Changes to automatically enable large file support on some systems.

I believe this works on Linux (tested both on a system with large file
support and one without it), and it may work on Solaris 2.7.

The changes are twofold:

(1) The configure script now boldly tries to set the two symbols that
    are recommended (for Solaris and Linux), and then tries a test
    script that does some simple seeking without writing.

(2) The _portable_{fseek,ftell} functions are a little more systematic
    in how they try the different large file support options: first
    try fseeko/ftello, but only if off_t is large; then try
    fseek64/ftell64; then try hacking with fgetpos/fsetpos.

I'm keeping my fingers crossed.  The meaning of the
HAVE_LARGEFILE_SUPPORT macro is not at all clear.

I'll see if I can get it to work on Windows as well.

Objects/fileobject.c

@@ -208,11 +208,15 @@ file_close(PyFileObject *f)
 }
 
 
-/* An 8-byte off_t-like type */
-#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8
+/* Our very own off_t-like type, 64-bit if possible */
+#if !defined(HAVE_LARGEFILE_SUPPORT)
+typedef off_t Py_off_t;
+#elif SIZEOF_OFF_T >= 8
+typedef off_t Py_off_t;
+#elif SIZEOF_FPOS_T >= 8
 typedef fpos_t Py_off_t;
 #else
-typedef off_t Py_off_t;
+#error "Large file support, but neither off_t nor fpos_t is large enough."
 #endif
 
 
@@ -221,13 +225,15 @@ typedef off_t Py_off_t;
 static int
 _portable_fseek(FILE *fp, Py_off_t offset, int whence)
 {
-#if defined(HAVE_FSEEKO)
+#if !defined(HAVE_LARGEFILE_SUPPORT)
+	return fseek(fp, offset, whence);
+#elif defined(HAVE_FSEEKO) && SIZEOF_OFF_T >= 8
 	return fseeko(fp, offset, whence);
 #elif defined(HAVE_FSEEK64)
 	return fseek64(fp, offset, whence);
 #elif defined(__BEOS__)
 	return _fseek(fp, offset, whence);
-#elif defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_FPOS_T >= 8
+#elif SIZEOF_FPOS_T >= 8
 	/* lacking a 64-bit capable fseek(), use a 64-bit capable fsetpos()
 	   and fgetpos() to implement fseek()*/
 	fpos_t pos;
@@ -245,7 +251,7 @@ _portable_fseek(FILE *fp, Py_off_t offset, int whence)
 	}
 	return fsetpos(fp, &offset);
 #else
-	return fseek(fp, offset, whence);
+#error "Large file support, but no way to fseek."
 #endif
 }
 
@@ -256,17 +262,19 @@ _portable_fseek(FILE *fp, Py_off_t offset, int whence)
 static Py_off_t
 _portable_ftell(FILE* fp)
 {
-#if SIZEOF_FPOS_T >= 8 && defined(HAVE_LARGEFILE_SUPPORT)
+#if !defined(HAVE_LARGEFILE_SUPPORT)
+	return ftell(fp);
+#elif defined(HAVE_FTELLO) && SIZEOF_OFF_T >= 8
+	return ftello(fp);
+#elif defined(HAVE_FTELL64)
+	return ftell64(fp);
+#elif SIZEOF_FPOS_T >= 8
 	fpos_t pos;
 	if (fgetpos(fp, &pos) != 0)
 		return -1;
 	return pos;
-#elif defined(HAVE_FTELLO) && defined(HAVE_LARGEFILE_SUPPORT)
-	return ftello(fp);
-#elif defined(HAVE_FTELL64) && defined(HAVE_LARGEFILE_SUPPORT)
-	return ftell64(fp);
 #else
-	return ftell(fp);
+#error "Large file support, but no way to ftell."
 #endif
 }
 

acconfig.h

@@ -25,6 +25,9 @@
 /* Defined on Solaris to see additional function prototypes. */
 #undef __EXTENSIONS__
 
+/* This must be set to 64 on some systems to enable large file support */
+#undef _FILE_OFFSET_BITS
+
 /* Define if getpgrp() must be called as getpgrp(0). */
 #undef GETPGRP_HAVE_ARG
 
@@ -107,6 +110,9 @@
 /* Define if the compiler provides a wchar.h header file. */
 #undef HAVE_WCHAR_H
 
+/* This must be defined on some systems to enable large file support */
+#undef _LARGEFILE_SOURCE
+
 /* Define if you want to have a Unicode type. */
 #undef Py_USING_UNICODE
 

configure.in

@@ -273,11 +273,12 @@ cygwin*)
       ;;
 esac
 
-# MacOSX framework builds need more magic. LDLIBRARY is the dynamic library that
-# we build, but we do not want to link against it (we will find it with a -framework
-# option). For this reason there is an extra variable BLDLIBRARY against which Python
-# and the extension modules are linked, BLDLIBRARY. This is normally the same
-# as LDLIBRARY, but empty for MacOSX framework builds.
+# MacOSX framework builds need more magic. LDLIBRARY is the dynamic
+# library that we build, but we do not want to link against it (we
+# will find it with a -framework option). For this reason there is an
+# extra variable BLDLIBRARY against which Python and the extension
+# modules are linked, BLDLIBRARY. This is normally the same as
+# LDLIBRARY, but empty for MacOSX framework builds.
 if test "$enable_framework"
 then
   LDLIBRARY='$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
@@ -1018,7 +1019,8 @@ ipv6trylibc=no
 
 if test "$ipv6" = "yes"; then
 	AC_MSG_CHECKING([ipv6 stack type])
-	for i in inria kame linux-glibc linux-inet6 solaris toshiba v6d zeta; do
+	for i in inria kame linux-glibc linux-inet6 solaris toshiba v6d zeta;
+	do
 		case $i in
 		inria)
 			dnl http://www.kame.net/
@@ -1256,6 +1258,47 @@ AC_CHECK_FUNCS(alarm chown clock confstr ctermid ctermid_r execv \
 AC_CHECK_FUNCS(openpty,, AC_CHECK_LIB(util,openpty, [AC_DEFINE(HAVE_OPENPTY)] [LIBS="$LIBS -lutil"]))
 AC_CHECK_FUNCS(forkpty,, AC_CHECK_LIB(util,forkpty, [AC_DEFINE(HAVE_FORKPTY)] [LIBS="$LIBS -lutil"]))
 
+# Try defining symbols to enable large file support.
+# The particular combination of symbols used here is known to work
+# on Linux and Solaris [2.]7.
+AC_MSG_CHECKING(for CFLAGS to enable large files)
+OLD_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64"
+AC_TRY_RUN([
+#include <sys/types.h>
+#include <stdio.h>
+main() {
+	FILE *fp;
+	off_t seek = 0x80000000ul;
+	off_t tell = 0;
+	fp = fopen("conftestval", "wb");
+	if (fp == NULL) {
+		perror("conftestval");
+		exit(1);
+	}
+ 	if (fseeko(fp, seek, 0) < 0)
+		perror("fseeko");
+	else
+		tell = ftello(fp);
+	fclose(fp);
+	unlink("conftestval");
+	if (tell == seek) {
+		fprintf(stderr, "seek to 2**31 worked\n");
+		exit(0);
+	}
+	else {
+		exit(1);
+		fprintf(stderr, "seek to 2**31 didn't work\n");
+	}
+}
+],
+AC_MSG_RESULT(yes)
+AC_DEFINE(_LARGEFILE_SOURCE)
+AC_DEFINE(_FILE_OFFSET_BITS,64),
+AC_MSG_RESULT(no),
+AC_MSG_RESULT(no (cross-compiling)))
+CFLAGS="$OLD_CFLAGS"
+
 # check for long file support functions
 AC_CHECK_FUNCS(fseek64 fseeko fstatvfs ftell64 ftello statvfs)
 

pyconfig.h.in

@@ -90,6 +90,9 @@
 /* Defined on Solaris to see additional function prototypes. */
 #undef __EXTENSIONS__
 
+/* This must be set to 64 on some systems to enable large file support */
+#undef _FILE_OFFSET_BITS
+
 /* Define if getpgrp() must be called as getpgrp(0). */
 #undef GETPGRP_HAVE_ARG
 
@@ -166,6 +169,9 @@
 /* Define if the compiler provides a wchar.h header file. */
 #undef HAVE_WCHAR_H
 
+/* This must be defined on some systems to enable large file support */
+#undef _LARGEFILE_SOURCE
+
 /* Define if you want to have a Unicode type. */
 #undef Py_USING_UNICODE
 
@@ -716,10 +722,3 @@
 #define DL_EXPORT(RTYPE) __declspec(dllexport) RTYPE
 #endif
 #endif
-
-/* Define the macros needed if on a UnixWare 7.x system. */
-#if defined(__USLC__) && defined(__SCO_VERSION__)
-#define SCO_ACCEPT_BUG     /* Use workaround for UnixWare accept() bug */
-#define SCO_ATAN2_BUG      /* Use workaround for UnixWare atan2() bug */
-#define STRICT_SYSV_CURSES /* Don't use ncurses extensions */
-#endif