neogrep: Init repo

main.c

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+/*
+ * main.c - Main entry point for neogrep
+ * $author:        Buckwheat of Neo-Sekai Club
+ * $creation-date: 2026/02/28
+ * $version:       1.0.0
+ *
+ */
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+#define NEWLINE '\n'
+#define NULTERM '\0'
+
+/* Function Declarations */
+
+static int
+err_msg(const char*);
+
+static int
+substr_check(char*, const char*, int, int, int);
+
+/* Function Definitions */
+
+static int
+err_msg(const char* msg)
+{
+  printf("ERROR: %s\n", msg);
+  return 1;
+}
+
+static int
+substr_check(char* data, const char* substr, int start, int len, int line)
+{
+  int   newlen = len + 1;
+  char* str    = (char*)malloc(sizeof(char) * newlen);
+  
+  if (!str)
+    return -1;
+
+  for (int index = 0; index < newlen; index++)
+    if (index == len)
+      str[index] = NULTERM;
+    else
+      str[index] = data[index + start];
+
+  if (strstr(str, substr))
+    printf("\033[1;31mLine %d: \033[4;32m%s\033[0m", line, str);
+
+  free(str);
+        
+  return 0;
+}
+
+int
+main(int argc, char** argv)
+{
+  if (argc > 3 || argc < 3)
+    return err_msg("Insufficient arg count\nUsage: ng <file> <string>");
+
+  struct stat file_info;
+  char*       file_map;
+
+  int         char_count = 0;
+  int         file_size  = 0;
+  int         line_count = 0;
+  int         src_file   = -1;
+  const char* substr     = argv[2];
+  const char* src_name   = argv[1];
+
+  src_file = open(src_name, O_RDONLY, 0);
+  if (src_file == -1)
+    return err_msg("Could not open input file");
+
+  fstat(src_file, &file_info);
+  file_size = file_info.st_size;
+
+  file_map = (char*)mmap(NULL, file_size, PROT_READ,
+      MAP_SHARED, src_file, 0);
+  
+  if (file_map == MAP_FAILED)
+  {
+    close(src_file);
+    return err_msg("mmap failed");
+  }
+
+  for (int index = 0; index < file_size; index++)
+  {
+    char current = file_map[index];
+
+    if (current == NEWLINE)
+    {
+      line_count++;
+      char_count = substr_check(file_map, substr,
+          index - char_count, char_count + 1, line_count);
+    }
+    
+    else
+      char_count++;
+
+    if (char_count == -1)
+      return err_msg("Failed to malloc");
+  }
+
+  if (munmap(file_map, file_size) == -1)
+    return err_msg("munmap failed");
+        
+  return 0;
+}