primeiro commit - detecta eventos de conexión

.gitignore

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+# build results
+target
+

Makefile

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+CC ?= cc
+INSTALL_PATH ?= /usr
+
+all: build
+
+build: target/mpfm target/mpfm.service
+
+target/mpfm: mpfm.c
+	mkdir -p target
+	$(CC) -std=gnu99 -O2 mpfm.c -I/usr/include/libusb-1.0 -lusb-1.0 -o target/mpfm
+
+target/mpfm.service: mpfm.service
+	mkdir -p target
+	sed -E 's|__INSTALL_PATH__|$(INSTALL_PATH)|g' mpfm.service > target/mpfm.service
+
+install: build mpfm.rules
+	mkdir -p $(INSTALL_PATH)/{bin,lib/systemd/system}
+	install target/mpfm $(INSTALL_PATH)/bin/mpfm
+	install target/mpfm.service $(INSTALL_PATH)/lib/systemd/system/mpfm.service
+
+uninstall:
+	rm -f $(INSTALL_PATH)/lib/systemd/system/mpfm.service
+	rm -f $(INSTALL_PATH)/bin/mpfm
+
+clean:
+	rm -rf target
+
+.PHONY: all build clean install uninstall

README.md

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+# Music Player FM
+
+A idea é non cambiar o aparello de radio do coche e poder escoitar música desde
+unha unidade USB. Para esto vou usar unha raspberry para emitir a música que
+leva o pendrive a través de radio FM.
+
+Este proxecto estará «vixilando» a existencia de un pendrive conectado á raspberry
+e en canto sexa posible, montarao e reproducirá os arquivos de música. Levándoos
+ás ondas de radio gracias a [este outro proxecto](https://github.com/markondej/fm_transmitter).

mpfm.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <libusb.h>
+
+static int count = 0;
+
+int hotplug_callback(struct libusb_context *ctx, struct libusb_device *dev,
+        libusb_hotplug_event event, void *user_data) {
+    static libusb_device_handle *dev_handle = NULL;
+    struct libusb_device_descriptor desc;
+    int rc;
+    printf("Entering callback\n"); // DEBUG
+    (void)libusb_get_device_descriptor(dev, &desc);
+
+    if (LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED == event) {
+        rc = libusb_open(dev, &dev_handle);
+        if (LIBUSB_SUCCESS != rc) {
+            printf("Could not open USB device\n");
+        }
+    } else if (LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT == event) {
+        if (dev_handle) {
+            libusb_close(dev_handle);
+            dev_handle = NULL;
+        }
+    } else {
+        printf("Unhandled event %d\n", event);
+    }
+    count++;
+
+    return 0;
+}
+
+int main (void) {
+    libusb_hotplug_callback_handle callback_handle;
+    int rc;
+
+    libusb_init(NULL);
+
+    rc = libusb_hotplug_register_callback(
+            NULL,
+            LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED | LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT,
+            0,
+            LIBUSB_HOTPLUG_MATCH_ANY,
+            LIBUSB_HOTPLUG_MATCH_ANY,
+            LIBUSB_HOTPLUG_MATCH_ANY,
+            hotplug_callback,
+            NULL,
+            &callback_handle);
+    if (LIBUSB_SUCCESS != rc) {
+        printf("Error creating a hotplug callback\n");
+        libusb_exit(NULL);
+        return EXIT_FAILURE;
+    }
+
+    while (count < 2) {
+        libusb_handle_events_completed(NULL, NULL);
+        nanosleep(&(struct timespec){0, 10000000UL}, NULL);
+    }
+
+    libusb_hotplug_deregister_callback(NULL, callback_handle);
+    libusb_exit(NULL);
+
+    return 0;
+}

mpfm.service

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+[Unit]
+Description=Music Player FM
+
+[Service]
+ExecStart=__INSTALL_PATH__/bin/mpfm
+