transaction: detect an attempt to truncate-to-extend on playback, raise error On some networked filesystems, writes can have delayed finalization/confirmation and write races can occur such that a remote modification will "win" and modifications will be lost. There is no functionality for providing this feedback to userspace programs (in fact, there's not even functionality for providing this information to the Linux kernel...), so these programs may see the files suddenly change. We've noticed that there have been cases where Mercurial has detected something has gone wrong and attempts to abort (rolling back the transaction), which is good. However, when rolling back the transaction, for the append-only files, we attempt to "truncate" the file back to the size it was in before the hg transaction started, but end up *extending* it. This may be harmless, but if this happens to the 00changelog.i file, we get a bunch of nulls on the end of the file and this causes hg to become *really* confused. :) If we detect that some modification of the file outside of this Mercurial process has caused the file to be smaller than the size we are attempting to truncate to, let's just exit and stop trying to clean up the repository - continuing will likely just cause more damage. Differential Revision: https://phab.mercurial-scm.org/D6867

osutil: tolerate Py_GetArgcArgv not being set up properly Differential Revision: https://phab.mercurial-scm.org/D6866

osutil: allow disabling setprocname via a define passed to the compiler In some situations, we run a custom python launcher that appears to not set up Py_GetArgcArgv correctly. We then proceed to promptly crash when we attempt to dereference NULL. Being able to completely disable setprocname is beneficial in these situations, since we won't even attempt to use it, even if the case that causes the crash is fixed. Right now, if I compile osutil.so with -DSETPROCNAME_USE_NONE, the compilation fails on python3 due to SETPROCNAME_USE_NONE redefinition. I could possibly work around that, but it's likely helpful to have a way of disabling this completely without it being brittle (i.e. if python3 ever gains the ability to perform this operation). Differential Revision: https://phab.mercurial-scm.org/D6865

stack: use repo.revs() instead of revsetlang.formatspec() + scmutil.revrange() Using scmutil.revrange() it's possible to use multiple revsets at the same time, but we're not using that functionality in stack. I thought maybe that function could be used to make stack definition customizable (by combining various parts into one set), but scmutil.revrange() gives the union of all provided revsets, which is not very useful in stack's case (we want "and" between parts, not "or").

merge with stable

rust-hgpath: replace all paths and filenames with HgPath/HgPathBuf Differential Revision: https://phab.mercurial-scm.org/D6774

rust-hgpath: add HgPath and HgPathBuf structs to encapsulate handling of paths This change is a direct consequence of this discussion on the mailing list: https://www.mercurial-scm.org/pipermail/mercurial-devel/2019-August/133574.html The implementations of `HgPath` and `HgPathBuf` are, for the most part, taken directly from `OsStr` and `OsString` respectively from the standard library. What this change does *not* yet do is implement the Windows MBCS to WTF8 conversion, but it lays the basis for a very flexible interface for paths. Differential Revision: https://phab.mercurial-scm.org/D6773

wireprototypes: clarify documentation of getbundle argument types It seems like it was a mix of what the Python code would see and what was sent over the wire. I've tried to clarify both the type seen in Python and how it's transmitted. Differential Revision: https://phab.mercurial-scm.org/D6871

merge with stable

py3: don't double-convert "opts" to bytes The "opts" are already converted to bytes at the beginning of the function. Doing it twice results in a crash, which makes test-uncommit.t fail. The extra call was added recently, in ff1ff2aae132 (uncommit: add support to modify the commit message and date, 2019-09-07). test-uncommit.t passes again after this patch. Differential Revision: https://phab.mercurial-scm.org/D6864