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Simon Tatham bc91a39670 Proper buffer management between terminal and backend.
The return value of term_data() is used as the return value from the
GUI-terminal versions of the Seat output method, which means backends
will take it to be the amount of standard-output data currently
buffered, and exert back-pressure on the remote peer if it gets too
big (e.g. by ceasing to extend the window in that particular SSH-2
channel).

Historically, as a comment in term_data() explained, we always just
returned 0 from that function, on the basis that we were processing
all the terminal data through our terminal emulation code immediately,
and never retained any of it in the buffer at all. If the terminal
emulation code were to start running slowly, then it would slow down
the _whole_ PuTTY system, due to single-threadedness, and
back-pressure of a sort would be exerted on the remote by it simply
failing to get round to reading from the network socket. But by the
time we got back to the top level of term_data(), we'd have finished
reading all the data we had, so it was still appropriate to return 0.

That comment is still correct if you're thinking about the limiting
factor on terminal data processing being the CPU usage in term_out().
But now that's no longer the whole story, because sometimes we leave
data in term->inbuf without having processed it: during drag-selects
in the terminal window, and (just introduced) while waiting for the
response to a pending window resize request. For both those reasons,
we _don't_ always have a buffer size of zero when we return from
term_data().

So now that hole in our buffer size management is filled in:
term_data() returns the true size of the remaining unprocessed
terminal output, so that back-pressure will be exerted if the terminal
is currently not consuming it. And when processing resumes and we
start to clear our backlog, we call backend_unthrottle to let the
backend know it can relax the back-pressure if necessary.
2021-12-19 11:02:48 +00:00
charset Add missing dependencies on generated source files. 2021-04-18 17:01:50 +01:00
cmake Fix pre-GTK3 build failures in puttyapp / ptermapp. 2021-12-18 11:43:57 +00:00
contrib New script contrib/proveprime.py. 2021-06-12 13:50:51 +01:00
crypto Stop using short exponents for Diffie-Hellman. 2021-11-28 12:19:34 +00:00
doc Compatibility with older versions of cmake. 2021-10-29 18:08:18 +01:00
icons Make Windows versions of the pterm icons. 2021-05-08 17:33:25 +01:00
keygen Generalise strbuf_catf() into put_fmt(). 2021-11-19 11:32:47 +00:00
otherbackends Generalise strbuf_catf() into put_fmt(). 2021-11-19 11:32:47 +00:00
proxy Withdraw support for SHA-512-256 in HTTP Digest. 2021-11-27 11:41:00 +00:00
ssh Stop using short exponents for Diffie-Hellman. 2021-11-28 12:19:34 +00:00
stubs Move some more files into subdirectories. 2021-11-23 18:52:15 +00:00
terminal Proper buffer management between terminal and backend. 2021-12-19 11:02:48 +00:00
test Proper buffer management between terminal and backend. 2021-12-19 11:02:48 +00:00
unix Proper buffer management between terminal and backend. 2021-12-19 11:02:48 +00:00
utils Remove a redundant file in utils. 2021-11-30 18:48:06 +00:00
windows Proper buffer management between terminal and backend. 2021-12-19 11:02:48 +00:00
.gitignore Add .gitignore rules for in-tree builds. 2021-04-19 18:26:56 +01:00
aqsync.c Build outgoing SSH agent requests in a strbuf. 2018-05-25 14:36:16 +01:00
be_list.c Merge be_*.c into one ifdef-controlled module. 2021-11-26 17:58:55 +00:00
Buildscr Merge tag '0.76' into main 2021-07-17 11:49:44 +01:00
Buildscr.cv Replace mkfiles.pl with a CMake build system. 2021-04-17 13:53:02 +01:00
callback.c Add lots of missing 'static' keywords. 2020-01-29 06:44:18 +00:00
cgtest.c cmdgen: support configurable key fingerprint type. 2021-03-13 11:01:35 +00:00
CHECKLST.txt Compatibility with older versions of cmake. 2021-10-29 18:08:18 +01:00
clicons.c Change vtable defs to use C99 designated initialisers. 2020-03-10 21:06:29 +00:00
CMakeLists.txt Merge be_*.c into one ifdef-controlled module. 2021-11-26 17:58:55 +00:00
cmdgen.c cmdgen: add missing null pointer check in --dump mode. 2021-06-12 14:08:10 +01:00
cmdline.c Add -pwfile option, a more secure version of -pw. 2021-09-28 18:04:15 +01:00
config.c Lowercase version of BackendVtable's displayname. 2021-10-24 09:59:05 +01:00
console.c Mention the host name in host-key prompts. 2021-09-16 14:33:59 +01:00
console.h Mention the host name in host-key prompts. 2021-09-16 14:33:59 +01:00
defs.h Move STR() and CAT() into defs.h. 2021-11-26 17:46:06 +00:00
dialog.c dialog system: add a side-by-side alignment feature. 2021-04-10 09:43:25 +01:00
dialog.h dialog system: add a side-by-side alignment feature. 2021-04-10 09:43:25 +01:00
errsock.c Change vtable defs to use C99 designated initialisers. 2020-03-10 21:06:29 +00:00
import.c Spelling: standardise on "DSA", not "DSS". 2021-04-22 18:34:47 +01:00
LATEST.VER Update version number for 0.76 release. 2021-07-10 10:39:20 +01:00
ldisc.c free_prompts: deal with a reference from an Ldisc. 2021-09-16 13:55:10 +01:00
LICENCE It's a new year. 2021-01-11 21:37:51 +00:00
licence.pl Separate the functions of licence.pl. 2021-04-17 13:52:27 +01:00
logging.c sshproxy: share the caller's LogPolicy. 2021-09-13 17:18:31 +01:00
marshal.h marshal.[ch]: remove redundant declaration. 2021-11-19 15:09:17 +00:00
misc.h Generalise strbuf_catf() into put_fmt(). 2021-11-19 11:32:47 +00:00
mksrcarc.sh Replace mkfiles.pl with a CMake build system. 2021-04-17 13:53:02 +01:00
mkunxarc.sh Integrate the 'doc' subdir into the CMake system. 2021-05-03 17:01:55 +01:00
mpint.h Make mp_unsafe_mod_integer not be unsafe. 2021-08-27 17:43:40 +01:00
network.h Move some more files into subdirectories. 2021-11-23 18:52:15 +00:00
pageant.c New API for plug_closing() with a custom type enum. 2021-11-06 14:48:26 +00:00
pageant.h winpgnt: menu options to delete/reencrypt everything. 2021-04-04 10:02:24 +01:00
pinger.c Whitespace rationalisation of entire code base. 2019-09-08 20:29:21 +01:00
pscp.c PSCP: fix filename in 'compound pathname' error. 2021-12-12 10:49:31 +00:00
psftp.c Merge be_*.c into one ifdef-controlled module. 2021-11-26 17:58:55 +00:00
psftp.h Remove FLAG_VERBOSE. 2020-01-30 06:40:21 +00:00
psftpcommon.c Move the SSH implementation into its own subdirectory. 2021-04-22 18:09:13 +01:00
psocks.c New API for plug_closing() with a custom type enum. 2021-11-06 14:48:26 +00:00
psocks.h Auxiliary application: 'psocks', a simple SOCKS server. 2020-02-23 16:36:27 +00:00
putty.h Proper buffer management between terminal and backend. 2021-12-19 11:02:48 +00:00
puttymem.h Whitespace rationalisation of entire code base. 2019-09-08 20:29:21 +01:00
README Replace mkfiles.pl with a CMake build system. 2021-04-17 13:53:02 +01:00
release.pl Replace mkfiles.pl with a CMake build system. 2021-04-17 13:53:02 +01:00
settings.c Make BugDropStart default to FORCE_OFF, not AUTO. 2021-11-04 15:13:33 +00:00
sign.sh GPG key rollover. 2021-08-14 08:02:27 +01:00
ssh.h Stop using short exponents for Diffie-Hellman. 2021-11-28 12:19:34 +00:00
sshcr.h Assorted benign warning fixes. 2020-01-29 06:44:18 +00:00
sshkeygen.h Side-channel-safe rewrite of the Miller-Rabin test. 2021-08-27 18:04:49 +01:00
sshpubk.c Generalise strbuf_catf() into put_fmt(). 2021-11-19 11:32:47 +00:00
sshrand.c Remove dependency of sshrand.c on SHA-512. 2020-09-13 09:11:31 +01:00
storage.h Reorganise host key checking and confirmation. 2021-10-25 18:12:17 +01:00
timing.c Whitespace rationalisation of entire code base. 2019-09-08 20:29:21 +01:00
tree234.h Whitespace rationalisation of entire code base. 2019-09-08 20:29:21 +01:00
version.h Replace mkfiles.pl with a CMake build system. 2021-04-17 13:53:02 +01:00
x11disp.c Move the SSH implementation into its own subdirectory. 2021-04-22 18:09:13 +01:00

This is the README for PuTTY, a free Windows and Unix Telnet and SSH
client.

PuTTY is built using CMake <https://cmake.org/>. To compile in the
simplest way (on any of Linux, Windows or Mac), run these commands in
the source directory:

  cmake .
  cmake --build .

Documentation (in various formats including Windows Help and Unix
`man' pages) is built from the Halibut (`.but') files in the `doc'
subdirectory using `doc/Makefile'. If you aren't using one of our
source snapshots, you'll need to do this yourself. Halibut can be
found at <https://www.chiark.greenend.org.uk/~sgtatham/halibut/>.

The PuTTY home web site is

    https://www.chiark.greenend.org.uk/~sgtatham/putty/

If you want to send bug reports or feature requests, please read the
Feedback section of the web site before doing so. Sending one-line
reports saying `it doesn't work' will waste your time as much as
ours.

See the file LICENCE for the licence conditions.