453 lines
11 KiB
Plaintext
453 lines
11 KiB
Plaintext
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Linux USB HID gadget driver
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Introduction
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The HID Gadget driver provides emulation of USB Human Interface
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Devices (HID). The basic HID handling is done in the kernel,
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and HID reports can be sent/received through I/O on the
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/dev/hidgX character devices.
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For more details about HID, see the developer page on
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http://www.usb.org/developers/hidpage/
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Configuration
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g_hid is a platform driver, so to use it you need to add
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struct platform_device(s) to your platform code defining the
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HID function descriptors you want to use - E.G. something
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like:
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#include <linux/platform_device.h>
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#include <linux/usb/g_hid.h>
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/* hid descriptor for a keyboard */
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static struct hidg_func_descriptor my_hid_data = {
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.subclass = 0, /* No subclass */
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.protocol = 1, /* Keyboard */
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.report_length = 8,
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.report_desc_length = 63,
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.report_desc = {
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0x05, 0x01, /* USAGE_PAGE (Generic Desktop) */
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0x09, 0x06, /* USAGE (Keyboard) */
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0xa1, 0x01, /* COLLECTION (Application) */
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0x05, 0x07, /* USAGE_PAGE (Keyboard) */
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0x19, 0xe0, /* USAGE_MINIMUM (Keyboard LeftControl) */
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0x29, 0xe7, /* USAGE_MAXIMUM (Keyboard Right GUI) */
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0x15, 0x00, /* LOGICAL_MINIMUM (0) */
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0x25, 0x01, /* LOGICAL_MAXIMUM (1) */
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0x75, 0x01, /* REPORT_SIZE (1) */
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0x95, 0x08, /* REPORT_COUNT (8) */
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0x81, 0x02, /* INPUT (Data,Var,Abs) */
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0x95, 0x01, /* REPORT_COUNT (1) */
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0x75, 0x08, /* REPORT_SIZE (8) */
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0x81, 0x03, /* INPUT (Cnst,Var,Abs) */
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0x95, 0x05, /* REPORT_COUNT (5) */
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0x75, 0x01, /* REPORT_SIZE (1) */
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0x05, 0x08, /* USAGE_PAGE (LEDs) */
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0x19, 0x01, /* USAGE_MINIMUM (Num Lock) */
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0x29, 0x05, /* USAGE_MAXIMUM (Kana) */
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0x91, 0x02, /* OUTPUT (Data,Var,Abs) */
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0x95, 0x01, /* REPORT_COUNT (1) */
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0x75, 0x03, /* REPORT_SIZE (3) */
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0x91, 0x03, /* OUTPUT (Cnst,Var,Abs) */
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0x95, 0x06, /* REPORT_COUNT (6) */
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0x75, 0x08, /* REPORT_SIZE (8) */
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0x15, 0x00, /* LOGICAL_MINIMUM (0) */
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0x25, 0x65, /* LOGICAL_MAXIMUM (101) */
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0x05, 0x07, /* USAGE_PAGE (Keyboard) */
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0x19, 0x00, /* USAGE_MINIMUM (Reserved) */
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0x29, 0x65, /* USAGE_MAXIMUM (Keyboard Application) */
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0x81, 0x00, /* INPUT (Data,Ary,Abs) */
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0xc0 /* END_COLLECTION */
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}
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};
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static struct platform_device my_hid = {
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.name = "hidg",
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.id = 0,
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.num_resources = 0,
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.resource = 0,
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.dev.platform_data = &my_hid_data,
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};
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You can add as many HID functions as you want, only limited by
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the amount of interrupt endpoints your gadget driver supports.
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Configuration with configfs
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Instead of adding fake platform devices and drivers in order to pass
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some data to the kernel, if HID is a part of a gadget composed with
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configfs the hidg_func_descriptor.report_desc is passed to the kernel
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by writing the appropriate stream of bytes to a configfs attribute.
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Send and receive HID reports
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HID reports can be sent/received using read/write on the
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/dev/hidgX character devices. See below for an example program
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to do this.
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hid_gadget_test is a small interactive program to test the HID
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gadget driver. To use, point it at a hidg device and set the
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device type (keyboard / mouse / joystick) - E.G.:
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# hid_gadget_test /dev/hidg0 keyboard
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You are now in the prompt of hid_gadget_test. You can type any
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combination of options and values. Available options and
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values are listed at program start. In keyboard mode you can
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send up to six values.
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For example type: g i s t r --left-shift
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Hit return and the corresponding report will be sent by the
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HID gadget.
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Another interesting example is the caps lock test. Type
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--caps-lock and hit return. A report is then sent by the
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gadget and you should receive the host answer, corresponding
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to the caps lock LED status.
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--caps-lock
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recv report:2
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With this command:
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# hid_gadget_test /dev/hidg1 mouse
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You can test the mouse emulation. Values are two signed numbers.
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Sample code
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/* hid_gadget_test */
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#include <pthread.h>
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#include <string.h>
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#include <stdio.h>
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#include <ctype.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#define BUF_LEN 512
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struct options {
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const char *opt;
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unsigned char val;
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};
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static struct options kmod[] = {
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{.opt = "--left-ctrl", .val = 0x01},
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{.opt = "--right-ctrl", .val = 0x10},
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{.opt = "--left-shift", .val = 0x02},
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{.opt = "--right-shift", .val = 0x20},
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{.opt = "--left-alt", .val = 0x04},
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{.opt = "--right-alt", .val = 0x40},
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{.opt = "--left-meta", .val = 0x08},
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{.opt = "--right-meta", .val = 0x80},
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{.opt = NULL}
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};
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static struct options kval[] = {
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{.opt = "--return", .val = 0x28},
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{.opt = "--esc", .val = 0x29},
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{.opt = "--bckspc", .val = 0x2a},
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{.opt = "--tab", .val = 0x2b},
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{.opt = "--spacebar", .val = 0x2c},
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{.opt = "--caps-lock", .val = 0x39},
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{.opt = "--f1", .val = 0x3a},
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{.opt = "--f2", .val = 0x3b},
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{.opt = "--f3", .val = 0x3c},
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{.opt = "--f4", .val = 0x3d},
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{.opt = "--f5", .val = 0x3e},
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{.opt = "--f6", .val = 0x3f},
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{.opt = "--f7", .val = 0x40},
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{.opt = "--f8", .val = 0x41},
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{.opt = "--f9", .val = 0x42},
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{.opt = "--f10", .val = 0x43},
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{.opt = "--f11", .val = 0x44},
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{.opt = "--f12", .val = 0x45},
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{.opt = "--insert", .val = 0x49},
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{.opt = "--home", .val = 0x4a},
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{.opt = "--pageup", .val = 0x4b},
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{.opt = "--del", .val = 0x4c},
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{.opt = "--end", .val = 0x4d},
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{.opt = "--pagedown", .val = 0x4e},
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{.opt = "--right", .val = 0x4f},
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{.opt = "--left", .val = 0x50},
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{.opt = "--down", .val = 0x51},
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{.opt = "--kp-enter", .val = 0x58},
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{.opt = "--up", .val = 0x52},
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{.opt = "--num-lock", .val = 0x53},
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{.opt = NULL}
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};
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int keyboard_fill_report(char report[8], char buf[BUF_LEN], int *hold)
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{
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char *tok = strtok(buf, " ");
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int key = 0;
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int i = 0;
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for (; tok != NULL; tok = strtok(NULL, " ")) {
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if (strcmp(tok, "--quit") == 0)
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return -1;
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if (strcmp(tok, "--hold") == 0) {
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*hold = 1;
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continue;
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}
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if (key < 6) {
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for (i = 0; kval[i].opt != NULL; i++)
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if (strcmp(tok, kval[i].opt) == 0) {
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report[2 + key++] = kval[i].val;
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break;
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}
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if (kval[i].opt != NULL)
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continue;
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}
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if (key < 6)
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if (islower(tok[0])) {
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report[2 + key++] = (tok[0] - ('a' - 0x04));
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continue;
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}
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for (i = 0; kmod[i].opt != NULL; i++)
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if (strcmp(tok, kmod[i].opt) == 0) {
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report[0] = report[0] | kmod[i].val;
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break;
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}
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if (kmod[i].opt != NULL)
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continue;
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if (key < 6)
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fprintf(stderr, "unknown option: %s\n", tok);
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}
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return 8;
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}
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static struct options mmod[] = {
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{.opt = "--b1", .val = 0x01},
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{.opt = "--b2", .val = 0x02},
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{.opt = "--b3", .val = 0x04},
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{.opt = NULL}
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};
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int mouse_fill_report(char report[8], char buf[BUF_LEN], int *hold)
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{
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char *tok = strtok(buf, " ");
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int mvt = 0;
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int i = 0;
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for (; tok != NULL; tok = strtok(NULL, " ")) {
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if (strcmp(tok, "--quit") == 0)
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return -1;
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if (strcmp(tok, "--hold") == 0) {
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*hold = 1;
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continue;
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}
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for (i = 0; mmod[i].opt != NULL; i++)
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if (strcmp(tok, mmod[i].opt) == 0) {
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report[0] = report[0] | mmod[i].val;
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break;
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}
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if (mmod[i].opt != NULL)
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continue;
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if (!(tok[0] == '-' && tok[1] == '-') && mvt < 2) {
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errno = 0;
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report[1 + mvt++] = (char)strtol(tok, NULL, 0);
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if (errno != 0) {
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fprintf(stderr, "Bad value:'%s'\n", tok);
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report[1 + mvt--] = 0;
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}
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continue;
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}
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fprintf(stderr, "unknown option: %s\n", tok);
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}
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return 3;
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}
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static struct options jmod[] = {
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{.opt = "--b1", .val = 0x10},
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{.opt = "--b2", .val = 0x20},
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{.opt = "--b3", .val = 0x40},
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{.opt = "--b4", .val = 0x80},
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{.opt = "--hat1", .val = 0x00},
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{.opt = "--hat2", .val = 0x01},
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{.opt = "--hat3", .val = 0x02},
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{.opt = "--hat4", .val = 0x03},
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{.opt = "--hatneutral", .val = 0x04},
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{.opt = NULL}
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};
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int joystick_fill_report(char report[8], char buf[BUF_LEN], int *hold)
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{
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char *tok = strtok(buf, " ");
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int mvt = 0;
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int i = 0;
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*hold = 1;
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/* set default hat position: neutral */
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report[3] = 0x04;
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for (; tok != NULL; tok = strtok(NULL, " ")) {
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if (strcmp(tok, "--quit") == 0)
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return -1;
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for (i = 0; jmod[i].opt != NULL; i++)
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if (strcmp(tok, jmod[i].opt) == 0) {
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report[3] = (report[3] & 0xF0) | jmod[i].val;
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break;
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}
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if (jmod[i].opt != NULL)
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continue;
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if (!(tok[0] == '-' && tok[1] == '-') && mvt < 3) {
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errno = 0;
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report[mvt++] = (char)strtol(tok, NULL, 0);
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if (errno != 0) {
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fprintf(stderr, "Bad value:'%s'\n", tok);
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report[mvt--] = 0;
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}
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continue;
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}
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fprintf(stderr, "unknown option: %s\n", tok);
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}
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return 4;
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}
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void print_options(char c)
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{
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int i = 0;
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if (c == 'k') {
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printf(" keyboard options:\n"
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" --hold\n");
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for (i = 0; kmod[i].opt != NULL; i++)
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printf("\t\t%s\n", kmod[i].opt);
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printf("\n keyboard values:\n"
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" [a-z] or\n");
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for (i = 0; kval[i].opt != NULL; i++)
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printf("\t\t%-8s%s", kval[i].opt, i % 2 ? "\n" : "");
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printf("\n");
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} else if (c == 'm') {
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printf(" mouse options:\n"
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" --hold\n");
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for (i = 0; mmod[i].opt != NULL; i++)
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printf("\t\t%s\n", mmod[i].opt);
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printf("\n mouse values:\n"
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" Two signed numbers\n"
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"--quit to close\n");
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} else {
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printf(" joystick options:\n");
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for (i = 0; jmod[i].opt != NULL; i++)
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printf("\t\t%s\n", jmod[i].opt);
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printf("\n joystick values:\n"
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" three signed numbers\n"
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"--quit to close\n");
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}
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}
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int main(int argc, const char *argv[])
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{
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const char *filename = NULL;
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int fd = 0;
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char buf[BUF_LEN];
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int cmd_len;
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char report[8];
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int to_send = 8;
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int hold = 0;
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fd_set rfds;
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int retval, i;
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if (argc < 3) {
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fprintf(stderr, "Usage: %s devname mouse|keyboard|joystick\n",
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argv[0]);
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return 1;
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}
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if (argv[2][0] != 'k' && argv[2][0] != 'm' && argv[2][0] != 'j')
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return 2;
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filename = argv[1];
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if ((fd = open(filename, O_RDWR, 0666)) == -1) {
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perror(filename);
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return 3;
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}
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print_options(argv[2][0]);
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while (42) {
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FD_ZERO(&rfds);
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FD_SET(STDIN_FILENO, &rfds);
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FD_SET(fd, &rfds);
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retval = select(fd + 1, &rfds, NULL, NULL, NULL);
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if (retval == -1 && errno == EINTR)
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continue;
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if (retval < 0) {
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perror("select()");
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return 4;
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}
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if (FD_ISSET(fd, &rfds)) {
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cmd_len = read(fd, buf, BUF_LEN - 1);
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printf("recv report:");
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for (i = 0; i < cmd_len; i++)
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printf(" %02x", buf[i]);
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printf("\n");
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}
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if (FD_ISSET(STDIN_FILENO, &rfds)) {
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memset(report, 0x0, sizeof(report));
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cmd_len = read(STDIN_FILENO, buf, BUF_LEN - 1);
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if (cmd_len == 0)
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break;
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buf[cmd_len - 1] = '\0';
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hold = 0;
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memset(report, 0x0, sizeof(report));
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if (argv[2][0] == 'k')
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to_send = keyboard_fill_report(report, buf, &hold);
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else if (argv[2][0] == 'm')
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to_send = mouse_fill_report(report, buf, &hold);
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else
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to_send = joystick_fill_report(report, buf, &hold);
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if (to_send == -1)
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break;
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if (write(fd, report, to_send) != to_send) {
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perror(filename);
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return 5;
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}
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if (!hold) {
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memset(report, 0x0, sizeof(report));
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if (write(fd, report, to_send) != to_send) {
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perror(filename);
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return 6;
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}
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}
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}
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}
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close(fd);
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return 0;
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}
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