minix/commands/ash/mystring.c

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2005-04-21 16:53:53 +02:00
/*-
* Copyright (c) 1991 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Kenneth Almquist.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
static char sccsid[] = "@(#)mystring.c 5.1 (Berkeley) 3/7/91";
#endif /* not lint */
/*
* String functions.
*
* equal(s1, s2) Return true if strings are equal.
* scopy(from, to) Copy a string.
* scopyn(from, to, n) Like scopy, but checks for overflow.
* strchr(s, c) Find first occurance of c in s.
* bcopy(from, to, n) Copy a block of memory.
* number(s) Convert a string of digits to an integer.
* is_number(s) Return true if s is a string of digits.
*/
#include "shell.h"
#include "syntax.h"
#include "error.h"
#include "mystring.h"
char nullstr[1]; /* zero length string */
/*
* scopyn - copy a string from "from" to "to", truncating the string
* if necessary. "To" is always nul terminated, even if
* truncation is performed. "Size" is the size of "to".
*/
void
scopyn(from, to, size)
register char const *from;
register char *to;
register int size;
{
while (--size > 0) {
if ((*to++ = *from++) == '\0')
return;
}
*to = '\0';
}
/*
* strchr - find first occurrence of a character in a string.
*/
#ifndef SYS5
char *
mystrchr(s, charwanted)
char const *s;
register char charwanted;
{
register char const *scan;
/*
* The odd placement of the two tests is so NUL is findable.
*/
for (scan = s ; *scan != charwanted ; ) /* ++ moved down for opt. */
if (*scan++ == '\0')
return NULL;
return (char *)scan;
}
#endif
/*
* bcopy - copy bytes
*
* This routine was derived from code by Henry Spencer.
*/
void
mybcopy(src, dst, length)
pointer dst;
const pointer src;
register int length;
{
register char *d = dst;
register char *s = src;
while (--length >= 0)
*d++ = *s++;
}
/*
* prefix -- see if pfx is a prefix of string.
*/
int
prefix(pfx, string)
register char const *pfx;
register char const *string;
{
while (*pfx) {
if (*pfx++ != *string++)
return 0;
}
return 1;
}
/*
* Convert a string of digits to an integer, printing an error message on
* failure.
*/
int
number(s)
const char *s;
{
if (! is_number(s))
error2("Illegal number", (char *)s);
return atoi(s);
}
/*
* Check for a valid number. This should be elsewhere.
*/
int
is_number(p)
register const char *p;
{
do {
if (! is_digit(*p))
return 0;
} while (*++p != '\0');
return 1;
}