Bug#969488: Assertion failed when speaking some Unicode characters

[Dennis Filder]

Package: speechd-up
Version: 0.5~20110719-9

SYMPTOMS

I ran into a failed assertion.  When pressing certain Unicode
characters like U+20AC (EURO SIGN) or U+2192 (RIGHTWARDS ARROW) on the
console via a keyboard, speechd-up exits suddenly.  The same happens
when moving the cursor over a Unicode character in a text editor or on
a readline prompt.  I first ran into this under Buster.

DIAGNOSIS

>From strace:

...
write(2, "speechd-up: speechd-up.c:457: parse_buf: Assertion `bytes <= BUF_SIZE' failed.\n", 79) = 79
...

WORKAROUND

The problem only manifests when speechd-up is started with the default
command line "speechd-up -l1".  Putting this into
/etc/default/speechd-up prevents the bug from being triggered:
DAEMON_OPTS="$DAEMON_OPTS -D/dev/softsynthu -cUTF-8"

ANALYSIS

The error is in speechd-up.c:main():

750 ...
751		chars_read = read(fd, buf, BUF_SIZE);
752		if (chars_read < 0) {
753 ...

chars_read is declared as size_t, but read() returns ssize_t, thus a
failed read returning -1 (errno==11/EAGAIN in my case) triggers the
assertion in parse_buf().

The patch fixes the error and also adds code to retry the read after a
short delay.
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