diff options
| -rw-r--r-- | libio/genops.c | 2 | ||||
| -rw-r--r-- | manual/stdio.texi | 8 | ||||
| -rw-r--r-- | stdio-common/tst-ungetc.c | 2 |
3 files changed, 6 insertions, 6 deletions
diff --git a/libio/genops.c b/libio/genops.c index 1b629eb695..c27b3b1f41 100644 --- a/libio/genops.c +++ b/libio/genops.c @@ -635,7 +635,7 @@ _IO_sputbackc (FILE *fp, int c) { int result; - if (fp->_IO_read_ptr > fp->_IO_read_base + if (fp->_IO_read_ptr > fp->_IO_read_base && !_IO_in_backup (fp) && (unsigned char)fp->_IO_read_ptr[-1] == (unsigned char)c) { fp->_IO_read_ptr--; diff --git a/manual/stdio.texi b/manual/stdio.texi index 753c50920d..9f94dd1e78 100644 --- a/manual/stdio.texi +++ b/manual/stdio.texi @@ -1474,11 +1474,9 @@ program; usually @code{ungetc} is used only to unread a character that was just read from the same stream. @Theglibc{} supports this even on files opened in binary mode, but other systems might not. -@Theglibc{} only supports one character of pushback---in other -words, it does not work to call @code{ungetc} twice without doing input -in between. Other systems might let you push back multiple characters; -then reading from the stream retrieves the characters in the reverse -order that they were pushed. +@Theglibc{} supports pushing back multiple characters; subsequently +reading from the stream retrieves the characters in the reverse order +that they were pushed. Pushing back characters doesn't alter the file; only the internal buffering for the stream is affected. If a file positioning function diff --git a/stdio-common/tst-ungetc.c b/stdio-common/tst-ungetc.c index 5c808f0734..388b202493 100644 --- a/stdio-common/tst-ungetc.c +++ b/stdio-common/tst-ungetc.c @@ -48,6 +48,8 @@ do_test (void) TEST_VERIFY_EXIT (getc (fp) == 'b'); TEST_VERIFY_EXIT (getc (fp) == 'l'); TEST_VERIFY_EXIT (ungetc ('m', fp) == 'm'); + TEST_VERIFY_EXIT (ungetc ('n', fp) == 'n'); + TEST_VERIFY_EXIT (getc (fp) == 'n'); TEST_VERIFY_EXIT (getc (fp) == 'm'); TEST_VERIFY_EXIT ((c = getc (fp)) == 'a'); TEST_VERIFY_EXIT (getc (fp) == EOF); |