53 lines
1.0 KiB
C
53 lines
1.0 KiB
C
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#include <assert.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/uio.h>
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#include <unistd.h>
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#include "buf.h"
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#include "rand.h"
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static struct buf rand_buf = BUF_INIT;
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static int rand_fd;
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void rand_init() {
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rand_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
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assert(rand_fd >= 0);
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assert(read(rand_fd, buf_at(&rand_buf, 0), BUF_LEN_MAX) == BUF_LEN_MAX);
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rand_buf.length = BUF_LEN_MAX;
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}
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void rand_cleanup() {
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assert(!close(rand_fd));
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}
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void rand_fill(void *value, size_t size) {
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if (size <= rand_buf.length) {
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memcpy(value, buf_at(&rand_buf, 0), size);
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buf_consume(&rand_buf, size);
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return;
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}
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struct iovec iov[2] = {
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{
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.iov_base = rand_buf.buf,
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.iov_len = rand_buf.start,
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},
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{
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.iov_base = value,
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.iov_len = size,
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},
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};
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size_t bytes = rand_buf.start + size;
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assert(bytes < SSIZE_MAX);
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assert(readv(rand_fd, iov, 2) == (ssize_t) bytes);
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rand_buf.start = 0;
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rand_buf.length = BUF_LEN_MAX;
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}
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