diff options
Diffstat (limited to 'rio.c')
| -rw-r--r-- | rio.c | 88 |
1 files changed, 88 insertions, 0 deletions
@@ -0,0 +1,88 @@ +#include <err.h> +#include <fcntl.h> +#include <stdio.h> +#include <string.h> +#include <sys/select.h> +#include <unistd.h> + +#define MAXBUF 2048 + +int +main() +{ + char bufin[MAXBUF], bufout[MAXBUF], *bi, *bo; + fd_set rfds0, rfds1; + int c, fdin, fdout, flags, i, nin, nout, state; + struct timeval tv; + + if(!(fdin = open("/var/tmp/r.in", O_WRONLY))) + err(1, "open"); + if(!(fdout = open("/var/tmp/r.out", O_RDONLY))) + err(1, "open"); + + FD_ZERO(&rfds0); + FD_ZERO(&rfds1); + + tv.tv_sec = 0; + tv.tv_usec = 1; + + for(;;){ + /* + * User input is read from standard in and copied the + * input pipe. It is saved in bufin for later use. + */ + FD_SET(0, &rfds0); + if(select(0+1, &rfds0, NULL, NULL, &tv) > 0){ + nout = read(0, bufin, MAXBUF); + bufin[nout] = 0; + dprintf(fdin, "%s", bufin); + fflush(stdout); + } + + /* + * System output is read from the output pipe and copied + * to standard out for the user to see. + */ + FD_SET(fdout, &rfds1); + if(select(fdout+1, &rfds1, NULL, NULL, &tv) > 0){ + nout = read(fdout, bufout, MAXBUF); + if(!nout) continue; + bufout[nout] = 0; + + /* + * Bufin and bufout are copied to the temporary + * pointers bi and bo. Bo is incremented in order + * to skip any potential repetition of the command + * given by the user on standard in. (It is assumed + * that the typed command fits in bufin, i.e. is + * not larger than MAXBUF.) + */ + bi = bufin; + bo = bufout; + for(;;){ + if(*bo == '\n'){ + bo++; + break; + } + if(*bo == 13){ + bo++; + continue; + } + if(*bi != *bo){ + bo = bufout; + break; + } + bi++; bo++; + } + + /* + * Bo is printed and bufin is cleared, so as not + * to perform the skip again, incorrectly. + */ + printf("%s", bo); + fflush(stdout); + bufin[0] = 0; + } + } + +} |