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authorGravatar Denis Vlasenko <vda.linux@googlemail.com>2008-03-24 02:05:58 +0000
committerGravatar Denis Vlasenko <vda.linux@googlemail.com>2008-03-24 02:05:58 +0000
commit42cc304e9084843ad6b153afaf4b3f6c6528c364 (patch)
tree51d7cc0dfcd554658d980b9628180e39512f9b1b /printutils
parent39c77c37384f87075ad578855f0a11ecbf0681f3 (diff)
downloadbusybox-42cc304e9084843ad6b153afaf4b3f6c6528c364.tar.gz
busybox-42cc304e9084843ad6b153afaf4b3f6c6528c364.tar.bz2
lpr: add more accurate comments
*: trailing whitespace removal
Diffstat (limited to 'printutils')
-rw-r--r--printutils/lpd.c45
-rw-r--r--printutils/lpr.c2
2 files changed, 27 insertions, 20 deletions
diff --git a/printutils/lpd.c b/printutils/lpd.c
index cac881383..bc0348eba 100644
--- a/printutils/lpd.c
+++ b/printutils/lpd.c
@@ -10,37 +10,40 @@
/*
* A typical usage of BB lpd looks as follows:
* # tcpsvd -E 0 515 lpd SPOOLDIR [HELPER-PROG [ARGS...]]
- *
- * This means a network listener is started on port 515 (default for LP protocol).
+ *
+ * This means a network listener is started on port 515 (default for LP protocol).
* When a client connection is made (via lpr) lpd first change its working directory to SPOOLDIR.
- *
- * SPOOLDIR is the spool directory which contains printing queues
+ *
+ * SPOOLDIR is the spool directory which contains printing queues
* and should have the following structure:
- *
+ *
* SPOOLDIR/
* <queue1>
* ...
* <queueN>
- *
+ *
* <queueX> can be of two types:
* A. a printer character device or an ordinary file a link to such;
* B. a directory.
- *
- * In case A lpd just dumps the data it receives from client (lpr) to the
+ *
+ * In case A lpd just dumps the data it receives from client (lpr) to the
* end of queue file/device. This is non-spooling mode.
- *
- * In case B lpd enters spooling mode. It reliably saves client data along with control info
- * in two unique files under the queue directory. These files are named dfAXXXHHHH and cfAXXXHHHH,
- * where XXX is the job number and HHHH is the client hostname. Unless a printing helper application
+ *
+ * In case B lpd enters spooling mode. It reliably saves client data along with control info
+ * in two unique files under the queue directory. These files are named dfAXXXHHHH and cfAXXXHHHH,
+ * where XXX is the job number and HHHH is the client hostname. Unless a printing helper application
* is specified lpd is done at this point.
- *
+ *
+ * NB: file names are produced by peer! They actually may be anything at all!
+ * lpd only sanitizes them (by removing most non-alphanumerics).
+ *
* If HELPER-PROG (with optional arguments) is specified then lpd continues to process client data:
- * 1. it reads and parses control file (cfA...). The parse process results in setting environment
- * variables whose values were passed in control file; when parsing is complete, lpd deletes
+ * 1. it reads and parses control file (cfA...). The parse process results in setting environment
+ * variables whose values were passed in control file; when parsing is complete, lpd deletes
* control file.
- * 2. it spawns specified helper application. It is then the helper application who is responsible
+ * 2. it spawns specified helper application. It is then the helper application who is responsible
* for both actual printing and deleting processed data file.
- *
+ *
* A good lpr passes control files which when parsed provide the following variables:
* $H = host which issues the job
* $P = user who prints
@@ -49,13 +52,17 @@
* $L = print banner page
* $M = the user to whom a mail should be sent if a problem occurs
* $l = name of datafile ("dfAxxx") - file whose content are to be printed
- *
+ *
+ * lpd also provides $DATAFILE environment variable - the ACTUAL name
+ * of the datafile under which it was saved.
+ * $l is not reliable (you are at mercy of remote peer), DON'T USE IT.
+ *
* Thus, a typical helper can be something like this:
* #!/bin/sh
* cat "$l" >/dev/lp0
* mv -f "$l" save/
- *
*/
+
#include "libbb.h"
// strip argument of bad chars
diff --git a/printutils/lpr.c b/printutils/lpr.c
index 5313d5a20..d0bf5873e 100644
--- a/printutils/lpr.c
+++ b/printutils/lpr.c
@@ -49,7 +49,7 @@ int lpqr_main(int argc ATTRIBUTE_UNUSED, char *argv[])
OPT_U = 1 << 1, // -U username
LPR_V = 1 << 2, // -V: be verbose
- LPR_h = 1 << 3, // -h: want banner printed
+ LPR_h = 1 << 3, // -h: want banner printed
LPR_C = 1 << 4, // -C class: job "class" (? supposedly printed on banner)
LPR_J = 1 << 5, // -J title: the job title for the banner page
LPR_m = 1 << 6, // -m: send mail back to user