From 69e12f0df1485be0bfd427d7b8e58b04ef65c629 Mon Sep 17 00:00:00 2001
From: Alexander Zhylin <zheiling@hotmail.com>
Date: Thu, 28 May 2026 16:45:32 +0300
Subject: [PATCH] cancel download [needs testing]

---
 src/file_p.c  | 16 +++++++++++++++-
 src/main.c    |  1 -
 src/session.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/session.h |  1 +
 4 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/src/file_p.c b/src/file_p.c
index 3e5031b..a3179aa 100644
--- a/src/file_p.c
+++ b/src/file_p.c
@@ -293,7 +293,21 @@ void file_download(session *sess) {
   int source_d = sess->fd;
   int dest_d = sess->sd;
   char buf[INBUFSIZE];
-  int rlen = read(source_d, buf, INBUFSIZE);
+  int rlen = read(sess->sd, buf, INBUFSIZE);
+  if (rlen > 0) {
+    char *line;
+    query_extract_from_buf_2(buf, &rlen, &line);
+    if (!strcmp(line, "cancel\n")) {
+      free(line);
+      /* replace session buffer with the rest of the local buffer */
+      memcpy(sess->buf, buf, rlen);
+      sess->buf_used = rlen;
+      clear_file_from_sess(sess);
+      sess->state = OP_WAIT;
+      return;
+    }
+  }
+  rlen = read(source_d, buf, INBUFSIZE);
   if (rlen == 0) {
     if (sess->file->rest) {
       print_log(stdout, pl_error, "Error downloading file %s!\n",
diff --git a/src/main.c b/src/main.c
index 9c927bc..20a9de8 100644
--- a/src/main.c
+++ b/src/main.c
@@ -5,7 +5,6 @@
 #include "server.h"
 #include "utils.h"
 #include <db.h>
-#include <stdio.h>
 
 /* *** MAIN *** */
 int main(int argc, char *argv[]) {
diff --git a/src/session.c b/src/session.c
index dd66c31..c8ca2d1 100644
--- a/src/session.c
+++ b/src/session.c
@@ -31,6 +31,11 @@ int32_t accept_client(int ls, session *connections[], char *wm) {
     perror("accept");
     return -1;
   }
+  /* set non-blocking behaviour */
+  int flags = fcntl(sd, F_GETFL, 0);
+  flags = flags | O_NONBLOCK;
+  fcntl(sd, F_SETFL, flags);
+  
   session *sess = make_new_session(sd, &addr, wm);
   print_log(stdout, pl_info, "New connection: %s:%u\n",
             inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
@@ -135,6 +140,49 @@ int query_extract_from_buf(session *sess, char **output_line) {
   return pos + 1;
 }
 
+int query_extract_from_buf_2(char *buf, int *buf_used, char **output_line) {
+  char *line;
+  int pos = -1;
+  int _buf_used = *buf_used;
+
+  if (_buf_used > 0) {
+    char *cptr = strchr(buf, '\n');
+    if (cptr != NULL)
+      pos = cptr - buf;
+  } else {
+    return 0;
+  }
+
+  if (pos == -1) {
+    int b_used = _buf_used;
+    *buf_used = 0;
+    line = malloc(b_used + 1);
+    strncpy(line, buf, b_used);
+
+    line[b_used] = 0;
+
+    *output_line = line;
+    return b_used;
+  } else {
+    line = malloc(pos + 2);
+    strncpy(line, buf, pos + 1);
+    line[++pos] = 0;
+    _buf_used -= (pos);
+    if (!pos)
+      pos++;
+    memmove(buf, buf + pos, _buf_used);
+    buf[_buf_used] = 0;
+    if (line[pos - 2] == '\r') {
+      line[pos - 2] = line[pos - 1];
+      pos--;
+      line[pos - 1] = 0;
+    }
+    *output_line = line;
+    *buf_used = _buf_used;
+  }
+  return pos + 1;
+}
+
 void perform_session_action(session *sess, char *line, server_data_t *s_d) {
   int state = sess->state;
   int res;
diff --git a/src/session.h b/src/session.h
index 9a68ef0..577c12b 100644
--- a/src/session.h
+++ b/src/session.h
@@ -10,6 +10,7 @@ int query_extract_from_buf(session *sess, char **output_line);
 int session_do_read(session *sess, char **read_str);
 void perform_session_action(session *sess, char *line, server_data_t *s_d);
 void close_session(session *connections[], int sd);
+int query_extract_from_buf_2(char *buf, int *buf_used, char **output_line);
 /* session *make_new_session(int fd, struct sockaddr_in *from, char *wm); */
 /* int query_extract_from_sess(session *sess, char **output_line); */
 #endif
\ No newline at end of file