1 /*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Kenneth Almquist. 7 * 8 * %sccs.include.redist.c% 9 */ 10 11 #ifndef lint 12 static char sccsid[] = "@(#)mystring.c 8.1 (Berkeley) 05/31/93"; 13 #endif /* not lint */ 14 15 /* 16 * String functions. 17 * 18 * equal(s1, s2) Return true if strings are equal. 19 * scopy(from, to) Copy a string. 20 * scopyn(from, to, n) Like scopy, but checks for overflow. 21 * number(s) Convert a string of digits to an integer. 22 * is_number(s) Return true if s is a string of digits. 23 */ 24 25 #include "shell.h" 26 #include "syntax.h" 27 #include "error.h" 28 #include "mystring.h" 29 30 31 char nullstr[1]; /* zero length string */ 32 33 /* 34 * equal - #defined in mystring.h 35 */ 36 37 /* 38 * scopy - #defined in mystring.h 39 */ 40 41 42 /* 43 * scopyn - copy a string from "from" to "to", truncating the string 44 * if necessary. "To" is always nul terminated, even if 45 * truncation is performed. "Size" is the size of "to". 46 */ 47 48 void 49 scopyn(from, to, size) 50 register char const *from; 51 register char *to; 52 register int size; 53 { 54 55 while (--size > 0) { 56 if ((*to++ = *from++) == '\0') 57 return; 58 } 59 *to = '\0'; 60 } 61 62 63 /* 64 * prefix -- see if pfx is a prefix of string. 65 */ 66 67 int 68 prefix(pfx, string) 69 register char const *pfx; 70 register char const *string; 71 { 72 while (*pfx) { 73 if (*pfx++ != *string++) 74 return 0; 75 } 76 return 1; 77 } 78 79 80 /* 81 * Convert a string of digits to an integer, printing an error message on 82 * failure. 83 */ 84 85 int 86 number(s) 87 const char *s; 88 { 89 90 if (! is_number(s)) 91 error2("Illegal number", (char *)s); 92 return atoi(s); 93 } 94 95 96 97 /* 98 * Check for a valid number. This should be elsewhere. 99 */ 100 101 int 102 is_number(p) 103 register const char *p; 104 { 105 do { 106 if (! is_digit(*p)) 107 return 0; 108 } while (*++p != '\0'); 109 return 1; 110 } 111