Add a workaround for file.ftell() to raise IOError for ttys.

hyeshik · hyeshik · commit e237d5039043 · 2005-12-13T16:44:02.000Z
ftell(3) on BSD doesn't set errno even for ttys and returns useless
values.
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -12,6 +12,9 @@ What's New in Python 2.5 alpha 1?
 Core and builtins
 -----------------
 
+- Added a workaround for file.tell() to raise IOError when the file
+  is a tty on every platforms as documented in our library reference.
+
 - Patch #1350409: Work around signal handling bug in Visual Studio 2005.
 
 - Bug #1281408: Py_BuildValue now works correct even with unsigned longs
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
@@ -482,6 +482,13 @@ _portable_fseek(FILE *fp, Py_off_t offset, int whence)
 static Py_off_t
 _portable_ftell(FILE* fp)
 {
+#ifdef HAVE_BROKEN_FTELL
+	/* ftell doesn't fail for tty fds on FreeBSD and some others */
+	if (isatty(fileno(fp))) {
+		errno = ESPIPE;
+		return -1;
+	}
+#endif
 #if !defined(HAVE_LARGEFILE_SUPPORT)
 	return ftell(fp);
 #elif defined(HAVE_FTELLO) && SIZEOF_OFF_T >= 8
diff --git a/configure b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.in Revision: 39267 .
+# From configure.in Revision: 41662 .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.59 for python 2.5.
 #
@@ -20118,6 +20118,67 @@ _ACEOF
 
 fi
 
+echo "$as_me:$LINENO: checking for broken ftell()" >&5
+echo $ECHO_N "checking for broken ftell()... $ECHO_C" >&6
+if test "${ac_cv_broken_ftell+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+
+if test "$cross_compiling" = yes; then
+  ac_cv_broken_ftell=no
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#include <stdio.h>
+int main()
+{
+	long val = ftell(stdin);
+	if (val != -1)
+		exit(0);
+	exit(1);
+}
+
+_ACEOF
+rm -f conftest$ac_exeext
+if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
+  (eval $ac_link) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && { ac_try='./conftest$ac_exeext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_broken_ftell=yes
+else
+  echo "$as_me: program exited with status $ac_status" >&5
+echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+( exit $ac_status )
+ac_cv_broken_ftell=no
+fi
+rm -f core *.core gmon.out bb.out conftest$ac_exeext conftest.$ac_objext conftest.$ac_ext
+fi
+fi
+
+echo "$as_me:$LINENO: result: $ac_cv_broken_ftell" >&5
+echo "${ECHO_T}$ac_cv_broken_ftell" >&6
+if test "$ac_cv_broken_ftell" = yes
+then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_BROKEN_FTELL 1
+_ACEOF
+
+fi
+
 # Before we can test tzset, we need to check if struct tm has a tm_zone
 # (which is not required by ISO C or UNIX spec) and/or if we support
 # tzname[]
diff --git a/configure.in b/configure.in
@@ -2955,6 +2955,28 @@ then
       [Define if poll() sets errno on invalid file descriptors.])
 fi
 
+AC_MSG_CHECKING(for broken ftell())
+AC_CACHE_VAL(ac_cv_broken_ftell, [
+AC_TRY_RUN([
+#include <stdio.h>
+int main()
+{
+	long val = ftell(stdin);
+	if (val != -1)
+		exit(0);
+	exit(1);
+}
+],
+ac_cv_broken_ftell=yes,
+ac_cv_broken_ftell=no,
+ac_cv_broken_ftell=no)])
+AC_MSG_RESULT($ac_cv_broken_ftell)
+if test "$ac_cv_broken_ftell" = yes
+then
+  AC_DEFINE(HAVE_BROKEN_FTELL, 1,
+  [Define if ftell() set errno on tty files.])
+fi
+
 # Before we can test tzset, we need to check if struct tm has a tm_zone 
 # (which is not required by ISO C or UNIX spec) and/or if we support
 # tzname[]
diff --git a/pyconfig.h.in b/pyconfig.h.in
@@ -46,6 +46,9 @@
 /* Define to 1 if you have the <bluetooth.h> header file. */
 #undef HAVE_BLUETOOTH_H
 
+/* Define if ftell() set errno on tty files. */
+#undef HAVE_BROKEN_FTELL
+
 /* Define if nice() returns success/failure instead of the new priority. */
 #undef HAVE_BROKEN_NICE
 
