diff options
author | ache <ache@FreeBSD.org> | 2001-09-01 01:56:54 +0000 |
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committer | ache <ache@FreeBSD.org> | 2001-09-01 01:56:54 +0000 |
commit | 5610a6ae63a163468769d8b1400a386115b53ddf (patch) | |
tree | 7df1c1e8cadd1748528a154d73547f9a81702dae /lib/libc/stdio/fseek.c | |
parent | 8f95e37de3db8c34682949479172b82e88dbacc5 (diff) | |
download | FreeBSD-src-5610a6ae63a163468769d8b1400a386115b53ddf.zip FreeBSD-src-5610a6ae63a163468769d8b1400a386115b53ddf.tar.gz |
Back out disabling ungetc() at 0, use different solution:
keep negative offset internally, but return 0 externally in ftell*()
I.e. use 0 now as 'unspecified value' per POSIX ungetc() description.
Diffstat (limited to 'lib/libc/stdio/fseek.c')
-rw-r--r-- | lib/libc/stdio/fseek.c | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/lib/libc/stdio/fseek.c b/lib/libc/stdio/fseek.c index 7cf117a..a3c80c1 100644 --- a/lib/libc/stdio/fseek.c +++ b/lib/libc/stdio/fseek.c @@ -129,9 +129,10 @@ _fseeko(fp, offset, whence, ltest) * we have to first find the current stream offset via * ftell (see ftell for details). */ - if ((curoff = _ftello(fp)) == -1) + if (_ftello(fp, &curoff)) return (-1); - if (offset > 0 && curoff > OFF_MAX - offset) { + if ((offset > 0 && curoff > OFF_MAX - offset) || + (offset < 0 && curoff < OFF_MIN - offset)) { errno = EOVERFLOW; return (-1); } @@ -210,38 +211,46 @@ _fseeko(fp, offset, whence, ltest) } } - if (!havepos && (curoff = _ftello(fp)) == -1) + if (!havepos && _ftello(fp, &curoff)) goto dumb; /* + * (If the buffer was modified, we have to + * skip this; see fgetln.c.) + */ + if (fp->_flags & __SMOD) + goto abspos; + + /* * Compute the number of bytes in the input buffer (pretending * that any ungetc() input has been discarded). Adjust current * offset backwards by this count so that it represents the * file offset for the first byte in the current input buffer. */ if (HASUB(fp)) { - if (curoff > OFF_MAX - fp->_r) + if (curoff > 0 && fp->_r > OFF_MAX - curoff) goto abspos; curoff += fp->_r; /* kill off ungetc */ n = fp->_extra->_up - fp->_bf._base; + if (curoff < 0 && -((off_t)n) < OFF_MIN - curoff) + goto abspos; curoff -= n; n += fp->_ur; } else { n = fp->_p - fp->_bf._base; + if (curoff < 0 && -((off_t)n) < OFF_MIN - curoff) + goto abspos; curoff -= n; n += fp->_r; } - /* curoff can be negative at this point. */ /* * If the target offset is within the current buffer, * simply adjust the pointers, clear EOF, undo ungetc(), - * and return. (If the buffer was modified, we have to - * skip this; see fgetln.c.) + * and return. */ - if ((fp->_flags & __SMOD) == 0 && - target >= curoff && - (curoff <= 0 || curoff <= OFF_MAX - n) && + if (target >= curoff && + (curoff <= 0 || n <= OFF_MAX - curoff) && target < curoff + n) { size_t o = target - curoff; |