dhcpcd: stdout output sometimes empty when redirected to a file#364
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rsmarples merged 1 commit intoNetworkConfiguration:masterfrom Oct 10, 2024
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Running dhpcd --dumplease with input from stdin and redirecting stdout to a file outputs nothing to the output. The reason is that printf / fprintf is used to write the output but it is not explicitly flushed when done, or before exiting, and stdout to files is fully buffered by default while stdout to terminals is line buffered by default. This adds calls to fflush() at the end of dhcp_print_option_encoding() and script_dump(), plus one just before exiting dhcpcd. Signed-off-by: Diego Santa Cruz <[email protected]>
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Curious, why does the output not flush when dhcpcd exits? exit() should close stdout, which will implicitly flush it, right? |
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Good question, I think it is because with |
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Ahh. It uses _exit(). Then that explains it. Why it uses _exit() I don't know, but that answers my question. Thanks. |
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Running dhpcd --dumplease with input from stdin and redirecting stdout to a file outputs nothing to the output. The reason is that printf / fprintf is used to write the output but it is not explicitly flushed when done, or before exiting, and stdout to files is fully buffered by default while stdout to terminals is line buffered by default.
This adds calls to fflush() at the end of dhcp_print_option_encoding() and script_dump(), plus one just before exiting dhcpcd.