linux: freebsd: do check on proper pointer

[libserialport/gsi.git] / freebsd.c

/*
 * This file is part of the libserialport project.
 *
 * Copyright (C) 2015 Uffe Jakobsen <uffe@uffe.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * FreeBSD platform specific serial port information:
 *
 * FreeBSD has two device nodes for each serial port:
 *
 *  1) a call-in port
 *  2) a call-out port
 *
 * Quoting FreeBSD Handbook section 26.2.1
 * (https://www.freebsd.org/doc/handbook/serial.html)
 *
 * In FreeBSD, each serial port is accessed through an entry in /dev.
 * There are two different kinds of entries:
 *
 * 1) Call-in ports are named /dev/ttyuN where N is the port number,
 *    starting from zero. If a terminal is connected to the first serial port
 *    (COM1), use /dev/ttyu0 to refer to the terminal. If the terminal is on
 *    the second serial port (COM2), use /dev/ttyu1, and so forth.
 *    Generally, the call-in port is used for terminals. Call-in ports require
 *    that the serial line assert the "Data Carrier Detect" signal to work
 *    correctly.
 *
 * 2) Call-out ports are named /dev/cuauN on FreeBSD versions 10.x and higher
 *    and /dev/cuadN on FreeBSD versions 9.x and lower. Call-out ports are
 *    usually not used for terminals, but are used for modems. The call-out
 *    port can be used if the serial cable or the terminal does not support
 *    the "Data Carrier Detect" signal.
 *
 * FreeBSD also provides initialization devices (/dev/ttyuN.init and
 * /dev/cuauN.init or /dev/cuadN.init) and locking devices (/dev/ttyuN.lock
 * and /dev/cuauN.lock or /dev/cuadN.lock). The initialization devices are
 * used to initialize communications port parameters each time a port is
 * opened, such as crtscts for modems which use RTS/CTS signaling for flow
 * control. The locking devices are used to lock flags on ports to prevent
 * users or programs changing certain parameters.
 *
 * In line with the above device naming USB-serial devices have
 * the following naming:
 *
 * 1) call-in ports: /dev/ttyUN where N is the port number
 * 2) call-out ports: /dev/cuaUN where N is the port number
 *
 * See also: ucom(4), https://www.freebsd.org/cgi/man.cgi?query=ucom
 *
 * Getting USB serial port device description:
 *
 * In order to query USB serial ports for device description - the mapping
 * between the kernel device driver instances must be correlated with the
 * above mentioned device nodes.
 *
 * 1) For each USB-serial port (/dev/cuaUN) use libusb to lookup the device
 *    description and the name of the kernel device driver instance.
 * 2) Query sysctl for the kernel device driver instance info.
 * 3) Derive the ttyname and (serial) port count for the kernel device
 *    driver instance.
 * 4) If sysctl ttyname and port matches /dev/cuaUN apply the libusb
 *    device description.
 */

#include <config.h>
#include <unistd.h>
#include <stdint.h>
#include <stdlib.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/sysctl.h>
#include <dirent.h>
#include <libusb20.h>
#include <libusb20_desc.h>
#include "libserialport.h"
#include "libserialport_internal.h"

#define DEV_CUA_PATH "/dev/cua"

//#define DBG(...) printf(__VA_ARGS__)
#define DBG(...)

static char *strrspn(const char *s, const char *charset)
{
        char *t = (char *)s + strlen(s);
        while (t != (char *)s)
                if (!strchr(charset, *(--t)))
                        return ++t;
        return t;
}

static int strend(const char *str, const char *pattern)
{
        size_t slen = strlen(str);
        size_t plen = strlen(pattern);
        if (slen >= plen)
                return (!memcmp(pattern, (str + slen - plen), plen));
        return 0;
}

static int libusb_query_port(struct libusb20_device *dev, int idx,
                             char **drv_name_str, char **drv_inst_str)
{
        int rc;
        char *j;
        char sbuf[FILENAME_MAX];

        if (!drv_name_str || !drv_inst_str)
                return -1;

        rc = libusb20_dev_kernel_driver_active(dev, idx);
        if (rc < 0)
                return rc;

        sbuf[0] = 0;
        libusb20_dev_get_iface_desc(dev, idx, (char *)&sbuf,
                                    (uint8_t)sizeof(sbuf) - 1);
        if (sbuf[0] == 0)
                return rc;

        DBG("Device interface descriptor: idx=%003d '%s'\n", idx, sbuf);
        j = strchr(sbuf, ':');
        if (j > sbuf) {
                sbuf[j - sbuf] = 0;
                /*
                 * The device driver name may contain digits that
                 * is not a part of the device instance number - like "u3g".
                 */
                j = strrspn(sbuf, "0123456789");
                if (j > sbuf) {
                        *drv_name_str = strndup(sbuf, j - sbuf);
                        *drv_inst_str = strdup((j));
                }
        }

        return rc;
}

static int sysctl_query_dev_drv(const char *drv_name_str,
        const char *drv_inst_str, char **ttyname, int *const ttyport_cnt)
{
        int rc;
        char sbuf[FILENAME_MAX];
        char tbuf[FILENAME_MAX];
        size_t tbuf_len;

        if (!ttyname || !ttyport_cnt)
                return -1;

        snprintf(sbuf, sizeof(sbuf), "dev.%s.%s.ttyname", drv_name_str,
                 drv_inst_str);
        tbuf_len = sizeof(tbuf) - 1;
        if ((rc = sysctlbyname(sbuf, tbuf, &tbuf_len, NULL, 0)) != 0)
                return rc;

        tbuf[tbuf_len] = 0;
        *ttyname = strndup(tbuf, tbuf_len);
        DBG("sysctl: '%s' (%d) (%d): '%.*s'\n", sbuf, rc, (int)tbuf_len,
            (int)tbuf_len, tbuf);

        snprintf(sbuf, sizeof(sbuf), "dev.%s.%s.ttyports",
                 drv_name_str, drv_inst_str);
        tbuf_len = sizeof(tbuf) - 1;
        rc = sysctlbyname(sbuf, tbuf, &tbuf_len, NULL, 0);
        if (rc == 0) {
                *ttyport_cnt = *(uint32_t *)tbuf;
                DBG("sysctl: '%s' (%d) (%d): '%d'\n", sbuf, rc,
                    (int)tbuf_len, (int)ttyport_cnt);
        } else {
                *ttyport_cnt = 0;
        }

        return rc;
}

static int populate_port_struct_from_libusb_desc(struct sp_port *const port,
                                                 struct libusb20_device *dev)
{
        char tbuf[FILENAME_MAX];

        /* Populate port structure from libusb description. */
        struct LIBUSB20_DEVICE_DESC_DECODED *dev_desc =
                libusb20_dev_get_device_desc(dev);

        if (!dev_desc)
                return -1;

        port->transport = SP_TRANSPORT_USB;
        port->usb_vid = dev_desc->idVendor;
        port->usb_pid = dev_desc->idProduct;
        port->usb_bus = libusb20_dev_get_bus_number(dev);
        port->usb_address = libusb20_dev_get_address(dev);
        if (libusb20_dev_req_string_simple_sync
            (dev, dev_desc->iManufacturer, tbuf, sizeof(tbuf)) == 0) {
                port->usb_manufacturer = strdup(tbuf);
        }
        if (libusb20_dev_req_string_simple_sync
            (dev, dev_desc->iProduct, tbuf, sizeof(tbuf)) == 0) {
                port->usb_product = strdup(tbuf);
        }
        if (libusb20_dev_req_string_simple_sync
            (dev, dev_desc->iSerialNumber, tbuf, sizeof(tbuf)) == 0) {
                port->usb_serial = strdup(tbuf);
        }
        /* If present, add serial to description for better identification. */
        tbuf[0] = '\0';
        if (port->usb_product && port->usb_product[0])
                strncat(tbuf, port->usb_product, sizeof(tbuf) - 1);
        else
                strncat(tbuf, libusb20_dev_get_desc(dev), sizeof(tbuf) - 1);
        if (port->usb_serial && port->usb_serial[0]) {
                strncat(tbuf, " ", sizeof(tbuf) - 1);
                strncat(tbuf, port->usb_serial, sizeof(tbuf) - 1);
        }
        port->description = strdup(tbuf);
        port->bluetooth_address = NULL;

        return 0;
}

SP_PRIV enum sp_return get_port_details(struct sp_port *port)
{
        int rc;
        struct libusb20_backend *be;
        struct libusb20_device *dev, *dev_last;
        char tbuf[FILENAME_MAX];
        char *cua_sfx;
        int cua_dev_found;
        uint8_t idx;
        int sub_inst;

        DBG("Portname: '%s'\n", port->name);

        if (!strncmp(port->name, DEV_CUA_PATH, strlen(DEV_CUA_PATH))) {
                cua_sfx = port->name + strlen(DEV_CUA_PATH);
                DBG("'%s': '%s'\n", DEV_CUA_PATH, cua_sfx);
        } else {
                RETURN_ERROR(SP_ERR_ARG, "Device name not recognized");
        }

        /* Native UART enumeration. */
        if ((cua_sfx[0] == 'u') || (cua_sfx[0] == 'd')) {
                port->transport = SP_TRANSPORT_NATIVE;
                snprintf(tbuf, sizeof(tbuf), "cua%s", cua_sfx);
                port->description = strdup(tbuf);
                RETURN_OK();
        }

        /* USB device enumeration. */
        dev = dev_last = NULL;
        be = libusb20_be_alloc_default();
        cua_dev_found = 0;
        while (cua_dev_found == 0) {
                dev = libusb20_be_device_foreach(be, dev_last);
                if (!dev)
                        break;

                libusb20_dev_open(dev, 0);
                DBG("Device descriptor: '%s'\n", libusb20_dev_get_desc(dev));

                for (idx = 0; idx <= UINT8_MAX - 1; idx++) {
                        char *drv_name_str = NULL;
                        char *drv_inst_str = NULL;
                        char *ttyname = NULL;
                        int ttyport_cnt;

                        rc = libusb_query_port(dev, idx, &drv_name_str, &drv_inst_str);
                        if (rc == 0) {
                                rc = sysctl_query_dev_drv(drv_name_str,
                                          drv_inst_str, &ttyname, &ttyport_cnt);
                                if (rc == 0) {
                                        /* Handle multiple subinstances of serial ports in the same driver instance. */
                                        for (sub_inst = 0; sub_inst < ttyport_cnt; sub_inst++) {
                                                if (ttyport_cnt == 1)
                                                        snprintf(tbuf, sizeof(tbuf), "%s", ttyname);
                                                else
                                                        snprintf(tbuf, sizeof(tbuf), "%s.%d", ttyname, sub_inst);
                                                if (!strcmp(cua_sfx, tbuf)) {
                                                        DBG("MATCH: '%s' == '%s'\n", cua_sfx, tbuf);
                                                        cua_dev_found = 1;
                                                        populate_port_struct_from_libusb_desc(port, dev);
                                                        break; /* Break out of sub instance loop. */
                                                }
                                        }
                                }
                        }

                        /* Clean up. */
                        if (ttyname)
                                free(ttyname);
                        if (drv_name_str)
                                free(drv_name_str);
                        if (drv_inst_str)
                                free(drv_inst_str);
                        if (cua_dev_found)
                                break; /* Break out of USB device port idx loop. */
                }
                libusb20_dev_close(dev);
                dev_last = dev;
        }
        libusb20_be_free(be);

        if (cua_dev_found == 0)
                DBG("WARN: Found no match '%s' %s'\n", port->name, cua_sfx);

        RETURN_OK();
}

SP_PRIV enum sp_return list_ports(struct sp_port ***list)
{
        DIR *dir;
        struct dirent entry;
        struct dirent *result;
        struct termios tios;
        char name[PATH_MAX];
        int fd, ret;

        DEBUG("Enumerating tty devices");
        if (!(dir = opendir("/dev")))
                RETURN_FAIL("Could not open dir /dev");

        DEBUG("Iterating over results");
        while (!readdir_r(dir, &entry, &result) && result) {
                ret = SP_OK;
                if (entry.d_type != DT_CHR)
                        continue;
                if (strncmp(entry.d_name, "cuaU", 4) != 0)
                        if (strncmp(entry.d_name, "cuau", 4) != 0)
                                if (strncmp(entry.d_name, "cuad", 4) != 0)
                                        continue;
                if (strend(entry.d_name, ".init"))
                        continue;
                if (strend(entry.d_name, ".lock"))
                        continue;

                snprintf(name, sizeof(name), "/dev/%s", entry.d_name);
                DEBUG_FMT("Found device %s", name);

                /* Check that we can open tty/cua device in rw mode - we need that. */
                if ((fd = open(name, O_RDWR | O_NONBLOCK | O_NOCTTY | O_TTY_INIT | O_CLOEXEC)) < 0) {
                        DEBUG("Open failed, skipping");
                        continue;
                }

                /* Sanity check if we got a real tty. */
                if (!isatty(fd)) {
                        close(fd);
                        continue;
                }

                ret = tcgetattr(fd, &tios);
                close(fd);
                if (ret < 0 || cfgetospeed(&tios) <= 0 || cfgetispeed(&tios) <= 0)
                        continue;

                DEBUG_FMT("Found port %s", name);
                DBG("%s: %s\n", __func__, entry.d_name);

                *list = list_append(*list, name);
                if (!*list) {
                        SET_ERROR(ret, SP_ERR_MEM, "List append failed");
                        break;
                }
        }
        closedir(dir);

        return ret;
}