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Message-ID: <20240204155825.ditstifsbqndnce3@begin>
Date: Sun, 4 Feb 2024 16:58:25 +0100
From: Samuel Thibault <samuel.thibault@...-lyon.org>
To: gregkh@...uxfoundation.org
Cc: linux-kernel@...r.kernel.org, speakup@...ux-speakup.org
Subject: [PATCH] speakup: Add /dev/synthu device
/dev/synth has always been 8bit, but applications nowadays mostly
expect to be using utf-8 encoding. This adds /dev/synthu to be able
to synthesize non-latin1 characters. This however remains limited
to 16bit unicode like the rest of speakup. Any odd input or input
beyond 16bit is just discarded.
Signed-off-by: Samuel Thibault <samuel.thibault@...-lyon.org>
Index: linux-6.4/drivers/accessibility/speakup/devsynth.c
===================================================================
--- linux-6.4.orig/drivers/accessibility/speakup/devsynth.c
+++ linux-6.4/drivers/accessibility/speakup/devsynth.c
@@ -7,9 +7,10 @@
#include "speakup.h"
#include "spk_priv.h"
-static int misc_registered;
+static int synth_registered, synthu_registered;
static int dev_opened;
+/* Latin1 version */
static ssize_t speakup_file_write(struct file *fp, const char __user *buffer,
size_t nbytes, loff_t *ppos)
{
@@ -34,6 +35,97 @@ static ssize_t speakup_file_write(struct
return (ssize_t)nbytes;
}
+/* UTF-8 version */
+static ssize_t speakup_file_writeu(struct file *fp, const char __user *buffer,
+ size_t nbytes, loff_t *ppos)
+{
+ size_t count = nbytes, want;
+ const char __user *ptr = buffer;
+ size_t bytes;
+ unsigned long flags;
+ unsigned char buf[256];
+ u16 ubuf[256];
+ size_t in, in2, out;
+
+ if (!synth)
+ return -ENODEV;
+
+ want = 1;
+ while (count >= want) {
+ /* Copy some UTF-8 piece from userland */
+ bytes = min(count, sizeof(buf));
+ if (copy_from_user(buf, ptr, bytes))
+ return -EFAULT;
+
+ /* Convert to u16 */
+ for (in = 0, out = 0; in < bytes; in++) {
+ unsigned char c = buf[in];
+ int nbytes = 8 - fls(c ^ 0xff);
+ u32 value;
+
+ switch (nbytes) {
+ case 8: /* 0xff */
+ case 7: /* 0xfe */
+ case 1: /* 0x80 */
+ /* Invalid, drop */
+ goto drop;
+
+ case 0:
+ /* ASCII, copy */
+ ubuf[out++] = c;
+ continue;
+
+ default:
+ /* 2..6-byte UTF-8 */
+
+ if (bytes - in < nbytes) {
+ /* We don't have it all yet, stop here
+ * and wait for the rest
+ */
+ bytes = in;
+ want = nbytes;
+ continue;
+ }
+
+ /* First byte */
+ value = c & ((1u << (7 - nbytes)) - 1);
+
+ /* Other bytes */
+ for (in2 = 2; in2 <= nbytes; in2++) {
+ c = buf[in + 1];
+ if ((c & 0xc0) != 0x80) {
+ /* Invalid, drop the head */
+ want = 1;
+ goto drop;
+ }
+ value = (value << 6) | (c & 0x3f);
+ in++;
+ }
+
+ if (value < 0x10000)
+ ubuf[out++] = value;
+ want = 1;
+ break;
+ }
+drop:
+ }
+
+ count -= bytes;
+ ptr += bytes;
+
+ /* And speak this up */
+ if (out) {
+ spin_lock_irqsave(&speakup_info.spinlock, flags);
+ for (in = 0; in < out; in++)
+ synth_buffer_add(ubuf[in]);
+ synth_start();
+ spin_unlock_irqrestore(&speakup_info.spinlock, flags);
+ }
+ }
+
+ return (ssize_t)(nbytes - count);
+}
+
static ssize_t speakup_file_read(struct file *fp, char __user *buf,
size_t nbytes, loff_t *ppos)
{
@@ -62,31 +154,57 @@ static const struct file_operations synt
.release = speakup_file_release,
};
+static const struct file_operations synthu_fops = {
+ .read = speakup_file_read,
+ .write = speakup_file_writeu,
+ .open = speakup_file_open,
+ .release = speakup_file_release,
+};
+
static struct miscdevice synth_device = {
.minor = MISC_DYNAMIC_MINOR,
.name = "synth",
.fops = &synth_fops,
};
+static struct miscdevice synthu_device = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "synthu",
+ .fops = &synthu_fops,
+};
+
void speakup_register_devsynth(void)
{
- if (misc_registered != 0)
- return;
-/* zero it so if register fails, deregister will not ref invalid ptrs */
- if (misc_register(&synth_device)) {
- pr_warn("Couldn't initialize miscdevice /dev/synth.\n");
- } else {
- pr_info("initialized device: /dev/synth, node (MAJOR %d, MINOR %d)\n",
- MISC_MAJOR, synth_device.minor);
- misc_registered = 1;
+ if (!synth_registered) {
+ if (misc_register(&synth_device)) {
+ pr_warn("Couldn't initialize miscdevice /dev/synth.\n");
+ } else {
+ pr_info("initialized device: /dev/synth, node (MAJOR %d, MINOR %d)\n",
+ MISC_MAJOR, synth_device.minor);
+ synth_registered = 1;
+ }
+ }
+ if (!synthu_registered) {
+ if (misc_register(&synthu_device)) {
+ pr_warn("Couldn't initialize miscdevice /dev/synthu.\n");
+ } else {
+ pr_info("initialized device: /dev/synthu, node (MAJOR %d, MINOR %d)\n",
+ MISC_MAJOR, synthu_device.minor);
+ synthu_registered = 1;
+ }
}
}
void speakup_unregister_devsynth(void)
{
- if (!misc_registered)
- return;
- pr_info("speakup: unregistering synth device /dev/synth\n");
- misc_deregister(&synth_device);
- misc_registered = 0;
+ if (synth_registered) {
+ pr_info("speakup: unregistering synth device /dev/synth\n");
+ misc_deregister(&synth_device);
+ synth_registered = 0;
+ }
+ if (synthu_registered) {
+ pr_info("speakup: unregistering synth device /dev/synthu\n");
+ misc_deregister(&synthu_device);
+ synthu_registered = 0;
+ }
}
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