1/* inststr.c ... stolen from bdupdate.c, which stole it from perl 4. 2 * Theft by C. Scott Ananian <cananian@alumni.princeton.edu> 3 * Modified similarly to perl 5.8.3's alignment-checking code 48 by Paul Howarth <paul@city-fan.org> 5 * 6 * $Id: inststr.c,v 1.1.1.1 2008/10/15 03:30:51 james26_jang Exp $ 7 */ 8 9#include <string.h> 10 11#define PTRSIZE sizeof(void *) 12typedef unsigned long UL; 13 14void 15inststr(int argc, char **argv, char **environ, char *src) 16{ 17 if (strlen(src) <= strlen(argv[0])) 18 { 19 char *ptr; 20 21 for (ptr = argv[0]; *ptr; *(ptr++) = '\0'); 22 23 strcpy(argv[0], src); 24 } else 25 { 26 /* Stolen from the source to perl 4.036 (assigning to $0) */ 27 /* Modified to allow for aligned array members, assuming */ 28 /* no system has something bizarre like the argv[] */ 29 /* interleaved with some other data. Also allow for argv */ 30 /* array having higher numbered elements lower in memory */ 31 /* than lower numbered elements. */ 32 char *ptr, *ptr2; 33 int count; 34 UL mask = ~(UL)(PTRSIZE == 4 ? 3 : PTRSIZE == 8 ? 7 : PTRSIZE == 16 ? 15 : 0); 35 int aligned = (mask < ~(UL)0) && (((UL)(argv[0]) & mask) == (UL)(argv[0])); 36 ptr = argv[0] + strlen(argv[0]); 37 if (argv[argc - 1] >= argv[1]) { 38 /* argv pointers in ascending memory order */ 39 for (count = 1; count < argc; count++) { 40 if (argv[count] == ptr + 1 41 || 42 (aligned && argv[count] > ptr && argv[count] <= (char *)((UL)(ptr + PTRSIZE) & mask)) 43 ) { 44 ptr = argv[count] + strlen(argv[count]); 45 } 46 } 47 } else 48 { 49 /* sometimes the argv pointers go down in memory rather than up */ 50 for (count = argc - 1; count > 0; count--) { 51 if (argv[count] == ptr + 1 52 || 53 (aligned && argv[count] > ptr && argv[count] <= (char *)((UL)(ptr + PTRSIZE) & mask)) 54 ) { 55 ptr = argv[count] + strlen(argv[count]); 56 } 57 } 58 } 59 for (count = 0; environ[count]; count++) { 60 if (environ[count] == ptr + 1 61 || 62 (aligned && environ[count] > ptr && environ[count] <= (char *)((UL)(ptr + PTRSIZE) & mask)) 63 ) { 64 ptr = environ[count] + strlen(environ[count]); 65 } 66 } 67 count = 0; 68 for (ptr2 = argv[0]; ptr2 <= ptr; ptr2++) { 69 *ptr2 = '\0'; 70 count++; 71 } 72 strncpy(argv[0], src, count); 73 } 74} 75