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/*++
/* 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
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