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Date: Tue, 23 Feb 2010 00:09:22 +0100 (CET)
From: Tilman Schmidt <tilman@...p.cc>
To: Karsten Keil <isdn@...ux-pingi.de>,
David Miller <davem@...emloft.net>
CC: Hansjoerg Lipp <hjlipp@....de>, Karsten Keil <keil@...systems.de>,
isdn4linux@...tserv.isdn4linux.de,
i4ldeveloper@...tserv.isdn4linux.de, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] bas_gigaset: collapse CR/LF at end of AT response
From: Tilman Schmidt <tilman@...p.cc>
Subject: [PATCH 2/4] bas_gigaset: collapse CR/LF at end of AT response
Copy the mechanism from ser_/usb_gigaset to avoid producing
spurious empty responses for CR/LF sequences from the device.
Add a comment in all drivers documenting that behaviour.
Correct an off by one error that might result in a one byte
buffer overflow when receiving an unexpectedly long reply.
Impact: minor bugfix
Signed-off-by: Tilman Schmidt <tilman@...p.cc>
---
drivers/isdn/gigaset/asyncdata.c | 2 +
drivers/isdn/gigaset/gigaset.h | 4 +-
drivers/isdn/gigaset/isocdata.c | 44 ++++++++++++++++++++++++++-----------
3 files changed, 35 insertions(+), 15 deletions(-)
diff --git a/drivers/isdn/gigaset/asyncdata.c b/drivers/isdn/gigaset/asyncdata.c
index ccb2a7b..e913beb 100644
--- a/drivers/isdn/gigaset/asyncdata.c
+++ b/drivers/isdn/gigaset/asyncdata.c
@@ -40,6 +40,8 @@ static inline int muststuff(unsigned char c)
* Append received bytes to the command response buffer and forward them
* line by line to the response handler. Exit whenever a mode/state change
* might have occurred.
+ * Note: Received lines may be terminated by CR, LF, or CR LF, which will be
+ * removed before passing the line to the response handler.
* Return value:
* number of processed bytes
*/
diff --git a/drivers/isdn/gigaset/gigaset.h b/drivers/isdn/gigaset/gigaset.h
index e963a6c..c9ccf7d 100644
--- a/drivers/isdn/gigaset/gigaset.h
+++ b/drivers/isdn/gigaset/gigaset.h
@@ -38,7 +38,7 @@
#define GIG_COMPAT {0, 4, 0, 0}
#define MAX_REC_PARAMS 10 /* Max. number of params in response string */
-#define MAX_RESP_SIZE 512 /* Max. size of a response string */
+#define MAX_RESP_SIZE 511 /* Max. size of a response string */
#define MAX_EVENTS 64 /* size of event queue */
@@ -498,7 +498,7 @@ struct cardstate {
spinlock_t ev_lock;
/* current modem response */
- unsigned char respdata[MAX_RESP_SIZE];
+ unsigned char respdata[MAX_RESP_SIZE+1];
unsigned cbytes;
/* private data of hardware drivers */
diff --git a/drivers/isdn/gigaset/isocdata.c b/drivers/isdn/gigaset/isocdata.c
index 85394a6..16fd3bd 100644
--- a/drivers/isdn/gigaset/isocdata.c
+++ b/drivers/isdn/gigaset/isocdata.c
@@ -905,29 +905,49 @@ void gigaset_isoc_receive(unsigned char *src, unsigned count,
/* == data input =========================================================== */
+/* process a block of received bytes in command mode (mstate != MS_LOCKED)
+ * Append received bytes to the command response buffer and forward them
+ * line by line to the response handler.
+ * Note: Received lines may be terminated by CR, LF, or CR LF, which will be
+ * removed before passing the line to the response handler.
+ */
static void cmd_loop(unsigned char *src, int numbytes, struct inbuf_t *inbuf)
{
struct cardstate *cs = inbuf->cs;
unsigned cbytes = cs->cbytes;
+ unsigned char c;
while (numbytes--) {
- /* copy next character, check for end of line */
- switch (cs->respdata[cbytes] = *src++) {
- case '\r':
+ c = *src++;
+ switch (c) {
case '\n':
- /* end of line */
- gig_dbg(DEBUG_TRANSCMD, "%s: End of Command (%d Bytes)",
- __func__, cbytes);
- if (cbytes >= MAX_RESP_SIZE - 1)
- dev_warn(cs->dev, "response too large\n");
+ if (cbytes == 0 && cs->respdata[0] == '\r') {
+ /* collapse LF with preceding CR */
+ cs->respdata[0] = 0;
+ break;
+ }
+ /* --v-- fall through --v-- */
+ case '\r':
+ /* end of message line, pass to response handler */
+ if (cbytes >= MAX_RESP_SIZE) {
+ dev_warn(cs->dev, "response too large (%d)\n",
+ cbytes);
+ cbytes = MAX_RESP_SIZE;
+ }
cs->cbytes = cbytes;
+ gigaset_dbg_buffer(DEBUG_TRANSCMD, "received response",
+ cbytes, cs->respdata);
gigaset_handle_modem_response(cs);
cbytes = 0;
+
+ /* store EOL byte for CRLF collapsing */
+ cs->respdata[0] = c;
break;
default:
- /* advance in line buffer, checking for overflow */
- if (cbytes < MAX_RESP_SIZE - 1)
- cbytes++;
+ /* append to line buffer if possible */
+ if (cbytes < MAX_RESP_SIZE)
+ cs->respdata[cbytes] = c;
+ cbytes++;
}
}
@@ -958,8 +978,6 @@ void gigaset_isoc_input(struct inbuf_t *inbuf)
numbytes, src);
gigaset_if_receive(inbuf->cs, src, numbytes);
} else {
- gigaset_dbg_buffer(DEBUG_CMD, "received response",
- numbytes, src);
cmd_loop(src, numbytes, inbuf);
}
--
1.6.5.3.298.g39add
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