curl_easy_perform.3: extended and clarified

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.\" * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.

.\" * Copyright (C) 1998 - 2014, Daniel Stenberg, <daniel@haxx.se>, et al.

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.SH SYNOPSIS

.B #include <curl/curl.h>

.sp

.BI "CURLcode curl_easy_perform(CURL *" handle ");"

.BI "CURLcode curl_easy_perform(CURL *" easy_handle ");"

.ad

.SH DESCRIPTION

This function is called after the init and all the \fIcurl_easy_setopt(3)\fP

calls are made, and will perform the transfer as described in the options.  It

must be called with the same

.I handle

as input as the curl_easy_init call returned.

Invoke this function after \fIcurl_easy_init(3)\fP and all the

\fIcurl_easy_setopt(3)\fP calls are made, and will perform the transfer as

described in the options. It must be called with the same \fBeasy_handle\fP as

input as the \fIcurl_easy_init(3)\fP call returned.

\fIcurl_easy_perform(3)\fP performs the entire request in a blocking manner

and returns when done, or if it failed. For non-blocking behavior, see

\fIcurl_multi_perform(3)\fP.

You can do any amount of calls to \fIcurl_easy_perform(3)\fP while using the

same handle. If you intend to transfer more than one file, you are even

encouraged to do so. libcurl will then attempt to re-use the same connection

for the following transfers, thus making the operations faster, less CPU

intense and using less network resources. Just note that you will have to use

\fIcurl_easy_setopt(3)\fP between the invokes to set options for the following

curl_easy_perform.

same \fBeasy_handle\fP. If you intend to transfer more than one file, you are

even encouraged to do so. libcurl will then attempt to re-use the same

connection for the following transfers, thus making the operations faster,

less CPU intense and using less network resources. Just note that you will

have to use \fIcurl_easy_setopt(3)\fP between the invokes to set options for

the following curl_easy_perform.

You must never call this function simultaneously from two places using the

same handle. Let the function return first before invoking it another time. If

you want parallel transfers, you must use several curl handles.

same \fBeasy_handle\fP. Let the function return first before invoking it

another time. If you want parallel transfers, you must use several curl

easy_handles.

While the \fBeasy_handle\fP is added to a multi handle, it cannot be used by

\fIcurl_easy_perform(3)\fP.

.SH RETURN VALUE

0 means everything was ok, non-zero means an error occurred as

CURLE_OK (0) means everything was ok, non-zero means an error occurred as

.I <curl/curl.h>

defines. If the CURLOPT_ERRORBUFFER was set with

.I curl_easy_setopt

there will be a readable error message in the error buffer when non-zero is

returned.

defines - see \fIlibcurl-errors(3)\fP. If the \fBCURLOPT_ERRORBUFFER\fP was

set with \fIcurl_easy_setopt(3)\fP there will be a readable error message in

the error buffer when non-zero is returned.

.SH "SEE ALSO"

.BR curl_easy_init "(3), " curl_easy_setopt "(3), "

.BR curl_multi_add_handle "(3), " curl_multi_perform "(3), "

.BR libcurl-errors "(3), "