For the case when word is smaller than 4 characters, we should not look at
the 3rd or 4th character before checking the previous ones, otherwise
we'd at best read uninitialized data, at worse non-existing data.
Some rules test against character not being of a certain type. That may
match with the \0 end-of-text marker, and thus actually step over
it and let MatchRule continue with uninitialized data after it, leading
to potential random behavior.
This commits fixes it by making sure that we don't read past that \0.
This seems to be changing the pronunciation of "capitals" from k'apIt@Lz to
k'apIt,alz, I don't know why, I guess the rule for it was actually
bogus?
Special characters such as N, S1, etc. are not actually eating
characters. Their treatment should thus *not* update pre_ptr and post_ptr,
otherwise those would underflow/overflow, e.g. in the case
@) s (_NS1 [z]
this would overflow. This for instance noticeable with the memory sanitizer:
ESPEAK_DATA_PATH=$PWD ./src/espeak-ng -qX "capitals"
Translate 'capitals'
1 c [k]
1 a [a]
1 p [p]
1 i [I]
1 t [t]
1 a [a]
1 l [l]
20 l (C [l]
==2837201==WARNING: MemorySanitizer: use-of-uninitialized-value
#0 0x7f7f4422744b in utf8_in2 /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/translate.c:281:2
#1 0x7f7f442281bc in utf8_in /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/translate.c:332:9
#2 0x7f7f440e0d31 in MatchRule /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/dictionary.c:1767:21
#3 0x7f7f440d937f in TranslateRules /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/dictionary.c:2320:6
#4 0x7f7f44230e5f in TranslateWord3 /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/translate.c:733:15
#5 0x7f7f44229844 in TranslateWord /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/translate.c:1100:14
#6 0x7f7f44256e50 in TranslateWord2 /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/translate.c:1361:11
#7 0x7f7f4424d6cc in TranslateClause /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/translate.c:2623:17
#8 0x7f7f44213359 in SpeakNextClause /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/synthesize.c:1569:2
#9 0x7f7f441a9f56 in Synthesize /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/speech.c:457:2
#10 0x7f7f441a9023 in sync_espeak_Synth /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/speech.c:570:29
#11 0x7f7f441ad59f in espeak_ng_Synthesize /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/speech.c:678:10
#12 0x7f7f4410b3f4 in espeak_Synth /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/espeak_api.c:90:32
#13 0x4a8be3 in main /home/samy/brl/speech/espeak-ng-git/src/espeak-ng.c:691:3
#14 0x7f7f43a2e7fc in __libc_start_main csu/../csu/libc-start.c:332:16
#15 0x421449 in _start (/home/samy/ens/projet/1/speech/espeak-ng-git/src/.libs/espeak-ng+0x421449)
Uninitialized value was created by an allocation of 'sbuf' in the stack frame of function 'TranslateClause'
#0 0x7f7f4423a1f0 in TranslateClause /home/samy/brl/speech/espeak-ng-git/src/libespeak-ng/translate.c:1941
While trying to match _NS1, MatchRule is overflowing the buffer.
It happens that this had not usually posed problem because rules usually
have these non-eating special characters last in the rule and thus it wasn't
mattering that post_ptr is pointing outside valid text.
Valdis Vitolins