Linker.c 44.3 KB
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/* -----------------------------------------------------------------------------
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 * $Id: Linker.c,v 1.6 2000/12/15 17:29:35 simonmar Exp $
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 *
 * (c) The GHC Team, 2000
 *
 * RTS Object Linker
 *
 * ---------------------------------------------------------------------------*/

#include "Rts.h"
#include "RtsFlags.h"
#include "HsFFI.h"
#include "Hash.h"
#include "Linker.h"
#include "RtsUtils.h"

/* These two are POSIX headers */
#include <sys/types.h>
#include <sys/stat.h>

/* ToDo: configure this */
#include <dlfcn.h>

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#ifdef GHCI /* endif is right at end of file */

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/* A bucket in the symbol hash-table.  Primarily, maps symbol names to
 * absolute addresses.  All symbols from a given module are linked
 * together, so they can be freed at the same time.  There's also a
 * bucket link field for the hash table.
 */
typedef struct _SymbolVal {
    char   *lbl;
    void   *addr;
} SymbolVal;

typedef enum { OBJECT_LOADED, OBJECT_RESOLVED } OStatus;

/* Indication of section kinds for loaded objects.  Needed by
   the GC for deciding whether or not a pointer on the stack
   is a code pointer.
*/
typedef enum { SECTIONKIND_CODE_OR_RODATA,
               SECTIONKIND_RWDATA,
               SECTIONKIND_OTHER,
               SECTIONKIND_NOINFOAVAIL } 
   SectionKind;

typedef struct { void* start; void* end; SectionKind kind; } 
   Section;

/* Top-level structure for an object module.  One of these is allocated
 * for each object file in use.
 */
typedef struct _ObjectCode {
    OStatus   status;
    char*     fileName;
    int       fileSize;
    char*     formatName;            /* eg "ELF32", "DLL", "COFF", etc. */

    SymbolVal *symbols;
    int       n_symbols;

    /* ptr to malloc'd lump of memory holding the obj file */
    void*     image;

    /* The section-kind entries for this object module.  Dynamically expands. */
    Section*  sections;
    int       n_sections;
    
    /* Allow a chain of these things */
    struct _ObjectCode * next;
} ObjectCode;


/* Hash table mapping symbol names to Symbol */
/*Str*/HashTable *symhash;

/* List of currently loaded objects */
ObjectCode *objects;

#if defined(linux_TARGET_OS) || defined(solaris2_TARGET_OS)
static int ocVerifyImage_ELF    ( ObjectCode* oc );
static int ocGetNames_ELF       ( ObjectCode* oc );
static int ocResolve_ELF        ( ObjectCode* oc );
#elif defined(cygwin32_TARGET_OS)		
static int ocVerifyImage_PEi386 ( ObjectCode* oc );
static int ocGetNames_PEi386    ( ObjectCode* oc );
static int ocResolve_PEi386     ( ObjectCode* oc );
#endif

/* -----------------------------------------------------------------------------
 * Built-in symbols from the RTS
 */

#define RTS_SYMBOLS				\
      SymX(MainRegTable)			\
      Sym(stg_gc_enter_1)			\
      Sym(stg_gc_noregs)			\
      Sym(stg_gc_seq_1)				\
      Sym(stg_gc_d1)				\
      Sym(stg_gc_f1)				\
      Sym(stg_gc_ut_1_0)			\
      Sym(stg_gc_ut_0_1)			\
      Sym(stg_gc_unbx_r1)			\
      Sym(stg_chk_0)				\
      Sym(stg_chk_1)				\
      Sym(stg_gen_chk)				\
      SymX(stg_exit)				\
      SymX(stg_update_PAP)			\
110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138
      SymX(stg_ap_2_upd_info)			\
      SymX(stg_ap_3_upd_info)			\
      SymX(stg_ap_4_upd_info)			\
      SymX(stg_ap_5_upd_info)			\
      SymX(stg_ap_6_upd_info)			\
      SymX(stg_ap_7_upd_info)			\
      SymX(stg_ap_8_upd_info)			\
      SymX(stg_sel_0_upd_info)			\
      SymX(stg_sel_1_upd_info)			\
      SymX(stg_sel_2_upd_info)			\
      SymX(stg_sel_3_upd_info)			\
      SymX(stg_sel_4_upd_info)			\
      SymX(stg_sel_5_upd_info)			\
      SymX(stg_sel_6_upd_info)			\
      SymX(stg_sel_7_upd_info)			\
      SymX(stg_sel_8_upd_info)			\
      SymX(stg_sel_9_upd_info)			\
      SymX(stg_sel_10_upd_info)			\
      SymX(stg_sel_11_upd_info)			\
      SymX(stg_sel_12_upd_info)			\
      SymX(stg_upd_frame_info)			\
      SymX(stg_seq_frame_info)			\
      SymX(stg_CAF_BLACKHOLE_info)		\
      SymX(stg_IND_STATIC_info)			\
      SymX(stg_EMPTY_MVAR_info)			\
      SymX(stg_MUT_ARR_PTRS_FROZEN_info)	\
      SymX(stg_CHARLIKE_closure)		\
      SymX(stg_INTLIKE_closure)			\
      SymX(stg_CAF_UNENTERED_entry)		\
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      SymX(newCAF)				\
      SymX(putMVarzh_fast)			\
      SymX(newMVarzh_fast)			\
      SymX(takeMVarzh_fast)			\
      SymX(tryTakeMVarzh_fast)			\
      SymX(catchzh_fast)			\
      SymX(raisezh_fast)			\
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      SymX(forkzh_fast)				\
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      SymX(delayzh_fast)			\
      SymX(yieldzh_fast)			\
      SymX(killThreadzh_fast)			\
      SymX(waitReadzh_fast)			\
      SymX(waitWritezh_fast)			\
      SymX(suspendThread)			\
      SymX(resumeThread)			\
      SymX(stackOverflow)			\
      SymX(int2Integerzh_fast)			\
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      SymX(word2Integerzh_fast)			\
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      SymX(mkForeignObjzh_fast)			\
      SymX(__encodeDouble)			\
      SymX(decodeDoublezh_fast)			\
      SymX(decodeFloatzh_fast)			\
      SymX(gcdIntegerzh_fast)			\
      SymX(newArrayzh_fast)			\
      SymX(unsafeThawArrayzh_fast)		\
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      SymX(newByteArrayzh_fast)			\
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      SymX(newMutVarzh_fast)			\
      SymX(quotRemIntegerzh_fast)		\
      SymX(quotIntegerzh_fast)			\
      SymX(remIntegerzh_fast)			\
      SymX(divExactIntegerzh_fast)		\
      SymX(divModIntegerzh_fast)		\
      SymX(timesIntegerzh_fast)			\
      SymX(minusIntegerzh_fast)			\
      SymX(plusIntegerzh_fast)			\
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      SymX(andIntegerzh_fast)			\
      SymX(orIntegerzh_fast)			\
      SymX(xorIntegerzh_fast)			\
      SymX(complementIntegerzh_fast)		\
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      SymX(mkWeakzh_fast)			\
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      SymX(makeStableNamezh_fast)		\
      SymX(finalizzeWeakzh_fast)		\
      SymX(blockAsyncExceptionszh_fast)		\
      SymX(unblockAsyncExceptionszh_fast)	\
      SymX(isDoubleNaN)				\
      SymX(isDoubleInfinite)			\
      SymX(isDoubleDenormalized)		\
      SymX(isDoubleNegativeZero)		\
      SymX(__encodeFloat)			\
      SymX(isFloatNaN)				\
      SymX(isFloatInfinite)			\
      SymX(isFloatDenormalized)			\
      SymX(isFloatNegativeZero)			\
      SymX(__int_encodeFloat)			\
      SymX(__int_encodeDouble)			\
      SymX(__gmpz_cmp_si)			\
      SymX(__gmpz_cmp)				\
      SymX(__gmpn_gcd_1)			\
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      SymX(prog_argv)				\
      SymX(prog_argc)				\
      SymX(resetNonBlockingFd)			\
      SymX(getStablePtr)			\
      SymX(stable_ptr_table)			\
      SymX(shutdownHaskellAndExit)		\
      Sym(stg_enterStackTop)			\
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      Sym(stg_yield_to_interpreter)		\
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      Sym(StgReturn)				\
      Sym(init_stack)				\
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      SymX(cmp_thread)				\
      Sym(__init_PrelGHC)			\
      SymX(freeHaskellFunctionPtr)		\
      SymX(OnExitHook)				\
      SymX(ErrorHdrHook)			\
      SymX(NoRunnableThreadsHook)		\
      SymX(StackOverflowHook)			\
      SymX(OutOfHeapHook)			\
      SymX(MallocFailHook)			\
      SymX(PatErrorHdrHook)			\
      SymX(defaultsHook)			\
      SymX(PreTraceHook)			\
      SymX(PostTraceHook)

#ifndef SUPPORT_LONG_LONGS
#define RTS_LONG_LONG_SYMS /* nothing */
#else
#define RTS_LONG_LONG_SYMS \
      SymX(stg_gtWord64)			\
      SymX(stg_geWord64)			\
      SymX(stg_eqWord64)			\
      SymX(stg_neWord64)			\
      SymX(stg_ltWord64)			\
      SymX(stg_leWord64)			\
      SymX(stg_gtInt64)				\
      SymX(stg_geInt64)				\
      SymX(stg_eqInt64)				\
      SymX(stg_neInt64)				\
      SymX(stg_ltInt64)				\
      SymX(stg_leInt64)				\
      SymX(stg_remWord64)			\
      SymX(stg_quotWord64)			\
      SymX(stg_remInt64)			\
      SymX(stg_quotInt64)			\
      SymX(stg_negateInt64)			\
      SymX(stg_plusInt64)			\
      SymX(stg_minusInt64)			\
      SymX(stg_timesInt64)			\
      SymX(stg_and64)				\
      SymX(stg_or64)				\
      SymX(stg_xor64)				\
      SymX(stg_not64)				\
      SymX(stg_shiftL64)			\
      SymX(stg_shiftRL64)			\
      SymX(stg_iShiftL64)			\
      SymX(stg_iShiftRL64)			\
      SymX(stg_iShiftRA64)			\
      SymX(stg_intToInt64)			\
      SymX(stg_int64ToInt)			\
      SymX(stg_int64ToWord64)			\
      SymX(stg_wordToWord64)			\
      SymX(stg_word64ToWord)			\
      SymX(stg_word64ToInt64) 			\
      SymX(int64ToIntegerzh_fast)		\
      SymX(word64ToIntegerzh_fast)
#endif /* SUPPORT_LONG_LONGS */
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/* entirely bogus claims about types of these symbols */
#define Sym(vvv)  extern void (vvv);
#define SymX(vvv) /**/
RTS_SYMBOLS
#undef Sym
#undef SymX

#ifdef LEADING_UNDERSCORE
#define MAYBE_LEADING_UNDERSCORE_STR(s) ("_" s)
#else
#define MAYBE_LEADING_UNDERSCORE_STR(s) (s)
#endif

#define Sym(vvv) { MAYBE_LEADING_UNDERSCORE_STR(#vvv), \
                    (void*)(&(vvv)) },
#define SymX(vvv) Sym(vvv)

static SymbolVal rtsSyms[] = {
      RTS_SYMBOLS
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      RTS_LONG_LONG_SYMS
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      { 0, 0 } /* sentinel */
};

/* -----------------------------------------------------------------------------
 * initialize the object linker
 */
static void *dl_prog_handle;

void
initLinker( void )
{
    SymbolVal *sym;

    symhash = allocStrHashTable();

    /* populate the symbol table with stuff from the RTS */
    for (sym = rtsSyms; sym->lbl != NULL; sym++) {
	insertStrHashTable(symhash, sym->lbl, sym);
    }

    dl_prog_handle = dlopen(NULL, RTLD_LAZY);
}

/* -----------------------------------------------------------------------------
 * lookup a symbol in the hash table
 */  
void *
lookupSymbol( char *lbl )
{
    SymbolVal *val;
    val = lookupStrHashTable(symhash, lbl);

    if (val == NULL) {
	return dlsym(dl_prog_handle, lbl);
    } else {
	return val->addr;
    }
}

/* -----------------------------------------------------------------------------
 * Load an obj (populate the global symbol table, but don't resolve yet)
 *
 * Returns: 1 if ok, 0 on error.
 */
HsInt
loadObj( char *path )
{
   ObjectCode* oc;
   struct stat st;
   int r, n;
   FILE *f;

#ifdef DEBUG
   /* assert that we haven't already loaded this object */
   { 
       ObjectCode *o;
       for (o = objects; o; o = o->next)
	   ASSERT(strcmp(o->fileName, path));
   }
#endif /* DEBUG */   

   oc = stgMallocBytes(sizeof(ObjectCode), "loadObj(oc)");

#  if defined(linux_TARGET_OS) || defined(solaris2_TARGET_OS)
   oc->formatName = "ELF";
#  elif defined(cygwin32_TARGET_OS)
   oc->formatName = "PEi386";
#  else
   free(oc);
   barf("loadObj: not implemented on this platform");
#  endif

   r = stat(path, &st);
   if (r == -1) { return 0; }

   oc->fileName          = path;
   oc->fileSize          = st.st_size;
   oc->image             = stgMallocBytes( st.st_size, "loadObj(image)" );
   oc->symbols           = NULL;
   oc->sections          = NULL;

   /* chain it onto the list of objects */
   oc->next              = objects;
   objects               = oc;

   /* load the image into memory */
   f = fopen(path, "rb");
   if (!f) {
       barf("loadObj: can't read `%s'", path);
   }
   n = fread ( oc->image, 1, oc->fileSize, f );
   if (n != oc->fileSize) {
      fclose(f);
      barf("loadObj: error whilst reading `%s'", path);
   }

   /* verify the in-memory image */
#  if defined(linux_TARGET_OS) || defined(solaris2_TARGET_OS)
   r = ocVerifyImage_ELF ( oc );
#  elif defined(cygwin32_TARGET_OS)
   r = ocVerifyImage_PEi386 ( oc );
#  else
   barf("loadObj: no verify method");
#  endif
   if (!r) { return r; }

   /* build the symbol list for this image */
#  if defined(linux_TARGET_OS) || defined(solaris2_TARGET_OS)
   r = ocGetNames_ELF ( oc );
#  elif defined(cygwin32_TARGET_OS)
   r = ocGetNames_PEi386 ( oc );
#  else
   barf("loadObj: no getNames method");
#  endif
   if (!r) { return r; }

   /* loaded, but not resolved yet */
   oc->status = OBJECT_LOADED;

   return 1;
}

/* -----------------------------------------------------------------------------
 * resolve all the currently unlinked objects in memory
 *
 * Returns: 1 if ok, 0 on error.
 */
HsInt 
resolveObjs( void )
{
    ObjectCode *oc;
    int r;

    for (oc = objects; oc; oc = oc->next) {
	if (oc->status != OBJECT_RESOLVED) {
#  if defined(linux_TARGET_OS) || defined(solaris2_TARGET_OS)
	    r = ocResolve_ELF ( oc );
#  elif defined(cygwin32_TARGET_OS)
	    r = ocResolve_PEi386 ( oc );
#  else
	    barf("link: not implemented on this platform");
#  endif
	    if (!r) { return r; }
	    oc->status = OBJECT_RESOLVED;
	}
    }
    return 1;
}

/* -----------------------------------------------------------------------------
 * delete an object from the pool
 */
HsInt
unloadObj( char *path )
{
    ObjectCode *oc;

    for (oc = objects; oc; oc = oc->next) {
	if (!strcmp(oc->fileName,path)) {

	    /* Remove all the mappings for the symbols within this
	     * object..
	     */
	    { 
		SymbolVal *s;
		for (s = oc->symbols; s < oc->symbols + oc->n_symbols; s++) {
		    removeStrHashTable(symhash, s->lbl, NULL);
		}
	    }

	    /* We're going to leave this in place, in case there are
	       any pointers from the heap into it: */
	    /* free(oc->image); */
	    free(oc->symbols);
	    free(oc->sections);
	    free(oc);
	    return 1;
	}
    }
    
    belch("unloadObj: can't find `%s' to unload", path);
    return 0;
}

/* --------------------------------------------------------------------------
 * PEi386 specifics (cygwin32)
 * ------------------------------------------------------------------------*/

/* The information for this linker comes from 
      Microsoft Portable Executable 
      and Common Object File Format Specification
      revision 5.1 January 1998
   which SimonM says comes from the MS Developer Network CDs.
*/
      

#if defined(cygwin32_TARGET_OS)



typedef unsigned char  UChar;
typedef unsigned short UInt16;
typedef unsigned int   UInt32;
typedef          int   Int32;


typedef 
   struct {
      UInt16 Machine;
      UInt16 NumberOfSections;
      UInt32 TimeDateStamp;
      UInt32 PointerToSymbolTable;
      UInt32 NumberOfSymbols;
      UInt16 SizeOfOptionalHeader;
      UInt16 Characteristics;
   }
   COFF_header;

#define sizeof_COFF_header 20


typedef 
   struct {
      UChar  Name[8];
      UInt32 VirtualSize;
      UInt32 VirtualAddress;
      UInt32 SizeOfRawData;
      UInt32 PointerToRawData;
      UInt32 PointerToRelocations;
      UInt32 PointerToLinenumbers;
      UInt16 NumberOfRelocations;
      UInt16 NumberOfLineNumbers;
      UInt32 Characteristics; 
   }
   COFF_section;

#define sizeof_COFF_section 40


typedef
   struct {
      UChar  Name[8];
      UInt32 Value;
      UInt16 SectionNumber;
      UInt16 Type;
      UChar  StorageClass;
      UChar  NumberOfAuxSymbols;
   }
   COFF_symbol;

#define sizeof_COFF_symbol 18


typedef
   struct {
      UInt32 VirtualAddress;
      UInt32 SymbolTableIndex;
      UInt16 Type;
   }
   COFF_reloc;

#define sizeof_COFF_reloc 10


/* From PE spec doc, section 3.3.2 */
#define IMAGE_FILE_RELOCS_STRIPPED     0x0001
#define IMAGE_FILE_EXECUTABLE_IMAGE    0x0002
#define IMAGE_FILE_DLL                 0x2000
#define IMAGE_FILE_SYSTEM              0x1000
#define IMAGE_FILE_BYTES_REVERSED_HI   0x8000
#define IMAGE_FILE_BYTES_REVERSED_LO   0x0080
#define IMAGE_FILE_32BIT_MACHINE       0x0100

/* From PE spec doc, section 5.4.2 and 5.4.4 */
#define IMAGE_SYM_CLASS_EXTERNAL       2
#define IMAGE_SYM_CLASS_STATIC         3
#define IMAGE_SYM_UNDEFINED            0

/* From PE spec doc, section 4.1 */
#define IMAGE_SCN_CNT_CODE             0x00000020
#define IMAGE_SCN_CNT_INITIALIZED_DATA 0x00000040

/* From PE spec doc, section 5.2.1 */
#define IMAGE_REL_I386_DIR32           0x0006
#define IMAGE_REL_I386_REL32           0x0014


/* We use myindex to calculate array addresses, rather than
   simply doing the normal subscript thing.  That's because
   some of the above structs have sizes which are not 
   a whole number of words.  GCC rounds their sizes up to a
   whole number of words, which means that the address calcs
   arising from using normal C indexing or pointer arithmetic
   are just plain wrong.  Sigh.
*/
static UChar *
myindex ( int scale, int index, void* base )
{
   return
      ((UChar*)base) + scale * index;
}


static void
printName ( UChar* name, UChar* strtab )
{
   if (name[0]==0 && name[1]==0 && name[2]==0 && name[3]==0) {
      UInt32 strtab_offset = * (UInt32*)(name+4);
      fprintf ( stderr, "%s", strtab + strtab_offset );
   } else {
      int i;
      for (i = 0; i < 8; i++) {
         if (name[i] == 0) break;
         fprintf ( stderr, "%c", name[i] );
      }
   }
}


static void
copyName ( UChar* name, UChar* strtab, UChar* dst, int dstSize )
{
   if (name[0]==0 && name[1]==0 && name[2]==0 && name[3]==0) {
      UInt32 strtab_offset = * (UInt32*)(name+4);
      strncpy ( dst, strtab+strtab_offset, dstSize );
      dst[dstSize-1] = 0;
   } else {
      int i = 0;
      while (1) {
         if (i >= 8) break;
         if (name[i] == 0) break;
         dst[i] = name[i];
         i++;
      }
      dst[i] = 0;
   }
}


static UChar *
cstring_from_COFF_symbol_name ( UChar* name, UChar* strtab )
{
   UChar* newstr;
   /* If the string is longer than 8 bytes, look in the
      string table for it -- this will be correctly zero terminated. 
   */
   if (name[0]==0 && name[1]==0 && name[2]==0 && name[3]==0) {
      UInt32 strtab_offset = * (UInt32*)(name+4);
      return ((UChar*)strtab) + strtab_offset;
   }
   /* Otherwise, if shorter than 8 bytes, return the original,
      which by defn is correctly terminated.
   */
   if (name[7]==0) return name;
   /* The annoying case: 8 bytes.  Copy into a temporary
      (which is never freed ...)
   */
   newstr = malloc(9);
   if (newstr) {
      strncpy(newstr,name,8);
      newstr[8] = 0;
   }
   return newstr;
}


/* Just compares the short names (first 8 chars) */
static COFF_section *
findPEi386SectionCalled ( ObjectCode* oc,  char* name )
{
   int i;
   COFF_header* hdr 
      = (COFF_header*)(oc->image);
   COFF_section* sectab 
      = (COFF_section*) (
           ((UChar*)(oc->image)) 
           + sizeof_COFF_header + hdr->SizeOfOptionalHeader
        );
   for (i = 0; i < hdr->NumberOfSections; i++) {
      UChar* n1;
      UChar* n2;
      COFF_section* section_i 
         = (COFF_section*)
           myindex ( sizeof_COFF_section, i, sectab );
      n1 = (UChar*) &(section_i->Name);
      n2 = name;
      if (n1[0]==n2[0] && n1[1]==n2[1] && n1[2]==n2[2] && 
          n1[3]==n2[3] && n1[4]==n2[4] && n1[5]==n2[5] && 
          n1[6]==n2[6] && n1[7]==n2[7])
         return section_i;
   }

   return NULL;
}


static void
zapTrailingAtSign ( UChar* sym )
{
   int i, j;
   if (sym[0] == 0) return;
   i = 0; 
   while (sym[i] != 0) i++;
   i--;
   j = i;
   while (j > 0 && isdigit(sym[j])) j--;
   if (j > 0 && sym[j] == '@' && j != i) sym[j] = 0;
}


static int
ocVerifyImage_PEi386 ( ObjectCode* oc )
{
   int i, j;
   COFF_header*  hdr;
   COFF_section* sectab;
   COFF_symbol*  symtab;
   UChar*        strtab;

   hdr = (COFF_header*)(oc->image);
   sectab = (COFF_section*) (
               ((UChar*)(oc->image)) 
               + sizeof_COFF_header + hdr->SizeOfOptionalHeader
            );
   symtab = (COFF_symbol*) (
               ((UChar*)(oc->image))
               + hdr->PointerToSymbolTable 
            );
   strtab = ((UChar*)(oc->image))
            + hdr->PointerToSymbolTable
            + hdr->NumberOfSymbols * sizeof_COFF_symbol;

   if (hdr->Machine != 0x14c) {
      oc->errMsg("Not x86 PEi386");
      return FALSE;
   }
   if (hdr->SizeOfOptionalHeader != 0) {
      oc->errMsg("PEi386 with nonempty optional header");
      return FALSE;
   }
   if ( /* (hdr->Characteristics & IMAGE_FILE_RELOCS_STRIPPED) || */
        (hdr->Characteristics & IMAGE_FILE_EXECUTABLE_IMAGE) ||
        (hdr->Characteristics & IMAGE_FILE_DLL) ||
        (hdr->Characteristics & IMAGE_FILE_SYSTEM) ) {
      oc->errMsg("Not a PEi386 object file");
      return FALSE;
   }
   if ( (hdr->Characteristics & IMAGE_FILE_BYTES_REVERSED_HI) ||
        !(hdr->Characteristics & IMAGE_FILE_32BIT_MACHINE) ) {
      oc->errMsg("Invalid PEi386 word size or endiannness");
      return FALSE;
   }

   if (!verb) return TRUE;
   /* No further verification after this point; only debug printing. */

   fprintf ( stderr, 
             "sectab offset = %d\n", ((UChar*)sectab) - ((UChar*)hdr) );
   fprintf ( stderr, 
             "symtab offset = %d\n", ((UChar*)symtab) - ((UChar*)hdr) );
   fprintf ( stderr, 
             "strtab offset = %d\n", ((UChar*)strtab) - ((UChar*)hdr) );

   fprintf ( stderr, "\n" );
   fprintf ( stderr, 
             "Machine:           0x%x\n", (UInt32)(hdr->Machine) );
   fprintf ( stderr, 
             "# sections:        %d\n",   (UInt32)(hdr->NumberOfSections) );
   fprintf ( stderr,
             "time/date:         0x%x\n", (UInt32)(hdr->TimeDateStamp) );
   fprintf ( stderr,
             "symtab offset:     %d\n",   (UInt32)(hdr->PointerToSymbolTable) );
   fprintf ( stderr, 
             "# symbols:         %d\n",   (UInt32)(hdr->NumberOfSymbols) );
   fprintf ( stderr, 
             "sz of opt hdr:     %d\n",   (UInt32)(hdr->SizeOfOptionalHeader) );
   fprintf ( stderr,
             "characteristics:   0x%x\n", (UInt32)(hdr->Characteristics) );

   fprintf ( stderr, "\n" );
   fprintf ( stderr, "string table has size 0x%x\n", * (UInt32*)strtab );
   fprintf ( stderr, "---START of string table---\n");
   for (i = 4; i < *(UInt32*)strtab; i++) {
      if (strtab[i] == 0) 
         fprintf ( stderr, "\n"); else 
         fprintf( stderr, "%c", strtab[i] );
   }
   fprintf ( stderr, "--- END  of string table---\n");

   fprintf ( stderr, "\n" );
   for (i = 0; i < hdr->NumberOfSections; i++) {
      COFF_reloc* reltab;
      COFF_section* sectab_i
         = (COFF_section*)
           myindex ( sizeof_COFF_section, i, sectab );
      fprintf ( stderr, 
                "\n"
                "section %d\n"
                "     name `",
                i 
              );
      printName ( sectab_i->Name, strtab );
      fprintf ( stderr, 
                "'\n"
                "    vsize %d\n"
                "    vaddr %d\n"
                "  data sz %d\n"
                " data off %d\n"
                "  num rel %d\n"
                "  off rel %d\n",
                sectab_i->VirtualSize,
                sectab_i->VirtualAddress,
                sectab_i->SizeOfRawData,
                sectab_i->PointerToRawData,
                sectab_i->NumberOfRelocations,
                sectab_i->PointerToRelocations
              );
      reltab = (COFF_reloc*) (
                  ((UChar*)(oc->image)) + sectab_i->PointerToRelocations
               );
      for (j = 0; j < sectab_i->NumberOfRelocations; j++) {
         COFF_symbol* sym;
         COFF_reloc* rel = (COFF_reloc*)
                           myindex ( sizeof_COFF_reloc, j, reltab );
         fprintf ( stderr, 
                   "        type 0x%-4x   vaddr 0x%-8x   name `",
                   (UInt32)rel->Type, 
                   rel->VirtualAddress );
         sym = (COFF_symbol*)
               myindex ( sizeof_COFF_symbol, rel->SymbolTableIndex, symtab );
         printName ( sym->Name, strtab );
         fprintf ( stderr, "'\n" );
      }
      fprintf ( stderr, "\n" );
   }


   fprintf ( stderr, "\n" );
   i = 0;
   while (1) {
      COFF_symbol* symtab_i;
      if (i >= hdr->NumberOfSymbols) break;
      symtab_i = (COFF_symbol*)
                 myindex ( sizeof_COFF_symbol, i, symtab );
      fprintf ( stderr, 
                "symbol %d\n"
                "     name `",
                i 
              );
      printName ( symtab_i->Name, strtab );
      fprintf ( stderr, 
                "'\n"
                "    value 0x%x\n"
                "     sec# %d\n"
                "     type 0x%x\n"
                "   sclass 0x%x\n"
                "     nAux %d\n",
                symtab_i->Value,
                (Int32)(symtab_i->SectionNumber) - 1,
                (UInt32)symtab_i->Type,
                (UInt32)symtab_i->StorageClass,
                (UInt32)symtab_i->NumberOfAuxSymbols 
              );
      i += symtab_i->NumberOfAuxSymbols;
      i++;
   }

   fprintf ( stderr, "\n" );

   return TRUE;
}


static int
ocGetNames_PEi386 ( ObjectCode* oc )
{
   COFF_header*  hdr;
   COFF_section* sectab;
   COFF_symbol*  symtab;
   UChar*        strtab;

   UChar* sname;
   void*  addr;
   int    i;
   
   hdr = (COFF_header*)(oc->image);
   sectab = (COFF_section*) (
               ((UChar*)(oc->image)) 
               + sizeof_COFF_header + hdr->SizeOfOptionalHeader
            );
   symtab = (COFF_symbol*) (
               ((UChar*)(oc->image))
               + hdr->PointerToSymbolTable 
            );
   strtab = ((UChar*)(oc->image))
            + hdr->PointerToSymbolTable
            + hdr->NumberOfSymbols * sizeof_COFF_symbol;

   /* Copy exported symbols into the ObjectCode. */
   i = 0;
   while (1) {
      COFF_symbol* symtab_i;
      if (i >= hdr->NumberOfSymbols) break;
      symtab_i = (COFF_symbol*)
                 myindex ( sizeof_COFF_symbol, i, symtab );

      if (symtab_i->StorageClass == IMAGE_SYM_CLASS_EXTERNAL &&
          symtab_i->SectionNumber != IMAGE_SYM_UNDEFINED) {

         /* This symbol is global and defined, viz, exported */
         COFF_section* sectabent;

         sname = cstring_from_COFF_symbol_name ( 
                    symtab_i->Name, strtab 
                 );
         if (!sname) {
            oc->errMsg("Out of memory when copying PEi386 symbol");
            return FALSE;
         }

         /* for IMAGE_SYMCLASS_EXTERNAL 
                && !IMAGE_SYM_UNDEFINED,
            the address of the symbol is: 
                address of relevant section + offset in section
         */
         sectabent = (COFF_section*)
                     myindex ( sizeof_COFF_section, 
                               symtab_i->SectionNumber-1,
                               sectab );
         addr = ((UChar*)(oc->image))
                + (sectabent->PointerToRawData
                   + symtab_i->Value);
         /* fprintf ( stderr, "addSymbol %p `%s'\n", addr,sname); */
         if (!addSymbol(oc,sname,addr)) return FALSE;
      }
      i += symtab_i->NumberOfAuxSymbols;
      i++;
   }

   oc->sections = stgMallocBytes( NumberOfSections * sizeof(Section), 
				    "ocGetNamesPEi386" );

   /* Copy section information into the ObjectCode. */
   for (i = 0; i < hdr->NumberOfSections; i++) {
      UChar* start;
      UChar* end;

      SectionKind kind 
         = SECTIONKIND_OTHER;
      COFF_section* sectab_i
         = (COFF_section*)
           myindex ( sizeof_COFF_section, i, sectab );
      /* fprintf ( stderr, "section name = %s\n", sectab_i->Name ); */

#if 0
      /* I'm sure this is the Right Way to do it.  However, the 
         alternative of testing the sectab_i->Name field seems to
         work ok with Cygwin.
      */
      if (sectab_i->Characteristics & IMAGE_SCN_CNT_CODE || 
          sectab_i->Characteristics & IMAGE_SCN_CNT_INITIALIZED_DATA)
         kind = SECTIONKIND_CODE_OR_RODATA;
#endif

      if (0==strcmp(".text",sectab_i->Name))
         kind = SECTIONKIND_CODE_OR_RODATA;
      if (0==strcmp(".data",sectab_i->Name) ||
          0==strcmp(".bss",sectab_i->Name))
         kind = SECTIONKIND_RWDATA;

      start = ((UChar*)(oc->image)) 
              + sectab_i->PointerToRawData;
      end   = start 
              + sectab_i->SizeOfRawData - 1;

      if (kind != SECTIONKIND_OTHER) {
         addSection ( oc, start, end, kind );
      } else {
         fprintf ( stderr, "unknown section name = `%s'\n", 
                   sectab_i->Name);
         oc->errMsg("Unknown PEi386 section name");
         return FALSE;
      }
   }

   return TRUE;   
}


static int
ocResolve_PEi386 ( ObjectCode* oc, int verb )
{
   COFF_header*  hdr;
   COFF_section* sectab;
   COFF_symbol*  symtab;
   UChar*        strtab;

   UInt32        A;
   UInt32        S;
   UInt32*       pP;

   int i, j;
   char symbol[1000]; // ToDo
   
   hdr = (COFF_header*)(oc->image);
   sectab = (COFF_section*) (
               ((UChar*)(oc->image)) 
               + sizeof_COFF_header + hdr->SizeOfOptionalHeader
            );
   symtab = (COFF_symbol*) (
               ((UChar*)(oc->image))
               + hdr->PointerToSymbolTable 
            );
   strtab = ((UChar*)(oc->image))
            + hdr->PointerToSymbolTable
            + hdr->NumberOfSymbols * sizeof_COFF_symbol;

   for (i = 0; i < hdr->NumberOfSections; i++) {
      COFF_section* sectab_i
         = (COFF_section*)
           myindex ( sizeof_COFF_section, i, sectab );
      COFF_reloc* reltab
         = (COFF_reloc*) (
              ((UChar*)(oc->image)) + sectab_i->PointerToRelocations
           );
      for (j = 0; j < sectab_i->NumberOfRelocations; j++) {
         COFF_symbol* sym;
         COFF_reloc* reltab_j 
            = (COFF_reloc*)
              myindex ( sizeof_COFF_reloc, j, reltab );

         /* the location to patch */
         pP = (UInt32*)(
                 ((UChar*)(oc->image)) 
                 + (sectab_i->PointerToRawData 
                    + reltab_j->VirtualAddress)
              );
         /* the existing contents of pP */
         A = *pP;
         /* the symbol to connect to */
         sym = (COFF_symbol*)
               myindex ( sizeof_COFF_symbol, 
                         reltab_j->SymbolTableIndex, symtab );
         if (verb) {
            fprintf ( stderr, 
                   "reloc sec %2d num %3d:  type 0x%-4x   "
                   "vaddr 0x%-8x   name `",
                   i, j,
                   (UInt32)reltab_j->Type, 
                   reltab_j->VirtualAddress );
            printName ( sym->Name, strtab );
            fprintf ( stderr, "'\n" );
         }

         if (sym->StorageClass == IMAGE_SYM_CLASS_STATIC) {
            COFF_section* section_sym 
               = findPEi386SectionCalled ( oc, sym->Name );
            if (!section_sym) {
               fprintf ( stderr, "bad section = `%s'\n", sym->Name );
               oc->errMsg("Can't find abovementioned PEi386 section");
               return FALSE;
            }
            S = ((UInt32)(oc->image))
                + (section_sym->PointerToRawData
                   + sym->Value);
         } else {
         copyName ( sym->Name, strtab, symbol, 1000 );
         zapTrailingAtSign ( symbol );
         S = (UInt32) ocLookupSym ( oc, symbol );
         if (S == 0) 
            S = (UInt32)(oc->clientLookup ( symbol ));
         if (S == 0) {
	     belch("%s: unresolvable reference to `%s'", oc->fileName, symbol);
	     return FALSE;
         }
         }

         switch (reltab_j->Type) {
            case IMAGE_REL_I386_DIR32: 
               *pP = A + S; 
               break;
            case IMAGE_REL_I386_REL32:
               /* Tricky.  We have to insert a displacement at
                  pP which, when added to the PC for the _next_
                  insn, gives the address of the target (S).
                  Problem is to know the address of the next insn
                  when we only know pP.  We assume that this
                  literal field is always the last in the insn,
                  so that the address of the next insn is pP+4
                  -- hence the constant 4.
                  Also I don't know if A should be added, but so
                  far it has always been zero.
	       */
               ASSERT(A==0);
               *pP = S - ((UInt32)pP) - 4;
               break;
            default: 
               fprintf(stderr, 
                       "unhandled PEi386 relocation type %d\n",
                       reltab_j->Type);
               oc->errMsg("unhandled PEi386 relocation type");
               return FALSE;
         }

      }
   }
   
   return TRUE;
}

#endif /* defined(cygwin32_TARGET_OS) */


/* --------------------------------------------------------------------------
 * ELF specifics (Linux, Solaris)
 * ------------------------------------------------------------------------*/

#if defined(linux_TARGET_OS) || defined(solaris2_TARGET_OS)

#define FALSE 0
#define TRUE  1

#include <elf.h>

static char *
findElfSection ( void* objImage, Elf32_Word sh_type )
{
   int i;
   char* ehdrC = (char*)objImage;
   Elf32_Ehdr* ehdr = ( Elf32_Ehdr*)ehdrC;
   Elf32_Shdr* shdr = (Elf32_Shdr*) (ehdrC + ehdr->e_shoff);
   char* ptr = NULL;
   for (i = 0; i < ehdr->e_shnum; i++) {
      if (shdr[i].sh_type == sh_type &&
          i !=  ehdr->e_shstrndx) {
         ptr = ehdrC + shdr[i].sh_offset;
         break;
      }
   }
   return ptr;
}


static int
ocVerifyImage_ELF ( ObjectCode* oc )
{
   Elf32_Shdr* shdr;
   Elf32_Sym*  stab;
   int i, j, nent, nstrtab, nsymtabs;
   char* sh_strtab;
   char* strtab;

   char*       ehdrC = (char*)(oc->image);
   Elf32_Ehdr* ehdr  = ( Elf32_Ehdr*)ehdrC;

   if (ehdr->e_ident[EI_MAG0] != ELFMAG0 ||
       ehdr->e_ident[EI_MAG1] != ELFMAG1 ||
       ehdr->e_ident[EI_MAG2] != ELFMAG2 ||
       ehdr->e_ident[EI_MAG3] != ELFMAG3) {
      belch("ocVerifyImage_ELF: not an ELF header");
      return 0;
   }
   IF_DEBUG(linker,belch( "Is an ELF header" ));

   if (ehdr->e_ident[EI_CLASS] != ELFCLASS32) {
      belch("ocVerifyImage_ELF: not 32 bit ELF" );
      return 0;
   }

   IF_DEBUG(linker,belch( "Is 32 bit ELF" ));

   if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB) {
       IF_DEBUG(linker,belch( "Is little-endian" ));
   } else
   if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB) {
       IF_DEBUG(linker,belch( "Is big-endian" ));
   } else {
       belch("ocVerifyImage_ELF: unknown endiannness");
       return 0;
   }

   if (ehdr->e_type != ET_REL) {
      belch("ocVerifyImage_ELF: not a relocatable object (.o) file");
      return 0;
   }
   IF_DEBUG(linker, belch( "Is a relocatable object (.o) file" ));

   IF_DEBUG(linker,belch( "Architecture is " ));
   switch (ehdr->e_machine) {
      case EM_386:   IF_DEBUG(linker,belch( "x86" )); break;
      case EM_SPARC: IF_DEBUG(linker,belch( "sparc" )); break;
      default:       IF_DEBUG(linker,belch( "unknown" )); 
                     belch("ocVerifyImage_ELF: unknown architecture");
                     return 0;
   }

   IF_DEBUG(linker,belch(
             "\nSection header table: start %d, n_entries %d, ent_size %d", 
             ehdr->e_shoff, ehdr->e_shnum, ehdr->e_shentsize  ));

   ASSERT (ehdr->e_shentsize == sizeof(Elf32_Shdr));

   shdr = (Elf32_Shdr*) (ehdrC + ehdr->e_shoff);

   if (ehdr->e_shstrndx == SHN_UNDEF) {
      belch("ocVerifyImage_ELF: no section header string table");
      return 0;
   } else {
      IF_DEBUG(linker,belch( "Section header string table is section %d", 
                          ehdr->e_shstrndx));
      sh_strtab = ehdrC + shdr[ehdr->e_shstrndx].sh_offset;
   }

   for (i = 0; i < ehdr->e_shnum; i++) {
      IF_DEBUG(linker,fprintf(stderr, "%2d:  ", i ));
      IF_DEBUG(linker,fprintf(stderr, "type=%2d  ", shdr[i].sh_type ));
      IF_DEBUG(linker,fprintf(stderr, "size=%4d  ", shdr[i].sh_size ));
      IF_DEBUG(linker,fprintf(stderr, "offs=%4d  ", shdr[i].sh_offset ));
      IF_DEBUG(linker,fprintf(stderr, "  (%p .. %p)  ",
               ehdrC + shdr[i].sh_offset, 
		      ehdrC + shdr[i].sh_offset + shdr[i].sh_size - 1));

      if (shdr[i].sh_type == SHT_REL) {
	  IF_DEBUG(linker,fprintf(stderr, "Rel  " ));
      } else if (shdr[i].sh_type == SHT_RELA) {
	  IF_DEBUG(linker,fprintf(stderr, "RelA " ));
      } else {
	  IF_DEBUG(linker,fprintf(stderr,"     "));
      }
      if (sh_strtab) {
	  IF_DEBUG(linker,fprintf(stderr, "sname=%s\n", sh_strtab + shdr[i].sh_name ));
      }
   }

   IF_DEBUG(linker,belch( "\nString tables" ));
   strtab = NULL;
   nstrtab = 0;
   for (i = 0; i < ehdr->e_shnum; i++) {
      if (shdr[i].sh_type == SHT_STRTAB &&
          i !=  ehdr->e_shstrndx) {
	  IF_DEBUG(linker,belch("   section %d is a normal string table", i ));
         strtab = ehdrC + shdr[i].sh_offset;
         nstrtab++;
      }
   }  
   if (nstrtab != 1) {
      belch("ocVerifyImage_ELF: no string tables, or too many");
      return 0;
   }

   nsymtabs = 0;
   IF_DEBUG(linker,belch( "\nSymbol tables" )); 
   for (i = 0; i < ehdr->e_shnum; i++) {
      if (shdr[i].sh_type != SHT_SYMTAB) continue;
      IF_DEBUG(linker,belch( "section %d is a symbol table", i ));
      nsymtabs++;
      stab = (Elf32_Sym*) (ehdrC + shdr[i].sh_offset);
      nent = shdr[i].sh_size / sizeof(Elf32_Sym);
      IF_DEBUG(linker,belch( "   number of entries is apparently %d (%d rem)",
               nent,
               shdr[i].sh_size % sizeof(Elf32_Sym)
             ));
      if (0 != shdr[i].sh_size % sizeof(Elf32_Sym)) {
         belch("ocVerifyImage_ELF: non-integral number of symbol table entries");
         return 0;
      }
      for (j = 0; j < nent; j++) {
         IF_DEBUG(linker,fprintf(stderr, "   %2d  ", j ));
         IF_DEBUG(linker,fprintf(stderr, "  sec=%-5d  size=%-3d  val=%5p  ", 
                             (int)stab[j].st_shndx,
                             (int)stab[j].st_size,
                             (char*)stab[j].st_value ));

         IF_DEBUG(linker,fprintf(stderr, "type=" ));
         switch (ELF32_ST_TYPE(stab[j].st_info)) {
            case STT_NOTYPE:  IF_DEBUG(linker,fprintf(stderr, "notype " )); break;
            case STT_OBJECT:  IF_DEBUG(linker,fprintf(stderr, "object " )); break;
            case STT_FUNC  :  IF_DEBUG(linker,fprintf(stderr, "func   " )); break;
            case STT_SECTION: IF_DEBUG(linker,fprintf(stderr, "section" )); break;
            case STT_FILE:    IF_DEBUG(linker,fprintf(stderr, "file   " )); break;
            default:          IF_DEBUG(linker,fprintf(stderr, "?      " )); break;
         }
         IF_DEBUG(linker,fprintf(stderr, "  " ));

         IF_DEBUG(linker,fprintf(stderr, "bind=" ));
         switch (ELF32_ST_BIND(stab[j].st_info)) {
            case STB_LOCAL :  IF_DEBUG(linker,fprintf(stderr, "local " )); break;
            case STB_GLOBAL:  IF_DEBUG(linker,fprintf(stderr, "global" )); break;
            case STB_WEAK  :  IF_DEBUG(linker,fprintf(stderr, "weak  " )); break;
            default:          IF_DEBUG(linker,fprintf(stderr, "?     " )); break;
         }
         IF_DEBUG(linker,fprintf(stderr, "  " ));

         IF_DEBUG(linker,fprintf(stderr, "name=%s\n", strtab + stab[j].st_name ));
      }
   }

   if (nsymtabs == 0) {
      belch("ocVerifyImage_ELF: didn't find any symbol tables");
      return 0;
   }

   return 1;
}


static int
ocGetNames_ELF ( ObjectCode* oc )
{
   int i, j, k, nent;
   Elf32_Sym* stab;

   char*       ehdrC      = (char*)(oc->image);
   Elf32_Ehdr* ehdr       = (Elf32_Ehdr*)ehdrC;
   char*       strtab     = findElfSection ( ehdrC, SHT_STRTAB );
   Elf32_Shdr* shdr       = (Elf32_Shdr*) (ehdrC + ehdr->e_shoff);
   char*       sh_strtab  = ehdrC + shdr[ehdr->e_shstrndx].sh_offset;

   if (!strtab) {
      belch("ocGetNames_ELF: no strtab");
      return 0;
   }

   k = 0;
   oc->sections = stgMallocBytes( ehdr->e_shnum * sizeof(Section), 
				    "ocGetNames_ELF" );
   oc->n_sections = ehdr->e_shnum;

   for (i = 0; i < ehdr->e_shnum; i++) {

      /* make a section entry for relevant sections */
      SectionKind kind = SECTIONKIND_OTHER;
      if (!strcmp(".data",sh_strtab+shdr[i].sh_name) ||
          !strcmp(".data1",sh_strtab+shdr[i].sh_name))
	  kind = SECTIONKIND_RWDATA;
      if (!strcmp(".text",sh_strtab+shdr[i].sh_name) ||
          !strcmp(".rodata",sh_strtab+shdr[i].sh_name) ||
          !strcmp(".rodata1",sh_strtab+shdr[i].sh_name))
	  kind = SECTIONKIND_CODE_OR_RODATA;

      /* fill in the section info */
      oc->sections[i].start = ehdrC + shdr[i].sh_offset;
      oc->sections[i].end   = ehdrC + shdr[i].sh_offset + shdr[i].sh_size - 1;
      oc->sections[i].kind  = kind;
      
      if (shdr[i].sh_type != SHT_SYMTAB) continue;

      /* copy stuff into this module's object symbol table */
      stab = (Elf32_Sym*) (ehdrC + shdr[i].sh_offset);
      nent = shdr[i].sh_size / sizeof(Elf32_Sym);
      oc->symbols = malloc(nent * sizeof(SymbolVal));
      for (j = 0; j < nent; j++) {
         if ( ( ELF32_ST_BIND(stab[j].st_info)==STB_GLOBAL /* ||
	        ELF32_ST_BIND(stab[j].st_info)==STB_LOCAL */
              )
	      /* and not an undefined symbol */
	      && stab[j].st_shndx != SHN_UNDEF
	      &&
	      /* and it's a not a section or string table or anything silly */
              ( ELF32_ST_TYPE(stab[j].st_info)==STT_FUNC ||
                ELF32_ST_TYPE(stab[j].st_info)==STT_OBJECT ||
	        ELF32_ST_TYPE(stab[j].st_info)==STT_NOTYPE )
		) { 
            char* nm = strtab + stab[j].st_name;
            char* ad = ehdrC 
                       + shdr[ stab[j].st_shndx ].sh_offset
                       + stab[j].st_value;
            ASSERT(nm != NULL);
            ASSERT(ad != NULL);
	    IF_DEBUG(linker,belch( "addOTabName: %10p  %s %s",
                       ad, oc->fileName, nm ));
	    oc->symbols[j].lbl  = nm;
	    oc->symbols[j].addr = ad;
	    insertStrHashTable(symhash, nm, &(oc->symbols[j]));
         }
	 else {
	     IF_DEBUG(linker,belch( "skipping `%s'", strtab +
			     stab[j].st_name ));
	     oc->symbols[j].lbl  = NULL;
	     oc->symbols[j].addr = NULL;
	 }
      }
   }

   return 1;
}


static int
ocResolve_ELF ( ObjectCode* oc )
{
   char *strtab, *symbol;
   int   i, j;
   Elf32_Sym*  stab = NULL;
   char*       ehdrC = (char*)(oc->image);
   Elf32_Ehdr* ehdr = (Elf32_Ehdr*) ehdrC;
   Elf32_Shdr* shdr = (Elf32_Shdr*) (ehdrC + ehdr->e_shoff);
   Elf32_Word* targ;

   /* first find "the" symbol table */
   stab = (Elf32_Sym*) findElfSection ( ehdrC, SHT_SYMTAB );

   /* also go find the string table */
   strtab = findElfSection ( ehdrC, SHT_STRTAB );

   if (stab == NULL || strtab == NULL) {
      belch("ocResolve_ELF: can't find string or symbol table");
      return 0; 
   }

   for (i = 0; i < ehdr->e_shnum; i++) {
      if (shdr[i].sh_type == SHT_REL ) {
         Elf32_Rel*  rtab = (Elf32_Rel*) (ehdrC + shdr[i].sh_offset);
         int         nent = shdr[i].sh_size / sizeof(Elf32_Rel);
         int target_shndx = shdr[i].sh_info;
         int symtab_shndx = shdr[i].sh_link;
         stab  = (Elf32_Sym*) (ehdrC + shdr[ symtab_shndx ].sh_offset);
         targ  = (Elf32_Word*)(ehdrC + shdr[ target_shndx ].sh_offset);
	 IF_DEBUG(linker,belch( "relocations for section %d using symtab %d",
			 target_shndx, symtab_shndx ));
         for (j = 0; j < nent; j++) {
            Elf32_Addr offset = rtab[j].r_offset;
            Elf32_Word info   = rtab[j].r_info;

            Elf32_Addr  P = ((Elf32_Addr)targ) + offset;
            Elf32_Word* pP = (Elf32_Word*)P;
            Elf32_Addr  A = *pP;
            Elf32_Addr  S;

            IF_DEBUG(linker,belch( "Rel entry %3d is raw(%6p %6p)   ", 
                                j, (void*)offset, (void*)info ));
            if (!info) {
               IF_DEBUG(linker,belch( " ZERO" ));
               S = 0;
            } else {
               /* First see if it is a nameless local symbol. */
               if (stab[ ELF32_R_SYM(info)].st_name == 0) {
		   symbol = "(noname)";
		   S = (Elf32_Addr)(ehdrC
				    + shdr[stab[ELF32_R_SYM(info)].st_shndx ].sh_offset
				    + stab[ELF32_R_SYM(info)].st_value
		       );
               } else {
		   /* No?  Should be in the symbol table then. */
		   symbol = strtab+stab[ ELF32_R_SYM(info)].st_name;
		   (void *)S = lookupSymbol( symbol );
               }
               if (!S) {
		   barf("ocResolve_ELF: %s: unknown symbol `%s'",
			oc->fileName, symbol);
               }
               IF_DEBUG(linker,belch( "`%s' resolves to %p", symbol, (void*)S ));
	    }
            IF_DEBUG(linker,fprintf ( stderr, "Reloc: P = %p   S = %p   A = %p\n", (void*)P, (void*)S, (void*)A )); 
            switch (ELF32_R_TYPE(info)) {
               case R_386_32:   *pP = S + A;     break;
               case R_386_PC32: *pP = S + A - P; break;
               default: fprintf(stderr, 
                                "unhandled ELF relocation type %d",
                                ELF32_R_TYPE(info));
                        belch("ocResolve_ELF: unhandled ELF relocation type");
                        return 0;
	    }

         }
      }
      else
      if (shdr[i].sh_type == SHT_RELA) {
         belch("ocResolve_ELF: RelA style reloc table -- not yet done");
         return 0;
      }
   }

   return 1;
}


#endif /* defined(linux_TARGET_OS) || defined(solaris2_TARGET_OS) */

/* -----------------------------------------------------------------------------
 * Look up an address to discover whether it is in text or data space.
 *
 * Used by the garbage collector when walking the stack.
 * -------------------------------------------------------------------------- */

1469
static __inline__ SectionKind
1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488
lookupSection ( void* addr )
{
   int          i;
   ObjectCode*  oc;
   
   for ( oc = objects; oc; oc = oc->next ) {
       for (i = 0; i < oc->n_sections; i++) {
	   if (oc->sections[i].start <= addr 
	       && addr <= oc->sections[i].end)
	       return oc->sections[i].kind;
       }
   }
   return SECTIONKIND_OTHER;
}

int
is_dynamically_loaded_code_or_rodata_ptr ( char* p )
{
   SectionKind sk = lookupSection(p);
1489
   ASSERT (sk != SECTIONKIND_NOINFOAVAIL);
1490 1491 1492 1493 1494 1495 1496 1497
   return (sk == SECTIONKIND_CODE_OR_RODATA);
}


int
is_dynamically_loaded_rwdata_ptr ( char* p )
{
   SectionKind sk = lookupSection(p);
1498
   ASSERT (sk != SECTIONKIND_NOINFOAVAIL);
1499 1500 1501 1502 1503 1504 1505 1506
   return (sk == SECTIONKIND_RWDATA);
}


int
is_not_dynamically_loaded_ptr ( char* p )
{
   SectionKind sk = lookupSection(p);
1507
   ASSERT (sk != SECTIONKIND_NOINFOAVAIL);
1508 1509 1510
   return (sk == SECTIONKIND_OTHER);
}

1511
#endif /* GHCI */