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| author | Daniel Stenberg <daniel@haxx.se> | 2018-02-16 11:23:12 +0100 |
|---|---|---|
| committer | Daniel Stenberg <daniel@haxx.se> | 2018-02-16 22:54:51 +0100 |
| commit | 174212972c5d508cf54664f97217d5fe63134490 (patch) | |
| tree | 879dfbc0f65385d733f9e6cfbcf72a4c5b3cd5d3 | |
| parent | 70cbb921348db5193549efbe30877a0398b559a0 (diff) | |
| download | curl-174212972c5d508cf54664f97217d5fe63134490.tar.gz | |
CURLOPT_HEADER.3: clarify problems with different data sizes
| -rw-r--r-- | docs/libcurl/opts/CURLOPT_HEADER.3 | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/docs/libcurl/opts/CURLOPT_HEADER.3 b/docs/libcurl/opts/CURLOPT_HEADER.3 index b650163d1..76dea467e 100644 --- a/docs/libcurl/opts/CURLOPT_HEADER.3 +++ b/docs/libcurl/opts/CURLOPT_HEADER.3 @@ -5,7 +5,7 @@ .\" * | (__| |_| | _ <| |___ .\" * \___|\___/|_| \_\_____| .\" * -.\" * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al. +.\" * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al. .\" * .\" * This software is licensed as described in the file COPYING, which .\" * you should have received as part of this distribution. The terms @@ -28,14 +28,20 @@ CURLOPT_HEADER \- pass headers to the data stream CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HEADER, long onoff); .SH DESCRIPTION -Pass in \fIonoff\fP set to 1 to tell the library to include the header in the -body output for requests with this \fIhandle\fP. This option is relevant for -protocols that actually have headers or other meta-data (like HTTP and FTP). +Pass the long value \fIonoff\fP set to 1 to ask libcurl to include the headers +in the write callback (\fICURLOPT_WRITEFUNCTION(3)\fP). This option is +relevant for protocols that actually have headers or other meta-data (like +HTTP and FTP). -When asking to get the header info passed to the same callback as the body, it -is not possible to accurately separate them again without detailed knowledge +When asking to get the headers passed to the same callback as the body, it is +not possible to accurately separate them again without detailed knowledge about the protocol in use. +Further: the \fCURLOPT_WRITEFUNCTION(3)\fP callback is limited to only ever +get a maximum of \fICURL_MAX_WRITE_SIZE\fP bytes passed to it (16KB), while a +header can be longer and the \fICURLOPT_HEADERFUNCTION(3)\fP supports getting +called with headers up to \fICURL_MAX_HTTP_HEADER\fP bytes big (100KB). + It is often better to use \fICURLOPT_HEADERFUNCTION(3)\fP to get the header data separately. |