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CameraServer: Add VID/PID support for Linux USB devices (#1960)

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This commit is contained in:
Peter Johnson
2019-10-20 14:12:00 -07:00
committed by GitHub
parent 3fc89c84d6
commit c59f9cea5f
6 changed files with 90 additions and 33 deletions
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89
cscore/src/main/native/linux/UsbCameraImpl.cpp
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@@ -143,10 +143,36 @@ int UsbCameraImpl::PercentageToRaw(const UsbCameraProperty& rawProp,
(rawProp.maximum - rawProp.minimum) * (percentValue / 100.0);
}
static bool GetDescriptionSysV4L(wpi::StringRef path, std::string* desc) {
wpi::SmallString<64> ifpath{"/sys/class/video4linux/"};
ifpath += path.substr(5);
ifpath += "/device/interface";
static bool GetVendorProduct(int dev, int* vendor, int* product) {
wpi::SmallString<64> ifpath;
{
wpi::raw_svector_ostream oss{ifpath};
oss << "/sys/class/video4linux/video" << dev << "/device/modalias";
}
int fd = open(ifpath.c_str(), O_RDONLY);
if (fd < 0) return false;
char readBuf[128];
ssize_t n = read(fd, readBuf, sizeof(readBuf));
close(fd);
if (n <= 0) return false;
wpi::StringRef readStr{readBuf};
if (readStr.substr(readStr.find('v')).substr(1, 4).getAsInteger(16, *vendor))
return false;
if (readStr.substr(readStr.find('p')).substr(1, 4).getAsInteger(16, *product))
return false;
return true;
}
static bool GetDescriptionSysV4L(int dev, std::string* desc) {
wpi::SmallString<64> ifpath;
{
wpi::raw_svector_ostream oss{ifpath};
oss << "/sys/class/video4linux/video" << dev << "/device/interface";
}
int fd = open(ifpath.c_str(), O_RDONLY);
if (fd < 0) return false;
@@ -192,23 +218,35 @@ static bool GetDescriptionIoctl(const char* cpath, std::string* desc) {
return true;
}
static std::string GetDescriptionImpl(const char* cpath) {
static int GetDeviceNum(const char* cpath) {
wpi::StringRef path{cpath};
char pathBuf[128];
std::string rv;
std::string pathBuf;
// If trying to get by id or path, follow symlink
if (path.startswith("/dev/v4l/by-id/")) {
ssize_t n = readlink(cpath, pathBuf, sizeof(pathBuf));
if (n > 0) path = wpi::StringRef(pathBuf, n);
} else if (path.startswith("/dev/v4l/by-path/")) {
ssize_t n = readlink(cpath, pathBuf, sizeof(pathBuf));
if (n > 0) path = wpi::StringRef(pathBuf, n);
// it might be a symlink; if so, find the symlink target (e.g. /dev/videoN),
// add that to the list and make it the keypath
if (wpi::sys::fs::is_symlink_file(cpath)) {
char* target = ::realpath(cpath, nullptr);
if (target) {
pathBuf = target;
path = pathBuf;
std::free(target);
}
}
if (path.startswith("/dev/video")) {
path = wpi::sys::path::filename(path);
if (!path.startswith("video")) return -1;
int dev = -1;
if (path.substr(5).getAsInteger(10, dev)) return -1;
return dev;
}
static std::string GetDescriptionImpl(const char* cpath) {
std::string rv;
int dev = GetDeviceNum(cpath);
if (dev >= 0) {
// Sometimes the /sys tree gives a better name.
if (GetDescriptionSysV4L(path, &rv)) return rv;
if (GetDescriptionSysV4L(dev, &rv)) return rv;
}
// Otherwise use an ioctl to query the caps and get the card name
@@ -1318,24 +1356,15 @@ UsbCameraInfo GetUsbCameraInfo(CS_Source source, CS_Status* status) {
std::string keypath = static_cast<UsbCameraImpl&>(*data->source).GetPath();
info.path = keypath;
// it might be a symlink; if so, find the symlink target (e.g. /dev/videoN),
// add that to the list and make it the keypath
if (wpi::sys::fs::is_symlink_file(keypath)) {
char* target = ::realpath(keypath.c_str(), nullptr);
if (target) {
keypath.assign(target);
info.otherPaths.emplace_back(keypath);
std::free(target);
}
}
// device number
wpi::StringRef fname = wpi::sys::path::filename(keypath);
if (fname.startswith("video")) fname.substr(5).getAsInteger(10, info.dev);
info.dev = GetDeviceNum(keypath.c_str());
// description
info.name = GetDescriptionImpl(keypath.c_str());
// vendor/product id
GetVendorProduct(info.dev, &info.vendorId, &info.productId);
// look through /dev/v4l/by-id and /dev/v4l/by-path for symlinks to the
// keypath
wpi::SmallString<128> path;
@@ -1386,6 +1415,8 @@ std::vector<UsbCameraInfo> EnumerateUsbCameras(CS_Status* status) {
info.name = GetDescriptionImpl(path.c_str());
if (info.name.empty()) continue;
GetVendorProduct(dev, &info.vendorId, &info.productId);
if (dev >= retval.size()) retval.resize(info.dev + 1);
retval[info.dev] = std::move(info);
}