.gitignore

@@ -1,2 +1,4 @@
 a.out
+ics_analyzer
 .gitconfig
+*.o

README.md

@@ -21,14 +21,17 @@ sudo make install
 
 the default path is for evolution ics files at `~/.local/share/evolution/calendar/system/calendar.ics`
 ```
-ics_analyzer
+icscli
 ```
 
 for a custom path
 ```
-ics_analyzer -f path/to/ics/file.ics
+icscli -f path/to/ics/file.ics
 ```
 
+```
+icscli -h
+```
 
 
 #### uninstall
@@ -39,9 +42,6 @@ sudo make uninstall
 
 #### TODO
 
-- option to add events (evolution does not care about duplicate uuids)
-(but use libuuid to create uuids)
 - add option to print upcoming events only until a certain date
-- improve makefile
-- rename executable to ics_cli
+- show end date for events that span over multiple days
 - tests

docs/ics_format.txt

@@ -0,0 +1,33 @@
+ICS files from Microsoft Outlook differ from those that were created by Gnome Evolution.
+(semicolons are used instead of colons at some position)
+
+Evolution
+---------
+all line endings are \r\n
+
+all day event:
+DTSTART;VALUE=DATE:20230908
+DTEND;VALUE=DATE:20230909
+
+an all day event can span over multiple days and look like this:
+DTSTART;VALUE=DATE:20230911^M$
+DTEND;VALUE=DATE:20230916^M$
+
+appointment:
+DTSTART;TZID=/freeassociation.sourceforge.net/Continent/City:
+ 20230909T090000
+DTEND;TZID=/freeassociation.sourceforge.net/Continent/City:
+ 20230909T093000
+
+appointments can also span over multiple days:
+DTSTART;TZID=/freeassociation.sourceforge.net/Europe/Berlin:
+ 20230913T230000
+DTEND;TZID=/freeassociation.sourceforge.net/Europe/Berlin:
+ 20230914T040000
+
+SEQUENCE is the number of times the event was modified.
+Evolution sets this to 2 after it has been generated.
+
+Appointments include the continent and city of the used time zone.
+
+"DESCRIPTION:" is an optional field.

makefile

@@ -1,32 +0,0 @@
-all:
-	gcc -Wall ./src/*.c
-
-.PHONY: debug
-debug:
-	gcc -Wall -g ./src/*.c
-	gdb a.out
-
-.PHONY: run
-run:
-	gcc -Wall ./src/*.c
-	./a.out
-
-.PHONY: install
-install: a.out
-	cp a.out /usr/local/bin/ics_analyzer
-
-.PHONY: clean
-clean:
-	rm a.out
-
-.PHONY: uninstall
-uninstall:
-	rm /usr/local/bin/ics_analyzer
-
-.PHONY: test
-test:
-	./a.out
-	@echo
-	./a.out -h
-	@echo
-	./a.out -f tests/calendar.ics

src/Makefile

@@ -1,33 +1,42 @@
-.PHONY:all
-all:
-	gcc -Wall *.c
+CC = gcc
+CFLAGS = -Wall
+LDFLAGS = -luuid
 
-.PHONY:debug
-debug:
-	gcc -Wall -g *.c
-	gdb a.out
+# List of all source files (assuming they're all in the same directory)
+SRC_FILES = $(wildcard *.c)
 
-.PHONY:run
-run:
-	gcc -Wall *.c
-	./a.out
+# Generate a list of object files by replacing the .c extension with .o
+OBJ_FILES = $(SRC_FILES:.c=.o)
+
+EXECUTABLE = "icscli"
+
+# linking
+$(EXECUTABLE): $(OBJ_FILES)
+	gcc -Wall $(OBJ_FILES) -o $(EXECUTABLE) $(LDFLAGS)
+
+main.o: main.c
+	$(CC) $(CFLAGS) -c $<
+
+# use implicit rule to compile C source files to object files
+%.o: %.c %.h
+	$(CC) $(CFLAGS) -c $<
 
 .PHONY:install
-install: a.out
-	cp a.out /usr/local/bin/ics_analyzer
+install: $(EXECUTABLE)
+	cp $(EXECUTABLE) /usr/local/bin/$(EXECUTABLE)
 
 .PHONY:clean
 clean:
-	-rm a.out
+	-rm $(EXECUTABLE) *.o
 
 .PHONY:uninstall
 uninstall:
-	-rm /usr/local/bin/ics_analyzer
+	-rm /usr/local/bin/$(EXECUTABLE)
 
 .PHONY:test
 test:
-	./a.out
+	./$(EXECUTABLE)
 	@echo
-	./a.out -h
+	./$(EXECUTABLE) -h
 	@echo
-	./a.out -f ../tests/calendar.ics
+	./$(EXECUTABLE) -f ../tests/calendar.ics

src/cli_arg_parsing.c

@@ -1,3 +1,4 @@
+#include "insert_event.h"
 #include "cli_arg_parsing.h"
 #include <stdio.h>
 #include <stdlib.h>
@@ -5,37 +6,38 @@
 #include <string.h>
 
 void usage() {
-  printf ("-h\tprint this help\n");
-  printf ("-f\tspecify ics file path\n");
-  exit(0);
+	printf ("-f [FILE PATH]\t\tspecify ics file path\n");
+	printf ("-h\t\t\tprint this help\n");
+	printf ("-i\t\t\tinsert an event\n");
+	exit(0);
 }
 
 void get_cli_args(int argc, char **argv, char **file_name) {
-  int opt = 0;
+	int opt = 0;
 
-  memset(file_name, '\0', strlen(*file_name));
+	memset(file_name, '\0', strlen(*file_name));
 
-  if (argc < 2) {
-    char *home = getenv("HOME");
-    *file_name = home;
+	char *home = getenv("HOME");
+	*file_name = home;
 
-    if (home != NULL) {
-      strcat(*file_name, "/.local/share/evolution/calendar/system/calendar.ics");
-    } else {
-      printf ("Environment variable HOME is not set.\n");
-      exit(1);
-    }
-    return;
-  }
+	if (home != NULL) {
+	  strcat(*file_name, "/.local/share/evolution/calendar/system/calendar.ics");
+	} else {
+	  printf ("Environment variable HOME is not set.\n");
+	  exit(1);
+	}
 
-  while ((opt = getopt(argc, argv, "f:h")) != -1) {
-    switch(opt) {
-      case 'f':
-      *file_name = optarg;
-      break;
-      case 'h':
-      usage();
-    }
-  }
+	while ((opt = getopt(argc, argv, "f:hi")) != -1) {
+    	switch(opt) {
+		  case 'f':
+		  *file_name = optarg;
+		  break;
+		  case 'h':
+		  usage();
+		  break;
+		  case 'i':
+		  insert_event(*file_name);
+		  break;
+    	}
+	}
 }
-

src/cut_string.c

@@ -1,41 +0,0 @@
-// cut a string into two parts by the first occurence of delimiter
-// and choose the first part (side 0) or the second part (side 1)
-// the chosen part will overwrite the original string
-
-// cut a string into two parts by delimiter
-// and choose the first part (side 0) or the second part (side 1)
-// the chosen part will overwrite the original string
-
-#include <string.h>
-
-void cut_string(char my_string[], char delimiter, int side) {
-	char part1[256] = "";
-	char part2[256] = "";
-
-	int split = 0;
-
-	int j = 0;
-	for (int i = 0; i < strlen(my_string); i++) {
-		if (my_string[i] == delimiter) {
-			if (split == 0) {
-				split = 1;
-				continue;
-			}
-		}
-
-		if (split == 0) {
-			part1[i] = my_string[i];
-		} else {
-			part2[j] = my_string[i];
-			j++;
-		}
-	}
-
-	memset(my_string, '\0', strlen(my_string));
-	if (side == 0) {
-		strcpy(my_string, part1);
-	} else {
-		strcpy(my_string, part2);
-	}
-}
-

src/cut_string.h

@@ -1,5 +0,0 @@
-#pragma once
-
-// cut string into two parts and choose one part
-// side is 0 or 1
-void cut_string(char my_string[], char delimiter, int side);

src/date_time_handling.c

@@ -1,15 +1,23 @@
 #include "date_time_handling.h"
+#include "string_handling.h"
 #include <stdio.h>
 #include <stdlib.h>
-#include <time.h>
 #include <string.h>
+#include <time.h>
+#include <unistd.h>
 
+// buffer needs to contain a string with a strlen of 15 (format: "xxxxxxxxTxxxxxx")
+// or a strlen of 16 (format: "YYYYmmddTHHMMSSZ")
 void get_date(char buffer[]) {
 	// add 1 because strlen does not include the null character
 	size_t buffer_size = strlen(buffer) + 1;
 	time_t my_unix_ts = time(NULL);
 	struct tm* my_tm_local = localtime(&my_unix_ts);
-	strftime(buffer, buffer_size, "%Y%m%dT%H%M%S", my_tm_local);
+	if (strlen(buffer) == 15) {
+		strftime(buffer, buffer_size, "%Y%m%dT%H%M%S", my_tm_local);
+	} else if (strlen(buffer) == 16) {
+		strftime(buffer, buffer_size, "%Y%m%dT%H%M%SZ", my_tm_local);
+	}
 }
 
 // 20230823T194138 -> 2023-08-23 19:41:38
@@ -31,6 +39,26 @@ void pretty_print_date_time(char date_time[]) {
 	}
 }
 
+void marshall_date_time(char date_time[]) {
+	char transformed_string[strlen(date_time)];
+	int j = 0;
+	remove_nl_and_cr(date_time);
+	for (int i = 0; i<=strlen(date_time); i++) {
+		if (date_time[i] != ':' && date_time[i] != '-') {
+			if (date_time[i] == ' ') {
+				transformed_string[j] = 'T';
+			} else {
+				transformed_string[j] = date_time[i];
+			}
+			
+			j++;
+		}
+	
+	}
+	memset(date_time, '\0', strlen(date_time));
+	strcpy(date_time, transformed_string);
+}
+
 void print_end_date(char end_date[]) {
 	// end_date is all day event
 	if (strlen(end_date) == 8)
@@ -44,3 +72,17 @@ void print_end_date(char end_date[]) {
 	printf ("%c%c", time[4], time[5]);
 }
 
+char *get_tz() {
+	char *timezone_path = malloc(256);
+	ssize_t bytes_read = readlink("/etc/localtime", timezone_path, 255);
+
+	if (bytes_read != -1) {
+		// Null-terminate the string
+    	timezone_path[bytes_read] = '\0';
+	} else {
+		perror("readlink");
+		exit(1);
+	}
+
+	return timezone_path;
+}

src/date_time_handling.h

@@ -2,5 +2,7 @@
 #include <string.h>
 
 void get_date(char buffer[]);
+char *get_tz();
 void pretty_print_date_time(char date_time[]);
+void marshall_date_time(char date_time[]);
 void print_end_date(char end_date[]);

src/insert_event.c

@@ -0,0 +1,187 @@
+#include "insert_event.h"
+#include "string_handling.h"
+#include "date_time_handling.h"
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <uuid/uuid.h>
+
+void insert_event(char *file_name) {
+	int myfd = open(file_name, O_RDWR);
+	int all_day_event = 0;
+	char summary_buf[256] = "SUMMARY:";
+	char *input_buffer = &summary_buf[8];
+	uuid_t uuid;
+	char uuid_str[37] = "";
+	char dtstamp[] = "YYYYmmddTHHMMSSZ";
+	char *time_zone = get_tz();
+	char *dtstart_buffer = malloc(128);
+	char *dtend_buffer = malloc(128);
+
+	remove_until_delim(time_zone, '/', 4);
+
+	printf("Insert a new event\n");
+
+	printf("Is this an all day event? [y/n] ");
+	all_day_event = binary_user_choice();
+
+	printf("SUMMARY: ");
+	fgets (input_buffer, (sizeof(summary_buf)-strlen(summary_buf)), stdin);
+
+	if (strchr(input_buffer, '\n') == NULL)
+		printf ("The input has been truncated to:\n%s\n", input_buffer);
+
+	// modify the string to have \r\n line ending
+	summary_buf[strlen(summary_buf)+1] = '\0';
+	summary_buf[strlen(summary_buf)-1] = '\r';
+	summary_buf[strlen(summary_buf)] = '\n';
+
+	uuid_generate(uuid);
+	// parse uuid to a string
+	uuid_unparse(uuid, uuid_str);
+
+	get_date(dtstamp);
+
+	get_dtstart_dtend(dtstart_buffer, all_day_event, "start");
+	marshall_date_time(dtstart_buffer);
+	form_dtstart_string(dtstart_buffer, time_zone);
+
+	get_dtstart_dtend(dtend_buffer, all_day_event, "end");
+	marshall_date_time(dtend_buffer);
+	form_dtend_string(dtend_buffer, time_zone);
+
+	seek_cal_end(myfd);
+	write(myfd, "BEGIN:VEVENT\r\n", strlen("BEGIN:VEVENT\r\n"));
+	write(myfd, "UID:", strlen("UID:"));
+	write(myfd, uuid_str, strlen(uuid_str));
+	write(myfd, "\r\n", strlen("\r\n"));
+	write(myfd, "DTSTAMP:", strlen("DTSTAMP:"));
+	write(myfd, dtstamp, strlen(dtstamp));
+	write(myfd, "\r\n", strlen("\r\n"));
+	write(myfd, dtstart_buffer, strlen(dtstart_buffer));
+	write(myfd, dtend_buffer, strlen(dtend_buffer));
+	write(myfd, "SEQUENCE:2\r\n", strlen("SEQUENCE:2\r\n"));
+	write(myfd, summary_buf, strlen(summary_buf));
+	write(myfd, "TRANSP:OPAQUE\r\n", strlen("TRANSP:OPAQUE\r\n"));
+	write(myfd, "CLASS:PUBLIC\r\n", strlen("CLASS:PUBLIC\r\n"));
+	write(myfd, "CREATED:", strlen("CREATED:"));
+	write(myfd, dtstamp, strlen(dtstamp));
+	write(myfd, "\r\n", strlen("\r\n"));
+	write(myfd, "LAST-MODIFIED:", strlen("LAST-MODIFIED:"));
+	write(myfd, dtstamp, strlen(dtstamp));
+	write(myfd, "\r\n", strlen("\r\n"));
+	write(myfd, "END:VEVENT\r\n", strlen("END:VEVENT\r\n"));
+	
+	write(myfd, "END:VCALENDAR\r\n", strlen("END:VCALENDAR\r\n"));
+
+	close(myfd);
+	free(time_zone);
+	free(dtstart_buffer);
+	free(dtend_buffer);
+
+	exit(0);
+}
+
+void seek_cal_end(int fd) {
+	char search_string[] = "END:VCALENDAR";
+	int j = 0;
+	char char_reader = '\0';
+
+	lseek(fd, -1, SEEK_END);
+
+	while(read(fd, &char_reader, 1)) {
+		// no need to compare to the null terminator of the search_string
+		if (char_reader == search_string[strlen(search_string)-j-1]) {
+			j++;
+		} else {
+			j = 0;
+		}
+		if (j == (strlen(search_string))) {
+			lseek(fd, -1, SEEK_CUR);
+			break;
+		}
+		lseek(fd, -2, SEEK_CUR);
+	}
+}
+
+int binary_user_choice() {
+	char input_buffer[64] = "";
+	if (fgets (input_buffer, sizeof(input_buffer), stdin) == NULL) {
+		printf ("an fgets error occured\n");
+	}
+	if (! strchr(input_buffer, '\n')) {
+		printf ("Input buffer overflow!\n");
+		exit(1);
+	}
+	if (input_buffer[0] == 'n' || input_buffer[0] == 'N') {
+		return 0;
+	} else if (input_buffer[0] == 'y' || input_buffer[0] == 'Y') {
+		return 1;
+	} else {
+		printf ("Please enter a N/n or Y/y character!\n");
+		exit(1);
+	}
+}
+
+// char *start_or_end should contain "start" or "end"
+void get_dtstart_dtend(char input_buffer[], int all_day_event, char *start_or_end) {
+	if (all_day_event) {
+		printf("Enter the %s date in YYYY-mm-dd format!\n", start_or_end);
+		if (fgets(input_buffer, 128, stdin) == NULL) {
+			perror ("fgets");
+			exit(1);
+		}
+		if (strlen(input_buffer) != 11) {
+			printf ("Wrong format!\n");
+			exit(1);
+		}
+	} else {
+		printf("Enter the %s date in YYYY-mm-dd HH:MM:SS format!\n", start_or_end);
+		if (fgets(input_buffer, 128, stdin) == NULL) {
+			perror ("fgets");
+			exit(1);
+		}
+		if (strlen(input_buffer) != 20) {
+			printf ("Wrong format!\n");
+			exit(1);
+		}
+	}
+}
+
+void form_dtstart_string(char dtstart_buffer[], char time_zone[]) {
+	char dtstart_copy[strlen(dtstart_buffer)];
+	strcpy(dtstart_copy, dtstart_buffer);
+
+	// not all day event
+	if (strlen(dtstart_buffer) == 15) {
+		strcpy(dtstart_buffer, "DTSTART;TZID=/freeassociation.sourceforge.net");
+		strcat(dtstart_buffer, time_zone);
+		strcat(dtstart_buffer, ":\r\n ");
+		strcat(dtstart_buffer, dtstart_copy);
+	} else {
+		// all day event
+		strcpy(dtstart_buffer, "DTSTART;VALUE=DATE:");
+		strcat(dtstart_buffer, dtstart_copy);
+	}
+	strcat(dtstart_buffer, "\r\n");
+}
+
+void form_dtend_string(char dtend_buffer[], char time_zone[]) {
+	char dtend_copy[strlen(dtend_buffer)];
+	strcpy(dtend_copy, dtend_buffer);
+
+	// not all day event
+	if (strlen(dtend_buffer) == 15) {
+		strcpy(dtend_buffer, "DTEND;TZID=/freeassociation.sourceforge.net");
+		strcat(dtend_buffer, time_zone);
+		strcat(dtend_buffer, ":\r\n ");
+		strcat(dtend_buffer, dtend_copy);
+	} else {
+		// all day event
+		strcpy(dtend_buffer, "DTEND;VALUE=DATE:");
+		strcat(dtend_buffer, dtend_copy);
+	}
+	strcat(dtend_buffer, "\r\n");
+}

src/insert_event.h

@@ -0,0 +1,8 @@
+#pragma once
+
+void insert_event(char *file_name);
+void seek_cal_end(int fd);
+int binary_user_choice();
+void get_dtstart_dtend(char input_buffer[], int all_day_event, char *start_or_end);
+void form_dtstart_string(char dtstart_buffer[], char time_zone[]);
+void form_dtend_string(char dtend_buffer[], char time_zone[]);

src/main.c

@@ -1,12 +1,11 @@
 #include "cli_arg_parsing.h"
 #include "date_time_handling.h"
 #include "list_handling.h"
-#include "cut_string.h"
+#include "string_handling.h"
 #include "move_lines.h"
 #include "read_until_nl.h"
 #include "read_until_string.h"
 #include "seek_string_a.h"
-#include "remove_whitespace.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <fcntl.h>
@@ -14,8 +13,8 @@
 #include <limits.h>
 
 int main(int argc, char **argv) {
-  char *ics_path = "";
-  get_cli_args(argc, argv, &ics_path);
+	char *ics_path = "";
+	get_cli_args(argc, argv, &ics_path);
 
 	char my_line[4096] = "";
 

src/remove_whitespace.c

@@ -1,45 +0,0 @@
-// this function removes all new lines and carriage returns from a string
-// you might want to write a new function that replaces '\r' and '\n'
-// with a delimiter of user's choice
-
-#include <string.h>
-
-void remove_nl_and_cr(char raw_string[]) {
-  char processed_string[strlen(raw_string)];
-
-  // counter for num of elements of processed_string
-  int j = 0;
-  for (int i = 0; i<strlen(raw_string); i++) {
-    if (raw_string[i] == '\n' || raw_string[i] == '\r') {
-      continue;
-    } else {
-      processed_string[j] = raw_string[i];
-      j++;
-    }
-  }
-  processed_string[j] = '\0';
-
-  memset(raw_string, '\0', strlen(raw_string));
-  strcpy(raw_string, processed_string);
-}
-
-// remove new lines, carriage returns and spaces
-void remove_whitespace(char raw_string[]) {
-  char processed_string[strlen(raw_string)];
-
-  // counter for num of elements of processed_string
-  int j = 0;
-  for (int i = 0; i<strlen(raw_string); i++) {
-    if (raw_string[i] == '\n' || raw_string[i] == '\r' \
-			|| raw_string[i] == ' ') {
-      continue;
-    } else {
-      processed_string[j] = raw_string[i];
-      j++;
-    }
-  }
-  processed_string[j] = '\0';
-
-  memset(raw_string, '\0', strlen(raw_string));
-  strcpy(raw_string, processed_string);
-}

src/remove_whitespace.h

@@ -1,8 +0,0 @@
-// this function removes all new lines and carriage returns from a string
-// you might want to write a new function that replaces '\r' and '\n'
-// with a delimiter of user's choice
-
-#pragma once
-
-void remove_nl_and_cr(char raw_string[]);
-void remove_whitespace(char raw_string[]);

src/string_handling.c

@@ -0,0 +1,103 @@
+// cut a string into two parts by the first occurence of delimiter
+// and choose the first part (side 0) or the second part (side 1)
+// the chosen part will overwrite the original string
+
+// cut a string into two parts by delimiter
+// and choose the first part (side 0) or the second part (side 1)
+// the chosen part will overwrite the original string
+
+#include <string.h>
+#include <stdlib.h>
+
+void cut_string(char my_string[], char delimiter, int side) {
+	char part1[256] = "";
+	char part2[256] = "";
+
+	int split = 0;
+
+	int j = 0;
+	for (int i = 0; i < strlen(my_string); i++) {
+		if (my_string[i] == delimiter) {
+			if (split == 0) {
+				split = 1;
+				continue;
+			}
+		}
+
+		if (split == 0) {
+			part1[i] = my_string[i];
+		} else {
+			part2[j] = my_string[i];
+			j++;
+		}
+	}
+
+	memset(my_string, '\0', strlen(my_string));
+	if (side == 0) {
+		strcpy(my_string, part1);
+	} else {
+		strcpy(my_string, part2);
+	}
+}
+
+// this function removes all new lines and carriage returns from a string
+// you might want to write a new function that replaces '\r' and '\n'
+// with a delimiter of user's choice
+void remove_nl_and_cr(char raw_string[]) {
+  char processed_string[strlen(raw_string)];
+
+  // counter for num of elements of processed_string
+  int j = 0;
+  for (int i = 0; i<strlen(raw_string); i++) {
+    if (raw_string[i] == '\n' || raw_string[i] == '\r') {
+      continue;
+    } else {
+      processed_string[j] = raw_string[i];
+      j++;
+    }
+  }
+  processed_string[j] = '\0';
+
+  memset(raw_string, '\0', strlen(raw_string));
+  strcpy(raw_string, processed_string);
+}
+
+// remove new lines, carriage returns and spaces
+void remove_whitespace(char raw_string[]) {
+  char processed_string[strlen(raw_string)];
+
+  // counter for num of elements of processed_string
+  int j = 0;
+  for (int i = 0; i<strlen(raw_string); i++) {
+    if (raw_string[i] == '\n' || raw_string[i] == '\r' \
+			|| raw_string[i] == ' ') {
+      continue;
+    } else {
+      processed_string[j] = raw_string[i];
+      j++;
+    }
+  }
+  processed_string[j] = '\0';
+
+  memset(raw_string, '\0', strlen(raw_string));
+  strcpy(raw_string, processed_string);
+}
+
+void remove_until_delim(char raw_string[], char delimiter, int occurence) {
+	int chunk = 0;
+	int j = 0;
+	char *tmp_string = malloc(strlen(raw_string));
+	memset(tmp_string, '\0', strlen(raw_string));
+
+	for (int i = 0; i < strlen(raw_string); i++) {
+		if (raw_string[i] == delimiter) {
+			chunk++;
+		}
+		if (chunk >= occurence) {
+			tmp_string[j] = raw_string[i];
+			j++;
+		}
+	}
+	strcpy(raw_string, tmp_string);
+	free(tmp_string);
+}

src/string_handling.h

@@ -0,0 +1,8 @@
+#pragma once
+
+// cut string into two parts and choose one part
+// side is 0 or 1
+void cut_string(char my_string[], char delimiter, int side);
+void remove_nl_and_cr(char raw_string[]);
+void remove_whitespace(char raw_string[]);
+void remove_until_delim(char raw_string[], char delimiter, int occurence);