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-rw-r--r--zbarcam/scan_video.c227
1 files changed, 227 insertions, 0 deletions
diff --git a/zbarcam/scan_video.c b/zbarcam/scan_video.c
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+++ b/zbarcam/scan_video.c
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+/*------------------------------------------------------------------------
+ * Copyright 2008-2009 (c) Jeff Brown <spadix@users.sourceforge.net>
+ *
+ * This file is part of the ZBar Bar Code Reader.
+ *
+ * The ZBar Bar Code Reader is free software; you can redistribute it
+ * and/or modify it under the terms of the GNU Lesser Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * The ZBar Bar Code Reader is distributed in the hope that it will be
+ * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser Public License
+ * along with the ZBar Bar Code Reader; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301 USA
+ *
+ * http://sourceforge.net/projects/zbar
+ *------------------------------------------------------------------------*/
+
+#include "config.h"
+
+#include <fcntl.h>
+#include <ftw.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <linux/videodev2.h>
+
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#ifdef MAJOR_IN_SYSMACROS
+#include <sys/sysmacros.h>
+#endif
+typedef void(cb_t)(void *userdata, const char *device);
+
+struct devnodes {
+ char *fname;
+ int minor;
+ int is_valid;
+};
+
+static unsigned int n_devices = 0;
+static struct devnodes *devices = NULL;
+
+/*
+ * Sort order:
+ *
+ * - Valid devices comes first
+ * - Lowest minors comes first
+ *
+ * For devnode names, it sorts on this order:
+ * - custom udev given names
+ * - /dev/v4l/by-id/
+ * - /dev/v4l/by-path/
+ * - /dev/video
+ * - /dev/char/
+ *
+ * - Device name is sorted alphabetically if follows same pattern
+ */
+static int sort_devices(const void *__a, const void *__b)
+{
+ const struct devnodes *a = __a;
+ const struct devnodes *b = __b;
+ int val_a, val_b;
+
+ if (a->is_valid != b->is_valid)
+ return !a->is_valid - !b->is_valid;
+
+ if (a->minor != b->minor)
+ return a->minor - b->minor;
+
+ /* Ensure that /dev/video* devices will stay at the top */
+
+ if (strstr(a->fname, "by-id"))
+ val_a = 1;
+ if (strstr(a->fname, "by-path"))
+ val_a = 2;
+ else if (strstr(a->fname, "/dev/video"))
+ val_a = 3;
+ else if (strstr(a->fname, "char"))
+ val_a = 4;
+ else /* Customized names comes first */
+ val_a = 0;
+
+ if (strstr(b->fname, "by-id"))
+ val_b = 1;
+ if (strstr(b->fname, "by-path"))
+ val_b = 2;
+ else if (strstr(b->fname, "/dev/video"))
+ val_b = 3;
+ else if (strstr(b->fname, "char"))
+ val_b = 4;
+ else /* Customized names comes first */
+ val_b = 0;
+
+ if (val_a != val_b)
+ return val_a - val_b;
+
+ /* Finally, just use alphabetic order */
+ return strcmp(a->fname, b->fname);
+}
+
+static int handle_video_devs(const char *file, const struct stat *st, int flag)
+{
+ int dev_minor, first_device = -1, fd;
+ unsigned int i;
+ struct v4l2_capability vid_cap = { 0 };
+
+ /* Discard devices that can't be a videodev */
+ if (!S_ISCHR(st->st_mode) || major(st->st_rdev) != 81)
+ return 0;
+
+ dev_minor = minor(st->st_rdev);
+
+ /* check if it is an already existing device */
+ if (devices) {
+ for (i = 0; i < n_devices; i++) {
+ if (dev_minor == devices[i].minor) {
+ first_device = i;
+ break;
+ }
+ }
+ }
+
+ devices = realloc(devices, (n_devices + 1) * sizeof(struct devnodes));
+ if (!devices) {
+ perror("Can't allocate memory to store devices");
+ exit(1);
+ }
+ memset(&devices[n_devices], 0, sizeof(struct devnodes));
+
+ if (first_device < 0) {
+ fd = open(file, O_RDWR);
+ if (fd < 0) {
+ devices[n_devices].is_valid = 0;
+ } else {
+ if (ioctl(fd, VIDIOC_QUERYCAP, &vid_cap) == -1) {
+ devices[n_devices].is_valid = 0;
+ } else {
+#ifdef V4L2_CID_ALPHA_COMPONENT
+ /*
+ * device_caps was added on Kernel 3.3. The preferred
+ * way to handle such compat stuff would be to include
+ * a recent videodev2.h at ZBar's source and check the
+ * V4L2 API returned by VIDIOC_QUERYCAP.
+ * However, doing that require some care, as other
+ * compat code should be checked to see if they would work.
+ * Also, it is painful to keep updating the Kernel headers.
+ * Thankfully, V4L2_CID_ALPHA_COMPONENT was also added on
+ * Kernel 3.3, so just checking if this is defined should
+ * be enough to do the right thing.
+ */
+ if (!(vid_cap.device_caps & V4L2_CAP_VIDEO_CAPTURE))
+ devices[n_devices].is_valid = 0;
+ else
+ devices[n_devices].is_valid = 1;
+#else
+ if (!(vid_cap.device_caps & V4L2_CAP_VIDEO_CAPTURE))
+ devices[n_devices].is_valid = 0;
+ else
+ devices[n_devices].is_valid = 1;
+#endif
+ }
+ }
+
+ close(fd);
+ } else {
+ devices[n_devices].is_valid = devices[first_device].is_valid;
+ }
+
+ devices[n_devices].fname = strdup(file);
+ devices[n_devices].minor = dev_minor;
+
+ n_devices++;
+
+ return (0);
+}
+
+/* scan /dev for v4l video devices and call add_device for each.
+ * also looks for a specified "default" device (if not NULL)
+ * if not found, the default will be appended to the list.
+ * returns the index+1 of the default_device, or 0 if the default
+ * was not specified. NB *not* reentrant
+ */
+int scan_video(cb_t add_dev, void *userdata, const char *default_dev)
+{
+ unsigned int i, idx = 0;
+ int default_idx = -1, last_minor = -1;
+
+ if (ftw("/dev", handle_video_devs, 4)) {
+ perror("search for video devices failed");
+ return -1;
+ }
+ qsort(devices, n_devices, sizeof(struct devnodes), sort_devices);
+
+ for (i = 0; i < n_devices; i++) {
+ if (!devices[i].is_valid)
+ continue;
+
+ if (devices[i].minor == last_minor)
+ continue;
+
+ add_dev(userdata, devices[i].fname);
+ last_minor = devices[i].minor;
+ idx++;
+
+ if (default_dev && !strcmp(default_dev, devices[i].fname))
+ default_idx = idx;
+ else if (!default_dev && default_idx < 0)
+ default_idx = idx;
+ }
+
+ for (i = 0; i < n_devices; i++)
+ free(devices[i].fname);
+ free(devices);
+
+ n_devices = 0;
+ devices = NULL;
+
+ return (default_idx);
+}
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