[m-rev.] for review: fix autoconf cross-compilation warning

[Fergus Henderson]

For review by stayl.

Estimated hours taken: 0.75
Branches: main

Eliminate an autoconf warning about checking for file existence
not working with cross compilation.

trace/mercury_trace_internal.c:
	Check for the existence of /dev/ptmx at run-time, using access(),
	rather than at configure-time.
	Also fix a bug where it was calling perror() after the value
	of errno had already been clobbered by another system call.

configure.in:
	Delete the check for /dev/ptmx.
	Add a check for the access() function.

runtime/mercury_conf.h.in:
	Delete definition of MR_HAVE_DEV_PTMX.
	Add definition of MR_HAVE_ACCESS.

runtime/mercury_conf_bootstrap.h:
	Delete references to (MR_)HAVE_DEV_PTMX.

Workspace: /home/ceres/fjh/ws-ceres2/mercury
Index: configure.in
===================================================================
RCS file: /home/mercury1/repository/mercury/configure.in,v
retrieving revision 1.318
diff -u -d -r1.318 configure.in
--- configure.in	12 Sep 2002 17:41:37 -0000	1.318
+++ configure.in	12 Sep 2002 17:42:30 -0000
@@ -470,7 +470,8 @@
 		snprintf vsnprintf _vsnprintf strerror \
 		open close dup dup2 fdopen fileno fstat stat isatty \
 		getpid setpgid fork execlp wait kill \
-		grantpt unlockpt ptsname tcgetattr tcsetattr ioctl
+		grantpt unlockpt ptsname tcgetattr tcsetattr ioctl \
+		access
 
 #-----------------------------------------------------------------------------#
 # This is also used by MERCURY_CHECK_READLINE in aclocal.m4.
@@ -495,8 +496,6 @@
 if test "$MR_HAVE_UCONTEXT_H" != 1; then
 	mercury_check_for_headers sys/ucontext.h
 fi
-#-----------------------------------------------------------------------------#
-AC_CHECK_FILE(/dev/ptmx, AC_DEFINE(MR_HAVE_DEV_PTMX))
 #-----------------------------------------------------------------------------#
 #
 # check the basics of sigaction
Index: runtime/mercury_conf.h.in
===================================================================
RCS file: /home/mercury1/repository/mercury/runtime/mercury_conf.h.in,v
retrieving revision 1.43
diff -u -d -r1.43 mercury_conf.h.in
--- runtime/mercury_conf.h.in	12 Mar 2002 16:33:31 -0000	1.43
+++ runtime/mercury_conf.h.in	12 Sep 2002 17:36:45 -0000
@@ -145,12 +145,6 @@
 #undef	MR_HAVE_SYS_STROPTS_H
 
 /*
-** MR_HAVE_DEV_PTMX is defined if /dev/ptmx (used to allocate
-** pseudo-terminals) exists.
-*/
-#undef MR_HAVE_DEV_PTMX
-
-/*
 ** MR_HAVE_POSIX_TIMES is defined if we have the POSIX
 ** `struct tms' struct and times() function.
 */
@@ -182,22 +176,22 @@
 **	MR_HAVE_WAIT		we have the wait() function.
 **	MR_HAVE_KILL		we have the kill() function.
 ** 	MR_HAVE_GETHOSTNAME	we have the gethostname() function.
-**	MR_HAVE_SNPRINTF 		we have the snprintf() function.
-**	MR_HAVE_VSNPRINTF 		we have the vsnprintf() function.
+**	MR_HAVE_SNPRINTF 	we have the snprintf() function.
+**	MR_HAVE_VSNPRINTF 	we have the vsnprintf() function.
 **	MR_HAVE__VSNPRINTF 	we have the _vsnprintf() function.
 **	MR_HAVE_SYSCONF     	we have the sysconf() system call.
-**	MR_HAVE_SIGACTION		we have the sigaction() system call.
+**	MR_HAVE_SIGACTION	we have the sigaction() system call.
 **	MR_HAVE_GETPAGESIZE 	we have the getpagesize() system call.
 **	MR_HAVE_MPROTECT    	we have the mprotect() system call.
 **	MR_HAVE_MEMALIGN    	we have the memalign() function.
 **	MR_HAVE_STRERROR    	we have the strerror() function.
 **	MR_HAVE_SIGINTERRUPT	we have the siginterrupt() function.
 **	MR_HAVE_SETITIMER   	we have the setitimer() function.
-**	MR_HAVE_MEMMOVE   		we have the memmove() function.
-**	MR_HAVE_DLOPEN   		we have the dlopen() function.
-**	MR_HAVE_DLCLOSE   		we have the dlclose() function.
-**	MR_HAVE_DLSYM   		we have the dlsym() function.
-**	MR_HAVE_DLERROR   		we have the dlerror() function.
+**	MR_HAVE_MEMMOVE   	we have the memmove() function.
+**	MR_HAVE_DLOPEN   	we have the dlopen() function.
+**	MR_HAVE_DLCLOSE   	we have the dlclose() function.
+**	MR_HAVE_DLSYM   	we have the dlsym() function.
+**	MR_HAVE_DLERROR   	we have the dlerror() function.
 **	MR_HAVE_STAT 		we have the stat() function.
 **	MR_HAVE_FSTAT 		we have the fstat() function.
 **	MR_HAVE_FDOPEN 		we have the fdopen() function.
@@ -211,11 +205,12 @@
 **				#if defined(fileno) || defined(MR_HAVE_FILENO)
 **	MR_HAVE_ISATTY 		we have the isatty() function.
 **	MR_HAVE_GRANTPT		we have the grantpt() function.
-**	MR_HAVE_UNLOCKPT		we have the unlockpt() function.
+**	MR_HAVE_UNLOCKPT	we have the unlockpt() function.
 **	MR_HAVE_PTSNAME		we have the ptsname() function.
-**	MR_HAVE_TCGETATTR		we have the tcgetattr() function.
-**	MR_HAVE_TCSETATTR		we have the tcsetattr() function.
+**	MR_HAVE_TCGETATTR	we have the tcgetattr() function.
+**	MR_HAVE_TCSETATTR	we have the tcsetattr() function.
 **	MR_HAVE_IOCTL		we have the ioctl() function.
+**	MR_HAVE_ACCESS		we have the access() function.
 */
 #undef	MR_HAVE_GETPID
 #undef	MR_HAVE_SETPGID
@@ -255,6 +250,7 @@
 #undef	MR_HAVE_TCGETATTR
 #undef	MR_HAVE_TCSETATTR
 #undef	MR_HAVE_IOCTL
+#undef	MR_HAVE_ACCESS
 
 /*
 ** We use mprotect() and signals to catch stack and heap overflows.
Index: runtime/mercury_conf_bootstrap.h
===================================================================
RCS file: /home/mercury1/repository/mercury/runtime/mercury_conf_bootstrap.h,v
retrieving revision 1.5
diff -u -d -r1.5 mercury_conf_bootstrap.h
--- runtime/mercury_conf_bootstrap.h	14 Mar 2002 04:31:14 -0000	1.5
+++ runtime/mercury_conf_bootstrap.h	12 Sep 2002 17:37:32 -0000
@@ -287,9 +287,6 @@
 #ifdef MR_PC_ACCESS
   #define PC_ACCESS MR_PC_ACCESS
 #endif
-#ifdef MR_HAVE_DEV_PTMX
-  #define HAVE_DEV_PTMX 1
-#endif
 
 #endif /* !MR_NO_CONF_BACKWARDS_COMPAT && !MR_NO_BACKWARDS_COMPAT */
 
Index: trace/mercury_trace_internal.c
===================================================================
RCS file: /home/mercury1/repository/mercury/trace/mercury_trace_internal.c,v
retrieving revision 1.137
diff -u -d -r1.137 mercury_trace_internal.c
--- trace/mercury_trace_internal.c	11 Sep 2002 07:20:31 -0000	1.137
+++ trace/mercury_trace_internal.c	12 Sep 2002 17:35:21 -0000
@@ -723,9 +723,9 @@
 #if defined(MR_HAVE_OPEN) && defined(O_RDWR) && defined(MR_HAVE_FDOPEN) && \
 	defined(MR_HAVE_CLOSE) && defined(MR_HAVE_DUP) && \
 	defined(MR_HAVE_DUP2) && defined(MR_HAVE_FORK) && \
-	defined(MR_HAVE_EXECLP) && defined(MR_HAVE_DEV_PTMX) && \
+	defined(MR_HAVE_EXECLP) && \
 	defined(MR_HAVE_GRANTPT) && defined(MR_HAVE_UNLOCKPT) && \
-	defined(MR_HAVE_PTSNAME)
+	defined(MR_HAVE_PTSNAME) && defined(MR_HAVE_ACCESS) && defined(F_OK)
 
 	int master_fd = -1;
 	int slave_fd = -1;
@@ -735,13 +735,26 @@
 		defined(MR_HAVE_TCSETATTR) && defined(ECHO) && defined(TCSADRAIN)
 	struct termios termio;
 #endif
+
+	/*
+	** first check whether /dev/ptmx even exists, so that we can give
+	** a slightly better error message if it doesn't.
+	*/
+	if (access("/dev/ptmx", F_OK) != 0) {
+		MR_mdb_perror("can't access /dev/ptmx");
+		MR_mdb_warning(
+		    "Sorry, `mdb --window' not supported on this platform.\n");
+		return MR_FALSE;
+	}
+
+	/* OK, /dev/ptmx exists; now go ahead and open it. */
 	master_fd = open("/dev/ptmx", O_RDWR);
 	if (master_fd == -1 || grantpt(master_fd) == -1
 			|| unlockpt(master_fd) == -1)
 	{
-		close(master_fd);
 		MR_mdb_perror(
 		    "error opening master pseudo-terminal for mdb window");
+		close(master_fd);
 		return MR_FALSE;
 	}
 	if ((slave_name = ptsname(master_fd)) == NULL) {

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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