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bug#12216: peek-char incorrectly *CONSUMES* eof
From: |
Mark H Weaver |
Subject: |
bug#12216: peek-char incorrectly *CONSUMES* eof |
Date: |
Sun, 31 Mar 2013 22:05:45 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
Mark H Weaver <address@hidden> writes:
> Andy Wingo <address@hidden> writes:
>> Maybe if it is somehow confined to scm_peek_char and scm_fill_input it
>> could be doable.
>
> I think I now see a reasonable way to fix this.
>
> First of all, all interfaces that do something like 'peek' would, when
> returning an EOF, set a 'pending_eof' flag in the port structure. Then
> 'scm_fill_input' would start by checking this flag; if it is set, then
> it would clear the flag and return EOF.
>
> We would also need to clear the 'pending_eof' flag in a few other
> places, most notably in 'scm_end_input'. In theory, that might be
> enough, but to be on the safe side we should also clear the flag in any
> procedure that writes or seeks.
Upon further thought, I decided that we shouldn't clear it on writes.
If 'rw_random' is set, then 'scm_end_input' will be called anyway. If
'rw_random' is not set, then we should *not* clear the flag on writes,
because it indicates that the read and write streams are independent,
e.g. a terminal or socket.
On the other hand, the 'pending_eof' flag should of course be cleared
when putting characters back (unget).
I've attached a proposed patch. It depends on the three preliminary
patches posted here:
http://lists.gnu.org/archive/html/guile-devel/2013-03/msg00221.html
Thoughts?
Regards,
Mark
>From e732d035b86a990ea0cfb56a710ee9224d8dbd31 Mon Sep 17 00:00:00 2001
From: Mark H Weaver <address@hidden>
Date: Sun, 31 Mar 2013 19:06:51 -0400
Subject: [PATCH 4/5] Peeks do not consume EOFs.
* libguile/ports-internal.h (struct scm_port_internal): Add
'pending_eof' flag.
* libguile/inline.h (scm_peek_byte_or_eof): Set 'pending_eof' flag
before returning EOF.
* libguile/ports.c (scm_i_set_pending_eof): New function.
(scm_i_clear_pending_eof): New static function.
(scm_new_port_table_entry): Initialize 'pending_eof'.
(scm_fill_input): Check for 'pending_eof'.
(scm_end_input, scm_unget_byte, scm_seek): Clear 'pending_eof'.
(scm_peek_char): Set 'pending_eof' flag before returning EOF.
* libguile/ports.h (scm_i_set_pending_eof): Add prototype.
---
libguile/inline.h | 5 ++++-
libguile/ports-internal.h | 1 +
libguile/ports.c | 33 +++++++++++++++++++++++++++++++--
libguile/ports.h | 1 +
4 files changed, 37 insertions(+), 3 deletions(-)
diff --git a/libguile/inline.h b/libguile/inline.h
index 88ba7f7..fffe101 100644
--- a/libguile/inline.h
+++ b/libguile/inline.h
@@ -134,7 +134,10 @@ scm_peek_byte_or_eof (SCM port)
if (pt->read_pos >= pt->read_end)
{
if (SCM_UNLIKELY (scm_fill_input (port) == EOF))
- return EOF;
+ {
+ scm_i_set_pending_eof (port);
+ return EOF;
+ }
}
c = *pt->read_pos;
diff --git a/libguile/ports-internal.h b/libguile/ports-internal.h
index d52eab2..5bde9d0 100644
--- a/libguile/ports-internal.h
+++ b/libguile/ports-internal.h
@@ -48,6 +48,7 @@ struct scm_port_internal
{
scm_t_port_encoding_mode encoding_mode;
scm_t_iconv_descriptors *iconv_descriptors;
+ int pending_eof;
};
typedef struct scm_port_internal scm_t_port_internal;
diff --git a/libguile/ports.c b/libguile/ports.c
index 1ac9106..89e1714 100644
--- a/libguile/ports.c
+++ b/libguile/ports.c
@@ -241,6 +241,18 @@ scm_set_port_input_waiting (scm_t_bits tc, int
(*input_waiting) (SCM))
scm_ptobs[SCM_TC2PTOBNUM (tc)].input_waiting = input_waiting;
}
+void
+scm_i_set_pending_eof (SCM port)
+{
+ SCM_INTERNAL_PTAB_ENTRY (port)->pending_eof = 1;
+}
+
+static void
+scm_i_clear_pending_eof (SCM port)
+{
+ SCM_INTERNAL_PTAB_ENTRY (port)->pending_eof = 0;
+}
+
SCM_DEFINE (scm_char_ready_p, "char-ready?", 0, 1, 0,
@@ -634,6 +646,8 @@ scm_new_port_table_entry (scm_t_bits tag)
entry->input_cd = pti; /* XXX pointer to the internal port structure */
entry->output_cd = NULL; /* XXX unused */
+ pti->pending_eof = 0;
+
SCM_SET_CELL_TYPE (z, tag);
SCM_SETPTAB_ENTRY (z, entry);
@@ -1410,9 +1424,16 @@ int
scm_fill_input (SCM port)
{
scm_t_port *pt = SCM_PTAB_ENTRY (port);
+ scm_t_port_internal *pti = SCM_INTERNAL_PTAB_ENTRY (port);
assert (pt->read_pos == pt->read_end);
+ if (pti->pending_eof)
+ {
+ pti->pending_eof = 0;
+ return EOF;
+ }
+
if (pt->read_buf == pt->putback_buf)
{
/* finished reading put-back chars. */
@@ -1652,6 +1673,7 @@ scm_end_input (SCM port)
long offset;
scm_t_port *pt = SCM_PTAB_ENTRY (port);
+ scm_i_clear_pending_eof (port);
if (pt->read_buf == pt->putback_buf)
{
offset = pt->read_end - pt->read_pos;
@@ -1675,6 +1697,7 @@ scm_unget_byte (int c, SCM port)
{
scm_t_port *pt = SCM_PTAB_ENTRY (port);
+ scm_i_clear_pending_eof (port);
if (pt->read_buf == pt->putback_buf)
/* already using the put-back buffer. */
{
@@ -1846,7 +1869,10 @@ SCM_DEFINE (scm_peek_char, "peek-char", 0, 1, 0,
result = SCM_BOOL_F;
}
else if (c == EOF)
- result = SCM_EOF_VAL;
+ {
+ scm_i_set_pending_eof (port);
+ result = SCM_EOF_VAL;
+ }
else
result = SCM_MAKE_CHAR (c);
@@ -1945,7 +1971,10 @@ SCM_DEFINE (scm_seek, "seek", 3, 0, 0,
SCM_MISC_ERROR ("port is not seekable",
scm_cons (fd_port, SCM_EOL));
else
- rv = ptob->seek (fd_port, off, how);
+ {
+ scm_i_clear_pending_eof (fd_port);
+ rv = ptob->seek (fd_port, off, how);
+ }
return scm_from_off_t_or_off64_t (rv);
}
else /* file descriptor?. */
diff --git a/libguile/ports.h b/libguile/ports.h
index 95545cd..5aca26d 100644
--- a/libguile/ports.h
+++ b/libguile/ports.h
@@ -319,6 +319,7 @@ SCM_API SCM scm_set_port_filename_x (SCM port, SCM
filename);
SCM_INTERNAL const char *scm_i_default_port_encoding (void);
SCM_INTERNAL void scm_i_set_default_port_encoding (const char *);
SCM_INTERNAL void scm_i_set_port_encoding_x (SCM port, const char *str);
+SCM_INTERNAL void scm_i_set_pending_eof (SCM port);
SCM_API SCM scm_port_encoding (SCM port);
SCM_API SCM scm_set_port_encoding_x (SCM port, SCM encoding);
SCM_INTERNAL scm_t_string_failed_conversion_handler
--
1.7.10.4
- bug#12216: peek-char incorrectly *CONSUMES* eof, (continued)
- bug#12216: peek-char incorrectly *CONSUMES* eof, Daniel Hartwig, 2013/03/09
- bug#12216: peek-char incorrectly *CONSUMES* eof, Andy Wingo, 2013/03/13
- bug#12216: peek-char incorrectly *CONSUMES* eof, David A. Wheeler, 2013/03/13
- bug#12216: peek-char incorrectly *CONSUMES* eof, Andy Wingo, 2013/03/13
- bug#12216: peek-char incorrectly *CONSUMES* eof, Mark H Weaver, 2013/03/13
- bug#12216: peek-char incorrectly *CONSUMES* eof, Andy Wingo, 2013/03/13
- bug#12216: peek-char incorrectly *CONSUMES* eof, Mark H Weaver, 2013/03/14
- bug#12216: peek-char incorrectly *CONSUMES* eof, David A. Wheeler, 2013/03/14
- bug#12216: peek-char incorrectly *CONSUMES* eof, Mark H Weaver, 2013/03/30
- bug#12216: peek-char incorrectly *CONSUMES* eof, David A. Wheeler, 2013/03/30
- bug#12216: peek-char incorrectly *CONSUMES* eof,
Mark H Weaver <=