153 lines
3.4 KiB
C
153 lines
3.4 KiB
C
/*++
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/* NAME
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/* off_cvt 3
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/* SUMMARY
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/* off_t conversions
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/* SYNOPSIS
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/* #include <off_cvt.h>
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/*
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/* off_t off_cvt_string(string)
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/* const char *string;
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/*
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/* VSTRING *off_cvt_number(result, offset)
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/* VSTRING *result;
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/* off_t offset;
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/* DESCRIPTION
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/* This module provides conversions between \fIoff_t\fR and string.
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/*
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/* off_cvt_string() converts a string, containing a non-negative
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/* offset, to numerical form. The result is -1 in case of problems.
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/*
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/* off_cvt_number() converts a non-negative offset to string form.
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/*
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/* Arguments:
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/* .IP string
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/* String with non-negative number to be converted to off_t.
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/* .IP result
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/* Buffer for storage of the result of conversion to string.
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/* .IP offset
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/* Non-negative off_t value to be converted to string.
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/* BUGS
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/* The string to number conversion routine has no reliable way to
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/* detect an overflow error, so the result may be much smaller
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/* than the number specified in the input.
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/* DIAGNOSTICS
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/* Panic: negative offset
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/* LICENSE
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/* .ad
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/* .fi
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/* The Secure Mailer license must be distributed with this software.
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/* AUTHOR(S)
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/* Wietse Venema
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/* IBM T.J. Watson Research
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/* P.O. Box 704
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/* Yorktown Heights, NY 10598, USA
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/*--*/
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/* System library. */
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#include <sys_defs.h>
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#include <ctype.h>
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/* Utility library. */
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#include <msg.h>
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#include <vstring.h>
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/* Global library. */
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#include "off_cvt.h"
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/* Application-specific. */
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#define STR vstring_str
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#define END vstring_end
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#define SWAP(type, a, b) { type temp; temp = a; a = b; b = temp; }
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/* off_cvt_string - string to number */
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off_t off_cvt_string(const char *str)
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{
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int ch;
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off_t result;
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/*
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* We're not doing this often, so simplicity has precedence over
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* performance. XXX Need a portable way to correctly detect overflow.
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* Bear in mind that an off_t is not necessarily a long integer, so using
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* raw bit patterns is not going to be a portable solution.
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*/
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for (result = 0; (ch = *(unsigned char *) str) != 0; str++) {
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if (!ISDIGIT(ch))
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return (-1);
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result *= 10;
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result += ch - '0';
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if (result < 0)
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return (-1);
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}
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return (result);
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}
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/* off_cvt_number - number to string */
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VSTRING *off_cvt_number(VSTRING *buf, off_t offset)
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{
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static char digs[] = "0123456789";
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char *start;
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char *last;
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int i;
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/*
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* Sanity checks
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*/
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if (offset < 0)
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msg_panic("off_cvt_number: negative offset %s",
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STR(off_cvt_number(buf, -offset)));
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/*
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* First accumulate the result, backwards.
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*/
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VSTRING_RESET(buf);
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while (offset != 0) {
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VSTRING_ADDCH(buf, digs[offset % 10]);
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offset /= 10;
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}
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VSTRING_TERMINATE(buf);
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/*
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* Then, reverse the result.
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*/
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start = STR(buf);
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last = END(buf) - 1;
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for (i = 0; i < VSTRING_LEN(buf) / 2; i++)
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SWAP(int, start[i], last[-i]);
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return (buf);
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}
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#ifdef TEST
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/*
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* Proof-of-concept test program. Read a number from stdin, convert to
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* off_t, back to string, and print the result.
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*/
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#include <vstream.h>
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#include <vstring_vstream.h>
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int main(int unused_argc, char **unused_argv)
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{
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VSTRING *buf = vstring_alloc(100);
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off_t offset;
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while (vstring_fgets_nonl(buf, VSTREAM_IN)) {
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if ((offset = off_cvt_string(STR(buf))) < 0) {
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msg_warn("bad input %s", STR(buf));
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} else {
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vstream_printf("%s\n", STR(off_cvt_number(buf, offset)));
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}
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vstream_fflush(VSTREAM_OUT);
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}
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vstring_free(buf);
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}
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#endif
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