[Printing-architecture] [PATCH] braille: Add virtual BRF backend
Samuel Thibault
samuel.thibault at ens-lyon.org
Sun Sep 17 13:34:42 UTC 2017
Samuel Thibault, on dim. 17 sept. 2017 15:11:18 +0200, wrote:
> @@ -997,6 +1004,8 @@ if ENABLE_DRIVERLESS
> $(LN_S) -r -f $(DESTDIR)$(pkgppdgendir)/driverless $(DESTDIR)$(pkgbackenddir)
> endif
> if ENABLE_BRAILLE
> + # This needs to be run as root
> + chmod g-rwx,o-rwx $(DESTDIR)/$(pkgbackenddir)/cups-brf
Mmm, this fails because apparently install-exec-hook is not run after
pkgbackend_PROGRAMS installation. Here is a fixed patch.
Samuel
-------------- next part --------------
=== modified file 'Makefile.am'
---
Makefile.am | 10 +++
README | 13 ++++
backend/cups-brf.c | 162 +++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 185 insertions(+)
--- a/Makefile.am
+++ b/Makefile.am
@@ -65,6 +65,13 @@ test1284_SOURCES = \
test1284_LDADD = $(CUPS_LIBS)
test1284_CFLAGS = $(CUPS_CFLAGS)
+if ENABLE_BRAILLE
+pkgbackend_PROGRAMS += cups-brf
+
+cups_brf_SOURCES = \
+ backend/cups-brf.c
+endif
+
# ==============
# PPD Generators
# ==============
@@ -1020,6 +1027,9 @@ if RCLINKS
endif
$(LN_S) -f pdf.utf-8.simple \
$(DESTDIR)$(pkgcharsetdir)/pdf.utf-8
+if ENABLE_BRAILLE
+ chmod g-rwx,o-rwx $(DESTDIR)/$(pkgbackenddir)/cups-brf
+endif
uninstall-hook:
--- a/README
+++ b/README
@@ -1758,6 +1758,19 @@ the default values are shown here.
lp -o "LibLouis=fr-fr-g1 LibLouis2=gr-gr-g1 TextDotDistance=250 LineSpacing=500" file.txt
+---------------
+BRF file output
+---------------
+
+One can generate BRF files by adding a virtual BRF printer.
+
+When creating it in the cups interface, choose the CUPS-BRF local printer,
+select the Generic maker, and choose the Generic Braille embosser model.
+
+Printing to the resulting printer will generate a .brf file in a BRF
+subdirectory of the home directory.
+
+
----------------------------
Remark about the source code
----------------------------
--- /dev/null
+++ b/backend/cups-brf.c
@@ -0,0 +1,162 @@
+/*
+ * BRF (Braille-Ready Format) virtual backend
+ *
+ * Copyright (c) 2017 by Samuel Thibault <samuel.thibault at ens-lyon.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "backend-private.h"
+#include <string.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <pwd.h>
+
+int main(int argc, char *argv[]) {
+ char *user;
+ char *dir;
+ char *title;
+ char *outfile;
+ char *c;
+ char buffer[4096];
+ ssize_t sizein, sizeout, done;
+ struct passwd *pw;
+ int ret;
+ int fd;
+
+ if (setuid(0)) {
+ /* We need to be root to be able to turn into another user. */
+ fprintf(stderr,"ERROR: cups-brf must be called as root\n");
+ return CUPS_BACKEND_FAILED;
+ }
+
+ if (argc == 1) {
+ /* This is just discovery. */
+ printf("file cups-brf:/ \"Virtual Braille BRF Printer\" \"CUPS-BRF\" \"MFG:Generic;MDL:CUPS-BRF Printer;DES:Generic CUPS-BRF Printer;CLS:PRINTER;CMD:BRF;\"\n");
+ return CUPS_BACKEND_OK;
+ }
+
+ if (argc < 6) {
+ /* Invalid number of parameters. */
+ fprintf(stderr, "ERROR: cups-brf jobid user name nb options [filename]\n");
+ return CUPS_BACKEND_FAILED;
+ }
+
+ if (argc == 7) {
+ /* Explicit file name, open it. */
+ char *filename = argv[6];
+ fd = open(filename, O_RDONLY);
+ if (dup2(fd, STDIN_FILENO) < 0) {
+ fprintf(stderr, "ERROR: opening file \"%s\"\n", filename);
+ return CUPS_BACKEND_FAILED;
+ }
+ }
+
+ /* Now we have everything, turn into the user */
+ user = argv[2];
+ pw = getpwnam(user);
+ if (pw == NULL) {
+ fprintf(stderr, "ERROR: getting user \"%s\" information\n", user);
+ return CUPS_BACKEND_FAILED;
+ }
+ if (setgid(pw->pw_gid)) {
+ fprintf(stderr, "ERROR: turning gid into %u\n", pw->pw_gid);
+ return CUPS_BACKEND_FAILED;
+ }
+ if (setuid(pw->pw_uid)) {
+ fprintf(stderr, "ERROR: turning uid into %u\n", pw->pw_uid);
+ return CUPS_BACKEND_FAILED;
+ }
+
+ /* Now we act as user */
+ umask(0077);
+
+ /* Create BRF directory in $HOME */
+ if (asprintf(&dir, "%s/BRF", pw->pw_dir) < 0) {
+ fprintf(stderr, "ERROR: could not allocate memory\n");
+ return CUPS_BACKEND_FAILED;
+ }
+ fprintf(stderr, "DEBUG: creating directory \"%s\n", dir);
+ ret = mkdir(dir, 0700);
+ if (ret == -1 && errno != EEXIST) {
+ fprintf(stderr, "ERROR: could not create directory \"%s\": %s\n", dir, strerror(errno));
+ return CUPS_BACKEND_FAILED;
+ }
+
+ /* Avoid escaping from the directory */
+ title = argv[3];
+ for (c = title; *c; c++) {
+ if (*c == '/')
+ *c = '_';
+ }
+ /* Avoid hiding the file */
+ while (*title == '.')
+ title++;
+
+ /* Avoid empty title */
+ if (!*title)
+ title = "unknown";
+
+ /* generate mask */
+ if (asprintf(&outfile, "%s/%s.XXXXXX.brf", dir, title) < 0) {
+ fprintf(stderr, "ERROR: could not allocate memory\n");
+ return CUPS_BACKEND_FAILED;
+ }
+
+ /* Create file */
+ fprintf(stderr, "DEBUG: creating file \"%s\n", outfile);
+ fd = mkstemps(outfile, 4);
+ if (fd < 0) {
+ fprintf(stderr, "ERROR: could not create file \"%s\": %s\n", outfile, strerror(errno));
+ return CUPS_BACKEND_FAILED;
+ }
+
+ /* We are all set, copy data. */
+ while (1) {
+ /* Read some. */
+ sizein = read(STDIN_FILENO, buffer, sizeof(buffer));
+ if (sizein < 0) {
+ fprintf(stderr, "ERROR: while reading input: %s\n", strerror(errno));
+ return CUPS_BACKEND_FAILED;
+ }
+ if (sizein == 0)
+ /* We are done! */
+ break;
+
+ /* Write it. */
+ for (done = 0; done < sizein; done += sizeout) {
+ sizeout = write(fd, buffer + done, sizein - done);
+ if (sizeout < 0) {
+ fprintf(stderr, "ERROR: while writing to \"%s\": %s\n", outfile, strerror(errno));
+ return CUPS_BACKEND_FAILED;
+ }
+ }
+ }
+ if (close(fd) < 0) {
+ fprintf(stderr, "ERROR: while closing \"%s\": %s\n", outfile, strerror(errno));
+ return CUPS_BACKEND_FAILED;
+ }
+
+ return CUPS_BACKEND_OK;
+}
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