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strptime length #82

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Merged
nobu merged 5 commits into from
Dec 18, 2022
Merged

strptime length #82

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a45f8f0
Match abbreviated day and month names with head of full names
nobu Oct 29, 2022
7fe2bd5
Remove `merid_names` table
nobu Oct 29, 2022
945e26e
Remove `extz_pats` table
nobu Oct 29, 2022
3bfed83
Consider the length of string to parse
nobu Oct 29, 2022
3f666fa
Extract `head_match_p` and abbreviated name length constants
nobu Dec 18, 2022
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105 changes: 51 additions & 54 deletions ext/date/date_strptime.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,28 +10,15 @@
static const char *day_names[] = {
"Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday",
"Sun", "Mon", "Tue", "Wed",
"Thu", "Fri", "Sat"
};
static const int ABBREVIATED_DAY_NAME_LENGTH = 3;

static const char *month_names[] = {
"January", "February", "March", "April",
"May", "June", "July", "August", "September",
"October", "November", "December",
"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

static const char *merid_names[] = {
"am", "pm",
"a.m.", "p.m."
};

static const char *extz_pats[] = {
":z",
"::z",
":::z"
};
static const int ABBREVIATED_MONTH_NAME_LENGTH = 3;

#define sizeof_array(o) (sizeof o / sizeof o[0])

Expand Down Expand Up @@ -75,15 +62,15 @@ num_pattern_p(const char *s)
#define NUM_PATTERN_P() num_pattern_p(&fmt[fi + 1])

static long
read_digits(const char *s, VALUE *n, size_t width)
read_digits(const char *s, size_t slen, VALUE *n, size_t width)
{
size_t l;

if (!width)
return 0;

l = 0;
while (ISDIGIT(s[l])) {
while (l < slen && ISDIGIT(s[l])) {
if (++l == width) break;
}

Expand Down Expand Up @@ -131,7 +118,7 @@ do { \
#define READ_DIGITS(n,w) \
do { \
size_t l; \
l = read_digits(&str[si], &n, w); \
l = read_digits(&str[si], slen - si, &n, w); \
if (l == 0) \
fail(); \
si += l; \
Expand Down Expand Up @@ -161,16 +148,31 @@ do { \

VALUE date_zone_to_diff(VALUE);

static inline int
head_match_p(size_t len, const char *name, const char *str, size_t slen, size_t si)
{
return slen - si >= len && strncasecmp(name, &str[si], len) == 0;
}

static size_t
date__strptime_internal(const char *str, size_t slen,
const char *fmt, size_t flen, VALUE hash)
{
size_t si, fi;
int c;

#define HEAD_MATCH_P(len, name) head_match_p(len, name, str, slen, si)
si = fi = 0;

while (fi < flen) {
if (isspace((unsigned char)fmt[fi])) {
while (si < slen && isspace((unsigned char)str[si]))
si++;
while (++fi < flen && isspace((unsigned char)fmt[fi]));
continue;
}

if (si >= slen) fail();

switch (fmt[fi]) {
case '%':
Expand All @@ -194,12 +196,11 @@ date__strptime_internal(const char *str, size_t slen,
{
int i;

for (i = 0; i < (int)sizeof_array(extz_pats); i++)
if (strncmp(extz_pats[i], &fmt[fi],
strlen(extz_pats[i])) == 0) {
fi += i;
goto again;
}
for (i = 1; i < 3 && fi + i < flen && fmt[fi+i] == ':'; ++i);
if (fmt[fi+i] == 'z') {
fi += i - 1;
goto again;
}
fail();
}

Expand All @@ -209,10 +210,12 @@ date__strptime_internal(const char *str, size_t slen,
int i;

for (i = 0; i < (int)sizeof_array(day_names); i++) {
size_t l = strlen(day_names[i]);
if (strncasecmp(day_names[i], &str[si], l) == 0) {
const char *day_name = day_names[i];
size_t l = strlen(day_name);
if (HEAD_MATCH_P(l, day_name) ||
HEAD_MATCH_P(l = ABBREVIATED_DAY_NAME_LENGTH, day_name)) {
si += l;
set_hash("wday", INT2FIX(i % 7));
set_hash("wday", INT2FIX(i));
goto matched;
}
}
Expand All @@ -225,10 +228,12 @@ date__strptime_internal(const char *str, size_t slen,
int i;

for (i = 0; i < (int)sizeof_array(month_names); i++) {
size_t l = strlen(month_names[i]);
if (strncasecmp(month_names[i], &str[si], l) == 0) {
const char *month_name = month_names[i];
size_t l = strlen(month_name);
if (HEAD_MATCH_P(l, month_name) ||
HEAD_MATCH_P(l = ABBREVIATED_MONTH_NAME_LENGTH, month_name)) {
si += l;
set_hash("mon", INT2FIX((i % 12) + 1));
set_hash("mon", INT2FIX(i + 1));
goto matched;
}
}
Expand Down Expand Up @@ -402,18 +407,19 @@ date__strptime_internal(const char *str, size_t slen,

case 'P':
case 'p':
if (slen - si < 2) fail();
{
int i;

for (i = 0; i < 4; i++) {
size_t l = strlen(merid_names[i]);
if (strncasecmp(merid_names[i], &str[si], l) == 0) {
si += l;
set_hash("_merid", INT2FIX((i % 2) == 0 ? 0 : 12));
goto matched;
}
char c = str[si];
const int hour = (c == 'P' || c == 'p') ? 12 : 0;
if (!hour && !(c == 'A' || c == 'a')) fail();
if ((c = str[si+1]) == '.') {
if (slen - si < 4 || str[si+3] != '.') fail();
c = str[si += 2];
}
fail();
if (!(c == 'M' || c == 'm')) fail();
si += 2;
set_hash("_merid", INT2FIX(hour));
goto matched;
}

case 'Q':
Expand Down Expand Up @@ -587,7 +593,7 @@ date__strptime_internal(const char *str, size_t slen,

b = rb_backref_get();
rb_match_busy(b);
m = f_match(pat, rb_usascii_str_new2(&str[si]));
m = f_match(pat, rb_usascii_str_new(&str[si], slen - si));

if (!NIL_P(m)) {
VALUE s, l, o;
Expand Down Expand Up @@ -619,22 +625,13 @@ date__strptime_internal(const char *str, size_t slen,
if (str[si] != '%')
fail();
si++;
if (fi < flen)
if (str[si] != fmt[fi])
if (fi < flen) {
if (si >= slen || str[si] != fmt[fi])
fail();
si++;
si++;
}
goto matched;
}
case ' ':
case '\t':
case '\n':
case '\v':
case '\f':
case '\r':
while (isspace((unsigned char)str[si]))
si++;
fi++;
break;
default:
ordinal:
if (str[si] != fmt[fi])
Expand Down