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#include "stdio_impl.h"
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int ungetc(int c, FILE *f)
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{
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if (c == EOF) return c;
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FLOCK(f);
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if (!f->rpos) __toread(f);
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if (!f->rpos || f->rpos <= f->buf - UNGET) {
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FUNLOCK(f);
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return EOF;
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}
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*--f->rpos = c;
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f->flags &= ~F_EOF;
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FUNLOCK(f);
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return (unsigned char)c;
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}
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