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2015-05-29fix failure of ungetc and ungetwc to work on files in eof statusRich Felker-1/+2
these functions were written to handle clearing eof status, but failed to account for the __toread function's handling of eof. with this patch applied, __toread still returns EOF when the file is in eof status, so that read operations will fail, but it also sets up valid buffer pointers for read mode, which are set to the end of the buffer rather than the beginning in order to make the whole buffer available to ungetc/ungetwc. minor changes to __uflow were needed since it's now possible to have non-zero buffer pointers while in eof status. as made, these changes remove a 'fast path' bypassing the function call to __toread, which could be reintroduced with slightly different logic, but since ordinary files have a syscall in f->read, optimizing the code path does not seem worthwhile. the __stdio_read function is also updated not to zero the read buffer pointers on eof/error. while not necessary for correctness, this change avoids the overhead of calling __toread in ungetc after reaching eof, and it also reduces code size and increases consistency with the fmemopen read operation which does not zero the pointers.
2011-03-28major stdio overhaul, using readv/writev, plus other changesRich Felker-15/+1
the biggest change in this commit is that stdio now uses readv to fill the caller's buffer and the FILE buffer with a single syscall, and likewise writev to flush the FILE buffer and write out the caller's buffer in a single syscall. making this change required fundamental architectural changes to stdio, so i also made a number of other improvements in the process: - the implementation no longer assumes that further io will fail following errors, and no longer blocks io when the error flag is set (though the latter could easily be changed back if desired) - unbuffered mode is no longer implemented as a one-byte buffer. as a consequence, scanf unreading has to use ungetc, to the unget buffer has been enlarged to hold at least 2 wide characters. - the FILE structure has been rearranged to maintain the locations of the fields that might be used in glibc getc/putc type macros, while shrinking the structure to save some space. - error cases for fflush, fseek, etc. should be more correct. - library-internal macros are used for getc_unlocked and putc_unlocked now, eliminating some ugly code duplication. __uflow and __overflow are no longer used anywhere but these macros. switch to read or write mode is also separated so the code can be better shared, e.g. with ungetc. - lots of other small things.
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+33