| 1 | /* |
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| 2 | * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com> |
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| 3 | * |
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| 4 | * Permission to use, copy, modify, and distribute this software for any |
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| 5 | * purpose with or without fee is hereby granted, provided that the above |
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| 6 | * copyright notice and this permission notice appear in all copies. |
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| 7 | * |
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| 8 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
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| 9 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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| 10 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
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| 11 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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| 12 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
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| 13 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
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| 14 | * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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| 15 | */ |
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| 16 | #include <sys/types.h> |
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| 17 | #include <sys/stat.h> |
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| 18 | #include <fcntl.h> |
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| 19 | #include <errno.h> |
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| 20 | #include <unistd.h> |
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| 21 | |
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| 22 | int main(void) |
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| 23 | { |
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| 24 | char buf[64]; |
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| 25 | int fd; |
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| 26 | |
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| 27 | fd = open("/proc/self/wchan" , O_RDONLY); |
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| 28 | if (fd == -1) { |
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| 29 | if (errno == ENOENT) |
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| 30 | return 4; |
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| 31 | return 1; |
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| 32 | } |
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| 33 | |
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| 34 | buf[0] = '\0'; |
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| 35 | if (read(fd, buf, sizeof(buf)) != 1) |
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| 36 | return 1; |
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| 37 | if (buf[0] != '0') |
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| 38 | return 1; |
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| 39 | return 0; |
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| 40 | } |
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| 41 | |
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