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[[!tag open_issue_glibc open_issue_llvm]]


# IRC, freenode, #hurd, 2011-12-14

    <pinotree> hm, interesting mmap bug
    <youpi> ?
    <pinotree> youpi: http://paste.debian.net/149252/
    #include <sys/types.h>
    #include <sys/mman.h>
    #include <fcntl.h>
    #include <stdio.h>
    #include <errno.h>
    #include <stdlib.h>
    #include <string.h>
    #include <unistd.h>
    
    void die(int x, const char *s)
    {
      perror(s);
      exit(x);
    }
    
    static const char s_file[] = "foo-mmaptest";
    
    int main()
    {
      int fd;
      void *p;
    
      fd = creat(s_file, 0777);
      if (fd < 0) die(1, "creat");
      errno = 0;
      p = mmap(NULL, 1, PROT_READ, MAP_SHARED, fd, 0);
      printf("> %p vs %p, %d (%s)\n", p, MAP_FAILED, errno, strerror(errno));
      unlink(s_file);
      return (p != MAP_FAILED);
    }
    <pinotree> on linux it returns 0 and fails with EACCESS (as it seems it
      should, by reading the mmap posix docs), on hurd it returns 1 and the
      mmap succeeds
    <pinotree> (taken from llvm's configure)
    <youpi> why should it? file size extension ?
    <pinotree> creat creates a o_wronly file, while the mmap specifies only
      read protection
    <youpi> oh, craet is always wo
    <youpi> I didn't know that