2  * Copyright (c) 1990 The Regents of the University of California.
19 <<ungetc>>---push data back into a stream
28 	int ungetc(int <[c]>, FILE *<[stream]>);
30 	int ungetc( int <[c]>, FILE *<[stream]>);
34 If <[c]> is EOF, the stream is unchanged.  Otherwise, the unsigned
35 char <[c]> is put back on the stream, and subsequent reads will see
42 character will clear the end-of-stream marker, and decrement the file
53 ANSI C requires <<ungetc>>, but only requires a pushback buffer of one
71  * Expand the ungetc buffer `in place'.  That is, adjust fp->_p when
74  * are all at the end (stack-style).
85   if (fp->_ub._base == fp->_ubuf)  in __submore()
92       fp->_ub._base = p;  in __submore()
93       fp->_ub._size = BUFSIZ;  in __submore()
94       p += BUFSIZ - sizeof (fp->_ubuf);  in __submore()
95       for (i = sizeof (fp->_ubuf); --i >= 0;)  in __submore()
96 	p[i] = fp->_ubuf[i];  in __submore()
97       fp->_p = p;  in __submore()
100   i = fp->_ub._size;  in __submore()
101   p = (unsigned char *) realloc ((void *) (fp->_ub._base), i << 1);  in __submore()
105   fp->_p = p + i;  in __submore()
106   fp->_ub._base = p;  in __submore()
107   fp->_ub._size = i << 1;  in __submore()
113        int c,  in ungetc()  argument
116   if (c == EOF)  in ungetc()
121      have already been called to get the char we are un-getting.  */  in ungetc()
128   fp->_flags &= ~__SEOF;  in ungetc()
130   if ((fp->_flags & __SRD) == 0)  in ungetc()
133        * Not already reading: no good unless reading-and-writing.  in ungetc()
136       if ((fp->_flags & __SRW) == 0)  in ungetc()
141       if (fp->_flags & __SWR)  in ungetc()
148 	  fp->_flags &= ~__SWR;  in ungetc()
149 	  fp->_w = 0;  in ungetc()
150 	  fp->_lbfsize = 0;  in ungetc()
152       fp->_flags |= __SRD;  in ungetc()
154   c = (unsigned char) c;  in ungetc()
163       if (fp->_r >= fp->_ub._size && __submore (fp))  in ungetc()
168       *--fp->_p = c;  in ungetc()
169       fp->_r++;  in ungetc()
171       return c;  in ungetc()
180   if (fp->_bf._base != NULL && fp->_p > fp->_bf._base && fp->_p[-1] == c)  in ungetc()
182       fp->_p--;  in ungetc()
183       fp->_r++;  in ungetc()
185       return c;  in ungetc()
193   fp->_ur = fp->_r;  in ungetc()
194   fp->_up = fp->_p;  in ungetc()
195   fp->_ub._base = fp->_ubuf;  in ungetc()
196   fp->_ub._size = sizeof (fp->_ubuf);  in ungetc()
197   fp->_ubuf[sizeof (fp->_ubuf) - 1] = c;  in ungetc()
198   fp->_p = &fp->_ubuf[sizeof (fp->_ubuf) - 1];  in ungetc()
199   fp->_r = 1;  in ungetc()
201   return c;  in ungetc()