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

4 files changed, 25 insertions, 10 deletions

diff --git a/libbb/full_write.c b/libbb/full_write.c
index 7bbacb8ac..7503c8b42 100644
--- a/libbb/full_write.c
+++ b/libbb/full_write.c
@@ -24,8 +24,14 @@ ssize_t full_write(int fd, const void *buf, size_t len)
         while (len) {
                 cc = safe_write(fd, buf, len);
 
-                if (cc < 0)
+                if (cc < 0) {
+                        if (total) {
+                                /* we already wrote some! */
+                                /* user can do another write to know the error code */
+                                return total;
+                        }
                         return cc;      /* write() returns -1 on failure. */
+                }
 
                 total += cc;
                 buf = ((const char *)buf) + cc;
diff --git a/libbb/isdirectory.c b/libbb/isdirectory.c
index b35919869..1d2477f47 100644
--- a/libbb/isdirectory.c
+++ b/libbb/isdirectory.c
@@ -12,7 +12,7 @@
 #include "libbb.h"
 
 /*
- * Return TRUE if a fileName is a directory.
+ * Return TRUE if fileName is a directory.
  * Nonexistent files return FALSE.
  */
 int is_directory(const char *fileName, const int followLinks, struct stat *statBuf)
@@ -21,8 +21,8 @@ int is_directory(const char *fileName, const int followLinks, struct stat *statB
         struct stat astatBuf;
 
         if (statBuf == NULL) {
-            /* set from auto stack buffer */
-            statBuf = &astatBuf;
+                /* use auto stack buffer */
+                statBuf = &astatBuf;
         }
 
         if (followLinks)
@@ -30,10 +30,7 @@ int is_directory(const char *fileName, const int followLinks, struct stat *statB
         else
                 status = lstat(fileName, statBuf);
 
-        if (status < 0 || !(S_ISDIR(statBuf->st_mode))) {
-            status = FALSE;
-        }
-        else status = TRUE;
+        status = (status == 0 && S_ISDIR(statBuf->st_mode));
 
         return status;
 }
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;
diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index 17760a3c3..18e696a7a 100644
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -577,6 +577,12 @@ void xchdir(const char *path)
                 bb_perror_msg_and_die("chdir(%s)", path);
 }
 
+void xchroot(const char *path)
+{
+        if (chroot(path))
+                bb_perror_msg_and_die("can't change root directory to %s", path);
+}
+
 // Print a warning message if opendir() fails, but don't die.
 DIR *warn_opendir(const char *path)
 {