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POWriting a shell in C, closing stdin somewhere
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2012-04-07T19:01:17.197
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2012-04-07T21:18:25.863
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2012-04-07T21:18:25.863
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I'm writing a shell and I seem to be closing stdin at some point, but I can't figure out where. I have poured and poured over this code, but can't find where I might be closing it. It only gets closed when I use a pipe like so: <pre><code>cat f2.txt | cat </code></pre> or <pre><code>cat < f2.txt | cat </code></pre> or <pre><code>cat | cat | cat </code></pre> The lines where this code is handled is 232 through 268 and then 270 through 288 I can't seem to get the formatting right so here is the formatted code: <a href="http://pastebin.com/pe8BkVPV" rel="nofollow">http://pastebin.com/pe8BkVPV</a> I will also paste the section in question below. Any ideas? <pre><code>if (ct->recieve_input == 1 && ct->redirect_output == 0) { ptr = dll_prev(tmp) ; ctmp = jval_v(ptr->val) ; //fprintf(stderr, "Previous->command = %s\n", ctmp->command) ; fflush(stdout) ; fs = fork() ; if (fs == 0) { if (ct->tdw == 1) { /* If we are redirecting output */ fprintf(stderr, "ct->tdw = 1\n") ; if (dup2(ct->fd1, 1) != 1) { perror("dup2 tdw A") ; exit(1) ; } if (close(ct->fd1) < 0) { perror("c1"); exit(1); } } /* tdw == 1 */ if (ct->tdr == 1) { /* If we are recieving input */ fprintf(stderr, "ct->tdr = 1\n") ; if (dup2(ct->fd0, 0) != 0) { perror("dup2 tdr A") ; exit(1) ; } if (close(ct->fd0) < 0) { perror("c0"); exit(1); } } if (dup2(ctmp->pipefd[0], 0) != 0) { perror("dup2 : 0, 0") ; exit(1) ; } //close(ct->pipefd[1]) ; //close(ct->pipefd[0]) ; close(ctmp->pipefd[1]) ; close(ct->pipefd[1]) ; status = execvp(ct->command, ct->args) ; fprintf(stderr, "execvp command failed\n") ; exit(1) ; } } if (ct->redirect_output == 1 && ct->recieve_input == 0) { ptr = (to_exec)->blink ; ctmp = jval_v(ptr->val) ; ctmp->recieve_input = 1 ; fflush(stdout) ; fs = fork() ; if (fs == 0) { if (dup2(ct->pipefd[1], 1) == -1) { perror("dup2 : RD== 1:1, 1") ; exit(1) ; } //close(ct->pipefd[0]) ; // TODO status = execvp(ct->command, ct->args) ; fprintf(stderr, "exevp command failed\n") ; exit(1) ; } } /* End redirect output */ </code></pre>
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<c><shell><pipe><system>
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Writing a shell in C, closing stdin somewhere
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1. COThe stdin in closed when the pipe ends. The fgetchar() should return -1 at this point.
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