Introduce the (undocumented) variable fetchRestartCalls, which controls whether

or not interrupted system calls will be restarted. This fixes a bug where
fetch(1) would hang (potentially forever) if a server stopped responding,
because the signal handler would absorb the user's efforts to interrupt the
transfer.

lib/libfetch/common.c

@@ -262,7 +262,7 @@ _fetch_getln(int fd, char **buf, size_t *size, size_t *len)
 	    }
 	    r = select(fd+1, &readfds, NULL, NULL, &wait);
 	    if (r == -1) {
-		if (errno == EINTR)
+		if (errno == EINTR && fetchRestartCalls)
 		    continue;
 		/* EBADF or EINVAL: shouldn't happen */
 		return -1;
@@ -274,7 +274,7 @@ _fetch_getln(int fd, char **buf, size_t *size, size_t *len)
 	if (r == 0)
 	    break;
 	if (r == -1) {
-	    if (errno == EINTR)
+	    if (errno == EINTR && fetchRestartCalls)
 		continue;
 	    /* any other error is bad news */
 	    return -1;

lib/libfetch/fetch.c

@@ -43,6 +43,7 @@
 int	 fetchLastErrCode;
 char	 fetchLastErrString[MAXERRSTRING];
 int	 fetchTimeout;
+int	 fetchRestartCalls = 1;
 
 
 /*** Local data **************************************************************/