[Global]: loading init

deps/curl/docs/libcurl/curl_easy_recv.md

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+---
+c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
+SPDX-License-Identifier: curl
+Title: curl_easy_recv
+Section: 3
+Source: libcurl
+See-also:
+  - curl_easy_getinfo (3)
+  - curl_easy_perform (3)
+  - curl_easy_send (3)
+  - curl_easy_setopt (3)
+---
+
+# NAME
+
+curl_easy_recv - receives raw data on an "easy" connection
+
+# SYNOPSIS
+
+~~~c
+#include <curl/curl.h>
+
+CURLcode curl_easy_recv(CURL *curl, void *buffer, size_t buflen, size_t *n);
+~~~
+
+# DESCRIPTION
+
+This function receives raw data from the established connection. You may use
+it together with curl_easy_send(3) to implement custom protocols using
+libcurl. This functionality can be particularly useful if you use proxies
+and/or SSL encryption: libcurl takes care of proxy negotiation and connection
+setup.
+
+**buffer** is a pointer to your buffer memory that gets populated by the
+received data. **buflen** is the maximum amount of data you can get in that
+buffer. The variable **n** points to receives the number of received bytes.
+
+To establish the connection, set CURLOPT_CONNECT_ONLY(3) option before
+calling curl_easy_perform(3) or curl_multi_perform(3). Note that
+curl_easy_recv(3) does not work on connections that were created without
+this option.
+
+The call returns **CURLE_AGAIN** if there is no data to read - the socket is
+used in non-blocking mode internally. When **CURLE_AGAIN** is returned, use
+your operating system facilities like *select(2)* to wait for data. The
+socket may be obtained using curl_easy_getinfo(3) with
+CURLINFO_ACTIVESOCKET(3).
+
+Wait on the socket only if curl_easy_recv(3) returns **CURLE_AGAIN**.
+The reason for this is libcurl or the SSL library may internally cache some
+data, therefore you should call curl_easy_recv(3) until all data is
+read which would include any cached data.
+
+Furthermore if you wait on the socket and it tells you there is data to read,
+curl_easy_recv(3) may return **CURLE_AGAIN** if the only data that was
+read was for internal SSL processing, and no other data is available.
+
+# EXAMPLE
+
+~~~c
+int main(void)
+{
+  CURL *curl = curl_easy_init();
+  if(curl) {
+    CURLcode res;
+    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
+    /* Do not do the transfer - only connect to host */
+    curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
+    res = curl_easy_perform(curl);
+
+    if(res == CURLE_OK) {
+      char buf[256];
+      size_t nread;
+      long sockfd;
+
+      /* Extract the socket from the curl handle - we need it for waiting. */
+      res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);
+
+      /* read data */
+      res = curl_easy_recv(curl, buf, sizeof(buf), &nread);
+    }
+  }
+}
+~~~
+
+# AVAILABILITY
+
+Added in 7.18.2.
+
+# RETURN VALUE
+
+On success, returns **CURLE_OK**, stores the received data into
+**buffer**, and the number of bytes it actually read into ***n**.
+
+On failure, returns the appropriate error code.
+
+The function may return **CURLE_AGAIN**. In this case, use your operating
+system facilities to wait until data can be read, and retry.
+
+Reading exactly 0 bytes indicates a closed connection.
+
+If there is no socket available to use from the previous transfer, this function
+returns **CURLE_UNSUPPORTED_PROTOCOL**.