1 #include <stdio.h> 2 #include <signal.h> 3 #include <errno.h> 4 #define tst(a,b) (*mode == 'r'? (b) : (a)) 5 #define RDR 0 6 #define WTR 1 7 static int popen_pid[20]; 8 static char *sccsid = "@(#)popen.c 1.5 10/21/82"; 9 10 # ifndef VMUNIX 11 # define vfork fork 12 # endif VMUNIX 13 #ifndef SIGRETRO 14 #define sigchild() 15 #endif 16 17 FILE * 18 popen(cmd,mode) 19 char *cmd; 20 char *mode; 21 { 22 int p[2]; 23 register myside, hisside, pid; 24 25 if(pipe(p) < 0) 26 return NULL; 27 myside = tst(p[WTR], p[RDR]); 28 hisside = tst(p[RDR], p[WTR]); 29 if((pid = vfork()) == 0) { 30 /* myside and hisside reverse roles in child */ 31 sigchild(); 32 close(myside); 33 dup2(hisside, tst(0, 1)); 34 close(hisside); 35 execl("/bin/csh", "sh", "-c", cmd, 0); 36 _exit(1); 37 } 38 if(pid == -1) 39 return NULL; 40 popen_pid[myside] = pid; 41 close(hisside); 42 return(fdopen(myside, mode)); 43 } 44 45 pclose(ptr) 46 FILE *ptr; 47 { 48 register f, r; 49 int status; 50 extern int errno; 51 52 f = fileno(ptr); 53 fclose(ptr); 54 # ifdef VMUNIX 55 sighold(SIGINT); 56 sighold(SIGQUIT); 57 sighold(SIGHUP); 58 # endif VMUNIX 59 while((r = wait(&status)) != popen_pid[f] && r != -1 && errno != EINTR) 60 ; 61 if(r == -1) 62 status = -1; 63 # ifdef VMUNIX 64 sigrelse(SIGINT); 65 sigrelse(SIGQUIT); 66 sigrelse(SIGHUP); 67 # endif VMUNIX 68 return(status); 69 } 70