> dump -f temacs
+
+temacs:
+
+                    **** ELF HEADER ****
+Class        Data       Type         Machine     Version
+Entry        Phoff      Shoff        Flags       Ehsize
+Phentsize    Phnum      Shentsz      Shnum       Shstrndx
+
+1            1          2            3           1
+0x80499cc    0x34       0x792f4      0           0x34
+0x20         5          0x28         21          19
+
+raid:/nfs/raid/src/dist-18.56/src> dump -f xemacs
+
+xemacs:
+
+                    **** ELF HEADER ****
+Class        Data       Type         Machine     Version
+Entry        Phoff      Shoff        Flags       Ehsize
+Phentsize    Phnum      Shentsz      Shnum       Shstrndx
+
+1            1          2            3           1
+0x80499cc    0x34       0x96200      0           0x34
+0x20         5          0x28         22          19
+
+ * These are the program headers.  "Offset" is the file offset to the
+ * segment.  "Vaddr" is the memory load address.  "Filesz" is the
+ * segment size as it appears in the file, and "Memsz" is the size in
+ * memory.  Below, the third segment is the code and the fourth is the
+ * data: the difference between Filesz and Memsz is .bss
+
+raid:/nfs/raid/src/dist-18.56/src> dump -o temacs
+
+temacs:
+ ***** PROGRAM EXECUTION HEADER *****
+Type        Offset      Vaddr       Paddr
+Filesz      Memsz       Flags       Align
+
+6           0x34        0x8048034   0           
+0xa0        0xa0        5           0           
+
+3           0xd4        0           0           
+0x13        0           4           0           
+
+1           0x34        0x8048034   0           
+0x3f2f9     0x3f2f9     5           0x1000      
+
+1           0x3f330     0x8088330   0           
+0x215c4     0x25a60     7           0x1000      
+
+2           0x60874     0x80a9874   0           
+0x80        0           7           0           
+
+raid:/nfs/raid/src/dist-18.56/src> dump -o xemacs
+
+xemacs:
+ ***** PROGRAM EXECUTION HEADER *****
+Type        Offset      Vaddr       Paddr
+Filesz      Memsz       Flags       Align
+
+6           0x34        0x8048034   0           
+0xa0        0xa0        5           0           
+
+3           0xd4        0           0           
+0x13        0           4           0           
+
+1           0x34        0x8048034   0           
+0x3f2f9     0x3f2f9     5           0x1000      
+
+1           0x3f330     0x8088330   0           
+0x3e4d0     0x3e4d0     7           0x1000      
+
+2           0x60874     0x80a9874   0           
+0x80        0           7           0           
+
+
+ */
+
+/* Modified by wtien@urbana.mcd.mot.com of Motorola Inc. 
+ * 
+ * The above mechanism does not work if the unexeced ELF file is being
+ * re-layout by other applications (such as `strip'). All the applications 
+ * that re-layout the internal of ELF will layout all sections in ascending
+ * order of their file offsets. After the re-layout, the data2 section will 
+ * still be the LAST section in the section header vector, but its file offset 
+ * is now being pushed far away down, and causes part of it not to be mapped
+ * in (ie. not covered by the load segment entry in PHDR vector), therefore 
+ * causes the new binary to fail.
+ *
+ * The solution is to modify the unexec algorithm to insert the new data2
+ * section header right before the new bss section header, so their file
+ * offsets will be in the ascending order. Since some of the section's (all 
+ * sections AFTER the bss section) indexes are now changed, we also need to 
+ * modify some fields to make them point to the right sections. This is done 
+ * by macro PATCH_INDEX. All the fields that need to be patched are:
+ * 
+ * 1. ELF header e_shstrndx field.
+ * 2. section header sh_link and sh_info field.
+ * 3. symbol table entry st_shndx field.
+ *
+ * The above example now should look like:
+
+           **** SECTION HEADER TABLE ****
+[No]    Type    Flags   Addr         Offset       Size          Name
+        Link    Info    Adralgn      Entsize
+
+[1]     1       2       0x80480d4    0xd4         0x13          .interp
+        0       0       0x1          0            
+
+[2]     5       2       0x80480e8    0xe8         0x388         .hash
+        3       0       0x4          0x4          
+
+[3]     11      2       0x8048470    0x470        0x7f0         .dynsym
+        4       1       0x4          0x10         
+
+[4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
+        0       0       0x1          0            
+
+[5]     9       2       0x8049010    0x1010       0x338         .rel.plt
+        3       7       0x4          0x8          
+
+[6]     1       6       0x8049348    0x1348       0x3           .init
+        0       0       0x4          0            
+
+[7]     1       6       0x804934c    0x134c       0x680         .plt
+        0       0       0x4          0x4          
+
+[8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
+        0       0       0x4          0            
+
+[9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
+        0       0       0x4          0            
+
+[10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
+        0       0       0x4          0            
+
+[11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
+        0       0       0x4          0            
+
+[12]    1       3       0x8088330    0x3f330      0x20afc       .data
+        0       0       0x4          0            
+
+[13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
+        0       0       0x4          0            
+
+[14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
+        0       0       0x4          0x4          
+
+[15]    6       3       0x80a9874    0x60874      0x80          .dynamic
+        4       0       0x4          0x8          
+
+[16]    1       3       0x80a98f4    0x608f4      0x1cf0c       .data
+        0       0       0x4          0            
+
+[17]    8       3       0x80c6800    0x7d800      0             .bss
+        0       0       0x4          0            
+
+[18]    2       0       0            0x7d800      0x9b90        .symtab
+        19      371     0x4          0x10         
+
+[19]    3       0       0            0x87390      0x8526        .strtab
+        0       0       0x1          0            
+
+[20]    3       0       0            0x8f8b6      0x93          .shstrtab
+        0       0       0x1          0            
+
+[21]    1       0       0            0x8f949      0x68b7        .comment
+        0       0       0x1          0            
+
+ */
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <memory.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <elf.h>
+#include <sys/mman.h>
+
+#ifndef emacs
+#define fatal(a, b, c) fprintf(stderr, a, b, c), exit(1)
+#else
+extern void fatal(char *, ...);
+#endif
+
+/* Get the address of a particular section or program header entry,
+ * accounting for the size of the entries.
+ */
+
+#define OLD_SECTION_H(n) \
+     (*(Elf32_Shdr *) ((byte *) old_section_h + old_file_h->e_shentsize * (n)))
+#define NEW_SECTION_H(n) \
+     (*(Elf32_Shdr *) ((byte *) new_section_h + new_file_h->e_shentsize * (n)))
+#define OLD_PROGRAM_H(n) \
+     (*(Elf32_Phdr *) ((byte *) old_program_h + old_file_h->e_phentsize * (n)))
+#define NEW_PROGRAM_H(n) \
+     (*(Elf32_Phdr *) ((byte *) new_program_h + new_file_h->e_phentsize * (n)))
+
+#define PATCH_INDEX(n) \
+  do { \
+         if ((n) >= old_bss_index) \
+           (n)++; } while (0)
+typedef unsigned char byte;
+
+/* Round X up to a multiple of Y.  */
+
+int
+round_up (x, y)
+     int x, y;
+{
+  int rem = x % y;
+  if (rem == 0)
+    return x;
+  return x - rem + y;
+}
+
+/* ****************************************************************
+ * unexec
+ *
+ * driving logic.
+ *
+ * In ELF, this works by replacing the old .bss section with a new
+ * .data section, and inserting an empty .bss immediately afterwards.
+ *
+ */
+void
+unexec (new_name, old_name, data_start, bss_start, entry_address)
+     char *new_name, *old_name;
+     unsigned data_start, bss_start, entry_address;
+{
+  extern unsigned int bss_end;
+  int new_file, old_file, new_file_size;
+
+  /* Pointers to the base of the image of the two files. */
+  caddr_t old_base, new_base;
+
+  /* Pointers to the file, program and section headers for the old and new
+   * files.
+   */
+  Elf32_Ehdr *old_file_h, *new_file_h;
+  Elf32_Phdr *old_program_h, *new_program_h;
+  Elf32_Shdr *old_section_h, *new_section_h;
+
+  /* Point to the section name table in the old file */
+  char *old_section_names;
+
+  Elf32_Addr old_bss_addr, new_bss_addr;
+  Elf32_Word old_bss_size, new_data2_size;
+  Elf32_Off  new_data2_offset;
+  Elf32_Addr new_data2_addr;
+
+  int n, nn, old_bss_index, old_data_index, new_data2_index;
+  struct stat stat_buf;
+
+  /* Open the old file & map it into the address space. */
+
+  old_file = open (old_name, O_RDONLY);
+
+  if (old_file < 0)
+    fatal ("Can't open %s for reading: errno %d\n", old_name, errno);
+
+  if (fstat (old_file, &stat_buf) == -1)
+    fatal ("Can't fstat(%s): errno %d\n", old_name, errno);
+
+  old_base = mmap (0, stat_buf.st_size, PROT_READ, MAP_SHARED, old_file, 0);
+
+  if (old_base == (caddr_t) -1)
+    fatal ("Can't mmap(%s): errno %d\n", old_name, errno);
+
+#ifdef DEBUG
+  fprintf (stderr, "mmap(%s, %x) -> %x\n", old_name, stat_buf.st_size,
+           old_base);
+#endif
+
+  /* Get pointers to headers & section names */
+
+  old_file_h = (Elf32_Ehdr *) old_base;
+  old_program_h = (Elf32_Phdr *) ((byte *) old_base + old_file_h->e_phoff);
+  old_section_h = (Elf32_Shdr *) ((byte *) old_base + old_file_h->e_shoff);
+  old_section_names = (char *) old_base
+    + OLD_SECTION_H(old_file_h->e_shstrndx).sh_offset;
+
+  /* Find the old .bss section.  Figure out parameters of the new
+   * data2 and bss sections.
+   */
+
+  for (old_bss_index = 1; old_bss_index < old_file_h->e_shnum; old_bss_index++)
+    {
+#ifdef DEBUG
+      fprintf (stderr, "Looking for .bss - found %s\n",
+               old_section_names + OLD_SECTION_H(old_bss_index).sh_name);
+#endif
+      if (!strcmp (old_section_names + OLD_SECTION_H(old_bss_index).sh_name,
+                   ".bss"))
+        break;
+    }
+  if (old_bss_index == old_file_h->e_shnum)
+    fatal ("Can't find .bss in %s.\n", old_name, 0);
+
+  old_bss_addr = OLD_SECTION_H(old_bss_index).sh_addr;
+  old_bss_size = OLD_SECTION_H(old_bss_index).sh_size;
+#if defined(emacs) || !defined(DEBUG)
+  bss_end = (unsigned int) sbrk (0);
+  new_bss_addr = (Elf32_Addr) bss_end;
+#else
+  new_bss_addr = old_bss_addr + old_bss_size + 0x1234;
+#endif
+  new_data2_addr = old_bss_addr;
+  new_data2_size = new_bss_addr - old_bss_addr;
+  new_data2_offset = OLD_SECTION_H(old_bss_index).sh_offset;
+
+#ifdef DEBUG
+  fprintf (stderr, "old_bss_index %d\n", old_bss_index);
+  fprintf (stderr, "old_bss_addr %x\n", old_bss_addr);
+  fprintf (stderr, "old_bss_size %x\n", old_bss_size);
+  fprintf (stderr, "new_bss_addr %x\n", new_bss_addr);
+  fprintf (stderr, "new_data2_addr %x\n", new_data2_addr);
+  fprintf (stderr, "new_data2_size %x\n", new_data2_size);
+  fprintf (stderr, "new_data2_offset %x\n", new_data2_offset);
+#endif
+
+  if ((unsigned) new_bss_addr < (unsigned) old_bss_addr + old_bss_size)
+    fatal (".bss shrank when undumping???\n", 0, 0);
+
+  /* Set the output file to the right size and mmap(2) it.  Set
+   * pointers to various interesting objects.  stat_buf still has
+   * old_file data.
+   */
+
+  new_file = open (new_name, O_RDWR | O_CREAT, 0666);
+  if (new_file < 0)
+    fatal ("Can't creat(%s): errno %d\n", new_name, errno);
+
+  new_file_size = stat_buf.st_size + old_file_h->e_shentsize + new_data2_size;
+
+  if (ftruncate (new_file, new_file_size))
+    fatal ("Can't ftruncate(%s): errno %d\n", new_name, errno);
+
+  new_base = mmap (0, new_file_size, PROT_READ | PROT_WRITE, MAP_SHARED,
+                   new_file, 0);
+
+  if (new_base == (caddr_t) -1)
+    fatal ("Can't mmap(%s): errno %d\n", new_name, errno);
+
+  new_file_h = (Elf32_Ehdr *) new_base;
+  new_program_h = (Elf32_Phdr *) ((byte *) new_base + old_file_h->e_phoff);
+  new_section_h = (Elf32_Shdr *)
+    ((byte *) new_base + old_file_h->e_shoff + new_data2_size);
+
+  /* Make our new file, program and section headers as copies of the
+   * originals.
+   */
+
+  memcpy (new_file_h, old_file_h, old_file_h->e_ehsize);
+  memcpy (new_program_h, old_program_h,
+          old_file_h->e_phnum * old_file_h->e_phentsize);
+
+  /* Modify the e_shstrndx if necessary. */
+  PATCH_INDEX (new_file_h->e_shstrndx);
+
+  /* Fix up file header.  We'll add one section.  Section header is
+   * further away now.
+   */
+
+  new_file_h->e_shoff += new_data2_size;
+  new_file_h->e_shnum += 1;
+
+#ifdef DEBUG
+  fprintf (stderr, "Old section offset %x\n", old_file_h->e_shoff);
+  fprintf (stderr, "Old section count %d\n", old_file_h->e_shnum);
+  fprintf (stderr, "New section offset %x\n", new_file_h->e_shoff);
+  fprintf (stderr, "New section count %d\n", new_file_h->e_shnum);
+#endif
+
+  /* Fix up a new program header.  Extend the writable data segment so
+   * that the bss area is covered too. Find that segment by looking
+   * for a segment that ends just before the .bss area.  Make sure
+   * that no segments are above the new .data2.  Put a loop at the end
+   * to adjust the offset and address of any segment that is above
+   * data2, just in case we decide to allow this later.
+   */
+
+  for (n = new_file_h->e_phnum - 1; n >= 0; n--)
+    {
+      /* Compute maximum of all requirements for alignment of section.  */
+      int alignment = (NEW_PROGRAM_H (n)).p_align;
+      if ((OLD_SECTION_H (old_bss_index)).sh_addralign > alignment)
+        alignment = OLD_SECTION_H (old_bss_index).sh_addralign;
+
+      if (NEW_PROGRAM_H(n).p_vaddr + NEW_PROGRAM_H(n).p_filesz > old_bss_addr)
+        fatal ("Program segment above .bss in %s\n", old_name, 0);
+
+      if (NEW_PROGRAM_H(n).p_type == PT_LOAD
+          && (round_up ((NEW_PROGRAM_H (n)).p_vaddr
+                        + (NEW_PROGRAM_H (n)).p_filesz,
+                        alignment)
+              == round_up (old_bss_addr, alignment)))
+        break;
+    }
+  if (n < 0)
+    fatal ("Couldn't find segment next to .bss in %s\n", old_name, 0);
+
+  NEW_PROGRAM_H(n).p_filesz += new_data2_size;
+  NEW_PROGRAM_H(n).p_memsz = NEW_PROGRAM_H(n).p_filesz;
+
+#if 0 /* Maybe allow section after data2 - does this ever happen? */
+  for (n = new_file_h->e_phnum - 1; n >= 0; n--)
+    {
+      if (NEW_PROGRAM_H(n).p_vaddr
+          && NEW_PROGRAM_H(n).p_vaddr >= new_data2_addr)
+        NEW_PROGRAM_H(n).p_vaddr += new_data2_size - old_bss_size;
+
+      if (NEW_PROGRAM_H(n).p_offset >= new_data2_offset)
+        NEW_PROGRAM_H(n).p_offset += new_data2_size;
+    }
+#endif
+
+  /* Fix up section headers based on new .data2 section.  Any section
+   * whose offset or virtual address is after the new .data2 section
+   * gets its value adjusted.  .bss size becomes zero and new address
+   * is set.  data2 section header gets added by copying the existing
+   * .data header and modifying the offset, address and size.
+   */
+  for (old_data_index = 1; old_data_index < old_file_h->e_shnum;
+       old_data_index++)
+    if (!strcmp (old_section_names + OLD_SECTION_H(old_data_index).sh_name,
+                 ".data"))
+      break;
+  if (old_data_index == old_file_h->e_shnum)
+    fatal ("Can't find .data in %s.\n", old_name, 0);
+
+  /* Walk through all section headers, insert the new data2 section right 
+     before the new bss section. */
+  for (n = 1, nn = 1; n < old_file_h->e_shnum; n++, nn++)
+    {
+      caddr_t src;
+      /* If it is bss section, insert the new data2 section before it. */
+      if (n == old_bss_index)
+        {
+          /* Steal the data section header for this data2 section. */
+          memcpy (&NEW_SECTION_H(nn), &OLD_SECTION_H(old_data_index),
+                  new_file_h->e_shentsize);
+          
+          NEW_SECTION_H(nn).sh_addr = new_data2_addr;
+          NEW_SECTION_H(nn).sh_offset = new_data2_offset;
+          NEW_SECTION_H(nn).sh_size = new_data2_size;
+          /* Use the bss section's alignment. This will assure that the
+             new data2 section always be placed in the same spot as the old
+             bss section by any other application. */
+          NEW_SECTION_H(nn).sh_addralign = OLD_SECTION_H(n).sh_addralign;
+
+          /* Now copy over what we have in the memory now. */
+          memcpy (NEW_SECTION_H(nn).sh_offset + new_base, 
+                  (caddr_t) OLD_SECTION_H(n).sh_addr, 
+                  new_data2_size);
+          nn++;
+        }
+      
+      memcpy (&NEW_SECTION_H(nn), &OLD_SECTION_H(n), 
+              old_file_h->e_shentsize);
+      
+      /* The new bss section's size is zero, and its file offset and virtual
+         address should be off by NEW_DATA2_SIZE. */
+      if (n == old_bss_index)
+        {
+          /* NN should be `old_bss_index + 1' at this point. */
+          NEW_SECTION_H(nn).sh_offset += new_data2_size;
+          NEW_SECTION_H(nn).sh_addr += new_data2_size;
+          /* Let the new bss section address alignment be the same as the
+             section address alignment followed the old bss section, so 
+             this section will be placed in exactly the same place. */
+          NEW_SECTION_H(nn).sh_addralign = OLD_SECTION_H(nn).sh_addralign;
+          NEW_SECTION_H(nn).sh_size = 0;
+        }
+      /* Any section that was original placed AFTER the bss section should now
+         be off by NEW_DATA2_SIZE. */
+      else if (NEW_SECTION_H(nn).sh_offset >= new_data2_offset)
+        NEW_SECTION_H(nn).sh_offset += new_data2_size;
+      
+      /* If any section hdr refers to the section after the new .data
+         section, make it refer to next one because we have inserted 
+         a new section in between. */
+      
+      PATCH_INDEX(NEW_SECTION_H(nn).sh_link);
+      PATCH_INDEX(NEW_SECTION_H(nn).sh_info);
+      
+      /* Now, start to copy the content of sections. */
+      if (NEW_SECTION_H(nn).sh_type == SHT_NULL
+          || NEW_SECTION_H(nn).sh_type == SHT_NOBITS)
+        continue;
+      
+      /* Write out the sections. .data and .data1 (and data2, called
+       * ".data" in the strings table) get copied from the current process
+       * instead of the old file.
+       */
+      if (!strcmp (old_section_names + NEW_SECTION_H(n).sh_name, ".data")
+          || !strcmp ((old_section_names + NEW_SECTION_H(n).sh_name),
+                      ".data1"))
+        src = (caddr_t) OLD_SECTION_H(n).sh_addr;
+      else
+        src = old_base + OLD_SECTION_H(n).sh_offset;
+      
+      memcpy (NEW_SECTION_H(nn).sh_offset + new_base, src,
+              NEW_SECTION_H(nn).sh_size);
+
+      /* If it is the symbol table, its st_shndx field needs to be patched. */
+      if (NEW_SECTION_H(nn).sh_type == SHT_SYMTAB
+          || NEW_SECTION_H(nn).sh_type == SHT_DYNSYM)
+        {
+          Elf32_Shdr *spt = &NEW_SECTION_H(nn);
+          unsigned int num = spt->sh_size / spt->sh_entsize;
+          Elf32_Sym * sym = (Elf32_Sym *) (NEW_SECTION_H(nn).sh_offset + 
+                                           new_base);
+          for (; num--; sym++)
+            {
+              if ((sym->st_shndx == SHN_UNDEF)
+                  || (sym->st_shndx == SHN_ABS)
+                  || (sym->st_shndx == SHN_COMMON))
+                continue;
+        
+              PATCH_INDEX(sym->st_shndx);
+            }
+        }
+    }
+
+  /* Close the files and make the new file executable */
+
+  if (close (old_file))
+    fatal ("Can't close(%s): errno %d\n", old_name, errno);
+
+  if (close (new_file))
+    fatal ("Can't close(%s): errno %d\n", new_name, errno);
+
+  if (stat (new_name, &stat_buf) == -1)
+    fatal ("Can't stat(%s): errno %d\n", new_name, errno);
+
+  n = umask (777);
+  umask (n);
+  stat_buf.st_mode |= 0111 & ~n;
+  if (chmod (new_name, stat_buf.st_mode) == -1)
+    fatal ("Can't chmod(%s): errno %d\n", new_name, errno);
+}