@@ -943,15 +943,14 @@ do_ftell (_IO_FILE *fp)
yet. */
if (fp->_IO_buf_base != NULL)
{
- bool was_writing = (fp->_IO_write_ptr > fp->_IO_write_base
- || _IO_in_put_mode (fp));
+ bool unflushed_writes = (fp->_IO_write_ptr > fp->_IO_write_base);
bool append_mode = (fp->_flags & _IO_IS_APPENDING) == _IO_IS_APPENDING;
/* When we have unflushed writes in append mode, seek to the end of the
file and record that offset. This is the only time we change the file
stream state and it is safe since the file handle is active. */
- if (was_writing && append_mode)
+ if (unflushed_writes && append_mode)
{
result = _IO_SYSSEEK (fp, 0, _IO_seek_end);
if (result == _IO_pos_BAD)
@@ -961,7 +960,7 @@ do_ftell (_IO_FILE *fp)
}
/* Adjust for unflushed data. */
- if (!was_writing)
+ if (!unflushed_writes)
offset -= fp->_IO_read_end - fp->_IO_read_ptr;
/* We don't trust _IO_read_end to represent the current file offset when
writing in append mode because the value would have to be shifted to
@@ -88,6 +88,100 @@ static size_t file_len;
typedef int (*fputs_func_t) (const void *data, FILE *fp);
fputs_func_t fputs_func;
+/* This test verifies that the offset reported by ftell is correct after the
+ file is truncated using ftruncate. ftruncate does not change the file
+ offset on truncation and hence, SEEK_CUR should continue to point to the
+ old offset and not be changed to the new offset. */
+static int
+do_ftruncate_test (const char *filename)
+{
+ FILE *fp = NULL;
+ int fd;
+ int ret = 0;
+ struct test
+ {
+ const char *mode;
+ int fd_mode;
+ } test_modes[] = {
+ {"r+", O_RDWR},
+ {"w", O_WRONLY},
+ {"w+", O_RDWR},
+ {"a", O_WRONLY},
+ {"a+", O_RDWR}
+ };
+
+ for (int j = 0; j < 2; j++)
+ {
+ for (int i = 0; i < sizeof (test_modes) / sizeof (struct test); i++)
+ {
+ int fileret;
+ printf ("\tftruncate: %s (file, \"%s\"): ",
+ j == 0 ? "fopen" : "fdopen",
+ test_modes[i].mode);
+
+ if (j == 0)
+ fileret = get_handles_fopen (filename, fd, fp, test_modes[i].mode);
+ else
+ fileret = get_handles_fdopen (filename, fd, fp,
+ test_modes[i].fd_mode,
+ test_modes[i].mode);
+
+ if (fileret != 0)
+ return fileret;
+
+ /* Write some data. */
+ size_t written = fputs_func (data, fp);
+
+ if (written == EOF)
+ {
+ printf ("fputs[1] failed to write data\n");
+ ret |= 1;
+ }
+
+ /* Record the offset. */
+ long offset = ftell (fp);
+
+ /* Flush data to allow switching active handles. */
+ if (fflush (fp))
+ {
+ printf ("Flush failed: %m\n");
+ ret |= 1;
+ }
+
+ /* Now truncate the file. */
+ if (ftruncate (fd, 0) != 0)
+ {
+ printf ("Failed to truncate file: %m\n");
+ ret |= 1;
+ }
+
+ /* Switch active handles again. */
+ if (fseek (fp, 0, SEEK_CUR))
+ {
+ printf ("Failed to seek to current position: %m\n");
+ ret |= 1;
+ }
+
+ long new_offset = ftell (fp);
+
+ /* The offset should remain unchanged since ftruncate does not update
+ it. */
+ if (offset != new_offset)
+ {
+ printf ("Incorrect offset. Expected %zu, but got %ld\n",
+ offset, new_offset);
+
+ ret |= 1;
+ }
+ else
+ printf ("offset = %ld\n", offset);
+
+ fclose (fp);
+ }
+ }
+
+ return ret;
+}
/* Test that ftell output after a rewind is correct. */
static int
do_rewind_test (const char *filename)
@@ -481,6 +575,7 @@ do_one_test (const char *filename)
ret |= do_write_test (filename);
ret |= do_append_test (filename);
ret |= do_rewind_test (filename);
+ ret |= do_ftruncate_test (filename);
return ret;
}
@@ -626,16 +626,15 @@ do_ftell_wide (_IO_FILE *fp)
const wchar_t *wide_read_base;
const wchar_t *wide_read_ptr;
const wchar_t *wide_read_end;
- bool was_writing = ((fp->_wide_data->_IO_write_ptr
- > fp->_wide_data->_IO_write_base)
- || _IO_in_put_mode (fp));
+ bool unflushed_writes = (fp->_wide_data->_IO_write_ptr
+ > fp->_wide_data->_IO_write_base);
bool append_mode = (fp->_flags & _IO_IS_APPENDING) == _IO_IS_APPENDING;
/* When we have unflushed writes in append mode, seek to the end of the
file and record that offset. This is the only time we change the file
stream state and it is safe since the file handle is active. */
- if (was_writing && append_mode)
+ if (unflushed_writes && append_mode)
{
result = _IO_SYSSEEK (fp, 0, _IO_seek_end);
if (result == _IO_pos_BAD)
@@ -674,7 +673,7 @@ do_ftell_wide (_IO_FILE *fp)
struct _IO_codecvt *cv = fp->_codecvt;
int clen = (*cv->__codecvt_do_encoding) (cv);
- if (!was_writing)
+ if (!unflushed_writes)
{
if (clen > 0)
{