Implement check for user input and file data, add file append

mygrep/mygrep.c

@@ -1,6 +1,8 @@
+#define _GNU_SOURCE // in order for strcasestr to work
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <string.h>
 #include "mygrep.h"
 
 void main(int argc, char *argv[]) {
@@ -12,6 +14,7 @@ void main(int argc, char *argv[]) {
     char *filename = NULL;
     int c;
 
+    // Get the options
     while((c = getopt(argc, argv, "io:h")) != -1) {
         switch(c) {
             case 'i':
@@ -21,7 +24,9 @@ void main(int argc, char *argv[]) {
                 ofile = optarg;
                 break;
             case 'h':
+                printf("Command usage:\n");
                 print_usage();
+                exit(EXIT_SUCCESS);
                 break;
             case '?':
                 print_usage();
@@ -31,6 +36,7 @@ void main(int argc, char *argv[]) {
         }
     }
 
+     // Check if the required argument is there
     if(argv[optind] == NULL) {
         printf("Mandatory argument 'keyword' missing.\n");
         print_usage();
@@ -40,8 +46,31 @@ void main(int argc, char *argv[]) {
         filename = argv[optind + 1];
     }
 
-    if(filename == NULL) {
-        check_for_string("test", keyword);
+    // Get user input if there is no input file defined
+    while(filename == NULL) {
+        size_t len; // Define an unsigned string length value
+
+        if(getline(&filename, &len, stdin)) {  // Read until new line
+            check_for_string(filename, keyword, iflag, ofile);
+            filename = NULL; // Reset the input
+        }
+    }
+
+    // Get data from input file
+    if(filename != NULL) {
+        FILE *in;
+        if((in = fopen(filename, "r")) == NULL) {
+            printf("Error opening the file %s\n", filename);
+            exit(EXIT_FAILURE);
+        }
+
+        size_t len;
+        char *line = NULL; // Define a pointer to hold our value
+
+        // Read the file line by line and execute check_for_string for each line
+        while(getline(&line, &len, in) != -1) {
+            check_for_string(line, keyword, iflag, ofile);
+        }
     }
 
     exit(EXIT_SUCCESS);
@@ -51,6 +80,7 @@ void print_usage() {
     printf("mygrep [-i] [-o outfile] keyword [file...]\n");
 }
 
+// Check for coorect number of options
 void check_opts_number(int argc, char *argv[]) {
     if(argc <= 1) {
         fprintf(stderr, "At least one argument expected.\n");
@@ -63,6 +93,32 @@ void check_opts_number(int argc, char *argv[]) {
     }
 }
 
-void check_for_string(char *to_check, char *to_find) {
-    printf("Not implemented. This function will search for the substring %s in the string %s.\n", to_find, to_check);
+void check_for_string(char *to_check, char *to_find, int iflag, char *ofile) {
+    if(ofile == NULL) {
+        /**
+         * Find the first occurance of needle in haystack and return it as a pointer.
+         * If found, print haystack
+         **/
+        if(iflag == 0 && strstr(to_check, to_find) != NULL)  printf("%s", to_check);
+        else if(iflag == 1 && strcasestr(to_check, to_find)) printf("%s", to_check);
+    } else {
+        /**
+         * Open the specified file for appending
+         * Find the first occurance of needle in haystack and return it as a pointer.
+         * If found, append haystack to the end of the file
+         * Close the file
+         **/
+        FILE *out;
+
+        // Check if the file was opened successfully
+        if((out = fopen(ofile, "a")) == NULL) {
+            printf("Error opening the file %s\n", ofile);
+            exit(EXIT_FAILURE);
+        }
+
+        if(iflag == 0 && strstr(to_check, to_find)) fprintf(out, "%s", to_check);
+        else if(iflag == 1 && strcasestr(to_check, to_find)) fprintf(out, "%s", to_check);
+
+        fclose(out);
+    }
 }

mygrep/mygrep.h

@@ -3,6 +3,6 @@
 
 void print_usage();
 void check_opts_number(int argc, char *argv[]);
-void check_for_string(char *to_check, char *to_find);
+void check_for_string(char *to_check, char *to_find, int iflag, char *ofile);
 
 #endif