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From: Joachim Falk
Subject: p/scripts/find-sed with djgpp; cygwin rts.c; problem building rts gpc
Date: 24 Jul 2000, 21:35:27

On Mon, 24 Jul 2000, Frank Heckenbach wrote:

> Joachim Falk wrote:
[SNIP]
> > The Problem is that the latest version of cygwin downloaded just 3 days
> > ago doesnt have MAP_FAILED in /usr/include/sys/mman.h
> > this prevents rts.c to compile
> > I dont know if this is a bug in the cygwin header files or in
> > gpc
> 
> I don't know either, but it seems easy enough to change in GPC. Just
> to be sure: It does have mmap, but not MAP_FAILED? What does mmap
> return on failure? If it's either NULL or ((void *) -1), it should
> be alright after my change. If it's something else, let me know.
> 
[SNIP to end]

I have made a test program and it seams it does return (void *) -1 on
failure


#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>

char *basename( char *file ) {
  char *ptr = strrchr( file, '/' );
  if ( !ptr ) ptr = strrchr( file, '\\' );
  if ( !ptr ) ptr = file - 1;
  return ptr + 1;
}

int main( int argc, char *argv[] ) {
  char   *map_file;
  int     map_fd;
  void   *map_region;
  size_t  pagesize;
  char   *progname = "UNKNOWN";

  if ( argc > 0 ) progname = basename( argv[0] );
  if ( argc != 2 ) {
    fprintf( stderr, "%s <file to map>\n", progname );
    exit( -1 );
  }
  map_file = argv[1];
  map_fd = open( map_file, O_RDWR );
  if ( map_fd < 0 ) {
    fprintf( stderr, "%s: can't open file %s for reading: %s\n",
	     progname, map_file, strerror( errno ) );
    // exit( -1 );
    map_fd = 9999;
  }
  pagesize = getpagesize();
  map_region = mmap( NULL, pagesize, PROT_READ | PROT_WRITE,
                     MAP_SHARED, map_fd, 0 );
  printf( "map_region = %lX\n", (long) map_region );
  printf( "errno = %d => %s\n", errno, strerror( errno ) );
  return 0;
}

=> get
map_test.exe: can't open file foo for reading: No such file or directory
map_region = FFFFFFFF
errno = 9 => Bad file number
=> yep its (void *) -1 
						Joachim Falk

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