added sysfs functionality

makefile

@@ -65,6 +65,10 @@ $(OBJDIR):
 $(DEPDIR):
 	$(call mkdir,"$@")
 
+.PHONY: install
+install: $(MAIN_EXECUTABLE)
+	install -m 755 "$(MAIN_EXECUTABLE)" /usr/bin/
+
 .PHONY: clean
 clean:
 	$(call rmdir,"$(DEPDIR)")

src/rex-edid.c

@@ -21,6 +21,10 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <dirent.h>
+
+#define REX_EDID_VERSION_MAJ 0u
+#define REX_EDID_VERSION_MIN 2u
 
 #define RANDR_MIN_VER_MAJ 1u
 #define RANDR_MIN_VER_MIN 3u
@@ -74,7 +78,14 @@ _Noreturn void help(int ret){
 	printf("Usage: rex-edid [--help]\n");
 	printf("\n");
 	printf("Options:\n");
-	printf("%-20s%s\n", "\t--help|-h", "show this help message");
+	printf("\t--help|-h\n");
+	printf("\t\tshow this help message\n");
+	printf("\t--sysfs|-s\n");
+	printf("\t\tget edid data and device names from sysfs\n");
+	printf("\t\tNOT intended for use other than by udev rule\n");
+	printf("\t--xrandr|-s\n");
+	printf("\t\tget edid data and device names from X using randr extension\n");
+	printf("\t\trequires randr version %u.%u or newer\n", RANDR_MIN_VER_MAJ, RANDR_MIN_VER_MIN);
 	printf("\n");
 	printf("rex-edid  Copyright (C) 2018  rexy712\n");
 	printf("This program comes with ABSOLUTELY NO WARRANTY; for details type refer to the LICENSE file.\n");
@@ -82,8 +93,16 @@ _Noreturn void help(int ret){
 	printf("under certain conditions; see the LICENSE file for details.\n");
 	exit(ret);
 }
+_Noreturn void version(void){
+	printf("rex-edid version %u.%u\n", REX_EDID_VERSION_MAJ, REX_EDID_VERSION_MIN);
+	printf("Copyright (C) 2018  rexy712\n");
+	printf("This program comes with ABSOLUTELY NO WARRANTY; for details type refer to the LICENSE file.\n");
+	printf("This is free software, and you are welcome to redistribute it\n");
+	printf("under certain conditions; see the LICENSE file for details.\n");
+	exit(0);
+}
 
-int main(int argc, char* argv[]){
+int rex_edid_xrandr(void){
 	xcb_connection_t*     connection;         /*connection to x server*/
 	xcb_window_t          root;               /*handle on root window of screen???*/
 	xcb_timestamp_t       timestamp;          /*timestamp of resource reply???*/
@@ -96,15 +115,6 @@ int main(int argc, char* argv[]){
 	xcb_randr_get_screen_resources_current_reply_t* randr_resources_reply; /*X server reply to our resource query*/
 
 
-	for(i = 1;i < argc;++i){
-		if(!strcmp(argv[i], "--help") || !strcmp(argv[i], "-h"))
-			help(0);
-		else{
-			fprintf(stderr, "Unrecognized option '%s'\n", argv[i]);
-			help(1);
-		}
-	}
-
 	/*initialize connection to x server*/
 	connection = xcb_connect(NULL, &screen_num);
 	if(xcb_connection_has_error(connection)){
@@ -175,4 +185,128 @@ int main(int argc, char* argv[]){
 
 	free(randr_resources_reply);
 	xcb_disconnect(connection);
+	return 0;
+}
+
+/*get device name from DEVPATH environment variable and prepend '/sys' to it*/
+char* get_device_path(int* len){
+	char* devpath;
+	int length;
+	char* tmp;
+
+	/*udev stores the device location in sysfs in DEVPATH environment variable*/
+	devpath = getenv("DEVPATH");
+	if(!devpath)
+		return NULL;
+	length = strlen(devpath) + 5;
+	tmp = malloc(length);
+	if(!tmp)
+		return NULL;
+	tmp[length-1] = 0;
+
+	snprintf(tmp, length, "/sys%s", devpath);
+	if(len)
+		*len = length-1;
+	return tmp;
+}
+
+/*extract device name from the device path (the last part of the pathname)*/
+char* get_device_name(char* devpath, int strlength){
+	int i;
+	for(i = strlength-1;i >= 0;--i){
+		if(devpath[i] == '/'){
+			if(i == strlength)
+				return NULL;
+			return &(devpath[i])+1;
+		}
+	}
+	return NULL;
+}
+
+int rex_edid_sysfs(void){
+	int devpath_len;    /*length of device path name*/
+	int devname_len;    /*length of device name*/
+	char* devpath;      /*name of device path*/
+	char* devname;      /*name of the device*/
+	DIR* dp;            /*pointer to open device directory in sysfs*/
+	struct dirent* dir; /*accessor to sysfs directory*/
+
+	/*set up device names*/
+	devpath = get_device_path(&devpath_len);
+	if(!devpath){
+		fprintf(stderr, "DEVPATH is empty!\n");
+		return -3;
+	}
+	devname = get_device_name(devpath, devpath_len);
+	devname_len = strlen(devname);
+
+	/*open directory*/
+	dp = opendir(devpath);
+	if(!dp){
+		fprintf(stderr, "Unable to open DEVPATH!\n");
+		return -2;
+	}
+
+	/*check all contents of device directory*/
+	while((dir = readdir(dp))){
+		if(!strncmp(dir->d_name, devname, devname_len)){
+			int edid_len;    /*length of full path to edid file*/
+			char* edid_file; /*buffer for edid path name*/
+			unsigned char c; /*place to store char from file*/
+
+			/*set up edid file path*/
+			edid_len = strlen(dir->d_name)+1 + devpath_len + 6;
+			edid_file = malloc(edid_len);
+			snprintf(edid_file, edid_len, "%s/%s/edid", devpath, dir->d_name);
+			printf("%s:", dir->d_name + devname_len+1);
+
+			/*read in edid data from file*/
+			FILE* fd = fopen(edid_file, "r");
+			if(!fd){
+				fprintf(stderr, "Unable to open edid file\n");
+				free(edid_file);
+				printf("\n");
+				continue;
+			}
+
+			c = fgetc(fd);
+			while(!feof(fd)){
+				printf("%02x", c);
+				c = fgetc(fd);
+			}
+
+			/*cleanup*/
+			fclose(fd);
+			free(edid_file);
+			printf("\n");
+		}
+	}
+
+	closedir(dp);
+	free(devpath);
+	return 0;
+}
+
+int main(int argc, char* argv[]){
+	int i;
+
+	if(argc == 1){
+		help(1);
+	}
+
+	for(i = 1;i < argc;++i){
+		if(!strcmp(argv[i], "--help") || !strcmp(argv[i], "-h")){
+			help(0);
+		}else if(!strcmp(argv[i], "--sysfs") || !strcmp(argv[i], "-s")){
+			return rex_edid_sysfs();
+		}else if(!strcmp(argv[i], "--xrandr") || !strcmp(argv[i], "-x")){
+			return rex_edid_xrandr();
+		}else if(!strcmp(argv[i], "--version")){
+			version();
+		}else{
+			fprintf(stderr, "Unrecognized option '%s'\n", argv[i]);
+			help(1);
+		}
+	}
+	return 1;
 }