Renaming folders

chp3_process/osh_shell/history.c

@@ -0,0 +1,109 @@
+#include "history.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define HISTORY_FILENAME "osh_history"
+#define W_MODE "w"
+#define R_MODE "r"
+#define A_MODE "a+"
+
+int allocate_history(void) {
+  FILE *file;
+  if (access(HISTORY_FILENAME, F_OK) == -1) {
+    if ((file = fopen(HISTORY_FILENAME, W_MODE)) == NULL) {
+      perror("Error");
+      return -1;
+    }
+    fclose(file);
+  }
+
+  if ((file = fopen(HISTORY_FILENAME, R_MODE)) == NULL) {
+    perror("Error");
+    return -1;
+  }
+
+  int count = -1;
+  char line[MAXLEN];
+  while (!feof(file)) {
+    fgets(line, sizeof(line), file);
+    count++;
+  }
+
+  fclose(file);
+  return count;
+}
+
+history_entry_t *get_history(int history_count) {
+  FILE *file = fopen(HISTORY_FILENAME, R_MODE);
+  if (!file) {
+    perror("Error");
+    exit(EXIT_FAILURE);
+  }
+
+  int num = 0;
+  char line[MAXLEN];
+  const int offset = history_count - HISTORY_SIZE;
+  history_entry_t *history = calloc(HISTORY_SIZE, sizeof(history_entry_t));
+  while (fgets(line, sizeof(line), file)) {
+    if (num >= offset) {
+      history_entry_t entry;
+      entry.line_number = num + 1;
+      strcpy(entry.command, line);
+      history[num - offset] = entry;
+    }
+    num++;
+  }
+  fclose(file);
+  return history;
+}
+
+int add_history(int count, char *cmd) {
+  FILE *file = fopen(HISTORY_FILENAME, A_MODE);
+  if (!file) {
+    perror("Error");
+    exit(EXIT_FAILURE);
+  }
+
+  fprintf(file, "%s\n", cmd);
+  fclose(file);
+  return count + 1;
+}
+
+int last_command(char *last) {
+  FILE *file = fopen(HISTORY_FILENAME, A_MODE);
+  if (!file) {
+    perror("Error");
+    exit(EXIT_FAILURE);
+  }
+
+  char line[MAXLEN];
+  while (!feof(file)) {
+    fgets(line, sizeof(line), file);
+  }
+
+  fclose(file);
+  strcpy(last, line);
+  return 0;
+}
+
+int nth_command(char *s, int n) {
+  FILE *file = fopen(HISTORY_FILENAME, R_MODE);
+  if (!file) {
+    perror("Error");
+    exit(EXIT_FAILURE);
+  }
+
+  int num = 0;
+  char line[MAXLEN];
+  while (fgets(line, sizeof(line), file)) {
+    if ((num + 1) == n) {
+      strcpy(s, line);
+      return 0;
+    }
+    num++;
+  }
+  fclose(file);
+  return -1;
+}