[vlc-devel] [PATCH] Support for alternative libv4l2 library (userspace drivers)

[Markus Rechberger]

Attached patch adds support to access our userspace USB TV Tuner
drivers (the analogTV part - S-Video / Composite and AnalogTV)
directly via our interface library.
That way VLC would also be able to access our driver interface on
MacOSX, FreeBSD and Solaris.
It is fully compatible with the official V4L2 API, the patch will have
no effect on existing V4L2 devices.
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diff --git a/modules/access/v4l2/lib.c b/modules/access/v4l2/lib.c
index cf2b480..46057c5 100644
--- a/modules/access/v4l2/lib.c
+++ b/modules/access/v4l2/lib.c
@@ -25,6 +25,8 @@
 #include <pthread.h>
 #include <dlfcn.h>
 #include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 
@@ -34,6 +36,7 @@
 
 static void *v4l2_handle = NULL;
 static int (*v4l2_fd_open_) (int, int);
+static int (*v4l2_open_direct) (__const char *__file, int __oflag, ...);
 int (*v4l2_close) (int);
 int (*v4l2_ioctl) (int, unsigned long int, ...);
 ssize_t (*v4l2_read) (int, void *, size_t);
@@ -46,6 +49,87 @@ static int fd_open (int fd, int flags)
     return fd;
 }
 
+static int v4l2_check_socket() {
+        int fd;
+        char *buf=NULL;
+        int buflen=0;
+        int nread;
+        char rbuf[10240];
+        int rv;
+        struct stat statbuf;
+
+        const char *sockpath="@/de/sundtek/mediasocket";
+
+        /* FreeBSD, Solaris, MacOSX */
+        rv = stat("/tmp/.mediasocket", &statbuf);
+        if (rv == 0)
+                return 0;
+
+        fd = open("/proc/net/unix", O_RDONLY);
+        if (fd >= 0) {
+                while ((nread=read(fd, rbuf, 10240))>0) {
+                        buf = (char*)realloc(buf, buflen+nread+1);
+                        memcpy(&buf[buflen], rbuf, nread);
+                        buflen+=nread;
+                }
+                buf[buflen]=0;
+                if (strstr(buf, sockpath)) {
+                        free(buf);
+			close(fd);
+                        return 0;
+                }
+		close(fd);
+                free(buf);
+        }
+        return -1;
+}
+
+static int v4l2_net_open (char *path) {
+    void *h;
+    int fd;
+
+    h = dlopen ("libmcsimple.so", RTLD_LAZY | RTLD_LOCAL);
+    if (h == NULL) {
+	/* this is the default driver location */
+	h = dlopen("/opt/lib/libmcsimple.so", RTLD_LAZY | RTLD_LOCAL);
+	if (h == NULL)
+            goto fallback;
+    }
+    /* no need for that one */
+    v4l2_open_direct = dlsym (h, "net_open");
+    v4l2_close = dlsym (h, "net_close");
+    v4l2_ioctl = dlsym (h, "net_ioctl");
+    v4l2_read = dlsym (h, "__net_read");
+    v4l2_mmap = dlsym (h, "net_mmap");
+    v4l2_munmap = dlsym (h, "net_munmap");
+
+    if (v4l2_open_direct != NULL && v4l2_close != NULL && v4l2_ioctl != NULL
+     && v4l2_read != NULL && v4l2_mmap != NULL && v4l2_munmap != NULL)
+    {
+        v4l2_handle = h;
+        fd = v4l2_open_direct(path, O_RDWR);
+        if (fd == -1) {
+                v4l2_handle = NULL;
+                dlclose(h);
+                return -1;
+        } else {
+                return fd;
+        }
+    }
+
+    dlclose (h);
+fallback:
+    return -1;
+}
+
+int v4l2_check_device(char *path) {
+        int sk;
+        sk = v4l2_check_socket();
+        if (sk == 0)
+                return v4l2_net_open (path);
+        return -1;
+}
+
 static void v4l2_lib_load (void)
 {
     void *h = dlopen ("libv4l2.so.0", RTLD_LAZY | RTLD_LOCAL);
diff --git a/modules/access/v4l2/v4l2.c b/modules/access/v4l2/v4l2.c
index 7807a8a..beb95d9 100644
--- a/modules/access/v4l2/v4l2.c
+++ b/modules/access/v4l2/v4l2.c
@@ -466,21 +466,29 @@ int OpenDevice (vlc_object_t *obj, const char *path, uint32_t *restrict caps)
 {
     msg_Dbg (obj, "opening device '%s'", path);
 
-    int rawfd = vlc_open (path, O_RDWR);
-    if (rawfd == -1)
-    {
-        msg_Err (obj, "cannot open device '%s': %s", path,
-                 vlc_strerror_c(errno));
-        return -1;
-    }
-
-    int fd = v4l2_fd_open (rawfd, 0);
-    if (fd == -1)
-    {
-        msg_Warn (obj, "cannot initialize user-space library: %s",
-                  vlc_strerror_c(errno));
-        /* fallback to direct kernel mode anyway */
-        fd = rawfd;
+    int rawfd;
+    int fd;
+
+    fd = v4l2_check_device(path);
+
+    if (fd == -1) {
+
+	    rawfd = vlc_open (path, O_RDWR);
+	    if (rawfd == -1)
+	    {
+		msg_Err (obj, "cannot open device '%s': %s", path,
+			 vlc_strerror_c(errno));
+		return -1;
+	    }
+
+	    fd = v4l2_fd_open (rawfd, 0);
+	    if (fd == -1)
+	    {
+		msg_Warn (obj, "cannot initialize user-space library: %s",
+			  vlc_strerror_c(errno));
+		/* fallback to direct kernel mode anyway */
+		fd = rawfd;
+	    }
     }
 
     /* Get device capabilites */
diff --git a/modules/access/v4l2/v4l2.h b/modules/access/v4l2/v4l2.h
index 9888785..da28519 100644
--- a/modules/access/v4l2/v4l2.h
+++ b/modules/access/v4l2/v4l2.h
@@ -22,6 +22,7 @@
 
 /* libv4l2 functions */
 extern int v4l2_fd_open (int, int);
+extern int v4l2_check_device(char *path);
 extern int (*v4l2_close) (int);
 extern int (*v4l2_ioctl) (int, unsigned long int, ...);
 extern ssize_t (*v4l2_read) (int, void *, size_t);