view tests/sslcerts/client-key.pem @ 42377:0546ead39a7e stable

manifest: avoid corruption by dropping removed files with pure (issue5801)

Previously, removed files would simply be marked by overwriting the first byte
with NUL and dropping their entry in `self.position`.  But no effort was made to
ignore them when compacting the dictionary into text form.  This allowed them to
slip into the manifest revision, since the code seems to be trying to minimize
the string operations by copying as large a chunk as possible.  As part of this,
compact() walks the existing text based on entries in the `positions` list, and
consumed everything up to the next position entry.   This typically resulted in
a ValueError complaining about unsorted manifest entries.

Sometimes it seems that files do get dropped in large repos- it seems to
correspond to there being a new entry that would take the same slot.  A much
more trivial problem is that if the only changes were removals, `_compact()`
didn't even run because `__delitem__` doesn't add anything to `self.extradata`.
Now there's an explicit variable to flag this, both to allow `_compact()` to
run, and to avoid searching the manifest in cases where there are no removals.

In practice, this behavior was mostly obscured by the check in fastdelta() which
takes a different path that explicitly drops removed files if there are fewer
than 1000 changes.  However, timeless has a repo where after rebasing tens of
commits, a totally different path[1] is taken that bypasses the change count
check and hits this problem.

[1] https://www.mercurial-scm.org/repo/hg/file/2338bdea4474/mercurial/manifest.py#l1511

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: AES-256-CBC,ADE9D82AA8D8023CD4E9B67FECD9FE08

tjMPfTx/dFicleUbh4pH4f5RUtgZwamcU/uy246wk+f2EBG7pVKEEmoXm8rWW2tW
xlp9BjL6yCBxoB/GGPjFAoqjQmnUQMxy/P0OWqur3t0+GrB4Fw9hB82fxgnAaydF
10fw+bRMCfxJMRfa2nEkLzL9za6TF0IOvAYYza/rCxgOQiLg/py9V29wjVnIW9Dt
B/GxfblTv9K2JBEVdKNWIGT1ZGxem8qiXctbufIXDr+dEEoFUKh+wvkmwVhBaSXi
gw6fAoATz0Lpd+9d0bqEC1wC3NFdxABYUjZMQ7+xtNzaSCdXiWgv4ix1kzoY8rIi
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qZeO9kX3Dmoi7vzXL8vjf41ZY7eTU6kYWktdBw/gM65goGINPFx85gli3k5I7+TR
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iX/oW2DQmwN/C5owMPttM7dg2PvSw/Blte5lvloLbmhQTzzw0MDkPHkGt+5Hhjcl
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H1yWy6X6Wiqx6abPVq1ODZgeTmsjJsMLDB6PUbQyESp9ICRJyPPCrMi6UpLrWMto
A764n5w8B2g/GPJfz1sPePZYi6sumd9UqTQ8UhM644oOlxPWufiBeTiPm1W73PSZ
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rI/JrWSK+tu75Ot63QQpm1x7xSctMZg71w7riVipA+8F1FBdmp+lhOQkEMytngIA
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j+HEyepn4/A9xpHRBTWfCwBFFktAgSdCUOLh5xsT2MbbT/0wDoneD/uay0NakWXB
zuVsaasx0Yl2cqvXKVUMphmbqMa859BNVqEK3l3tYZdvHiwT8J1LnEEK4KiBa2zZ
+8FcFvD8x1NZBcCBArYP59MbCQOC2QBPJe/oCiUVhN8kRIwlwOhytbW+QIuLZHi4
-----END RSA PRIVATE KEY-----