33 lines
1.6 KiB
C
33 lines
1.6 KiB
C
#include "stdio_impl.h"
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/* Scan helper "stdio" functions for use by scanf-family and strto*-family
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* functions. These accept either a valid stdio FILE, or a minimal pseudo
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* FILE whose buffer pointers point into a null-terminated string. In the
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* latter case, the sh_fromstring macro should be used to setup the FILE;
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* the rest of the structure can be left uninitialized.
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*
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* To begin using these functions, shlim must first be called on the FILE
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* to set a field width limit, or 0 for no limit. For string pseudo-FILEs,
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* a nonzero limit is not valid and produces undefined behavior. After that,
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* shgetc, shunget, and shcnt are valid as long as no other stdio functions
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* are called on the stream.
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*
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* When used with a real FILE object, shunget has only one byte of pushback
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* available. Further shunget (up to a limit of the stdio UNGET buffer size)
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* will adjust the position but will not restore the data to be read again.
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* This functionality is needed for the wcsto*-family functions, where it's
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* okay because the FILE will be discarded immediately anyway. When used
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* with string pseudo-FILEs, shunget has unlimited pushback, back to the
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* beginning of the string. */
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hidden void __shlim(FILE *, off_t);
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hidden int __shgetc(FILE *);
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#define shcnt(f) ((f)->shcnt + ((f)->rpos - (f)->buf))
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#define shlim(f, lim) __shlim((f), (lim))
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#define shgetc(f) (((f)->rpos != (f)->shend) ? *(f)->rpos++ : __shgetc(f))
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#define shunget(f) ((f)->shlim>=0 ? (void)(f)->rpos-- : (void)0)
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#define sh_fromstring(f, s) \
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((f)->buf = (f)->rpos = (void *)(s), (f)->rend = (void*)-1)
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