632 lines
18 KiB
C
632 lines
18 KiB
C
static char *sccsid = "@(#) dismain.c, Ver. 2.1 created 00:00:00 87/09/01";
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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* *
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* Copyright (C) 1987 G. M. Harding, all rights reserved *
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* *
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* Permission to copy and redistribute is hereby granted, *
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* provided full source code, with all copyright notices, *
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* accompanies any redistribution. *
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* *
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* This file contains the source code for the machine- *
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* independent portions of a disassembler program to run *
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* in a Unix (System III) environment. It expects, as its *
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* input, a file in standard a.out format, optionally con- *
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* taining symbol table information. If a symbol table is *
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* present, it will be used in the disassembly; otherwise, *
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* all address references will be literal (absolute). *
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* *
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* The disassembler program was originally written for an *
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* Intel 8088 CPU. However, all details of the actual CPU *
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* architecture are hidden in three machine-specific files *
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* named distabs.c, dishand.c, and disfp.c (the latter *
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* file is specific to the 8087 numeric co-processor). The *
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* code in this file is generic, and should require mini- *
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* mal revision if a different CPU is to be targeted. If a *
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* different version of Unix is to be targeted, changes to *
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* this file may be necessary, and if a completely differ- *
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* ent OS is to be targeted, all bets are off. *
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* *
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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#include "dis.h" /* Disassembler declarations */
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extern char *release; /* Contains release string */
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static char *IFILE = NULL; /* Points to input file name */
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static char *OFILE = NULL; /* Points to output file name */
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static char *PRG; /* Name of invoking program */
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static unsigned long zcount; /* Consecutive "0" byte count */
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int objflg = 0; /* Flag: output object bytes */
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#define unix 1
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#define i8086 1
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#define ibmpc 1
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#if unix && i8086 && ibmpc /* Set the CPU identifier */
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static int cpuid = 1;
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#else
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static int cpuid = 0;
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#endif
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_PROTOTYPE(static void usage, (char *s ));
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_PROTOTYPE(static void fatal, (char *s, char *t ));
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_PROTOTYPE(static void zdump, (unsigned long beg ));
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_PROTOTYPE(static void prolog, (void));
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_PROTOTYPE(static void distext, (void));
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_PROTOTYPE(static void disdata, (void));
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_PROTOTYPE(static void disbss, (void));
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_PROTOTYPE(static char *invoker, (char *s));
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_PROTOTYPE(static int objdump, (char *c));
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_PROTOTYPE(static char *getlab, (int type));
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_PROTOTYPE(static void prolog, (void));
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/* * * * * * * MISCELLANEOUS UTILITY FUNCTIONS * * * * * * */
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static void
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usage(s)
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register char *s;
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{
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fprintf(stderr,"Usage: %s [-o] ifile [ofile]\n",s);
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exit(-1);
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}
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static void
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fatal(s,t)
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register char *s, *t;
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{
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fprintf(stderr,"\07%s: %s\n",s,t);
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exit(-1);
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}
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static void
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zdump(beg)
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unsigned long beg;
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{
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beg = PC - beg;
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if (beg > 1L)
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printf("\t.zerow\t%ld\n",(beg >> 1));
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if (beg & 1L)
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printf("\t.byte\t0\n");
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}
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static char *
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invoker(s)
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register char *s;
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{
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register int k;
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k = strlen(s);
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while (k--)
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if (s[k] == '/')
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{
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s += k;
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++s;
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break;
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}
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return (s);
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}
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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* *
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* This rather tricky routine supports the disdata() func- *
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* tion. Its job is to output the code for a sequence of *
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* data bytes whenever the object buffer is full, or when *
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* a symbolic label is to be output. However, it must also *
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* keep track of consecutive zero words so that lengthy *
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* stretches of null data can be compressed by the use of *
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* an appropriate assembler pseudo-op. It does this by *
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* setting and testing a file-wide flag which counts suc- *
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* cessive full buffers of null data. The function returns *
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* a logical TRUE value if it outputs anything, logical *
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* FALSE otherwise. (This enables disdata() to determine *
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* whether to output a new synthetic label when there is *
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* no symbol table.) *
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* *
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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static int
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objdump(c)
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register char *c;
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{/* * * * * * * * * * START OF objdump() * * * * * * * * * */
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register int k;
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int retval = 0;
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if (objptr == OBJMAX)
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{
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for (k = 0; k < OBJMAX; ++k)
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if (objbuf[k])
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break;
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if (k == OBJMAX)
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{
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zcount += k;
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objptr = 0;
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if (c == NULL)
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return (retval);
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}
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}
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if (zcount)
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{
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printf("\t.zerow\t%ld\n",(zcount >> 1));
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++retval;
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zcount = 0L;
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}
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if (objptr)
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{
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printf("\t.byte\t");
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++retval;
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}
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else
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return (retval);
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for (k = 0; k < objptr; ++k)
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{
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printf("0x%02.2x",objbuf[k]);
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if (k < (objptr - 1))
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putchar(',');
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else
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putchar('\n');
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}
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objptr = 0;
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return (retval);
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}/* * * * * * * * * * END OF objdump() * * * * * * * * * */
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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* *
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* This routine, called at the beginning of the input *
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* cycle for each object byte, and before any interpreta- *
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* tion is attempted, searches the symbol table for any *
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* symbolic name with a value corresponding to the cur- *
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* rent PC and a type corresponding to the segment type *
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* (i.e., text, data, or bss) specified by the function's *
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* argument. If any such name is found, a pointer to it is *
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* returned; otherwise, a NULL pointer is returned. *
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* *
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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static char *
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getlab(type)
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register int type;
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{/* * * * * * * * * * START OF getlab() * * * * * * * * * */
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register int k;
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static char b[32], c[10];
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if (symptr < 0)
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if ((type == N_TEXT)
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|| ((type == N_DATA) && ( ! objptr ) && ( ! zcount )))
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{
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if (type == N_TEXT)
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sprintf(b,"T%05.5lx:",PC);
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else
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sprintf(b,"D%05.5lx:",PC);
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return (b);
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}
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else
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return (NULL);
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for (k = 0; k <= symptr; ++k)
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if ((symtab[k].n_value == PC)
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&& ((symtab[k].n_sclass & N_SECT) == type))
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{
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sprintf(b,"%s:\n",getnam(k));
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if (objflg && (type != N_TEXT))
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sprintf(c,"| %05.5lx\n",PC);
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strcat(b,c);
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return (b);
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}
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return (NULL);
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}/* * * * * * * * * * * END OF getlab() * * * * * * * * * * */
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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* *
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* This routine performs a preliminary scan of the symbol *
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* table, before disassembly begins, and outputs declara- *
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* tions of globals and constants. *
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* *
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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static void
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prolog()
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{/* * * * * * * * * * START OF prolog() * * * * * * * * * */
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register int j, flag;
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if (symptr < 0)
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return;
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for (j = flag = 0; j <= symptr; ++j)
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if ((symtab[j].n_sclass & N_CLASS) == C_EXT)
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if (((symtab[j].n_sclass & N_SECT) > N_UNDF)
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&& ((symtab[j].n_sclass & N_SECT) < N_COMM))
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{
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char *c = getnam(j);
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printf("\t.globl\t%s",c);
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if (++flag == 1)
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{
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putchar('\t');
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if (strlen(c) < 8)
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putchar('\t');
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printf("| Internal global\n");
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}
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else
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putchar('\n');
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}
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else
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if (symtab[j].n_value)
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{
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char *c = getnam(j);
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printf("\t.comm\t%s,0x%08.8lx",c,
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symtab[j].n_value);
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if (++flag == 1)
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printf("\t| Internal global\n");
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else
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putchar('\n');
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}
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if (flag)
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putchar('\n');
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for (j = flag = 0; j <= relptr; ++j)
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if (relo[j].r_symndx < S_BSS)
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{
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char *c = getnam(relo[j].r_symndx);
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++flag;
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printf("\t.globl\t%s",c);
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putchar('\t');
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if (strlen(c) < 8)
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putchar('\t');
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printf("| Undef: %05.5lx\n",relo[j].r_vaddr);
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}
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if (flag)
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putchar('\n');
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for (j = flag = 0; j <= symptr; ++j)
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if ((symtab[j].n_sclass & N_SECT) == N_ABS)
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{
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char *c = getnam(j);
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printf("%s=0x%08.8lx",c,symtab[j].n_value);
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if (++flag == 1)
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{
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printf("\t\t");
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if (strlen(c) < 5)
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putchar('\t');
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printf("| Literal\n");
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}
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else
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putchar('\n');
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}
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if (flag)
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putchar('\n');
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}/* * * * * * * * * * * END OF prolog() * * * * * * * * * * */
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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* *
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* This function is responsible for disassembly of the *
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* object file's text segment. *
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* *
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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static void
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distext()
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{/* * * * * * * * * * START OF distext() * * * * * * * * * */
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char *c;
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register int j;
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register void (*f)();
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for (j = 0; j < (int)(HDR.a_hdrlen); ++j)
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getchar();
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printf("| %s, %s\n\n",PRG,release);
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printf("| @(");
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printf("#)\tDisassembly of %s",IFILE);
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if (symptr < 0)
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printf(" (no symbols)\n\n");
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else
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printf("\n\n");
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if (HDR.a_flags & A_EXEC)
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printf("| File is executable\n\n");
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if (HDR.a_flags & A_SEP)
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{
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printf("| File has split I/D space, and may have\n");
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printf("| extraneous instructions in text segment\n\n");
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}
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prolog();
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printf("\t.text\t\t\t| loc = %05.5lx, size = %05.5lx\n\n",
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PC,HDR.a_text);
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segflg = 0;
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for (PC = 0L; PC < HDR.a_text; ++PC)
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{
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j = getchar() & 0xff;
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if ((j == 0) && ((PC + 1L) == HDR.a_text))
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{
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++PC;
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break;
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}
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if ((c = getlab(N_TEXT)) != NULL)
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printf("%s",c);
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f = optab[j].func;
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(*f)(j);
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}
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}/* * * * * * * * * * END OF distext() * * * * * * * * * */
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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* *
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* This function handles the object file's data segment. *
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* There is no good way to disassemble a data segment, be- *
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* cause it is impossible to tell, from the object code *
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* alone, what each data byte refers to. If it refers to *
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* an external symbol, the reference can be resolved from *
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* the relocation table, if there is one. However, if it *
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* refers to a static symbol, it cannot be distinguished *
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* from numeric, character, or other pointer data. In some *
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* cases, one might make a semi-educated guess as to the *
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* nature of the data, but such guesses are inherently *
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* haphazard, and they are bound to be wrong a good por- *
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* tion of the time. Consequently, the data segment is *
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* disassembled as a byte stream, which will satisfy no *
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* one but which, at least, will never mislead anyone. *
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* *
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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static void
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disdata()
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{/* * * * * * * * * * START OF disdata() * * * * * * * * * */
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register char *c;
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register int j;
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unsigned long end;
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putchar('\n');
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if (HDR.a_flags & A_SEP)
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{
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PC = 0L;
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end = HDR.a_data;
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}
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else
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end = HDR.a_text + HDR.a_data;
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printf("\t.data\t\t\t| loc = %05.5lx, size = %05.5lx\n\n",
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PC,HDR.a_data);
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segflg = 0;
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for (objptr = 0, zcount = 0L; PC < end; ++PC)
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{
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if ((c = getlab(N_DATA)) != NULL)
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{
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objdump(c);
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printf("%s",c);
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}
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if (objptr >= OBJMAX)
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if (objdump(NULL) && (symptr < 0))
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printf("D%05.5lx:",PC);
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j = getchar() & 0xff;
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objbuf[objptr++] = j;
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}
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objdump("");
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}/* * * * * * * * * * END OF disdata() * * * * * * * * * */
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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* *
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* This function handles the object file's bss segment. *
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* Disassembly of the bss segment is easy, because every- *
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* thing in it is zero by definition. *
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* *
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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static void disbss()
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{/* * * * * * * * * * START OF disbss() * * * * * * * * * */
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register int j;
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register char *c;
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unsigned long beg, end;
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putchar('\n');
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if (HDR.a_flags & A_SEP)
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end = HDR.a_data + HDR.a_bss;
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else
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end = HDR.a_text + HDR.a_data + HDR.a_bss;
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printf("\t.bss\t\t\t| loc = %05.5lx, size = %05.5lx\n\n",
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PC,HDR.a_bss);
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segflg = 0;
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for (beg = PC; PC < end; ++PC)
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if ((c = getlab(N_BSS)) != NULL)
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{
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if (PC > beg)
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{
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zdump(beg);
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beg = PC;
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}
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printf("%s",c);
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}
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if (PC > beg)
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zdump(beg);
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}/* * * * * * * * * * * END OF disbss() * * * * * * * * * * */
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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* *
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* This is the program entry point. The command line is *
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* searched for an input file name, which must be present. *
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* An optional output file name is also permitted; if none *
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* is found, standard output is the default. One command- *
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* line option is available: "-o", which causes the pro- *
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* gram to include object code in comments along with its *
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* mnemonic output. *
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* *
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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int
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main(argc,argv)
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int argc; /* Command-line args from OS */
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char **argv;
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{/* * * * * * * * * * * START OF main() * * * * * * * * * * */
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char a[1024];
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register int fd;
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long taboff, tabnum;
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long reloff, relnum;
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PRG = invoker(*argv);
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while (*++argv != NULL) /* Process command-line args */
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if (**argv == '-')
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switch (*++*argv)
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{
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case 'o' :
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if (*++*argv)
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usage(PRG);
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else
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++objflg;
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break;
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default :
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usage(PRG);
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}
|
|
else
|
|
if (IFILE == NULL)
|
|
IFILE = *argv;
|
|
else if (OFILE == NULL)
|
|
OFILE = *argv;
|
|
else
|
|
usage(PRG);
|
|
|
|
if (IFILE == NULL)
|
|
usage(PRG);
|
|
else
|
|
if ((fd = open(IFILE,0)) < 0)
|
|
{
|
|
sprintf(a,"can't access input file %s",IFILE);
|
|
fatal(PRG,a);
|
|
}
|
|
|
|
if (OFILE != NULL)
|
|
if (freopen(OFILE,"w",stdout) == NULL)
|
|
{
|
|
sprintf(a,"can't open output file %s",OFILE);
|
|
fatal(PRG,a);
|
|
}
|
|
|
|
if ( ! cpuid )
|
|
fprintf(stderr,"\07%s: warning: host/cpu clash\n",PRG);
|
|
|
|
read(fd, (char *) &HDR,sizeof(struct exec));
|
|
|
|
if (BADMAG(HDR))
|
|
{
|
|
sprintf(a,"input file %s not in object format",IFILE);
|
|
fatal(PRG,a);
|
|
}
|
|
|
|
if (HDR.a_cpu != A_I8086)
|
|
{
|
|
sprintf(a,"%s is not an 8086/8088 object file",IFILE);
|
|
fatal(PRG,a);
|
|
}
|
|
|
|
if (HDR.a_hdrlen <= A_MINHDR)
|
|
HDR.a_trsize = HDR.a_drsize = 0L;
|
|
HDR.a_tbase = HDR.a_dbase = 0L;
|
|
/* AST emergency patch
|
|
HDR.a_lnums = HDR.a_toffs = 0L;
|
|
*/
|
|
|
|
reloff = HDR.a_text /* Compute reloc data offset */
|
|
+ HDR.a_data
|
|
+ (long)(HDR.a_hdrlen);
|
|
|
|
relnum =
|
|
(HDR.a_trsize + HDR.a_drsize) / sizeof(struct reloc);
|
|
|
|
taboff = reloff /* Compute name table offset */
|
|
+ HDR.a_trsize
|
|
+ HDR.a_drsize;
|
|
|
|
tabnum = HDR.a_syms / sizeof(struct nlist);
|
|
|
|
if (relnum > MAXSYM)
|
|
fatal(PRG,"reloc table overflow");
|
|
|
|
if (tabnum > MAXSYM)
|
|
fatal(PRG,"symbol table overflow");
|
|
|
|
if (relnum) /* Get reloc data */
|
|
if (lseek(fd,reloff,0) != reloff)
|
|
fatal(PRG,"lseek error");
|
|
else
|
|
{
|
|
for (relptr = 0; relptr < relnum; ++relptr)
|
|
read(fd, (char *) &relo[relptr],sizeof(struct reloc));
|
|
relptr--;
|
|
}
|
|
|
|
if (tabnum) /* Read in symtab */
|
|
if (lseek(fd,taboff,0) != taboff)
|
|
fatal(PRG,"lseek error");
|
|
else
|
|
{
|
|
for (symptr = 0; symptr < tabnum; ++symptr)
|
|
read(fd, (char *) &symtab[symptr],sizeof(struct nlist));
|
|
symptr--;
|
|
}
|
|
else
|
|
fprintf(stderr,"\07%s: warning: no symbols\n",PRG);
|
|
|
|
close(fd);
|
|
|
|
if (freopen(IFILE,"r",stdin) == NULL)
|
|
{
|
|
sprintf(a,"can't reopen input file %s",IFILE);
|
|
fatal(PRG,a);
|
|
}
|
|
|
|
distext();
|
|
|
|
disdata();
|
|
|
|
disbss();
|
|
|
|
exit(0);
|
|
|
|
}/* * * * * * * * * * * END OF main() * * * * * * * * * * */
|