| 1 | #include "stdio_impl.h" |
| 2 | |
| 3 | /* Scan helper "stdio" functions for use by scanf-family and strto*-family |
| 4 | * functions. These accept either a valid stdio FILE, or a minimal pseudo |
| 5 | * FILE whose buffer pointers point into a null-terminated string. In the |
| 6 | * latter case, the sh_fromstring macro should be used to setup the FILE; |
| 7 | * the rest of the structure can be left uninitialized. |
| 8 | * |
| 9 | * To begin using these functions, shlim must first be called on the FILE |
| 10 | * to set a field width limit, or 0 for no limit. For string pseudo-FILEs, |
| 11 | * a nonzero limit is not valid and produces undefined behavior. After that, |
| 12 | * shgetc, shunget, and shcnt are valid as long as no other stdio functions |
| 13 | * are called on the stream. |
| 14 | * |
| 15 | * When used with a real FILE object, shunget has only one byte of pushback |
| 16 | * available. Further shunget (up to a limit of the stdio UNGET buffer size) |
| 17 | * will adjust the position but will not restore the data to be read again. |
| 18 | * This functionality is needed for the wcsto*-family functions, where it's |
| 19 | * okay because the FILE will be discarded immediately anyway. When used |
| 20 | * with string pseudo-FILEs, shunget has unlimited pushback, back to the |
| 21 | * beginning of the string. */ |
| 22 | |
| 23 | hidden void __shlim(FILE *, off_t); |
| 24 | hidden int __shgetc(FILE *); |
| 25 | |
| 26 | #define shcnt(f) ((f)->shcnt + ((f)->rpos - (f)->buf)) |
| 27 | #define shlim(f, lim) __shlim((f), (lim)) |
| 28 | #define shgetc(f) (((f)->rpos != (f)->shend) ? *(f)->rpos++ : __shgetc(f)) |
| 29 | #define shunget(f) ((f)->shlim>=0 ? (void)(f)->rpos-- : (void)0) |
| 30 | |
| 31 | #define sh_fromstring(f, s) \ |
| 32 | ((f)->buf = (f)->rpos = (void *)(s), (f)->rend = (void*)-1) |