[libxml2] Copy xs:duration parser from libexslt

[Nick Wellnhofer <nwellnhof src gnome org>]

commit c0440868c3a86aa2a488aa226cde34d606f0511d
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Mon Jun 22 13:08:11 2020 +0200

    Copy xs:duration parser from libexslt
    
    The duration parser in libexslt checks for integer overflows.

 xmlschemastypes.c | 140 ++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 98 insertions(+), 42 deletions(-)
---
diff --git a/xmlschemastypes.c b/xmlschemastypes.c
index 164db94b..4249d700 100644
--- a/xmlschemastypes.c
+++ b/xmlschemastypes.c
@@ -1160,9 +1160,12 @@ static const unsigned int daysInMonthLeap[12] =
 #define VALID_DATETIME(dt)                                     \
        (VALID_DATE(dt) && VALID_TIME(dt))
 
-#define SECS_PER_MIN            (60)
-#define SECS_PER_HOUR           (60 * SECS_PER_MIN)
-#define SECS_PER_DAY            (24 * SECS_PER_HOUR)
+#define SECS_PER_MIN            60
+#define MINS_PER_HOUR           60
+#define HOURS_PER_DAY           24
+#define SECS_PER_HOUR           (MINS_PER_HOUR * SECS_PER_MIN)
+#define SECS_PER_DAY            (HOURS_PER_DAY * SECS_PER_HOUR)
+#define MINS_PER_DAY            (HOURS_PER_DAY * MINS_PER_HOUR)
 
 static const long dayInYearByMonth[12] =
        { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
@@ -1798,10 +1801,8 @@ xmlSchemaValidateDuration (xmlSchemaTypePtr type ATTRIBUTE_UNUSED,
     xmlSchemaValPtr dur;
     int isneg = 0;
     unsigned int seq = 0;
-    double         num;
-    int            num_type = 0;  /* -1 = invalid, 0 = int, 1 = floating */
-    const xmlChar  desig[]  = {'Y', 'M', 'D', 'H', 'M', 'S'};
-    const double   multi[]  = { 0.0, 0.0, 86400.0, 3600.0, 60.0, 1.0, 0.0};
+    long days, secs = 0;
+    double sec_frac = 0.0;
 
     if (duration == NULL)
        return -1;
@@ -1826,6 +1827,10 @@ xmlSchemaValidateDuration (xmlSchemaTypePtr type ATTRIBUTE_UNUSED,
        return -1;
 
     while (*cur != 0) {
+        long           num = 0;
+        size_t         has_digits = 0;
+        int            has_frac = 0;
+        const xmlChar  desig[] = {'Y', 'M', 'D', 'H', 'M', 'S'};
 
         /* input string should be empty or invalid date/time item */
         if (seq >= sizeof(desig))
@@ -1833,53 +1838,104 @@ xmlSchemaValidateDuration (xmlSchemaTypePtr type ATTRIBUTE_UNUSED,
 
         /* T designator must be present for time items */
         if (*cur == 'T') {
-            if (seq <= 3) {
-                seq = 3;
-                cur++;
-            } else
-                return 1;
+            if (seq > 3)
+                goto error;
+            cur++;
+            seq = 3;
         } else if (seq == 3)
             goto error;
 
-        /* parse the number portion of the item */
-        PARSE_NUM(num, cur, num_type);
+        /* Parse integral part. */
+        while (*cur >= '0' && *cur <= '9') {
+            long digit = *cur - '0';
 
-        if ((num_type == -1) || (*cur == 0))
-            goto error;
-
-        /* update duration based on item type */
-        while (seq < sizeof(desig)) {
-            if (*cur == desig[seq]) {
-
-                /* verify numeric type; only seconds can be float */
-                if ((num_type != 0) && (seq < (sizeof(desig)-1)))
-                    goto error;
+            if (num > LONG_MAX / 10)
+                goto error;
+            num *= 10;
+            if (num > LONG_MAX - digit)
+                goto error;
+            num += digit;
 
-                switch (seq) {
-                    case 0:
-                        dur->value.dur.mon = (long)num * 12;
-                        break;
-                    case 1:
-                        dur->value.dur.mon += (long)num;
-                        break;
-                    default:
-                        /* convert to seconds using multiplier */
-                        dur->value.dur.sec += num * multi[seq];
-                        seq++;
-                        break;
-                }
+            has_digits = 1;
+            cur++;
+        }
 
-                break;          /* exit loop */
+        if (*cur == '.') {
+            /* Parse fractional part. */
+            double mult = 1.0;
+            cur++;
+            has_frac = 1;
+            while (*cur >= '0' && *cur <= '9') {
+                mult /= 10.0;
+                sec_frac += (*cur - '0') * mult;
+                has_digits = 1;
+                cur++;
             }
-            /* no date designators found? */
-            if ((++seq == 3) || (seq == 6))
+        }
+
+        while (*cur != desig[seq]) {
+            seq++;
+            /* No T designator or invalid char. */
+            if (seq == 3 || seq == sizeof(desig))
                 goto error;
         }
        cur++;
-       if (collapse)
-           while IS_WSP_BLANK_CH(*cur) cur++;
+
+        if (!has_digits || (has_frac && (seq != 5)))
+            goto error;
+
+        switch (seq) {
+            case 0:
+                /* Year */
+                if (num > LONG_MAX / 12)
+                    goto error;
+                dur->value.dur.mon = num * 12;
+                break;
+            case 1:
+                /* Month */
+                if (dur->value.dur.mon > LONG_MAX - num)
+                    goto error;
+                dur->value.dur.mon += num;
+                break;
+            case 2:
+                /* Day */
+                dur->value.dur.day = num;
+                break;
+            case 3:
+                /* Hour */
+                days = num / HOURS_PER_DAY;
+                if (dur->value.dur.day > LONG_MAX - days)
+                    goto error;
+                dur->value.dur.day += days;
+                secs = (num % HOURS_PER_DAY) * SECS_PER_HOUR;
+                break;
+            case 4:
+                /* Minute */
+                days = num / MINS_PER_DAY;
+                if (dur->value.dur.day > LONG_MAX - days)
+                    goto error;
+                dur->value.dur.day += days;
+                secs += (num % MINS_PER_DAY) * SECS_PER_MIN;
+                break;
+            case 5:
+                /* Second */
+                days = num / SECS_PER_DAY;
+                if (dur->value.dur.day > LONG_MAX - days)
+                    goto error;
+                dur->value.dur.day += days;
+                secs += num % SECS_PER_DAY;
+                break;
+        }
+
+        seq++;
     }
 
+    days = secs / SECS_PER_DAY;
+    if (dur->value.dur.day > LONG_MAX - days)
+        goto error;
+    dur->value.dur.day += days;
+    dur->value.dur.sec = (secs % SECS_PER_DAY) + sec_frac;
+
     if (isneg) {
         dur->value.dur.mon = -dur->value.dur.mon;
         dur->value.dur.day = -dur->value.dur.day;