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| .TH curl_global_trace 3 "01 August 2023" "libcurl" "libcurl" |
| .SH NAME |
| curl_global_trace - Global libcurl logging configuration |
| .SH SYNOPSIS |
| .nf |
| #include <curl/curl.h> |
| |
| CURLcode curl_global_trace(const char *config); |
| .fi |
| .SH DESCRIPTION |
| This function configures the logging behavior, allowing to make some |
| parts of curl more verbose or silent than others. |
| |
| This function may be called during the initialization phase of a program. It |
| does not have to be. It can be called several times even, possibly overwriting |
| settings of previous calls. |
| |
| Calling this function after transfers have been started is undefined. On |
| some platforms/architectures it might take effect, on others not. |
| |
| This function is thread-safe since libcurl 8.3.0 if |
| \fIcurl_version_info(3)\fP has the CURL_VERSION_THREADSAFE feature bit set |
| (most platforms). |
| |
| If this is not thread-safe, you must not call this function when any other |
| thread in the program (i.e. a thread sharing the same memory) is running. |
| This does not just mean no other thread that is using libcurl. Because |
| \fIcurl_global_init(3)\fP may call functions of other libraries that are |
| similarly thread unsafe, it could conflict with any other thread that uses |
| these other libraries. |
| |
| If you are initializing libcurl from a Windows DLL you should not initialize |
| it from \fIDllMain\fP or a static initializer because Windows holds the loader |
| lock during that time and it could cause a deadlock. |
| |
| The \fIconfig\fP string is a list of comma-separated component names. Names |
| are case-insensitive and unknown names are ignored. The special name "all" |
| applies to all components. Names may be prefixed with '+' or '-' to enable |
| or disable detailed logging for a component. |
| |
| The list of component names is not part of curl's public API. Names may be |
| added or disappear in future versions of libcurl. Since unknown names are |
| silently ignored, outdated log configurations does not cause errors when |
| upgrading libcurl. Given that, some names can be expected to be fairly stable |
| and are listed below for easy reference. |
| |
| Note that log configuration applies only to transfers where debug logging |
| is enabled. See \fICURLOPT_VERBOSE(3)\fP or \fICURLOPT_DEBUGFUNCTION(3)\fP |
| on how to control that. |
| |
| .SH TRACE COMPONENTS |
| .IP tcp |
| Tracing of TCP socket handling: connect, reads, writes. |
| .IP ssl |
| Tracing of SSL/TLS operations, whichever SSL backend is used in your build. |
| .IP http/2 |
| Details about HTTP/2 handling: frames, events, I/O, etc. |
| .IP http/3 |
| Details about HTTP/3 handling: connect, frames, events, I/O etc. |
| .IP http-proxy |
| Involved when transfers are tunneled through a HTTP proxy. "h1-proxy" or |
| "h2-proxy" are also involved, depending on the HTTP version negotiated with |
| the proxy. |
| |
| In order to find out all components involved in a transfer, run it with "all" |
| configured. You can then see all names involved in your libcurl version in the |
| trace. |
| |
| .SH EXAMPLE |
| .nf |
| int main(void) |
| { |
| /* log details of HTTP/2 and SSL handling */ |
| curl_global_trace("http/2,ssl"); |
| |
| /* log all details, except SSL handling */ |
| curl_global_trace("all,-ssl"); |
| } |
| .fi |
| |
| Below is a trace sample where "http/2" was configured. The trace output |
| of an enabled component appears at the beginning in brackets. |
| .nf |
| * [HTTP/2] [h2sid=1] cf_send(len=96) submit https://example.com/ |
| \&... |
| * [HTTP/2] [h2sid=1] FRAME[HEADERS] |
| * [HTTP/2] [h2sid=1] 249 header bytes |
| \&... |
| .fi |
| |
| .SH AVAILABILITY |
| Added in 8.3 |
| .SH RETURN VALUE |
| If this function returns non-zero, something went wrong and the configuration |
| may not have any effects or may only been applied partially. |
| .SH "SEE ALSO" |
| .BR curl_global_init (3), |
| .BR libcurl (3) |
