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In this developer's tests, producing one gigabyte worth of NULs in a busy loop that writes out individual bytes, unbuffered, took ~27sec. Writing chunked 256kB buffers instead only took ~0.6sec This matters because we are about to introduce a pair of test cases that want to be able to produce 5GB of NULs, and we cannot use `/dev/zero` because of the HP NonStop platform's lack of support for that device. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
35 lines
651 B
C
35 lines
651 B
C
#include "test-tool.h"
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#include "git-compat-util.h"
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int cmd__genzeros(int argc, const char **argv)
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{
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/* static, so that it is NUL-initialized */
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static const char zeros[256 * 1024];
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intmax_t count;
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ssize_t n;
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if (argc > 2) {
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fprintf(stderr, "usage: %s [<count>]\n", argv[0]);
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return 1;
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}
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count = argc > 1 ? strtoimax(argv[1], NULL, 0) : -1;
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/* Writing out individual NUL bytes is slow... */
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while (count < 0)
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if (write(1, zeros, ARRAY_SIZE(zeros)) < 0)
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return -1;
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while (count > 0) {
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n = write(1, zeros, count < ARRAY_SIZE(zeros) ?
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count : ARRAY_SIZE(zeros));
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if (n < 0)
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return -1;
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count -= n;
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}
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return 0;
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}
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