1 files changed, 158 insertions, 0 deletions
diff --git a/src/global/off_cvt.c b/src/global/off_cvt.c
new file mode 100644
index 0000000..3efb0b7
--- /dev/null
+++ b/src/global/off_cvt.c
@@ -0,0 +1,158 @@
+/*++
+/* NAME
+/*	off_cvt 3
+/* SUMMARY
+/*	off_t conversions
+/* SYNOPSIS
+/*	#include <off_cvt.h>
+/*
+/*	off_t	off_cvt_string(string)
+/*	const char *string;
+/*
+/*	VSTRING	*off_cvt_number(result, offset)
+/*	VSTRING	*result;
+/*	off_t	offset;
+/* DESCRIPTION
+/*	This module provides conversions between \fIoff_t\fR and string.
+/*
+/*	off_cvt_string() converts a string, containing a non-negative
+/*	offset, to numerical form. The result is -1 in case of problems.
+/*
+/*	off_cvt_number() converts a non-negative offset to string form.
+/*
+/*	Arguments:
+/* .IP string
+/*	String with non-negative number to be converted to off_t.
+/* .IP result
+/*	Buffer for storage of the result of conversion to string.
+/* .IP offset
+/*	Non-negative off_t value to be converted to string.
+/* DIAGNOSTICS
+/*	Panic: negative offset
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <sys/types.h>
+#include <ctype.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <vstring.h>
+
+/* Global library. */
+
+#include "off_cvt.h"
+
+/* Application-specific. */
+
+#define STR	vstring_str
+#define END	vstring_end
+#define SWAP(type, a, b) { type temp; temp = a; a = b; b = temp; }
+
+/* off_cvt_string - string to number */
+
+off_t   off_cvt_string(const char *str)
+{
+    int     ch;
+    off_t   result;
+    off_t   digit_value;
+
+    /*
+     * Detect overflow before it happens. Code that attempts to detect
+     * overflow after-the-fact makes assumptions about undefined behavior.
+     * Compilers may invalidate such assumptions.
+     */
+    for (result = 0; (ch = *(unsigned char *) str) != 0; str++) {
+	if (!ISDIGIT(ch))
+	    return (-1);
+	digit_value = ch - '0';
+	if (result > OFF_T_MAX / 10
+	    || (result *= 10) > OFF_T_MAX - digit_value)
+	    return (-1);
+	result += digit_value;
+    }
+    return (result);
+}
+
+/* off_cvt_number - number to string */
+
+VSTRING *off_cvt_number(VSTRING *buf, off_t offset)
+{
+    static char digs[] = "0123456789";
+    char   *start;
+    char   *last;
+    int     i;
+
+    /*
+     * Sanity checks
+     */
+    if (offset < 0)
+	msg_panic("off_cvt_number: negative offset -%s",
+		  STR(off_cvt_number(buf, -offset)));
+
+    /*
+     * First accumulate the result, backwards.
+     */
+    VSTRING_RESET(buf);
+    while (offset != 0) {
+	VSTRING_ADDCH(buf, digs[offset % 10]);
+	offset /= 10;
+    }
+    VSTRING_TERMINATE(buf);
+
+    /*
+     * Then, reverse the result.
+     */
+    start = STR(buf);
+    last = END(buf) - 1;
+    for (i = 0; i < VSTRING_LEN(buf) / 2; i++)
+	SWAP(int, start[i], last[-i]);
+    return (buf);
+}
+
+#ifdef TEST
+
+ /*
+  * Proof-of-concept test program. Read a number from stdin, convert to
+  * off_t, back to string, and print the result.
+  */
+#include <vstream.h>
+#include <vstring_vstream.h>
+
+int     main(int unused_argc, char **unused_argv)
+{
+    VSTRING *buf = vstring_alloc(100);
+    off_t   offset;
+
+    while (vstring_fgets_nonl(buf, VSTREAM_IN)) {
+	if (STR(buf)[0] == '#' || STR(buf)[0] == 0)
+	    continue;
+	if ((offset = off_cvt_string(STR(buf))) < 0) {
+	    msg_warn("bad input %s", STR(buf));
+	} else {
+	    vstream_printf("%s\n", STR(off_cvt_number(buf, offset)));
+	}
+	vstream_fflush(VSTREAM_OUT);
+    }
+    vstring_free(buf);
+    return (0);
+}
+
+#endif