fix many undefined behaviour in usage of ctype functions

- cast all ctype(3) function argument to (unsigned char) to avoid UB

POSIX says:
"The c argument is an int, the value of which the application shall ensure is a
character representable as an unsigned char or equal to the value of the macro
EOF. If the argument has any other value, the behavior is undefined."

Many libc cast implicitly the value, but NetBSD does not, which is probably the
correct thing to interpret it.

- no need to cast for putchar + rename some fputc(..., stdout) to putchar

POSIX says:
"The fputc() function shall write the byte specified by c (converted to an
unsigned char) to the output stream pointed to by stream [...]"

Major thanks to Leonardo Taccari <iamleot@gmail.com> for reporting and testing
it on NetBSD!

5 files changed, 36 insertions, 36 deletions

diff --git a/sfeed.c b/sfeed.c
index f04f164..fd65f6c 100644
--- a/sfeed.c
+++ b/sfeed.c
@@ -247,10 +247,10 @@ string_print_encoded(String *s)
 		return;
 
 	/* skip leading whitespace */
-	for (p = s->data; *p && isspace((int)*p); p++)
+	for (p = s->data; *p && isspace((unsigned char)*p); p++)
 		;
 	/* seek location of trailing whitespace */
-	for (e = s->data + s->len; e > p && isspace((int)*(e - 1)); e--)
+	for (e = s->data + s->len; e > p && isspace((unsigned char)*(e - 1)); e--)
 		;
 
 	for (; *p && p != e; p++) {
@@ -260,7 +260,7 @@ string_print_encoded(String *s)
 		case '\t': fputs("\\t",  stdout); break;
 		default:
 			/* ignore control chars */
-			if (!iscntrl((int)*p))
+			if (!iscntrl((unsigned char)*p))
 				putchar(*p);
 			break;
 		}
@@ -278,18 +278,18 @@ string_print_trimmed(String *s)
 		return;
 
 	/* skip leading whitespace */
-	for (p = s->data; *p && isspace((int)*p); p++)
+	for (p = s->data; *p && isspace((unsigned char)*p); p++)
 		;
 	/* seek location of trailing whitespace */
-	for (e = s->data + s->len; e > p && isspace((int)*(e - 1)); e--)
+	for (e = s->data + s->len; e > p && isspace((unsigned char)*(e - 1)); e--)
 		;
 
 	for (; *p && p != e; p++) {
-		if (isspace((int)*p))
+		if (isspace((unsigned char)*p))
 			putchar(' '); /* any whitespace to space */
-		else if (!iscntrl((int)*p))
+		else if (!iscntrl((unsigned char)*p))
 			/* ignore other control chars */
-			putchar((int)*p);
+			putchar(*p);
 	}
 }
 
@@ -376,20 +376,20 @@ gettzoffset(const char *s)
 	int tzhour = 0, tzmin = 0;
 	size_t i, namelen;
 
-	for (; *s && isspace((int)*s); s++)
+	for (; *s && isspace((unsigned char)*s); s++)
 		;
 	switch (s[0]) {
 	case '-': /* offset */
 	case '+':
-		for (i = 0, p = s + 1; i < 2 && *p && isdigit(*p); i++, p++)
+		for (i = 0, p = s + 1; i < 2 && *p && isdigit((unsigned char)*p); i++, p++)
 			tzhour = (tzhour * 10) + (*p - '0');
-		if (*p && !isdigit(*p))
+		if (*p && !isdigit((unsigned char)*p))
 			p++;
-		for (i = 0; i < 2 && *p && isdigit(*p); i++, p++)
+		for (i = 0; i < 2 && *p && isdigit((unsigned char)*p); i++, p++)
 			tzmin = (tzmin * 10) + (*p - '0');
 		return ((tzhour * 3600) + (tzmin * 60)) * (s[0] == '-' ? -1 : 1);
 	default: /* timezone name */
-		for (i = 0; *s && isalpha((int)s[i]); i++)
+		for (i = 0; *s && isalpha((unsigned char)s[i]); i++)
 			;
 		namelen = i; /* end of name */
 		/* optimization: these are always non-matching */
@@ -429,49 +429,49 @@ parsetime(const char *s, time_t *tp)
 	int va[6] = { 0 }, i, j, v, vi;
 	size_t m;
 
-	for (; *s && isspace((int)*s); s++)
+	for (; *s && isspace((unsigned char)*s); s++)
 		;
-	if (!isdigit((int)*s) && !isalpha((int)*s))
+	if (!isdigit((unsigned char)*s) && !isalpha((unsigned char)*s))
 		return -1;
 
-	if (isdigit((int)*s)) {
+	if (isdigit((unsigned char)*s)) {
 		/* format "%Y-%m-%d %H:%M:%S" or "%Y-%m-%dT%H:%M:%S" */
 		vi = 0;
 time:
 		for (; *s && vi < 6; vi++) {
-			for (i = 0, v = 0; *s && i < 4 && isdigit((int)*s); s++, i++)
+			for (i = 0, v = 0; *s && i < 4 && isdigit((unsigned char)*s); s++, i++)
 				v = (v * 10) + (*s - '0');
 			va[vi] = v;
 			if ((vi < 2 && *s == '-') ||
-			    (vi == 2 && (*s == 'T' || isspace((int)*s))) ||
+			    (vi == 2 && (*s == 'T' || isspace((unsigned char)*s))) ||
 			    (vi > 2 && *s == ':'))
 				s++;
 		}
 		/* TODO: only if seconds are parsed (vi == 5)? */
 		/* skip milliseconds for: %Y-%m-%dT%H:%M:%S.000Z */
 		if (*s == '.') {
-			for (s++; *s && isdigit((int)*s); s++)
+			for (s++; *s && isdigit((unsigned char)*s); s++)
 				;
 		}
 		end = s;
-	} else if (isalpha((int)*s)) {
+	} else if (isalpha((unsigned char)*s)) {
 		/* format: "%a, %d %b %Y %H:%M:%S" */
 		/* parse "%a, %d %b %Y " part, then use time parsing as above */
-		for (; *s && isalpha((int)*s); s++)
+		for (; *s && isalpha((unsigned char)*s); s++)
 			;
-		for (; *s && isspace((int)*s); s++)
+		for (; *s && isspace((unsigned char)*s); s++)
 			;
 		if (*s != ',')
 			return -1;
-		for (s++; *s && isspace((int)*s); s++)
+		for (s++; *s && isspace((unsigned char)*s); s++)
 			;
-		for (v = 0, i = 0; *s && i < 4 && isdigit((int)*s); s++, i++)
+		for (v = 0, i = 0; *s && i < 4 && isdigit((unsigned char)*s); s++, i++)
 			v = (v * 10) + (*s - '0');
 		va[2] = v; /* day */
-		for (; *s && isspace((int)*s); s++)
+		for (; *s && isspace((unsigned char)*s); s++)
 			;
 		/* end of word month */
-		for (j = 0; *s && isalpha((int)s[j]); j++)
+		for (j = 0; *s && isalpha((unsigned char)s[j]); j++)
 			;
 		/* check month name */
 		if (j < 3 || j > 9)
@@ -487,12 +487,12 @@ time:
 		}
 		if (m >= 12)
 			return -1; /* no month found */
-		for (; *s && isspace((int)*s); s++)
+		for (; *s && isspace((unsigned char)*s); s++)
 			;
-		for (v = 0, i = 0; *s && i < 4 && isdigit((int)*s); s++, i++)
+		for (v = 0, i = 0; *s && i < 4 && isdigit((unsigned char)*s); s++, i++)
 			v = (v * 10) + (*s - '0');
 		va[0] = v; /* year */
-		for (; *s && isspace((int)*s); s++)
+		for (; *s && isspace((unsigned char)*s); s++)
 			;
 		/* parse regular time, see above */
 		vi = 3;
diff --git a/sfeed_opml_import.c b/sfeed_opml_import.c
index a254733..361b80f 100644
--- a/sfeed_opml_import.c
+++ b/sfeed_opml_import.c
@@ -18,14 +18,14 @@ static void
 printsafe(const char *s)
 {
 	for (; *s; s++) {
-		if (iscntrl((int)*s))
+		if (iscntrl((unsigned char)*s))
 			continue;
 		else if (*s == '\\')
 			fputs("\\\\", stdout);
 		else if (*s == '\'')
 			fputs("'\\''", stdout);
 		else
-			putchar((int)*s);
+			putchar(*s);
 	}
 }
 
diff --git a/sfeed_web.c b/sfeed_web.c
index bb7d9b6..5c5301e 100644
--- a/sfeed_web.c
+++ b/sfeed_web.c
@@ -22,7 +22,7 @@ static void
 printfeedtype(const char *s, FILE *fp)
 {
 	for (; *s; s++)
-		if (!isspace((int)*s))
+		if (!isspace((unsigned char)*s))
 			fputc(*s, fp);
 }
 
@@ -49,7 +49,7 @@ xmltagstartparsed(XMLParser *p, const char *tag, size_t taglen, int isshort)
 		fputs(abslink, stdout);
 	else
 		fputs(feedlink, stdout);
-	fputc('\t', stdout);
+	putchar('\t');
 	printfeedtype(feedtype, stdout);
 	putchar('\n');
 	found++;
diff --git a/sfeed_xmlenc.c b/sfeed_xmlenc.c
index 56edfeb..52a0be3 100644
--- a/sfeed_xmlenc.c
+++ b/sfeed_xmlenc.c
@@ -37,7 +37,7 @@ xmlattr(XMLParser *p, const char *tag, size_t taglen, const char *name,
 		if (*value) {
 			/* output lowercase */
 			for (; *value; value++)
-				putc(tolower((int)*value), stdout);
+				putchar(tolower((unsigned char)*value));
 			putchar('\n');
 		}
 		exit(0);
diff --git a/util.c b/util.c
index abe30a3..e74983f 100644
--- a/util.c
+++ b/util.c
@@ -31,7 +31,7 @@ parseuri(const char *s, struct uri *u, int rel)
 		p += 2; /* skip "//" */
 	} else {
 		/* protocol part */
-		for (p = s; *p && (isalpha((int)*p) || isdigit((int)*p) ||
+		for (p = s; *p && (isalpha((unsigned char)*p) || isdigit((unsigned char)*p) ||
 			       *p == '+' || *p == '-' || *p == '.'); p++)
 			;
 		if (!strncmp(p, "://", 3)) {
@@ -101,7 +101,7 @@ encodeuri(char *buf, size_t bufsiz, const char *s)
 	for (i = 0, b = 0; s[i]; i++) {
 		if ((int)s[i] == ' ' ||
 		    (unsigned char)s[i] > 127 ||
-		    iscntrl((int)s[i])) {
+		    iscntrl((unsigned char)s[i])) {
 			if (b + 3 >= bufsiz)
 				return -1;
 			buf[b++] = '%';