libiberty/aclocal.m4

   1 dnl See whether strncmp reads past the end of its string parameters.
   2 dnl On some versions of SunOS4 at least, strncmp reads a word at a time
   3 dnl but erroneously reads past the end of strings.  This can cause
   4 dnl a SEGV in some cases.
   5 AC_DEFUN(libiberty_AC_FUNC_STRNCMP,
   6 [AC_REQUIRE([AC_FUNC_MMAP])
   7 AC_CACHE_CHECK([for working strncmp], ac_cv_func_strncmp_works,
   8 [AC_TRY_RUN([
   9 /* Test by Jim Wilson and Kaveh Ghazi.
  10    Check whether strncmp reads past the end of its string parameters. */
  11 #include <sys/types.h>
  12
  13 #ifdef HAVE_FCNTL_H
  14 #include <fcntl.h>
  15 #endif
  16
  17 #ifdef HAVE_SYS_MMAN_H
  18 #include <sys/mman.h>
  19 #endif
  20
  21 #ifndef MAP_ANON
  22 #ifdef MAP_ANONYMOUS
  23 #define MAP_ANON MAP_ANONYMOUS
  24 #else
  25 #define MAP_ANON MAP_FILE
  26 #endif
  27 #endif
  28
  29 #ifndef MAP_FILE
  30 #define MAP_FILE 0
  31 #endif
  32 #ifndef O_RDONLY
  33 #define O_RDONLY 0
  34 #endif
  35
  36 #define MAP_LEN 0x10000
  37
  38 main ()
  39 {
  40 #if defined(HAVE_MMAP) || defined(HAVE_MMAP_ANYWHERE)
  41   char *p;
  42   int dev_zero;
  43
  44   dev_zero = open ("/dev/zero", O_RDONLY);
  45   if (dev_zero < 0)
  46     exit (1);
  47
  48   p = (char *) mmap (0, MAP_LEN, PROT_READ|PROT_WRITE,
  49                      MAP_ANON|MAP_PRIVATE, dev_zero, 0);
  50   if (p == (char *)-1)
  51     exit (2);
  52   else
  53     {
  54       char *string = "__si_type_info";
  55       char *q = (char *) p + MAP_LEN - strlen (string) - 2;
  56       char *r = (char *) p + 0xe;
  57
  58       strcpy (q, string);
  59       strcpy (r, string);
  60       strncmp (r, q, 14);
  61     }
  62 #endif /* HAVE_MMAP || HAVE_MMAP_ANYWHERE */
  63   exit (0);
  64 }
  65 ], ac_cv_func_strncmp_works=yes, ac_cv_func_strncmp_works=no,
  66   ac_cv_func_strncmp_works=no)
  67 rm -f core core.* *.core])
  68 if test $ac_cv_func_strncmp_works = no ; then
  69   LIBOBJS="$LIBOBJS strncmp.o"
  70 fi
  71 ])
  72
  73 dnl See if errno must be declared even when <errno.h> is included.
  74 AC_DEFUN(libiberty_AC_DECLARE_ERRNO,
  75 [AC_CACHE_CHECK(whether errno must be declared, libiberty_cv_declare_errno,
  76 [AC_TRY_COMPILE(
  77 [#include <errno.h>],
  78 [int x = errno;],
  79 libiberty_cv_declare_errno=no,
  80 libiberty_cv_declare_errno=yes)])
  81 if test $libiberty_cv_declare_errno = yes
  82 then AC_DEFINE(NEED_DECLARATION_ERRNO, 1,
  83   [Define if errno must be declared even when <errno.h> is included.])
  84 fi
  85 ])