tests/wireprotohelpers.sh

posix: always seek to EOF when opening a file in append mode

Python 3 already does this, so skip it there.

Consider the program:

   #include <stdio.h>

   int main() {
     FILE *f = fopen("narf", "w");
     fprintf(f, "narf\n");
     fclose(f);

     f = fopen("narf", "a");
     printf("%ld\n", ftell(f));
     fprintf(f, "troz\n");
     printf("%ld\n", ftell(f));

     return 0;
   }

on macOS, FreeBSD, and Linux with glibc, this program prints

   5
   10

but on musl libc (Alpine Linux and probably others) this prints

   0
   10

By my reading of
https://pubs.opengroup.org/onlinepubs/009695399/functions/fopen.html
this is technically correct, specifically:

> Opening a file with append mode (a as the first character in the
> mode argument) shall cause all subsequent writes to the file to be
> forced to the then current end-of-file, regardless of intervening
> calls to fseek().

in other words, the file position doesn't really matter in append-mode
files, and we can't depend on it being at all meaningful unless we
perform a seek() before tell() after open(..., 'a'). Experimentally
after a .write() we can do a .tell() and it'll always be reasonable,
but I'm unclear from reading the specification if that's a smart thing
to rely on. This matches what we do on Windows and what Python 3 does
for free, so let's just be consistent. Thanks to Yuya for the idea.

HTTPV2=exp-http-v2-0003
MEDIATYPE=application/mercurial-exp-framing-0006

sendhttpraw() {
  hg --verbose debugwireproto --peer raw http://$LOCALIP:$HGPORT/
}

sendhttpv2peer() {
  hg --config experimental.httppeer.v2-encoder-order=identity debugwireproto --nologhandshake --peer http2 http://$LOCALIP:$HGPORT/
}

sendhttpv2peerverbose() {
  hg --config experimental.httppeer.v2-encoder-order=identity --verbose debugwireproto --nologhandshake --peer http2 http://$LOCALIP:$HGPORT/
}

sendhttpv2peerhandshake() {
  hg --config experimental.httppeer.v2-encoder-order=identity --verbose debugwireproto --peer http2 http://$LOCALIP:$HGPORT/
}

cat > dummycommands.py << EOF
from mercurial import (
    wireprototypes,
    wireprotov1server,
    wireprotov2server,
)

@wireprotov1server.wireprotocommand(b'customreadonly', permission=b'pull')
def customreadonlyv1(repo, proto):
    return wireprototypes.bytesresponse(b'customreadonly bytes response')

@wireprotov2server.wireprotocommand(b'customreadonly', permission=b'pull')
def customreadonlyv2(repo, proto):
    yield b'customreadonly bytes response'

@wireprotov1server.wireprotocommand(b'customreadwrite', permission=b'push')
def customreadwrite(repo, proto):
    return wireprototypes.bytesresponse(b'customreadwrite bytes response')

@wireprotov2server.wireprotocommand(b'customreadwrite', permission=b'push')
def customreadwritev2(repo, proto):
    yield b'customreadwrite bytes response'
EOF

cat >> $HGRCPATH << EOF
[extensions]
drawdag = $TESTDIR/drawdag.py
EOF

enabledummycommands() {
  cat >> $HGRCPATH << EOF
[extensions]
dummycommands = $TESTTMP/dummycommands.py
EOF
}

enablehttpv2() {
  cat >> $1/.hg/hgrc << EOF
[experimental]
web.apiserver = true
web.api.http-v2 = true
EOF
}

enablehttpv2client() {
  cat >> $HGRCPATH << EOF
[experimental]
httppeer.advertise-v2 = true
# So tests are in plain text. Also, zstd isn't available in all installs,
# which would make tests non-deterministic.
httppeer.v2-encoder-order = identity
EOF
}