select() returns EBADF, Bad File Descriptor

["Goeritz, Stefan" <Stefan_Goeritz at bmc dot com>]

> Hello everybody,
>
> I am trying to compile and link a small program with the cygwin
> g++ compiler that I successfully compiled and linked with
> MS Dev Studio, but with success so far.
>
> The program calls a DLL function that is provided from another
> application that returns a socket descriptor s. When calling
> select() to wait for data sent by the application, the program
> compiled and linked with cygwin always returns with an error
> because the select() call returns (-1) and errno contains
> 9 (EBADF, Error bad file descriptor). The same app works
> fine when compiled and linked with MS Dev Studio so I
> assume that it has to do with the way ti is linked with
> the libraries for socket comm. ( wsock32.lib/wsock32.dll).
>
>
> I tried linking in several ways, first using the lib in
> /usr/lib/libwsock32.a:
>
> The result which does not work is linked with the following
> libs (output from objdump):
>
> -----------------------------------------------------
> There is an import table in .idata at 0x41b000
>
> The Import Tables (interpreted .idata section contents)
>  vma:            Hint    Time      Forward  DLL       First
>                  Table   Stamp     Chain    Name      Thunk
>  0001b000       0001b07c 00000000 00000000 0001b4f8 0001b154
>
>         DLL Name: cygwin1.dll
>         vma:  Hint/Ord Member-Name
>         1b228       6  __errno
>         1b234      23  __infinity
>         1b244      24  __main
>         1b250      91  _ctype_
>         1b25c     497  abort
>         1b264     527  atexit
>         1b270     539  calloc
>         1b27c     555  close
>         1b284     593  cygwin_internal
>         1b298     610  dll_crt0__FP11per_process
>         1b2b4     637  exit
>         1b2bc     647  fclose
>         1b2c8     655  fflush
>         1b2d4     660  fileno
>         1b2e0     674  fread
>         1b2e8     675  free
>         1b2f0     680  fseek
>         1b2f8     682  fstat
>         1b300     688  fwrite
>         1b30c     694  getc
>         1b314     765  isatty
>         1b320     810  lseek
>         1b328     812  malloc
>         1b334     818  memchr
>         1b340     820  memcpy
>         1b34c     821  memmove
>         1b358     842  open
>         1b360     848  perror
>         1b36c     854  printf
>         1b378     889  read
>         1b380     893  realloc
>         1b38c     969  signal
>         1b398     993  sprintf
>         1b3a4    1004  strcmp
>         1b3b0    1006  strcpy
>         1b3bc    1026  strtol
>         1b3c8    1028  strtoul
>         1b3d4    1089  write
>         The Import Address Table is identical
>
>  0001b014       0001b11c 00000000 00000000 0001b50c 0001b1f4
>
>         DLL Name: KERNEL32.dll
>         vma:  Hint/Ord Member-Name
>         1b3dc     290  GetModuleHandleA
>         1b3f0     644  Sleep
>         The Import Address Table is identical
>
>  0001b028       0001b12c 00000000 00000000 0001b520 0001b204
>
>         DLL Name: WSOCK32.DLL
>         vma:  Hint/Ord Member-Name
>         1b3f8      66  select
>         The Import Address Table is identical
>
>  0001b03c       0001b134 00000000 00000000 0001b404 0001b20c
>
>
> ......
> -----------------------------------------------------
>
> I also tried copying  the library file wsock32.lib from the Dev Stdio CD
> to the working directory and linking
>
> sample.exe:	sample.o
> 	g++   -g  -o sample.exe sample.o  -L. -lwsock32 -LC:/APP/lib  -lAPP
>
>
> but the same result.
>
> I also noticed, that when using the MS Dev Studio exe,
> I always get 132 as File descriptor and this works , but
> with the cygwin linked version I get always 212 as FD, and
> this always returns the (-1) for the select ().
>
>
> Is there anyone out there who can help me on this, I am
> trying to find out whats wrong here for quite a time ...
>
> Tschau
>
>
> Stefan

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