Clear errno before calling strtol() in spell.c.

Per POSIX, a caller of strtol() that wishes to check for errors must
set errno to 0 beforehand.  Several places in spell.c neglected that,
so that they risked delivering a false overflow error in case errno
had been ERANGE already.  Given the lack of field reports, this case
may be unreachable at present --- but it's surely trouble waiting to
happen, so fix it.

Author: Jacob Brazeal <jacob.brazeal@gmail.com>
Discussion: https://postgr.es/m/CA+COZaBhsq6EromFm+knMJfzK6nTpG23zJ+K2=nfUQQXcj_xcQ@mail.gmail.com
Backpatch-through: 13

diff --git a/src/backend/tsearch/spell.c b/src/backend/tsearch/spell.c
index 018b66d2c69a1d37e719629cdfa27e9d5e67915e..146801885d738ce6d932421145487c711435a5bf 100644 (file)
--- a/src/backend/tsearch/spell.c
+++ b/src/backend/tsearch/spell.c
@@ -375,6 +375,7 @@ getNextFlagFromString(IspellDict *Conf, const char **sflagset, char *sflag)
                stop = (maxstep == 0);
                break;
            case FM_NUM:
+               errno = 0;
                s = strtol(*sflagset, &next, 10);
                if (*sflagset == next || errno == ERANGE)
                    ereport(ERROR,
@@ -1037,6 +1038,7 @@ setCompoundAffixFlagValue(IspellDict *Conf, CompoundAffixFlag *entry,
        char       *next;
        int         i;
 
+       errno = 0;
        i = strtol(s, &next, 10);
        if (s == next || errno == ERANGE)
            ereport(ERROR,
@@ -1164,6 +1166,7 @@ getAffixFlagSet(IspellDict *Conf, char *s)
        int         curaffix;
        char       *end;
 
+       errno = 0;
        curaffix = strtol(s, &end, 10);
        if (s == end || errno == ERANGE)
            ereport(ERROR,
@@ -1740,6 +1743,7 @@ NISortDictionary(IspellDict *Conf)
 
            if (*Conf->Spell[i]->p.flag != '\0')
            {
+               errno = 0;
                curaffix = strtol(Conf->Spell[i]->p.flag, &end, 10);
                if (Conf->Spell[i]->p.flag == end || errno == ERANGE)
                    ereport(ERROR,