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/*
 * File:	coffpatch.c
 *
 * Purpose:	write into a coff file
 *
 * $Log: coffpatch.c,v $
 * Revision 1.1.1.1  2019/05/29 04:56:37  root
 * coherent
 *
 * Revision 1.3  93/05/18  07:32:31  bin
 * *** empty log message ***
 * 
 */

/*
 * ----------------------------------------------------------------------
 * Includes.
 */
#include <stdio.h>
#include <errno.h>
#include <coff.h>
#include <sys/types.h>

/*
 * ----------------------------------------------------------------------
 * Definitions.
 *	Constants.
 *	Macros with argument lists.
 *	Typedefs.
 *	Enums.
 */

/*
 * ----------------------------------------------------------------------
 * Functions.
 *	Import Functions.
 *	Export Functions.
 *	Local Functions.
 */
int coffpatch();

/*
 * ----------------------------------------------------------------------
 * Global Data.
 *	Import Variables.
 *	Export Variables.
 *	Local Variables.
 */
extern char xflag;

/*
 * ----------------------------------------------------------------------
 * Code.
 *
 * Perform peeks/patches as formatted by coffp0() in asypatch.c
 *
 * Return nonzero if success; zero if failure.
 */

int
coffpatch(fname, sym, stbl, buf, len, do_read)
char *fname;
SYMENT *sym;
char *stbl, *buf;
int len, do_read;
{
	int	ret = 0;
	int	fd;
	int	rwct, i;
	static FILEHDR mainhdr;
	static AOUTHDR opthdr;
	static SCNHDR sh;
	long	seek, sought;

	long	text_size;	/* Size of text section in bytes.  */
	vaddr_t	text_addr;	/* Virtual memory base address for text.  */
	short	text_scnum;	/* Section number of text section.  */
	fsize_t text_base;	/* File offset of start of text section.  */

	long	data_size;	/* Size of data section in bytes.  */
	vaddr_t	data_addr;	/* Virtual memory base address for data.  */
	short	data_scnum;	/* Section number of data section.  */
	fsize_t data_base;	/* File offset of start of data section.  */

	/*
	 * Open the file to be patched.
	 */
	if ((fd=open(fname, 2)) < 0) {
		fprintf(stderr, "Cannot open %s\n", fname);
		goto no_close_fd;
	}
	lseek(fd, 0, 0);

	/*
	 * Read filehdr.
	 */
	if (-1 == read(fd, &mainhdr, sizeof(FILEHDR))) {
		perror(fname);
		fprintf(stderr, "Cannot read executable header.\n");
		goto close_fd;
	}

	/*
	 * Check for valid magic and length of optional header.
	 */
	if (mainhdr.f_magic != C_386_MAGIC || (mainhdr.f_opthdr < sizeof(opthdr))) {
		fprintf(stderr, "Bad magic (not COFF) in %s.\n", fname);
		goto close_fd;
	}

	/*
	 *Read the optional header.
	 */
	if (-1 == read(fd, &opthdr, sizeof(AOUTHDR))) {
		perror(fname);
		fprintf(stderr, "Cannot read optional header.\n");
		goto close_fd;
	}
	
	/*
	 * Fill in the parameters we can get from the opthdr.
	 */
	text_size = opthdr.tsize;
	text_addr = opthdr.text_start;

	data_size = opthdr.dsize;
	data_addr = opthdr.data_start;

	/*
	 * Read section headers for offsets.
	 */
	text_scnum = -1;	/* Mark as not found.  */
	data_scnum = -1;	/* Mark as not found.  */
	for (i = 1; i <= mainhdr.f_nscns; ++i) {
		if (-1 == read(fd, &sh, sizeof(SCNHDR))) {
			perror(fname);
			fprintf(stderr, "Cannot read section header.\n");
			goto close_fd;
		}

		if (STYP_TEXT == sh.s_flags) {
			text_scnum = i;
			text_base = sh.s_scnptr;
		} else if (STYP_DATA == sh.s_flags) {
			data_scnum = i;
			data_base = sh.s_scnptr;
		} /* else ignore this section header.  */
	}

	/*
	 * Did we find both sections?
	 */
	if (-1 == text_scnum) {
		fprintf(stderr, "No text section in %s.\n", fname);
	}

	if (-1 == data_scnum) {
		fprintf(stderr, "No data section in %s.\n", fname);
	}

	/*
	 * Range check the patch address.
	 */
	if (sym->n_scnum == text_scnum) {
		if ((sym->n_value < text_addr) ||
		    (sym->n_value + len > text_addr + text_size) ) {

		    fprintf(stderr, "Symbol out of range for text section.\n");
		    fprintf(stderr, "%s: %x\n",
			stbl + sym->n_offset - sizeof(long),
			   sym->n_value);
		    goto close_fd;
		}
	} else if (sym->n_scnum == data_scnum) {
		if ((sym->n_value < data_addr) ||
		    (sym->n_value + len > data_addr + data_size) ) {

		    fprintf(stderr, "Symbol out of range for data section.\n");
		    fprintf(stderr, "%s: %x\n",
			   stbl + sym->n_offset - sizeof(long),
			   sym->n_value);
		    goto close_fd;
		}
	} else {
		fprintf(stderr,
			"Illegal section number %d for symbol %s.\n",
			sym->n_scnum,
			   stbl + sym->n_offset - sizeof(long));
		goto close_fd;
	}

	/*
	 * Seek and patch.
	 */
	seek = sym->n_value;
	/*
	 * Adjust the file offset for the symbol based on which
	 * segment it resides in.
	 */
	if (sym->n_scnum == text_scnum) {
		seek = (seek - text_addr) + text_base;
	} else if (sym->n_scnum == data_scnum) {
		seek = (seek - data_addr) + data_base;
	} else {
		fprintf(stderr, "Bad section number!!.\n");
		goto close_fd;
	}

	sought = lseek(fd, seek, 0);
	if (sought == -1) {
		fprintf(stderr, "asypatch: lseek to %x failed\n", seek);
	}

	if (xflag)
		printf("write(%d, [%x]=%x, %d)->%x\n",
		  fd, buf, *(int*)buf, len, sought);

	if (do_read) {
		if ((rwct = read(fd, buf, len)) != len) {
			fprintf(stderr, "asypatch %s: read %d bytes of %d\n",
			  stbl, rwct, len);
			goto close_fd;
		}
	} else {
		if ((rwct = write(fd, buf, len)) != len) {
			fprintf(stderr, "asypatch %s: wrote %d bytes of %d\n",
			  stbl, rwct, len);
			goto close_fd;
		}
	}
	ret = 1;

close_fd:
	close(fd);
no_close_fd:
	return ret;
}

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