Initial commit

.gitignore

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+build/

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.16)
+project(relaycontrol LANGUAGES C)
+
+set(CFLAGS "${CFLAGS} -Wall -Wextra -pedantic -Wformat-overflow=2 -Wformat-security -Winit-self -Wstrict-overflow=2 -Wstringop-overflow=2 -Walloc-zero -Wduplicated-branches -Wduplicated-cond -Wtrampolines -Wfloat-equal -Wshadow -Wunsafe-loop-optimizations -Wparentheses -fanalyzer -fstack-protector")
+if (NOT CMAKE_BUILD_TYPE)
+	set(CMAKE_BUILD_TYPE Debug)
+endif()
+if (CMAKE_BUILD_TYPE EQUAL "Debug")
+	set(CFLAGS "${CFLAGS} -Og")
+elseif (CMAKE_BUILD_TYPE EQUAL "Release")
+	set(CFLAGS "${CFLAGS} -O2 -Werror")
+endif()
+
+add_executable(relaycntl
+	src/main.c
+)
+set_property(TARGET relaycntl PROPERTY C_STANDARD 99)
+
+install(TARGETS relaycntl RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})

LICENSE

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+        DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE 
+                    Version 2, December 2004 
+
+ Copyright (C) 2004 Sam Hocevar <sam@hocevar.net> 
+
+ Everyone is permitted to copy and distribute verbatim or modified 
+ copies of this license document, and changing it is allowed as long 
+ as the name is changed. 
+
+            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE 
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 
+
+  0. You just DO WHAT THE FUCK YOU WANT TO.

README.md

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+# Raspberry PI General Purpose Input/Output Controller
+
+This is a simple GPIO pin controller for UNIX-like kernels/systems.
+
+## Requirements
+
+- CMake
+- ANSI C compiler
+- UNIX standard library
+
+## Building
+
+First, generate the build files with CMake:
+```
+cmake -H. -Bbuild -DCMAKE_BUILD_TYPE=Release
+```
+
+Second, install the binary:
+```
+cd build/
+sudo make install
+```
+
+## License
+WTFPL

src/main.c

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+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#define GPIO_IFACE_MISSING = -1
+#define GPIO_PIN_EXP_FAIL = -2
+#define GPIO_DIR_CONT_FAIL = -3
+#define GPIO_SWITCH_FAIL = -4
+#define GPIO_PIN_UNX_NF = -5
+#define GPIO_PIN_UNX_FAIL = -6
+
+#define GPIO_PREFIX "/sys/class/gpio/"
+#define GPIO_EXPORT "export"
+#define GPIO_UNEXPORT "unexport"
+
+#define MAX_PATHLEN 512
+
+#define PRINTERRANDRET(mesg, varfmt, var)                                                            \
+	{                                                                                            \
+		fprintf(stderr, "%s \"%" varfmt "\". %s (%i)\n", mesg, var, strerror(errno), errno); \
+		return 1;                                                                            \
+	}
+
+ssize_t exportPin(signed int pinno);
+ssize_t setPinDirection(signed int pinno, char* value);
+ssize_t setPinValue(signed int pinno, int value);
+
+int main(int argc, char* argv[])
+{
+	int pinno = (argc > 1) ? atoi(argv[1]) : 0;
+	bool value = (argc > 2) ? atoi(argv[2]) : 0;
+	if (pinno != exportPin(pinno))
+		return -1;
+	if (pinno != setPinDirection(pinno, "out"))
+		return -1;
+	if (pinno != setPinValue(pinno, value))
+		return -1;
+	return 0;
+}
+
+ssize_t exportPin(signed int pinno)
+{
+	if (chdir(GPIO_PREFIX) != 0)
+		PRINTERRANDRET("Failed to change directory to", "s", GPIO_PREFIX);
+	char buffer[MAX_PATHLEN];
+	int fd;
+	ssize_t nbytes;
+	if ((fd = open(GPIO_EXPORT, O_WRONLY)) < 0)
+		PRINTERRANDRET("Failed to open export", "s", GPIO_EXPORT);
+	if ((nbytes = snprintf(buffer, MAX_PATHLEN, "%i", pinno)) <= 0)
+		PRINTERRANDRET("Couldn't format pin number as string", "i", pinno);
+	if (write(fd, buffer, nbytes) != nbytes && errno != EBUSY)
+		PRINTERRANDRET("Couldn't write pin number to the exporter", "i", pinno);
+	if (close(fd) != 0)
+		PRINTERRANDRET("Couldn't close exporter", "i", pinno);
+	return pinno;
+}
+
+ssize_t setPinDirection(signed int pinno, char* value)
+{
+	if (chdir(GPIO_PREFIX) != 0)
+		PRINTERRANDRET("Failed to change directory to", "s", GPIO_PREFIX);
+	char buffer[MAX_PATHLEN];
+	int fd;
+	ssize_t nbytes;
+	if ((nbytes = snprintf(buffer, MAX_PATHLEN, "gpio%i/direction", pinno)) <= 0)
+		PRINTERRANDRET("Couldn't format pin path as string", "i", pinno);
+	if ((fd = open(buffer, O_WRONLY)) < 0)
+		PRINTERRANDRET("Failed to open pin path.", "s", GPIO_EXPORT);
+	if (write(fd, value, strlen(value)) != nbytes && errno != EBUSY)
+		PRINTERRANDRET("Couldn't write pin direction", "i", pinno);
+	if (close(fd) != 0)
+		PRINTERRANDRET("Couldn't close pin direction file", "i", pinno);
+	return pinno;
+}
+ssize_t setPinValue(signed int pinno, int value)
+{
+	if (chdir(GPIO_PREFIX) != 0)
+		PRINTERRANDRET("Failed to change directory to", "s", GPIO_PREFIX);
+	char buffer[MAX_PATHLEN];
+	int fd;
+	ssize_t nbytes;
+	if ((nbytes = snprintf(buffer, MAX_PATHLEN, "gpio%i/value", pinno)) <= 0)
+		PRINTERRANDRET("Couldn't format pin path as string", "i", pinno);
+	if ((fd = open(buffer, O_WRONLY)) < 0)
+		PRINTERRANDRET("Failed to open pin path.", "s", GPIO_EXPORT);
+	if ((nbytes = snprintf(buffer, MAX_PATHLEN, "%i", value)) <= 0)
+		PRINTERRANDRET("Couldn't format pin value as string", "i", value);
+	if (write(fd, buffer, nbytes) != nbytes && errno != EBUSY)
+		PRINTERRANDRET("Couldn't write pin value", "i", pinno);
+	if (close(fd) != 0)
+		PRINTERRANDRET("Couldn't close pin value file", "i", pinno);
+	return pinno;
+}

src/main.py

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+import time
+import sys
+import errno
+
+GPIO_IFACE_MISSING = -1
+GPIO_PIN_EXP_FAIL = -2
+GPIO_DIR_CONT_FAIL = -3
+GPIO_SWITCH_FAIL = -4
+GPIO_PIN_UNX_NF = -5
+GPIO_PIN_UNX_FAIL = -6
+
+PINLISTMISS = -1
+PINLISTTOKFAIL = -2
+
+def preparePin(pinno):
+    try: x = open('/sys/class/gpio/export', 'w')
+    except:
+        return GPIO_IFACE_MISSING
+    else:
+        try:
+            x.write(f'{pinno}')
+            x.close()
+        except OSError as e:
+            if (e.errno != errno.EBUSY): # Busy devices are already exported
+                return GPIO_PIN_EXP_FAIL
+            return
+        for i in range(0,5):
+            try: g = open(f'/sys/class/gpio/gpio{pinno}/direction', 'w')
+            except:
+                if (i == 4):
+                    return GPIO_DIR_CONT_FAIL
+                else: time.sleep(1)
+            else:
+                try: g.write('out')
+                except:
+                    g.close()
+                    return GPIO_SWITCH_FAIL
+                else:
+                    g.close()
+                    break
+
+def closePin(pinno):
+    try: x = open('/sys/class/gpio/unexport', 'w')
+    except: return GPIO_PIN_UNX_NF
+    else:
+        try: x.write(pinno)
+        except: return GPIO_PIN_UNX_FAIL
+    finally: x.close()
+
+try: preparePin(sys.argv[1])
+except GPIO_SWITCH_FAIL: print(f'GPIO Pin direction couldn\'t be switched to out. {sys.argv[1]}')
+except GPIO_DIR_CONT_FAIL: print(f'GPIO Pin control couldn\'t be opened. {sys.argv[1]}')
+except GPIO_PIN_EXP_FAIL:  print(f'GPIO Pin couldn\'t be exported. P: {sys.argv[1]}')
+except GPIO_IFACE_MISSING: print(f'GPIO Export interface couldn\'t be opened. {sys.argv[1]}')
+
+with open(f'/sys/class/gpio/gpio{sys.argv[1]}/value', 'w') as x:
+    if (len(sys.argv) == 3): x.write(sys.argv[2])
+    else: x.write('0')