bruce@stride.UUCP (Bruce Robertson) (10/23/85)
This should run under any System-V - just defined USG to get the System-V
code. Let me know if you have any problems, please.
Bruce Robertson
UUCP: cbosgd!utah-cs!utah-gr!stride!bruce
--------- cut here -------------
/*
* 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
* Copyright (c) 1982 Spencer W. Thomas
*
* 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.
*
* 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. Since
* the granularity of write-protection is on 1k page boundaries on the VAX, a
* given data_start value which is not on a page boundary is rounded down to
* the beginning of the page it is on. The default when 0 is given leaves the
* number of protected pages the same as it was before.
*
* 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
*
*/
#ifndef emacs
#define PERROR perror
#define ERROR fprintf
#define ERRORF stderr,
#else
#include "config.h"
#define PERROR(file) error ("Failure operating on %s", file)
#define ERROR error
#define ERRORF
#endif
#if defined(USG) || defined(STRIDE)
#include <sys/types.h>
#endif
#include <sys/param.h>
#include <stdio.h>
/* #include <sys/dir.h> */
#include <sys/stat.h>
#include <a.out.h>
#include <errno.h>
#if defined(USG) || defined(STRIDE)
static struct filehdr filehdr;
static struct filehdr old;
static struct aouthdr aouthdr;
static struct scnhdr text, data, bss;
static int pagemask;
extern char etext[];
/* ****************************************************************
* unexec
*
* driving logic.
*/
unexec (new_name, a_name, data_start, bss_start, entry_address)
char *new_name, *a_name;
unsigned data_start, bss_start, entry_address;
{
int new, a_out = -1;
if (a_name && (a_out = open( a_name, 0 )) < 0)
{
PERROR (a_name);
return -1;
}
if ((new = creat (new_name, 0666)) < 0)
{
PERROR( new_name );
return -1;
}
pagemask = MMU_PAGESIZE - 1;
filehdr.f_magic = MC68MAGIC;
filehdr.f_nscns = 3; /* text, data and bss */
time(&filehdr.f_timdat);
filehdr.f_opthdr = sizeof aouthdr;
filehdr.f_flags = F_RELFLG | F_EXEC | F_LNNO | F_AR32WR;
if (make_hdr( new, a_out, data_start, bss_start, entry_address) < 0 ||
copy_text_and_data( new ) < 0 ||
copy_sym( new, a_out ) < 0)
{
close (new);
/* unlink( new_name ); /* Failed, unlink new a.out */
return -1;
}
close (new);
if (a_out >= 0)
close (a_out);
mark_x (new_name);
return 0;
}
/* ****************************************************************
* make_hdr
*
* Make the header in the new a.out from the header in core.
* Modify the text and data sizes.
*/
static int
make_hdr( new, a_out, data_start, bss_start, entry_address)
int new, a_out;
unsigned data_start, bss_start, entry_address;
{
/* Adjust data/bss boundary. */
if ( bss_start != 0 )
{
/* bss_start = (bss_start + pagemask) & ~pagemask; /* (Up) to page bdry. */
if ( bss_start > sbrk (0))
{
ERROR( ERRORF
"unexec: Specified bss_start( %u ) is past end of program.\n",
bss_start );
return -1;
}
}
else
bss_start = sbrk (0);
/* Adjust text/data boundary. */
if (!data_start)
data_start = (int) etext;
data_start = data_start & ~pagemask; /* (Down) to page boundary. */
if ( data_start > bss_start ) /* Can't have negative data size. */
{
ERROR( ERRORF
"unexec: data_start(%u) can't be greater than bss_start( %u ).\n",
data_start, bss_start );
return -1;
}
aouthdr.magic = 0410;
aouthdr.vstamp = 0;
aouthdr.text_start = TEXT_START;
aouthdr.data_start = data_start;
aouthdr.entry = entry_address;
aouthdr.bsize = sbrk (0) - bss_start;
aouthdr.dsize = bss_start - data_start;
aouthdr.tsize = data_start - TEXT_START;
strcpy(text.s_name, _TEXT);
text.s_paddr = text.s_vaddr = aouthdr.text_start;
text.s_size = aouthdr.tsize;
text.s_scnptr = sizeof filehdr + sizeof aouthdr + 3 * SCNHSZ;
text.s_relptr = text.s_lnnoptr = text.s_nreloc = text.s_nlnno = 0;
text.s_flags = STYP_REG | STYP_TEXT;
strcpy(data.s_name, _DATA);
data.s_paddr = data.s_vaddr = aouthdr.data_start;
data.s_size = aouthdr.dsize;
data.s_scnptr = text.s_scnptr + text.s_size;
data.s_relptr = data.s_lnnoptr = data.s_nreloc = data.s_nlnno = 0;
data.s_flags = STYP_REG | STYP_DATA;
strcpy(bss.s_name, _BSS);
bss.s_paddr = bss.s_vaddr = data.s_paddr + data.s_size;
bss.s_size = aouthdr.bsize;
bss.s_scnptr = 0;
bss.s_relptr = bss.s_lnnoptr = bss.s_nreloc = bss.s_nlnno = 0;
bss.s_flags = STYP_REG | STYP_BSS;
/* Get symbol table info from header of a.out file if given one. */
if ( a_out >= 0 )
{
if ( read( a_out, &old, sizeof old ) != sizeof old )
{
PERROR( "Couldn't read header from a.out file" );
return -1;
}
if (old.f_magic != MC68MAGIC)
{
ERROR( ERRORF "a.out file doesn't have legal magic number\n" );
return -1;
}
filehdr.f_nsyms = old.f_nsyms;
filehdr.f_symptr = data.s_scnptr + data.s_size;
}
else
{
filehdr.f_nsyms = 0; /* No a.out, so no symbol info. */
filehdr.f_symptr = 0;
}
if (write(new, (char *) &filehdr, sizeof filehdr) != sizeof filehdr
|| write(new, (char *) &aouthdr, sizeof aouthdr) != sizeof aouthdr
|| write(new, (char *) &text, sizeof text) != sizeof text
|| write(new, (char *) &data, sizeof data) != sizeof data
|| write(new, (char *) &bss, sizeof bss) != sizeof bss)
{
PERROR( "Couldn't write header to new a.out file" );
return -1;
}
return 0;
}
/* ****************************************************************
* copy_text_and_data
*
* Copy the text and data segments from memory to the new a.out
*/
static int
copy_text_and_data( new )
int new;
{
int nwrite, ret;
int end;
int i;
int ptr;
char buf[80];
extern int errno;
end = aouthdr.tsize + aouthdr.dsize;
for (i = 0, ptr = TEXT_START; i < end;)
{
nwrite = 128;
if (nwrite > end - i) nwrite = end - i;
ret = write (new, ptr, nwrite);
if (ret == -1 && errno == EFAULT)
{
lseek (new, text.s_scnptr + i + nwrite, 0);
}
else if (nwrite != ret)
{
sprintf(buf, "Write failure in unexec: ptr 0x%x size 0x%x nwrite 0x%x errno %d",
ptr, nwrite, ret, errno);
PERROR(buf);
return -1;
}
i += nwrite;
ptr += nwrite;
}
return 0;
}
/* ****************************************************************
* copy_sym
*
* Copy the relocation information and symbol table from the a.out to the new
*/
static int
copy_sym( new, a_out )
int new, a_out;
{
char page[1024];
int n;
if ( a_out < 0 )
return 0;
lseek(a_out, old.f_symptr, 0);
while ( (n = read( a_out, page, sizeof page )) > 0 )
{
if ( write( new, page, n ) != n )
{
PERROR( "Error writing symbol table to new a.out" );
ERROR( ERRORF "new a.out should be ok otherwise\n" );
return 0;
}
}
if ( n < 0 )
{
PERROR( "Error reading symbol table from a.out,\n" );
ERROR( ERRORF "new a.out should be ok otherwise\n" );
}
return 0;
}
/* ****************************************************************
* mark_x
*
* After succesfully building the new a.out, mark it executable
*/
static
mark_x( name )
char *name;
{
struct stat sbuf;
int um;
um = umask( 777 );
umask( um );
if ( stat( name, &sbuf ) == -1 )
{
PERROR ( "Can't stat new a.out" );
ERROR( ERRORF "Setting protection to %o\n", 0777 & ~um );
sbuf.st_mode = 0777;
}
sbuf.st_mode |= 0111 & ~um;
if ( chmod( name, sbuf.st_mode ) == -1 )
PERROR( "Couldn't change mode of new a.out to executable" );
}
#else /* USG || STRIDE */
extern char etext;
static struct exec hdr, ohdr;
static int pagemask;
/* ****************************************************************
* unexec
*
* driving logic.
*/
unexec (new_name, a_name, data_start, bss_start, entry_address)
char *new_name, *a_name;
unsigned data_start, bss_start, entry_address;
{
int new, a_out = -1;
if (a_name && (a_out = open( a_name, 0 )) < 0)
{
PERROR (a_name);
return -1;
}
if ((new = creat (new_name, 0666)) < 0)
{
PERROR( new_name );
return -1;
}
pagemask = getpagesize () - 1;
if (make_hdr( new, a_out, data_start, bss_start, entry_address) < 0 ||
copy_text_and_data( new ) < 0 ||
copy_sym( new, a_out ) < 0)
{
close (new);
/* unlink( new_name ); /* Failed, unlink new a.out */
return -1;
}
close (new);
if (a_out >= 0)
close (a_out);
mark_x (new_name);
return 0;
}
/* ****************************************************************
* make_hdr
*
* Make the header in the new a.out from the header in core.
* Modify the text and data sizes.
*/
static int
make_hdr( new, a_out, data_start, bss_start, entry_address)
int new, a_out;
unsigned data_start, bss_start, entry_address;
{
/* Get symbol table info from header of a.out file if given one. */
if ( a_out >= 0 )
{
if ( read( a_out, &ohdr, sizeof hdr ) != sizeof hdr )
{
PERROR( "Couldn't read header from a.out file" );
return -1;
}
if N_BADMAG( ohdr )
{
ERROR( ERRORF "a.out file doesn't have legal magic number\n" );
return -1;
}
hdr.a_syms = ohdr.a_syms;
}
else
hdr.a_syms = 0; /* No a.out, so no symbol info. */
/* Construct header from user structure. */
hdr.a_magic = ZMAGIC;
hdr.a_trsize = 0;
hdr.a_drsize = 0;
hdr.a_entry = entry_address;
/* Adjust data/bss boundary. */
if ( bss_start != 0 )
{
bss_start = (bss_start + pagemask) & ~pagemask; /* (Up) to page bdry. */
if ( bss_start > sbrk (0))
{
ERROR( ERRORF
"unexec: Specified bss_start( %u ) is past end of program.\n",
bss_start );
return -1;
}
}
else
bss_start = (sbrk (0) + pagemask) & ~pagemask;
/* Adjust text/data boundary. */
if (!data_start)
data_start = (int) &etext;
#ifdef SUN
data_start = data_start & ~(SEGSIZ - 1); /* (Down) to segment boundary. */
#else
data_start = data_start & ~pagemask; /* (Down) to page boundary. */
#endif
if ( data_start > bss_start ) /* Can't have negative data size. */
{
ERROR( ERRORF
"unexec: data_start(%u) can't be greater than bss_start( %u ).\n",
data_start, bss_start );
return -1;
}
hdr.a_bss = sbrk (0) - bss_start;
hdr.a_data = bss_start - data_start;
hdr.a_text = data_start - TEXT_START;
if ( write( new, &hdr, sizeof hdr ) != sizeof hdr )
{
PERROR( "Couldn't write header to new a.out file" );
return -1;
}
return 0;
}
/* ****************************************************************
* copy_text_and_data
*
* Copy the text and data segments from memory to the new a.out
*/
static int
copy_text_and_data( new )
int new;
{
int nwrite, ret;
int end;
int i;
int ptr;
char buf[80];
extern int errno;
lseek (new, (long) N_TXTOFF (hdr), 0);
end = hdr.a_text + hdr.a_data;
for (i = 0, ptr = TEXT_START; i < end;)
{
nwrite = 128;
if (nwrite > end - i) nwrite = end - i;
ret = write (new, ptr, nwrite);
if (ret == -1 && errno == EFAULT)
{
lseek (new, (long) (N_TXTOFF (hdr) + i + nwrite), 0);
}
else if (nwrite != ret)
{
sprintf(buf, "Write failure in unexec: ptr 0x%x size 0x%x nwrite 0x%x errno %d",
ptr, nwrite, ret, errno);
PERROR(buf);
return -1;
}
i += nwrite;
ptr += nwrite;
}
return 0;
}
/* ****************************************************************
* copy_sym
*
* Copy the relocation information and symbol table from the a.out to the new
*/
static int
copy_sym( new, a_out )
int new, a_out;
{
char page[1024];
int n;
if ( a_out < 0 )
return 0;
lseek( a_out, (long)N_SYMOFF(ohdr), 0 ); /* Position a.out to symtab.*/
while ( (n = read( a_out, page, sizeof page )) > 0 )
{
if ( write( new, page, n ) != n )
{
PERROR( "Error writing symbol table to new a.out" );
ERROR( ERRORF "new a.out should be ok otherwise\n" );
return 0;
}
}
if ( n < 0 )
{
PERROR( "Error reading symbol table from a.out,\n" );
ERROR( ERRORF "new a.out should be ok otherwise\n" );
}
return 0;
}
/* ****************************************************************
* mark_x
*
* After succesfully building the new a.out, mark it executable
*/
static
mark_x( name )
char *name;
{
struct stat sbuf;
int um;
um = umask( 777 );
umask( um );
if ( stat( name, &sbuf ) == -1 )
{
PERROR ( "Can't stat new a.out" );
ERROR( ERRORF "Setting protection to %o\n", 0777 & ~um );
sbuf.st_mode = 0777;
}
sbuf.st_mode |= 0111 & ~um;
if ( chmod( name, sbuf.st_mode ) == -1 )
PERROR( "Couldn't change mode of new a.out to executable" );
}
#endif /* USG || STRIDE */
--
Bruce Robertson
UUCP: cbosgd!utah-cs!utah-gr!stride!bruce