1 files changed, 152 insertions, 0 deletions
diff --git a/lib/ss/pager.c b/lib/ss/pager.c
new file mode 100644
index 0000000..ba32b20
--- /dev/null
+++ b/lib/ss/pager.c
@@ -0,0 +1,152 @@
+/*
+ * Pager: Routines to create a "more" running out of a particular file
+ * descriptor.
+ *
+ * Copyright 1987, 1988 by MIT Student Information Processing Board
+ *
+ * Permission to use, copy, modify, and distribute this software and
+ * its documentation for any purpose is hereby granted, provided that
+ * the names of M.I.T. and the M.I.T. S.I.P.B. not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  M.I.T. and the
+ * M.I.T. S.I.P.B. make no representations about the suitability of
+ * this software for any purpose.  It is provided "as is" without
+ * express or implied warranty.
+ */
+
+#include "config.h"
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#ifdef HAVE_ERRNO_H
+#include <errno.h>
+#endif
+
+#include "ss_internal.h"
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/file.h>
+#include <signal.h>
+#ifdef HAVE_SYS_PRCTL_H
+#include <sys/prctl.h>
+#else
+#define PR_GET_DUMPABLE 3
+#endif
+#if (!defined(HAVE_PRCTL) && defined(linux))
+#include <sys/syscall.h>
+#endif
+
+static char MORE[] = "more";
+extern char *getenv PROTOTYPE((const char *));
+
+char *ss_safe_getenv(const char *arg)
+{
+	if ((getuid() != geteuid()) || (getgid() != getegid()))
+		return NULL;
+#if HAVE_PRCTL
+	if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
+		return NULL;
+#else
+#if (defined(linux) && defined(SYS_prctl))
+	if (syscall(SYS_prctl, PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
+		return NULL;
+#endif
+#endif
+
+#if defined(HAVE_SECURE_GETENV)
+	return secure_getenv(arg);
+#elif defined(HAVE___SECURE_GETENV)
+	return __secure_getenv(arg);
+#else
+	return getenv(arg);
+#endif
+}
+
+/*
+ * this needs a *lot* of work....
+ *
+ * run in same process
+ * handle SIGINT sensibly
+ * allow finer control -- put-page-break-here
+ */
+
+#ifndef NO_FORK
+int ss_pager_create(void)
+{
+	int filedes[2];
+
+	if (pipe(filedes) != 0)
+		return(-1);
+
+	switch(fork()) {
+	case -1:
+		return(-1);
+	case 0:
+		/*
+		 * Child; dup read half to 0, close all but 0, 1, and 2
+		 */
+		if (dup2(filedes[0], 0) == -1)
+			exit(1);
+		ss_page_stdin();
+	default:
+		/*
+		 * Parent:  close "read" side of pipe, return
+		 * "write" side.
+		 */
+		(void) close(filedes[0]);
+		return(filedes[1]);
+	}
+}
+#else /* don't fork */
+int ss_pager_create()
+{
+    int fd;
+    fd = open("/dev/tty", O_WRONLY, 0);
+    return fd;
+}
+#endif
+
+static int write_all(int fd, char *buf, size_t count)
+{
+	ssize_t ret;
+	int c = 0;
+
+	while (count > 0) {
+		ret = write(fd, buf, count);
+		if (ret < 0) {
+			if ((errno == EAGAIN) || (errno == EINTR))
+				continue;
+			return -1;
+		}
+		count -= ret;
+		buf += ret;
+		c += ret;
+	}
+	return c;
+}
+
+void ss_page_stdin(void)
+{
+	int i;
+	sigset_t mask;
+
+	for (i = 3; i < 32; i++)
+		(void) close(i);
+	(void) signal(SIGINT, SIG_DFL);
+	sigprocmask(SIG_BLOCK, 0, &mask);
+	sigdelset(&mask, SIGINT);
+	sigprocmask(SIG_SETMASK, &mask, 0);
+	if (_ss_pager_name == (char *)NULL) {
+		if ((_ss_pager_name = ss_safe_getenv("PAGER")) == (char *)NULL)
+			_ss_pager_name = MORE;
+	}
+	(void) execlp(_ss_pager_name, _ss_pager_name, (char *) NULL);
+	{
+		/* minimal recovery if pager program isn't found */
+		char buf[80];
+		register int n;
+		while ((n = read(0, buf, 80)) > 0)
+			write_all(1, buf, n);
+	}
+	exit(errno);
+}