lpd: spool mode added by Vladimir

lpr: more robust error reporting
*: introduce and use xchroot
libbb: full_read/write now will report partial data counts prior to error
isdirectory.c: style fixes

lpd_main                                             249     486    +237
xchroot                                                -      29     +29
get_response_or_say_and_die                          110     139     +29
full_write                                            52      60      +8
full_read                                             55      63      +8
static.newline                                         1       -      -1
switch_root_main                                     404     400      -4
chpst_main                                          1089    1079     -10
getopt32                                            1370    1359     -11
chroot_main                                          115     101     -14
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 4/4 up/down: 311/-40)           Total: 271 bytes
   text    data     bss     dec     hex filename
 798472     728    7484  806684   c4f1c busybox_old
 798775     728    7484  806987   c504b busybox_unstripped

1 files changed, 8 insertions, 2 deletions

diff --git a/libbb/read.c b/libbb/read.c
index 4ad41d589..575446536 100644
--- a/libbb/read.c
+++ b/libbb/read.c
@@ -88,8 +88,14 @@ ssize_t full_read(int fd, void *buf, size_t len)
         while (len) {
                 cc = safe_read(fd, buf, len);
 
-                if (cc < 0)
-                        return cc;      /* read() returns -1 on failure. */
+                if (cc < 0) {
+                        if (total) {
+                                /* we already have some! */
+                                /* user can do another read to know the error code */
+                                return total;
+                        }
+                        return cc; /* read() returns -1 on failure. */
+                }
                 if (cc == 0)
                         break;
                 buf = ((char *)buf) + cc;