From 645f97ced4d4b35deda3f8bde0927f898b163f5d Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Mon, 25 Jul 2016 14:54:29 -0300 Subject: libio: Multiple fixes for open_{w}memstram (BZ#18241 and BZ#20181) This patches fixes multiples issues on open_{w}memstream reported on both BZ#18241 and BZ#20181: - failed fseek does not set errno. - negative offset in fseek fails even when resulting position is a valid one. - a flush after write if the current write position is not at the end of the stream currupt data. The main fix is on seek operation for memstream (_IO_{w}str_seekoff), where both _IO_read_ptr and _IO_read_end pointer are updated if a write operation has occured (similar to default file operations). Also, to calculate the offset on both read and write pointers, a temporary value is instead of updating the argument supplied value. Negative offset are valid if resulting internal pointer is within the range of _IO_{read,write}_base and _IO_{read,write}_end. Also POSIX states that a null or wide null shall be appended to the current buffer iff a write moves the position to a value larger than the current lenght. Current implementation appends a null or wide null regardless of this condition. This patch fixes it by removing the 'else' condition on _IO_{w}mem_sync. Checked on x86_64. [BZ #18241] [BZ #20181] * libio/Makefile (test): Add tst-memstream3 and tst-wmemstream3. * libio/memstream.c (_IO_mem_sync): Only append a null byte if write position is at the end the buffer. * libio/wmemstream.c (_IO_wmem_sync): Likewise. * libio/strops.c (_IO_str_switch_to_get_mode): New function. (_IO_str_seekoff): Set correct offset from negative displacement and set EINVAL for invalid ones. * libio/wstrops.c (enlarge_userbuf): Use correct function to calculate buffer length. (_IO_wstr_switch_to_get_mode): New function. (_IO_wstr_seekoff): Set correct offset from negative displacement and set EINVAL for invalid ones. * libio/tst-memstream3.c: New file. * libio/tst-wmemstream3.c: Likewise. * manual/examples/memstrm.c: Remove warning when priting size_t. --- libio/strops.c | 81 +++++++++++++++++++++++++++++++++++++++------------------- 1 file changed, 55 insertions(+), 26 deletions(-) (limited to 'libio/strops.c') diff --git a/libio/strops.c b/libio/strops.c index 2ba3704dd2..1bb8a77932 100644 --- a/libio/strops.c +++ b/libio/strops.c @@ -230,6 +230,21 @@ enlarge_userbuf (_IO_FILE *fp, _IO_off64_t offset, int reading) return 0; } +static void +_IO_str_switch_to_get_mode (_IO_FILE *fp) +{ + if (_IO_in_backup (fp)) + fp->_IO_read_base = fp->_IO_backup_base; + else + { + fp->_IO_read_base = fp->_IO_buf_base; + if (fp->_IO_write_ptr > fp->_IO_read_end) + fp->_IO_read_end = fp->_IO_write_ptr; + } + fp->_IO_read_ptr = fp->_IO_read_end = fp->_IO_write_ptr; + + fp->_flags &= ~_IO_CURRENTLY_PUTTING; +} _IO_off64_t _IO_str_seekoff (_IO_FILE *fp, _IO_off64_t offset, int dir, int mode) @@ -239,14 +254,14 @@ _IO_str_seekoff (_IO_FILE *fp, _IO_off64_t offset, int dir, int mode) if (mode == 0 && (fp->_flags & _IO_TIED_PUT_GET)) mode = (fp->_flags & _IO_CURRENTLY_PUTTING ? _IOS_OUTPUT : _IOS_INPUT); + bool was_writing = (fp->_IO_write_ptr > fp->_IO_write_base + || _IO_in_put_mode (fp)); + if (was_writing) + _IO_str_switch_to_get_mode (fp); + if (mode == 0) { - /* Don't move any pointers. But there is no clear indication what - mode FP is in. Let's guess. */ - if (fp->_IO_file_flags & _IO_NO_WRITES) - new_pos = fp->_IO_read_ptr - fp->_IO_read_base; - else - new_pos = fp->_IO_write_ptr - fp->_IO_write_base; + new_pos = fp->_IO_read_ptr - fp->_IO_read_base; } else { @@ -256,48 +271,62 @@ _IO_str_seekoff (_IO_FILE *fp, _IO_off64_t offset, int dir, int mode) /* Move the get pointer, if requested. */ if (mode & _IOS_INPUT) { + _IO_ssize_t base; switch (dir) { - case _IO_seek_end: - offset += cur_size; + case _IO_seek_set: + base = 0; break; case _IO_seek_cur: - offset += fp->_IO_read_ptr - fp->_IO_read_base; + base = fp->_IO_read_ptr - fp->_IO_read_base; break; - default: /* case _IO_seek_set: */ + default: /* case _IO_seek_end: */ + base = cur_size; break; } - if (offset < 0) - return EOF; - if ((_IO_ssize_t) offset > cur_size - && enlarge_userbuf (fp, offset, 1) != 0) + _IO_ssize_t maxval = SSIZE_MAX - base; + if (offset < -base || offset > maxval) + { + __set_errno (EINVAL); + return EOF; + } + base += offset; + if (base > cur_size + && enlarge_userbuf (fp, base, 1) != 0) return EOF; - fp->_IO_read_ptr = fp->_IO_read_base + offset; + fp->_IO_read_ptr = fp->_IO_read_base + base; fp->_IO_read_end = fp->_IO_read_base + cur_size; - new_pos = offset; + new_pos = base; } /* Move the put pointer, if requested. */ if (mode & _IOS_OUTPUT) { + _IO_ssize_t base; switch (dir) { - case _IO_seek_end: - offset += cur_size; + case _IO_seek_set: + base = 0; break; case _IO_seek_cur: - offset += fp->_IO_write_ptr - fp->_IO_write_base; + base = fp->_IO_write_ptr - fp->_IO_write_base; break; - default: /* case _IO_seek_set: */ + default: /* case _IO_seek_end: */ + base = cur_size; break; } - if (offset < 0) - return EOF; - if ((_IO_ssize_t) offset > cur_size - && enlarge_userbuf (fp, offset, 0) != 0) + _IO_ssize_t maxval = SSIZE_MAX - base; + if (offset < -base || offset > maxval) + { + __set_errno (EINVAL); + return EOF; + } + base += offset; + if (base > cur_size + && enlarge_userbuf (fp, base, 0) != 0) return EOF; - fp->_IO_write_ptr = fp->_IO_write_base + offset; - new_pos = offset; + fp->_IO_write_ptr = fp->_IO_write_base + base; + new_pos = base; } } return new_pos; -- cgit 1.4.1