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https://github.com/fluencelabs/musl
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6d1a3dfeaf
the comparison f->wpos > f->buf has undefined behavior when f->wpos is a null pointer, despite the intuition (and actual compiler behavior, for all known compilers) being that NULL > ptr is false for all valid pointers ptr. the purpose of the comparison is to determine if the write buffer is non-empty, and the idiom used elsewhere for that is comparison against f->wbase, which is either a null pointer when not writing, or equal to f->buf when writing. in the former case, both f->wpos and f->wbase are null; in the latter they are both non-null and point into the same array.
22 lines
393 B
C
22 lines
393 B
C
#include <stdio_impl.h>
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int __toread(FILE *f)
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{
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f->mode |= f->mode-1;
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if (f->wpos > f->wbase) f->write(f, 0, 0);
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f->wpos = f->wbase = f->wend = 0;
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if (f->flags & F_NORD) {
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f->flags |= F_ERR;
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return EOF;
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}
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f->rpos = f->rend = f->buf + f->buf_size;
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return (f->flags & F_EOF) ? EOF : 0;
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}
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void __stdio_exit_needed(void);
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void __toread_needs_stdio_exit()
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{
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__stdio_exit_needed();
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}
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