Try to fix ctype issues by always calling these functions as

if (!isdigit(* (unsigned char *) p)) {

so that the argument is always in the range of unsigned char when
coerced to an int.

(See digit 1.)

access.c

@@ -38,7 +38,7 @@ static int match_address(char *addr, char *tok)
 
 	if (!addr || !*addr) return 0;
 
-	if (!isdigit(tok[0])) return 0;
+	if (!isdigit(* (unsigned char *) tok)) return 0;
 
 	p = strchr(tok,'/');
 	if (p) *p = 0;

clientserver.c

@@ -246,7 +246,7 @@ static int rsync_module(int fd, int i)
 	if (am_root) {
 		p = lp_uid(i);
 		if (!name_to_uid(p, &uid)) {
-			if (!isdigit(*p)) {
+			if (!isdigit(* (unsigned char *) p)) {
 				rprintf(FERROR,"Invalid uid %s\n", p);
 				io_printf(fd,"@ERROR: invalid uid %s\n", p);
 				return -1;
@@ -256,7 +256,7 @@ static int rsync_module(int fd, int i)
 
 		p = lp_gid(i);
 		if (!name_to_gid(p, &gid)) {
-			if (!isdigit(*p)) {
+			if (!isdigit(* (unsigned char *) p)) {
 				rprintf(FERROR,"Invalid gid %s\n", p);
 				io_printf(fd,"@ERROR: invalid gid %s\n", p);
 				return -1;

exclude.c

@@ -335,7 +335,7 @@ char *get_exclude_tok(char *p)
 		return(NULL);
 
 	/* Skip over any initial spaces */
-	while(isspace((int) *s))
+	while (isspace(* (unsigned char *) s))
 		s++;
 
 	/* Are we at the end of the string? */
@@ -348,7 +348,7 @@ char *get_exclude_tok(char *p)
 			s+=2;
 	
 		/* Skip to the next space or the end of the string */
-		while(!isspace((int) *s) && *s != '\0')
+		while (!isspace(* (unsigned char *) s) && *s != '\0')
 			s++;
 	} else {
 		t=NULL;

loadparm.c

@@ -479,11 +479,11 @@ static int strwicmp(char *psz1, char *psz2)
    /* sync the strings on first non-whitespace */
    while (1)
    {
-      while (isspace((int) *psz1))
+      while (isspace(* (unsigned char *) psz1))
          psz1++;
-      while (isspace((int) *psz2))
+      while (isspace(* (unsigned char *) psz2))
          psz2++;
-      if (toupper((int) *psz1) != toupper((int) *psz2)
+      if (toupper(* (unsigned char *) psz1) != toupper(* (unsigned char *) psz2)
 	  || *psz1 == '\0' || *psz2 == '\0')
          break;
       psz1++;

params.c

@@ -164,7 +164,7 @@ static int Continuation( char *line, int pos )
    */
   {
   pos--;
-  while( (pos >= 0) && isspace((int) line[pos]) )
+  while( (pos >= 0) && isspace(((unsigned char *)line)[pos]) )
      pos--;
 
   return( ((pos >= 0) && ('\\' == line[pos])) ? pos : -1 );
@@ -386,7 +386,7 @@ static BOOL Parameter( FILE *InFile, BOOL (*pfunc)(char *, char *), int c )
           c = 0;
         else
           {
-          for( end = i; (end >= 0) && isspace((int) bufr[end]); end-- )
+          for( end = i; (end >= 0) && isspace(((unsigned char *) bufr)[end]); end-- )
             ;
           c = getc( InFile );
           }

socket.c

@@ -70,7 +70,7 @@ static int establish_proxy_connection(int fd, char *host, int port)
 			buffer);
 		return -1;
 	}
-	for (cp = &buffer[5]; isdigit((int) *cp) || (*cp == '.'); cp++)
+	for (cp = &buffer[5]; isdigit(* (unsigned char *) cp) || (*cp == '.'); cp++)
 		;
 	while (*cp == ' ')
 		cp++;

util.c

@@ -532,8 +532,8 @@ void glob_expand(char *base1, char **argv, int *argc, int maxargs)
 void strlower(char *s)
 {
 	while (*s) {
-		if (isupper((int) *s))
-			*s = tolower((int) *s);
+		if (isupper(* (unsigned char *) s))
+			*s = tolower(* (unsigned char *) s);
 		s++;
 	}
 }