38 lines
718 B
C++
38 lines
718 B
C++
#include <fcntl.h>
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#include <sys/random.h>
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ssize_t getrandom(void* buf, size_t size, unsigned int flags)
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{
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const unsigned int valid_flags = GRND_RANDOM | GRND_NONBLOCK;
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if ((flags & valid_flags) != flags)
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{
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errno = EINVAL;
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return -1;
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}
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const char* path = (flags & GRND_RANDOM) ? "/dev/random" : "/dev/urandom";
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int oflag = O_RDONLY;
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if (flags & GRND_NONBLOCK)
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oflag |= O_NONBLOCK;
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int fd = open(path, oflag);
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if (fd == -1)
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return -1;
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uint8_t* ubuf = static_cast<uint8_t*>(buf);
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size_t total_read = 0;
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while (total_read < size)
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{
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const ssize_t nread = read(fd, ubuf + total_read, size - total_read);
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if (nread <= 0)
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break;
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total_read += nread;
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}
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close(fd);
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return total_read;
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}
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