diff options
Diffstat (limited to 'printutils')
| -rw-r--r-- | printutils/lpd.c | 94 |
1 files changed, 52 insertions, 42 deletions
diff --git a/printutils/lpd.c b/printutils/lpd.c index 4008e4396..f4c902c79 100644 --- a/printutils/lpd.c +++ b/printutils/lpd.c @@ -9,10 +9,11 @@ /* * A typical usage of BB lpd looks as follows: - * # tcpsvd -E 0 515 lpd SPOOLDIR [HELPER-PROG [ARGS...]] + * # tcpsvd -E 0 515 lpd [SPOOLDIR] [HELPER-PROG [ARGS...]] * - * 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. + * This starts TCP listener on port 515 (default for LP protocol). + * When a client connection is made (via lpr) lpd first changes its + * working directory to SPOOLDIR (current dir is the default). * * SPOOLDIR is the spool directory which contains printing queues * and should have the following structure: @@ -23,44 +24,50 @@ * <queueN> * * <queueX> can be of two types: - * A. a printer character device or an ordinary file a link to such; + * A. a printer character device, an ordinary file or a link to such; * B. a directory. * * 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! + * 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 - * control file. - * 2. it spawns specified helper application. It is then the helper application who is responsible - * for both actual printing and deleting processed data file. + * 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 control file. + * 2. it spawns specified helper application. It is then + * the helper application who is responsible for both actual printing + * and deleting of processed data file. * - * A good lpr passes control files which when parsed provide the following variables: + * A good lpr passes control files which when parsed provides the following + * variables: * $H = host which issues the job * $P = user who prints * $C = class of printing (what is printed on banner page) * $J = the name of the job * $L = print banner page * $M = the user to whom a mail should be sent if a problem occurs + * + * We specifically filter out and NOT provide: * $l = name of datafile ("dfAxxx") - file whose content are to be printed * - * lpd also provides $DATAFILE environment variable - the ACTUAL name + * lpd provides $DATAFILE instead - 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. + * $l would be not reliable (you would be at mercy of remote peer). * * Thus, a typical helper can be something like this: * #!/bin/sh - * cat "$l" >/dev/lp0 - * mv -f "$l" save/ + * cat ./"$DATAFILE" >/dev/lp0 + * mv -f ./"$DATAFILE" save/ */ #include "libbb.h" @@ -87,6 +94,8 @@ static void exec_helper(char **filenames, char **argv) char *p, *q; char var[2]; + var[1] = '\0'; + // read and delete ctrlfile q = xmalloc_open_read_close(filenames[0], NULL); unlink(filenames[0]); @@ -97,11 +106,13 @@ static void exec_helper(char **filenames, char **argv) && isalpha(*q) ) { *p++ = '\0'; - // here q is a line of <SYM><VALUE> - // let us set environment string <SYM>=<VALUE> - var[0] = *q++; - var[1] = '\0'; - xsetenv(var, q); + // q is a line of <SYM><VALUE>, + // we are setting environment string <SYM>=<VALUE>. + // Ignoring "l<datafile>", exporting others: + if (*q != 'l') { + var[0] = *q++; + xsetenv(var, q); + } // next line, plz! q = p; } @@ -110,7 +121,7 @@ static void exec_helper(char **filenames, char **argv) // (no daemonization is done) bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO | DAEMON_ONLY_SANITIZE, NULL); BB_EXECVP(*argv, argv); - exit(0); + exit(127); // it IS error if helper cannot be executed! } static char *xmalloc_read_stdin(void) @@ -124,7 +135,6 @@ int lpd_main(int argc, char *argv[]) MAIN_EXTERNALLY_VISIBLE; int lpd_main(int argc ATTRIBUTE_UNUSED, char *argv[]) { int spooling = spooling; // for compiler - int seen; char *s, *queue; char *filenames[2]; @@ -135,8 +145,8 @@ int lpd_main(int argc ATTRIBUTE_UNUSED, char *argv[]) // error messages of xfuncs will be sent over network xdup2(STDOUT_FILENO, STDERR_FILENO); - filenames[0] = NULL; // ctrlfile name - filenames[1] = NULL; // datafile name + // nullify ctrl/data filenames + memset(filenames, 0, sizeof(filenames)); // read command s = queue = xmalloc_read_stdin(); @@ -157,8 +167,7 @@ int lpd_main(int argc ATTRIBUTE_UNUSED, char *argv[]) // queue is a directory -> chdir to it and enter spooling mode spooling = chdir(queue) + 1; // 0: cannot chdir, 1: done - seen = 0; - // we don't free(queue), we might need it later + // we don't free(s), we might need "queue" var later while (1) { char *fname; @@ -175,7 +184,7 @@ int lpd_main(int argc ATTRIBUTE_UNUSED, char *argv[]) // N.B. we bail out on any error s = xmalloc_read_stdin(); if (!s) { // (probably) EOF - if (spooling /* && 6 != spooling - always true */) { + if (spooling /* && 7 != spooling - always true */) { // we didn't see both ctrlfile & datafile! goto err_exit; } @@ -187,11 +196,10 @@ int lpd_main(int argc ATTRIBUTE_UNUSED, char *argv[]) // we understand only "control file" or "data file" cmds if (2 != s[0] && 3 != s[0]) goto unsupported_cmd; - if (seen & (s[0] - 1)) { + if (spooling & (1 << (s[0]-1))) { printf("Duplicated subcommand\n"); goto err_exit; } - seen &= (s[0] - 1); // bit 1: ctrlfile; bit 2: datafile // get filename *strchrnul(s, '\n') = '\0'; fname = strchr(s, ' '); @@ -243,9 +251,10 @@ int lpd_main(int argc ATTRIBUTE_UNUSED, char *argv[]) goto err_exit; } // get ACK and see whether it is NUL (ok) - if (safe_read(STDIN_FILENO, s, 1) != 1 || s[0] != 0) { + // (and don't trash s[0]!) + if (safe_read(STDIN_FILENO, &s[1], 1) != 1 || s[1] != 0) { // don't send error msg to peer - it obviously - // don't follow the protocol, so probably + // doesn't follow the protocol, so probably // it can't understand us either goto err_exit; } @@ -254,14 +263,15 @@ int lpd_main(int argc ATTRIBUTE_UNUSED, char *argv[]) // chmod completely downloaded file as "readable+writable" fchmod(fd, 0600); // accumulate dump state - // N.B. after all files are dumped spooling should be 1+2+3==6 - spooling += s[0]; + // N.B. after all files are dumped spooling should be 1+2+4==7 + spooling |= (1 << (s[0]-1)); // bit 1: ctrlfile; bit 2: datafile } + free(s); close(fd); // NB: can do close(-1). Who cares? // spawn spool helper and exit if all files are dumped - if (6 == spooling && *argv) { + if (7 == spooling && *argv) { // signal OK safe_write(STDOUT_FILENO, "", 1); // does not return (exits 0) @@ -272,10 +282,10 @@ int lpd_main(int argc ATTRIBUTE_UNUSED, char *argv[]) err_exit: // don't keep corrupted files if (spooling) { - if (filenames[0]) - unlink(filenames[0]); - if (filenames[1]) - unlink(filenames[1]); +#define i spooling + for (i = 2; --i >= 0; ) + if (filenames[i]) + unlink(filenames[i]); } return EXIT_FAILURE; } |