diff options
Diffstat (limited to 'docs/INTERNALS')
| -rw-r--r-- | docs/INTERNALS | 109 |
1 files changed, 73 insertions, 36 deletions
diff --git a/docs/INTERNALS b/docs/INTERNALS index e0553409c..0cbd91a98 100644 --- a/docs/INTERNALS +++ b/docs/INTERNALS @@ -1,4 +1,4 @@ - Updated for curl 7.7 on March 13, 2001 + Updated for curl 7.7.2 on April 26, 2001 _ _ ____ _ ___| | | | _ \| | / __| | | | |_) | | @@ -73,7 +73,7 @@ Library makes sure we stay absolutely platform independent. curl_easy_init() allocates an internal struct and makes some initializations. - The returned handle does not revail internals. + The returned handle does not reveal internals. curl_easy_setopt() takes a three arguments, where the option stuff must be passed in pairs, the parameter-ID and the parameter-value. The list of @@ -81,33 +81,68 @@ Library curl_easy_perform() does a whole lot of things: - It starts off in the lib/easy.c file by calling curl_transfer(), but the main - work is lib/url.c. The function first analyzes the URL, it separates the - different components and connects to the remote host. This may involve using - a proxy and/or using SSL. The Curl_gethost() function in lib/hostip.c is used - for looking up host names. - - When connected, the proper protocol-specific function is called. The - functions are named after the protocols they handle. Curl_ftp(), Curl_http(), - Curl_dict(), etc. They all reside in their respective files (ftp.c, http.c - and dict.c). - - The protocol-specific functions of course deal with protocol-specific - negotiations and setup. They have access to the Curl_sendf() (from - lib/sendf.c) function to send printf-style formatted data to the remote host - and when they're ready to make the actual file transfer they call the - Curl_Transfer() function (in lib/transfer.c) to setup the transfer and - returns. Curl_perform() then calls Transfer() in lib/transfer.c that performs - the entire file transfer. Curl_perform() is what does the main "connect - do - - transfer - done" loop. It loops if there's a Location: to follow. - - During transfer, the progress functions in lib/progress.c are called at a - frequent interval (or at the user's choice, a specified callback might get - called). The speedcheck functions in lib/speedcheck.c are also used to verify - that the transfer is as fast as required. + It starts off in the lib/easy.c file by calling Curl_perform() and the main + work then continues lib/url.c. The flow continues with a call to + Curl_connect() to connect to the remote site. + + o Curl_connect() + + ... analyzes the URL, it separates the different components and connects to + the remote host. This may involve using a proxy and/or using SSL. The + Curl_gethost() function in lib/hostip.c is used for looking up host names. + + When Curl_connect is done, we are connected to the remote site. Then it is + time to tell the server to get a document/file. Curl_do() arranges this. + + o Curl_do() + + Curl_do() makes sure the proper protocol-specific function is called. The + functions are named after the protocols they handle. Curl_ftp(), + Curl_http(), Curl_dict(), etc. They all reside in their respective files + (ftp.c, http.c and dict.c). + + The protocol-specific functions of course deal with protocol-specific + negotiations and setup. They have access to the Curl_sendf() (from + lib/sendf.c) function to send printf-style formatted data to the remote + host and when they're ready to make the actual file transfer they call the + Curl_Transfer() function (in lib/transfer.c) to setup the transfer and + returns. + + o Transfer() + + Curl_perform() then calls Transfer() in lib/transfer.c that performs + the entire file transfer. + + During transfer, the progress functions in lib/progress.c are called at a + frequent interval (or at the user's choice, a specified callback might get + called). The speedcheck functions in lib/speedcheck.c are also used to + verify that the transfer is as fast as required. + + o Curl_done() + + Called after a transfer is done. This function takes care of everything + that has to be done after a transfer. This function attempts to leave + matters in a state so that Curl_do() should be possible to call again on + the same connection (in a persistent connection case). It may also soon be + closed with Curl_disconnect(). + + o Curl_disconnect() + + During normal connection and transfers, no one ever tries to close any + connection so this is not normally called when curl_easy_perform() is + used. This function is only used when we are certain that no more transfers + is going to be made on the connection (it can be also closed by + force). This function can also be called at times to make sure that libcurl + doesn't keep too many connections alive at the same time. + + This function cleans up all resources that are associated with a single + connection. + + Curl_perform() is the function that does the main "connect - do - transfer - + done" loop. It loops if there's a Location: to follow. When completed, the curl_easy_cleanup() should be called to free up used - resources. + resources. It runs Curl_disconnect() on all open connectons. A quick roundup on internal function sequences (many of these call protocol-specific function-pointers): @@ -257,6 +292,7 @@ Client ====== main() resides in src/main.c together with most of the client code. + src/hugehelp.c is automatically generated by the mkhelp.pl perl script to display the complete "manual" and the src/urlglob.c file holds the functions used for the URL-"globbing" support. Globbing in the sense that the {} and [] @@ -272,25 +308,26 @@ Client curl_easy_getinfo() function to extract useful information from the curl session. - Recent versions may loop and do all that several times if many URLs were + Recent versions may loop and do all this several times if many URLs were specified on the command line or config file. Memory Debugging ================ - The file named lib/memdebug.c contains debug-versions of a few - functions. Functions such as malloc, free, fopen, fclose, etc that somehow - deal with resources that might give us problems if we "leak" them. The - functions in the memdebug system do nothing fancy, they do their normal - function and then log information about what they just did. The logged data - can then be analyzed after a complete session, + The file lib/memdebug.c contains debug-versions of a few functions. Functions + such as malloc, free, fopen, fclose, etc that somehow deal with resources + that might give us problems if we "leak" them. The functions in the memdebug + system do nothing fancy, they do their normal function and then log + information about what they just did. The logged data can then be analyzed + after a complete session, - memanalyze.pl is a perl script present only present in CVS (not part of the + memanalyze.pl is the perl script present only present in CVS (not part of the release archives) that analyzes a log file generated by the memdebug system. It detects if resources are allocated but never freed and other kinds of errors related to resource management. - Use -DMALLOCDEBUG when compiling to enable memory debugging. + Use -DMALLOCDEBUG when compiling to enable memory debugging, this is also + switched on by running configure with --enable-debug. Test Suite ========== |