xref: /src/sys/arch/amiga/stand/binpatch/binpatch.c

/*	$NetBSD: binpatch.c,v 1.13 2016/05/30 02:41:39 dholland Exp $	*/

/* Author: Markus Wild mw (at) eunet.ch ???   */
/* Modified: Rob Leland leland (at) mitre.org */

#include <sys/types.h>
#include <a.out.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifdef __NetBSD__
/*
 * assume NMAGIC files are linked at 0 (for kernel)
 */
#undef N_TXTADDR
#define N_TXTADDR(ex) \
	((N_GETMAGIC2(ex) == (ZMAGIC|0x10000) || N_GETMAGIC2(ex) == NMAGIC) ? \
	0 : AOUT_LDPGSZ)
#endif


static char synusage[] =
"NAME\n"
"\t%s - Allows the patching of BSD binaries\n"
"SYNOPSIS\n"
"\t%s [-HELP]\n"
"\t%s [-b|-w|-l] -s symbol[[[index]][=value]] binary\n"
"\t%s [-b|-w|-l] [-o offset] -s symbol [-r value] binary\n"
"\t%s [-b|-w|-l] [-o offset] -a address [-r value] binary\n";

static char desusage[] =
"DESCRIPTION\n"
"\tAllows the patching of BSD binaries, for example,a distributed\n"
"\tkernel. Recient additions allows the user to index into an array\n"
"\tand assign a value. Binpatch has internal variables to allow\n"
"\tyou to test it on itself under NetBSD.\n"
"OPTIONS\n"
"\t-a  patch variable by specifying address in hex\n"
"\t-b  symbol or address to be patched is 1 byte\n"
"\t-l  symbol or address to be patched is 4 bytes  (default)\n"
"\t-o  offset to begin patching value relative to symbol or address\n"
"\t-r  replace value, and print out previous value to stdout\n"
"\t-s  patch variable by specifying symbol name. Use '[]'\n"
"\t    to specify the 'index'. If '-b, -w or -l' not specified\n"
"\t    then index value is used like an offset. Also can use '='\n"
"\t    to assign value\n"
"\t-w  symbol or address to be patched is 2 bytes\n"
"EXAMPLES\n"
"\tThis should print 100 (this is a nice reality check...)\n"
"\t\tbinpatch -l -s _hz netbsd\n"
"\tNow it gets more advanced, replace the value:\n"
"\t\tbinpatch -l -s _sbic_debug -r 1 netbsd\n"
"\tNow patch a variable at a given 'index' not offset,\n"
"\tunder NetBSD you must use '', under AmigaDos CLI '' is optional.:\n"
"\t\tbinpatch -w -s '_vieww[4]' -r 0 a.out\n"
"\tsame as\n"
"\t\tbinpatch -w -o 8 -s _vieww -r 0 a.out\n"
"\tAnother example of using []\n"
"\t\tbinpatch -s '_viewl[4]' -r 0 a.out\n"
"\tsame as\n"
"\t\tbinpatch -o 4 -s _viewl -r 0 a.out\n"
"\tOne last example using '=' and []\n"
"\t\tbinpatch -w -s '_vieww[4]=2' a.out\n"
"\tSo if the kernel is not finding your drives, you could enable\n"
"\tall available debugging options, helping to shed light on that problem.\n"
"\t\tbinpatch -l -s _sbic_debug -r 1 netbsd	scsi-level\n"
"\t\tbinpatch -l -s _sddebug -r 1 netbsd	sd-level (disk-driver)\n"
"\t\tbinpatch -l -s _acdebug -r 1 netbsd	autoconfig-level\n"
"SEE ALSO\n"
"\tbinpatch.c binpatch(1)\n";

extern char *optarg;
extern int optind;

void error (char *) __attribute__((__noreturn__));
static void Synopsis(char *program_name);
static void Usage(char *program_name);
static u_long FindAssign(char *symbol, u_long *rvalue);
static void FindOffset(char *symbol, u_long *index);

/* The following variables are so binpatch can be tested on itself */
int test = 1;
int testbss;
char foo = 23;
char  viewb[10] = {0,0,1,0,1,1,0,1,1,1};
short vieww[10] = {0,0,1,0,1,1,0,1,1,1};
long  viewl[10] = {0,0,1,0,1,1,0,1,1,1};
/* End of test binpatch variables */

int
main(int argc, char *argv[])
{
	struct exec e;
	int c;
	u_long addr = 0, offset = 0;
	u_long index = 0;/* Related to offset */
	u_long replace = 0, do_replace = 0;
	char *symbol = 0;
	char size = 4;  /* default to long */
	char size_opt = 0; /* Flag to say size option was set, used with index */
	char *fname;
	char *pgname = argv[0]; /* Program name */
	int fd;
	int type, off;
	u_long  lval;
	u_short sval;
	u_char  cval;


	while ((c = getopt (argc, argv, "H:a:bwlr:s:o:")) != -1)
		switch (c)
		{
		    case 'H':
			Usage(argv[0]);
			break;
		    case 'a':
			if (addr || symbol)
				error ("only one address/symbol allowed");
			if (! strncmp (optarg, "0x", 2))
				sscanf (optarg, "%x", &addr);
			else
				addr = atoi (optarg);
			if (! addr)
				error ("invalid address");
			break;

		    case 'b':
			size = 1;
			size_opt = 1;
			break;

		    case 'w':
			size = 2;
			size_opt = 1;
			break;

		    case 'l':
			size = 4;
			size_opt = 1;
			break;

		    case 'r':
			do_replace = 1;
			if (! strncmp (optarg, "0x", 2))
				sscanf (optarg, "%x", &replace);
			else
				replace = atoi (optarg);
			break;

		    case 's':
			if (addr || symbol)
				error ("only one address/symbol allowed");
			symbol = optarg;
			break;

		    case 'o':
			if (offset)
				error ("only one offset allowed");
			if (! strncmp (optarg, "0x", 2))
				sscanf (optarg, "%x", &offset);
			else
				offset = atoi (optarg);
			break;
		}/* while switch() */

	if (argc > 1)
	{
		if (addr || symbol)
		{
			argv += optind;
			argc -= optind;

			if (argc < 1)
				error ("No file to patch.");

			fname = argv[0];
			if ((fd = open (fname, 0)) < 0)
				error ("Can't open file");

			if (read (fd, &e, sizeof (e)) != sizeof (e)
			    || N_BADMAG (e))
				error ("Not a valid executable.");

			/* fake mid, so the N_ macros work on the amiga.. */
			e.a_midmag |= 127 << 16;

			if (symbol)
			{
				struct nlist nl[2];
				if (offset == 0)
				{
					u_long new_do_replace = 0;

					new_do_replace = FindAssign(symbol,&replace);
					if (new_do_replace && do_replace)
						error("Cannot use both '=' and '-r' option!");
					FindOffset(symbol,&index);
					if (size_opt)
						offset = index*size; /* Treat like an index */
					else
						offset = index; /* Treat index like an offset */
					if (new_do_replace)
						do_replace = new_do_replace;
				}
				nl[0].n_un.n_name = symbol;
				nl[1].n_un.n_name = 0;
				if (nlist (fname, nl) != 0)
				{
					fprintf(stderr,"Symbol is %s ",symbol);
					error ("Symbol not found.");
				}
				addr = nl[0].n_value;
				type = nl[0].n_type & N_TYPE;
			}
			else
			{
				type = N_UNDF;
				if (addr >= N_TXTADDR(e) && addr < N_DATADDR(e))
					type = N_TEXT;
				else if (addr >= N_DATADDR(e) && addr < N_DATADDR(e) + e.a_data)
					type = N_DATA;
			}
			addr += offset;

			/* if replace-mode, have to reopen the file for writing.
			   Can't do that from the beginning, or nlist() will not
			   work (at least not under AmigaDOS) */
			if (do_replace)
			{
				close (fd);
				if ((fd = open (fname, 2)) == -1)
					error ("Can't reopen file for writing.");
			}

			if (type != N_TEXT && type != N_DATA)
				error ("address/symbol is not in text or data section.");

			if (type == N_TEXT)
				off = addr - N_TXTADDR(e) + N_TXTOFF(e);
			else
				off = addr - N_DATADDR(e) + N_DATOFF(e);

			if (lseek (fd, off, 0) == -1)
				error ("lseek");

			/* not beautiful, but works on big and little endian machines */
			switch (size)
			{
			    case 1:
				if (read (fd, &cval, 1) != 1)
					error ("cread");
				lval = cval;
				break;

			    case 2:
				if (read (fd, &sval, 2) != 2)
					error ("sread");
				lval = sval;
				break;

			    case 4:
				if (read (fd, &lval, 4) != 4)
					error ("lread");
				break;
			}/* switch size */


			if (symbol)
				printf ("%s(0x%x): %d (0x%x)\n", symbol, addr, lval, lval);
			else
				printf ("0x%x: %d (0x%x)\n", addr, lval, lval);

			if (do_replace)
			{
				if (lseek (fd, off, 0) == -1)
					error ("write-lseek");
				switch (size)
				{
				    case 1:
					cval = replace;
					if (cval != replace)
						error ("byte-value overflow.");
					if (write (fd, &cval, 1) != 1)
						error ("cwrite");
					break;

				    case 2:
					sval = replace;
					if (sval != replace)
						error ("word-value overflow.");
					if (write (fd, &sval, 2) != 2)
						error ("swrite");
					break;

				    case 4:
					if (write (fd, &replace, 4) != 4)
						error ("lwrite");
					break;
				}/* switch(size) */
			}/* if (do_replace) */

			close (fd);
		}/* if(addr || symbol ) */
		else
		{
			error("Must specify either address or symbol.");
		}
	}/* if argc < 1 */
	else
	{
		Synopsis(pgname);
	}
	return(0);
}/* main () */



void error (char *str)
{
	fprintf (stderr, "%s\n", str);
	exit (1);
}

/* Give user very short help to avoid scrolling screen much */
static void Synopsis(char *pgname)
{
	fprintf(stdout, synusage, pgname, pgname, pgname, pgname, pgname);
}


static void Usage(char *pgname)
{
	Synopsis(pgname);
	fprintf(stdout, desusage);
	exit(0);
}


/* FindOffset() - Determine if there is an offset, -or- index
                 embedded in the symbol.
                 If there is, return it, and truncate symbol to
                 exclude the [...].
                 Example: If view is declared as short view[10],
                          and we want to index the 3rd. element.
                          which is offset = (3 -1)*sizeof(short) =4.
                 we would use view[4], which becomes view,4.
                 The was the code is implemented the [value] is
                 treated as a index if-and-only-if a '-b -w -l' option
                 was given. Otherwise it is treated like an offset.
                 See above documentation in for of help!
*/
static void FindOffset(char *symbol,u_long *index)
{
	char *sb=strchr(symbol,'['); /* Start of '[', now line must
					contain matching']' */
	char *eb=strchr(symbol,']'); /* End of ']' */
	short sz=strlen(symbol);    /* symbol size */
	if (sb)
	{
		if (eb && (eb > sb))
		{
			if ((eb - symbol) == (sz - 1))
			{
				char *sindex; /* Start of index */
				u_long newindex = 0;
				/* In the future we could get fancy and parse the
				   sindex string for mathmatical expressions like:
				   (3 - 1)*2 = 4 from above example,
				   ugh forget I mentioned ot :-) !
				*/
				sindex = sb + 1;
				*eb = '\0';
				newindex = (u_long)atoi(sindex);
				if (*index == 0)
				{
					*index = newindex;
					*sb = '\0'; /* Make _view[3] look like _view */
				}
				else
					fprintf(stderr,"Error index can only be specified once!\n");
			}
			else
			{
				fprintf(stderr,"Error: Garbage trailing ']'\n");
			}
		}
		else
		{
			fprintf(stderr,"Error ']' in symbol before '[' !\n");
		}
	}/* if sb != 0 */
}/* FindOffset */

/* FindAssign : Scans symbol name for an '=number' strips it off
   of the symbol and proceeds.
*/
static u_long FindAssign(char *symbol,u_long *rvalue)
{
	char *ce = rindex(symbol,'='); /* Assign symbol some number */
	char *cn = ce + 1; /* This should point at some number, no spaces allowed */
	u_long dr = 0; /* flag for do_replace */

	if (ce)
	{
		int nscan; /* number of variaables scanned in */
		/* get the number to assign to symbol and strip off = */
		for (cn=ce + 1; *cn==' '; cn++)
			;
		if (! strncmp (cn, "0x", 2))
			nscan = sscanf (cn, "%x",rvalue);
		else
			nscan = sscanf(cn,"%d",rvalue);
		if (nscan != 1)
			error("Invalid value following '='");
		dr = 1;
		*ce = '\0';/* Now were left with just symbol */
	}/* if (ce) */
	return(dr);
}/* FindAssign */