ac88ce4f7f
The mount() and bind() syscalls return -1 on error, and the mountid sequence number on success. The manpage states that the mountid sequence number is a positive integer, but the kernels implementation currently uses a unsigned 32-bit integer and does not guarantee that the mountid will not become negative. Most code just cares about the error, so test for the -1 error value only.
97 lines
1.7 KiB
C
97 lines
1.7 KiB
C
#include <u.h>
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#include <libc.h>
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#define TEMP "/n/temp"
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void
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usage(void)
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{
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fprint(2, "usage: pipefile [-d] [-r command] [-w command] file\n");
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exits("usage");
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}
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void
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connect(char *cmd, int fd0, int fd1)
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{
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switch(rfork(RFPROC|RFFDG|RFREND|RFNOWAIT)){
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case -1:
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sysfatal("fork %s: %r", cmd);
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break;
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default:
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close(fd0);
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close(fd1);
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return;
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case 0:
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dup(fd0, 0);
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dup(fd1, 1);
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close(fd0);
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close(fd1);
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execl("/bin/rc", "rc", "-c", cmd, nil);
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sysfatal("exec %s: %r", cmd);
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break;
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}
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}
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void
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main(int argc, char *argv[])
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{
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char *file;
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char *rcmd, *wcmd;
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int fd0, fd1, ifd0, ifd1, dupflag;
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rfork(RFNOTEG);
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dupflag = 0;
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rcmd = wcmd = nil;
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ARGBEGIN{
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case 'd':
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dupflag = 1;
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break;
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case 'r':
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rcmd = EARGF(usage());
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break;
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case 'w':
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wcmd = EARGF(usage());
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break;
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default:
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usage();
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}ARGEND
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if(argc!=1 || (rcmd==nil && wcmd==nil))
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usage();
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if(rcmd == nil)
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rcmd = "/bin/cat";
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if(wcmd == nil)
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wcmd = "/bin/cat";
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file = argv[0];
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if(dupflag){
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ifd0 = open(file, ORDWR);
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if(ifd0 < 0)
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sysfatal("open %s: %r", file);
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ifd1 = dup(ifd0, -1);
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}else{
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ifd0 = open(file, OREAD);
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if(ifd0 < 0)
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sysfatal("open %s: %r", file);
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ifd1 = open(file, OWRITE);
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if(ifd1 < 0)
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sysfatal("open %s: %r", file);
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}
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if(bind("#|", TEMP, MREPL) == -1)
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sysfatal("bind pipe %s: %r", TEMP);
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if(bind(TEMP "/data", file, MREPL) == -1)
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sysfatal("bind %s %s: %r", TEMP "/data", file);
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fd0 = open(TEMP "/data1", OREAD);
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if(fd0 < 0)
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sysfatal("open %s: %r", TEMP "/data1");
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connect(wcmd, fd0, ifd1);
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fd1 = open(TEMP "/data1", OWRITE);
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if(fd1 < 0)
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sysfatal("open %s: %r", TEMP "/data1");
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connect(rcmd, ifd0, fd1);
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unmount(nil, TEMP);
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exits(nil);
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}
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