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1 | /* |
| 2 | * Copyright (c) 2009, Stathis Kamperis |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions |
| 7 | * are met: |
| 8 | * 1. Redistributions of source code must retain the above copyright |
| 9 | * notice, this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer in the |
| 12 | * documentation and/or other materials provided with the distribution. |
| 13 | * |
| 14 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 15 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 16 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| 17 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| 18 | * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 19 | * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| 20 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 21 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| 22 | * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| 23 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| 24 | * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 25 | * SUCH DAMAGE. |
| 26 | */ |
| 27 | |
| 28 | #include <assert.h> |
| 29 | #include <errno.h> |
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30 | #include <mqueue.h> |
| 31 | #include <signal.h> |
| 32 | #include <stdio.h> |
| 33 | #include <stdlib.h> |
| 34 | #include <string.h> /* memset() */ |
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35 | #include <unistd.h> /* fork() */ |
| 36 | #include <sys/wait.h> |
| 37 | |
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38 | #define MQNAME "/t_mq_send2" |
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39 | |
| 40 | int |
| 41 | main(void) |
| 42 | { |
| 43 | /* Create a message queue with capacity `1'. */ |
| 44 | struct mq_attr attr; |
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45 | |
| 46 | memset(&attr, 0, sizeof(attr)); |
| 47 | attr.mq_maxmsg = 1; /* Maximum number of messages. */ |
| 48 | attr.mq_msgsize = 1024; /* Maximum message size. */ |
| 49 | |
| 50 | /* |
| 51 | * We intentionally omit the O_NONBLOCK flag as we want our queue to |
| 52 | * operate on blocking mode. |
| 53 | */ |
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54 | mqd_t md; |
| 55 | |
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56 | md = mq_open(MQNAME, O_CREAT | O_EXCL | O_WRONLY, 0777, &attr); |
| 57 | assert(md != (mqd_t)-1); |
| 58 | |
| 59 | /* Send a message to fill in the queue. */ |
| 60 | assert(mq_send(md, "foo", sizeof("foo"), /* priority */ 0) != -1); |
| 61 | |
| 62 | /* |
| 63 | * Fork and let the child block indefinitely on mq_send(). |
| 64 | * This would have caused a panic on {Net, DragonFly}BSD, but it is now |
| 65 | * fixed. |
| 66 | */ |
| 67 | pid_t pid = fork(); |
| 68 | assert(pid != -1); |
| 69 | |
| 70 | if (pid == 0) { |
| 71 | /* We are inside the child. */ |
| 72 | mqd_t md2; |
| 73 | |
| 74 | md2 = mq_open(MQNAME, O_WRONLY); |
| 75 | assert(md2 != (mqd_t)-1); |
| 76 | |
| 77 | assert(mq_send(md2, "foo", sizeof("foo"), |
| 78 | /* priority */ NULL) != -1); |
| 79 | |
| 80 | /* |
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81 | * There is no point in calling mq_close() here, as (normally) |
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82 | * this code block will never be reached. Instead we do it |
| 83 | * inside the parent. |
| 84 | */ |
| 85 | } else { |
| 86 | /* We are inside the parent. */ |
| 87 | /* Sleep for a while so that child manages to block on |
| 88 | * mq_send(). |
| 89 | */ |
| 90 | assert(sleep(3) == 0); |
| 91 | |
| 92 | /* |
| 93 | * Kill the child. We can't use wait() here, because if let |
| 94 | * alone, the child will (normally) live for ever, waiting |
| 95 | * on mq_send(). |
| 96 | */ |
| 97 | assert(kill(pid, SIGKILL) != -1); |
| 98 | |
| 99 | /* |
| 100 | * We now probe child's exit status to make sure that everything |
| 101 | * went as planned. |
| 102 | */ |
| 103 | int status; |
| 104 | assert(wait(&status) == pid); |
| 105 | |
| 106 | /* |
| 107 | * It MUST have exited due to a signal been delivered to it. |
| 108 | */ |
| 109 | assert(WIFSIGNALED(status)); |
| 110 | |
| 111 | /* |
| 112 | * And the signal MUST be the one _we_ send to it (SIGKILL). |
| 113 | */ |
| 114 | if (WTERMSIG(status) != SIGKILL) { |
| 115 | return (EXIT_FAILURE); |
| 116 | } |
| 117 | |
| 118 | /* Disassociate from message queue. */ |
| 119 | assert(mq_close(md) != -1); |
| 120 | |
| 121 | /* Remove message queue from the system. */ |
| 122 | assert(mq_unlink(MQNAME) != -1); |
| 123 | |
| 124 | printf("passed\n"); |
| 125 | |
| 126 | return (EXIT_SUCCESS); |
| 127 | } |
| 128 | |
| 129 | /* Child will (normally) never reach here. Nor parent. */ |
| 130 | return (EXIT_SUCCESS); |
| 131 | } |