126 lines
4.7 KiB
C++
126 lines
4.7 KiB
C++
#include "find_usb_serial_port.h"
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#include <unistd.h>
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#include <dirent.h>
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/*---------------------------------------------------------------------*\
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| find_usb_serial_port |
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| This function returns the name of the first USB serial port matching|
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| the given USB product and vendor ID. |
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| vid: Vendor ID code |
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| pid: Product ID code |
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| returns: std::string containing port name "COMx" or "/dev/ttyX" |
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\*---------------------------------------------------------------------*/
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std::string find_usb_serial_port(unsigned short vid, unsigned short pid)
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{
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std::string ret_string = "";
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DIR* dir;
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char symlink_path[1024] = {0};
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struct dirent* ent;
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char vid_pid[10] = {0}; //Store VID/PID
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/*-----------------------------------------------------------------*\
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| Open /sys/class/tty |
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\*-----------------------------------------------------------------*/
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dir = opendir("/sys/class/tty");
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if(dir == NULL)
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{
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return ret_string;
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}
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/*-----------------------------------------------------------------*\
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| Loop through all symlinks in /sys/class/tty directory to find |
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| paths with "usb" in them. These links should have the USB device |
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| index which can be used to find the VID/PID |
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\*-----------------------------------------------------------------*/
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ent = readdir(dir);
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while(ent != NULL)
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{
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if(ent->d_type == DT_LNK)
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{
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char tty_path[1024];
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strcpy(tty_path, "/sys/class/tty/");
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strcat(tty_path, ent->d_name);
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/*-----------------------------------------------------------------*\
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| readlink() does not null-terminate, so manually terminate it |
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\*-----------------------------------------------------------------*/
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ssize_t link_path_size = readlink(tty_path, symlink_path, 1024);
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symlink_path[link_path_size] = '\0';
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char * usb_string = strstr(symlink_path, "usb");
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if(usb_string != NULL)
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{
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char * usb_dev = strstr(usb_string, "/");
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usb_dev++;
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char * usb_end = strstr(usb_dev, "/tty");
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*usb_end = '\0';
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usb_end = strrchr(usb_dev, '/');
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*usb_end = '\0';
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char usb_path[1024];
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strcpy(usb_path, "/sys/bus/usb/devices/");
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strcat(usb_path, usb_dev);
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char vendor_path[1024];
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char product_path[1024];
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strcpy(vendor_path, usb_path);
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strcat(vendor_path, "/idVendor");
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strcpy(product_path, usb_path);
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strcat(product_path, "/idProduct");
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std::ifstream vendor_file;
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std::ifstream product_file;
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std::string vendor_string;
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std::string product_string;
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vendor_file.open(vendor_path);
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product_file.open(product_path);
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std::getline(vendor_file, vendor_string);
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std::getline(product_file, product_string);
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snprintf(vid_pid, 10, "%04x", vid);
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if(strcmp(vid_pid, vendor_string.c_str()) == 0)
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{
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snprintf(vid_pid, 10, "%04x", pid);
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if(strcmp(vid_pid, product_string.c_str()) == 0)
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{
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char* port_string = NULL;
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for(int i = strlen(tty_path); i > 0; i--)
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{
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if(tty_path[i] == '/')
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{
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port_string = &tty_path[i + 1];
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break;
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}
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}
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ret_string.append("/dev/");
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ret_string.append(port_string);
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return ret_string;
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}
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}
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}
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}
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ent = readdir(dir);
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}
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return ret_string;
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} /* find_usb_serial_port() */
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