objcvt.c

一个用在mips体系结构中的操作系统

/*
 * Copyright (C) 1996-1998 by the Board of Trustees
 *    of Leland Stanford Junior University.
 * 
 * This file is part of the SimOS distribution. 
 * See LICENSE file for terms of the license. 
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <a.out.h>
#include <malloc.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/file.h>
#include <elf.h>
#include <libelf.h>

/* #define DEBUG */

#define ELFLIB_BUG 1
/*
 *----------------------------------------------------------------------
 *
 * objcvt main program --
 *
 *   Convert an Irix object file to run under Sinos
 *	
 *	Usage:  objcvt objectFile [objectFile ..,]
 *
 * Results:
 *	exit status is the count of errors encounterd.
 *
 * Side effects:
 *	Files are updated in place.
 *
 *----------------------------------------------------------------------
 */
int
main(argc,argv)
    int argc;
    char **argv;
{
    int	argNum, errors, changed = 0;

    if (argc < 2) {
	fprintf(stderr,"Usage: %s objectFile [objectFile ...]\n", argv[0]);
	exit(1);
    }
    if (elf_version(EV_CURRENT) == EV_NONE) {
	fprintf(stderr, "%s: Linked with wrong ELF library\n", argv[0]);
	exit(2);
    }

    errors = 0;
    for (argNum = 1; argNum < argc; argNum++) { 
       int  fd, cmd; 
       Elf  *elf, *arf;
       Elf32_Ehdr *ehdr;
       Elf32_Shdr *shdr;
       Elf_Scn *scn;
       Elf_Data *data;
       register int i, numWordsToCheck;
       register unsigned int *textSeg;

       fd = open(argv[argNum],O_RDWR);
       if (fd < 0) {
	  perror(argv[argNum]);
	  errors++;
	  continue;
       }
       arf = elf_begin(fd, ELF_C_RDWR, (Elf *)0);
       if((arf == (Elf *) NULL) ||
	  ((elf_kind(arf) != ELF_K_ELF) && 
	   (elf_kind(arf) != ELF_K_AR))) {
	  fprintf(stderr, "%s: \"%s\" is not an ELF object\n",
		  argv[0], argv[argNum]);
	  errors++;
	  (void) close(fd);
	  continue;
       }
       cmd = ELF_C_RDWR;
       while ((elf = elf_begin(fd, cmd, arf)) != 0) {
	  if ((ehdr = elf32_getehdr(elf)) == 0) {
	     fprintf(stderr, "%s: \"%s\" does not have a header.\n",
		     argv[0], argv[argNum]);
	     errors++;
	     continue;	
	  }
	  scn = 0;
	  while ((scn = elf_nextscn(elf, scn)) != 0) {
	     char    *name;
	     name = NULL;
	     if ((shdr = elf32_getshdr(scn)) != NULL)
		name = elf_strptr(elf, ehdr->e_shstrndx, 
				  (size_t)shdr->sh_name);
	     if ((name != NULL)  & (strcmp(name, ELF_TEXT) == 0)) { 
		break;
	     }
	  }
	  if (scn == NULL) {
	  err:
	     fprintf(stderr,"%s: \"%s\" does not have a text section.\n",
		     argv[0], argv[argNum]);
	     errors++;
	     (void) close(fd);
	  }


	  data = NULL;
	  if ((data = elf_getdata(scn, data)) == 0 || data->d_size == 0) {
	     goto err;
	  }

	  textSeg = (unsigned int *) data->d_buf;
	  /*
	   * Look for IRIX system call routines.  Currently the system 
	   * calls * lookup something like:
	   *		li	v0, NNN  
	   *		syscall
	   *		bne     a3,zero,XXX
	   *		nop
	   *
	   */

	  /*
	   * Start looking for the syscall instruction.  We can ignore 
	   * the last * couple of words since its not a system
	   *  call routine.
	   */
	  changed = 0;
	  numWordsToCheck = data->d_size/sizeof(textSeg[0]) - 2;
	  for(i = 0; i < numWordsToCheck; i++) {
	     if ((textSeg[i] == 0x0000000c) && (i > 0)) { /* syscall */
		/* li v0,NNN*/
		if (((textSeg[i-1] & ~0x7fff) == 0x24020000) && 
		    /* bne a3,zero,XXX*/ 
		    ((textSeg[i+1] & ~0xffff) == 0x14e00000)) { 
		   int syscallnum = textSeg[i-1] & 0x7fff;
#ifdef DEBUG
		   printf("File %s - Converting syscall %d @ TEXT+0x%x\n", argv[argNum], syscallnum, i*4);
#endif
		   textSeg[i] = 0x8c020003; /* lw v0,3(zero) 
					     * This causes a SIGBUS */
		   changed = 1;
		   i += 1;
		} else if (textSeg[i-1] == (0x24020000 + 1088)) {
		   /*
		    * Special case sigreturns
		    */
#ifdef DEBUG
		   printf("File %s - Special casing sigreturn @ TEXT+0x%x\n", argv[argNum], i*4);
#endif
		   textSeg[i] = 0x8c020003; /* lw v0,3(zero) */
		   changed = 1;
		   i += 1;
		} else if (textSeg[i-1] == 0x8fa20018) {
		   /*
		    * Special case stupid _sprocsp routine.
		    */
		   textSeg[i] = 0x8c020003; /* lw v0,3(zero) */
		   changed = 1;
		   i += 1;
		} else {
		   /*
		    * Complain about traps if there not system calls
		    */
		   fprintf(stderr, "File %s - Found \"syscall\" @ TEXT+0x%x\n", 
			   argv[argNum],i*4);
		}
	     }
	  }
	  if (changed) { 
#ifndef ELFLIB_BUG
	     elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY);

	     if (elf_update(elf, ELF_C_WRITE) ==  -1) {
		fprintf(stderr, "%s: Error processing %s\n", argv[0],
			argv[argNum]);
		errors++;
	     }
#else
	     if ((lseek(fd, shdr->sh_offset, SEEK_SET) !=  shdr->sh_offset) || 
		 (write(fd, data->d_buf, data->d_size) != data->d_size)) {
		perror(argv[argNum]);
		fprintf(stderr, "%s: Error processing %s\n", argv[0], argv[argNum]);
		errors++;
	     }
#endif
	  }
	  cmd = elf_next(elf);
	  elf_end(elf);
       }

	
    error:
       elf_end(elf);
    }
    if (!changed) exit(-1);
    exit(errors);
    return 0;
 }