2.9BSD - /usr/src/cmd/learn/mysys.c

   1: #include "stdio.h"
   2: #include "signal.h"
   3: 
   4: #define EASY    1
   5: #define MEDIUM  2
   6: #define HARD    3
   7: 
   8: mysys(s)
   9: char *s;
  10: {
  11:     /* like "system" but rips off "mv", etc.*/
  12:     /* also tries to guess if can get away with exec cmd */
  13:     /* instead of sh cmd */
  14:     char p[300];
  15:     char *np[40];
  16:     register char *t;
  17:     int nv, type, stat;
  18: 
  19:     type = EASY;    /* we hope */
  20:     for (t = s; *t && type != HARD; t++) {
  21:         switch (*t) {
  22:         case '*':
  23:         case '[':
  24:         case '?':
  25:         case '>':
  26:         case '<':
  27:         case '$':
  28:         case '\'':
  29:         case '"':
  30:             type = MEDIUM;
  31:             break;
  32:         case '|':
  33:         case ';':
  34:         case '&':
  35:             type = HARD;
  36:             break;
  37:         }
  38:     }
  39:     switch (type) {
  40:     case HARD:
  41:         return(system(s));
  42:     case MEDIUM:
  43:         strcpy(p, "exec ");
  44:         strcat(p, s);
  45:         return(system(p));
  46:     case EASY:
  47:         strcpy(p,s);
  48:         nv = getargs(p, np);
  49:         t=np[0];
  50:         if ((strcmp(t, "mv") == 0)||
  51:             (strcmp(t, "cp") == 0)||
  52:             (strcmp(t, "rm") == 0)||
  53:             (strcmp(t, "ls") == 0) ) {
  54:             if (fork() == 0) {
  55:                 char b[100];
  56:                 signal(SIGINT, SIG_DFL);
  57:                 strcpy(b, "/bin/");
  58:                 strcat(b, t);
  59:                 np[nv] = 0;
  60:                 execv(b, np);
  61:                 fprintf(stderr, "Execv failed\n");
  62:                 exit(1);
  63:             }
  64:             wait(&stat);
  65:             return(stat);
  66:         }
  67:         return(system(s));
  68:     }
  69: }
  70: 
  71: /*
  72:  * system():
  73:  *	same as library version, except that resets
  74:  *	default handling of signals in child, so that
  75:  *	user gets the behavior he expects.
  76:  */
  77: 
  78: system(s)
  79: char *s;
  80: {
  81:     int status, pid, w;
  82:     register int (*istat)(), (*qstat)();
  83: 
  84:     istat = signal(SIGINT, SIG_IGN);
  85:     qstat = signal(SIGQUIT, SIG_IGN);
  86:     if ((pid = fork()) == 0) {
  87:         signal(SIGINT, SIG_DFL);
  88:         signal(SIGQUIT, SIG_DFL);
  89:         execl("/bin/sh", "sh", "-c", s, 0);
  90:         _exit(127);
  91:     }
  92:     while ((w = wait(&status)) != pid && w != -1)
  93:         ;
  94:     if (w == -1)
  95:         status = -1;
  96:     signal(SIGINT, istat);
  97:     signal(SIGQUIT, qstat);
  98:     return(status);
  99: }
 100: 
 101: getargs(s, v)
 102: char *s, **v;
 103: {
 104:     int i;
 105: 
 106:     i = 0;
 107:     for (;;) {
 108:         v[i++]=s;
 109:         while (*s != 0 && *s!=' '&& *s != '\t')
 110:             s++;
 111:         if (*s == 0)
 112:             break;
 113:         *s++ =0;
 114:         while (*s == ' ' || *s == '\t')
 115:             s++;
 116:         if (*s == 0)
 117:             break;
 118:     }
 119:     return(i);
 120: }

Defined functions

Defined macros