feat: history browsing with arrow keys

src/msh.c

@@ -153,6 +153,8 @@ int main(int argc, char** argv) {
     char**  history = NULL;
     size_t  historycapacity = 0;
     size_t  historyi = 0;
+    size_t  historyoffset = 0;
+    char*   oldline = NULL;
     
 
     int pid;
@@ -324,6 +326,8 @@ int main(int argc, char** argv) {
 
         memset(line, 0, linecapacity);
 
+        historyoffset = 0;
+
         while ((readc = getchar()) != '\n') {
             if (readc == EOF) {
                 printf("^D\n");
@@ -341,6 +345,56 @@ int main(int argc, char** argv) {
                     if (cursor < linelen) {
                         cursor++;
                     }
+
+                } else if (ansi == ANSI_CURSOR_UP || ansi == ANSI_CURSOR_DOWN) {
+                    int changed = 1;
+
+                    if (ansi == ANSI_CURSOR_UP && historyoffset < historyi) {
+                        historyoffset++;
+                    } else if (ansi == ANSI_CURSOR_DOWN && historyoffset > 0) {
+                        historyoffset--;
+
+                        if (historyoffset == 0) {
+                            free(line);
+                            line = oldline;
+                            linelen = strlen(line);
+                            linecapacity = linelen + 1;
+                            cursor = linelen;
+
+                            oldline = NULL;
+
+                            // Don't look up from history
+                            changed = 0;
+                        }
+                    } else {
+                        // We didn't actually change anything
+                        changed = 0;
+                    }
+
+
+                    if (changed == 1) {
+                        if (oldline != NULL) {
+                            free(oldline);
+                        }
+
+                        oldline = line;
+                        char*  historyline = history[historyi - (historyoffset)];
+                        size_t historylinelen = strlen(historyline);
+                        line = malloc(historylinelen + 1);
+                        if (line == NULL) {
+                            retval = 1;
+                            goto cleanup;
+                        }
+                        line = strcpy(line, historyline);
+                        if (line == NULL) {
+                            retval = 1;
+                            goto cleanup;
+                        }
+
+                        cursor = historylinelen;
+                        linecapacity = historylinelen + 1;
+                        linelen = historylinelen;
+                    }
                 } else if (ansi == ANSI_DELETE_WORD) {
                     if (cursor > 0) {
                         size_t index = strnrcspn(line, cursor, " \t");
@@ -355,12 +409,8 @@ int main(int argc, char** argv) {
                     size_t index = strnocspn(line, linelen, cursor, " \t");
                     cursor = index;
                 }
-
+            } else if (readc == 127) {
-                goto print_prompt;
-            }
-
                 // backspace
-            if (readc == 127) {
                 if (cursor > 0) {
                     cursor--;
                     linelen--;
@@ -371,11 +421,8 @@ int main(int argc, char** argv) {
                 } else {
                     memmove(line + cursor, line + cursor + 1, LINESIZE - (cursor));
                 }
-
+            } else {
-                // We don't want to change the line
+                // We are typing
-                goto print_prompt;
-            }
-
                 if (cursor != linelen) {
                     memmove(line + cursor + 1, line + cursor, LINESIZE - cursor - 1);
                 }
@@ -396,8 +443,8 @@ int main(int argc, char** argv) {
 
                     memset(line + linecapacity / 2, 0, linecapacity / 2);
                 }
+            }
 
-print_prompt:
             // Manual echo
             printf(ANSI_ESC "[2K" ANSI_ESC "[0G" "%s%s", prompt, line);
             for (int j = 0; j < linelen - cursor; j++) {
@@ -530,6 +577,10 @@ cleanup:
         free(line);
     }
 
+    if (oldline != NULL) {
+        free(oldline);
+    }
+
     if (tokenwork != NULL) {
         free(tokenwork);
     }