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76 lines
1.2 KiB
C
76 lines
1.2 KiB
C
#include <ent/config.h>
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/* ent.h undefs these constants and config.h is #pragma once. */
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#if defined(ENT_GETRANDOM)
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#define _ENT_GETRANDOM
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#define _GNU_SOURCE
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#endif
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#if defined(ENT_URANDOM)
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#define _ENT_URANDOM
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#endif
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#include <ent/ent.h>
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#if defined(_ENT_GETRANDOM) || defined(_ENT_URANDOM)
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#include <assert.h>
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#include <errno.h>
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#include <unistd.h>
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#if defined(_ENT_GETRANDOM)
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#include <sys/syscall.h>
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#elif defined(_ENT_URANDOM)
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#endif
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int
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ent_getentropy(void* buf, size_t len)
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{
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char *cuf = buf;
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int ret;
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#if defined(_ENT_URANDOM)
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int fd;
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#endif
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assert(len <= 256);
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if (!len)
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return 0;
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#if defined(_ENT_URANDOM)
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if ((fd = open("/dev/urandom", O_RDONLY)) < 0)
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return -1;
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#endif
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while (len &&
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#if defined(_ENT_GETRANDOM)
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(ret = syscall(SYS_getrandom, cuf, len, 0)) != 0
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#elif defined(_ENT_URANDOM)
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(ret = read(fd, cuf, len)) != 0
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#endif
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) {
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if (ret < 0) {
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if (errno == EINTR)
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continue;
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break;
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}
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len -= ret;
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cuf += ret;
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}
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#if defined(_ENT_URANDOM)
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(void) close(fd);
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#endif
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if (!ret) {
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ret = -1;
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errno = EIO;
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}
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return ret < 0 ? ret : 0;
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}
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#endif /* _ENT_GETRANDOM || _ENT_URANDOM */
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