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checkout: don't try to calculate oid for directories#3931

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ethomson merged 1 commit into
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ethomson/checkout_dont_calculate_oid_for_dirs
Oct 2, 2016
Merged

checkout: don't try to calculate oid for directories#3931
ethomson merged 1 commit into
masterfrom
ethomson/checkout_dont_calculate_oid_for_dirs

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When trying to determine if we can safely overwrite an existing workdir item, we may need to calculate the oid for the workdir item to determine if its identical to the old side (and eligible for removal).

We previously did this regardless of the type of entry in the workdir; if it was a directory, we would open(2) it and then try to read(2). The read(2) of a directory fails on many platforms, so we would treat it as if it were unmodified and continue to perform the checkout.

On FreeBSD, you can read(2) a directory, so this pattern failed. We would calculate an oid from the data read and determine that the directory was modified and would therefore generate a checkout conflict.

This reliance on read(2) is silly (and was most likely accidentally giving us the behavior we wanted), we should be explicit about the directory test.

Fixes #3911

When trying to determine if we can safely overwrite an existing workdir
item, we may need to calculate the oid for the workdir item to determine
if its identical to the old side (and eligible for removal).

We previously did this regardless of the type of entry in the workdir;
if it was a directory, we would open(2) it and then try to read(2).
The read(2) of a directory fails on many platforms, so we would treat it
as if it were unmodified and continue to perform the checkout.

On FreeBSD, you _can_ read(2) a directory, so this pattern failed.  We
would calculate an oid from the data read and determine that the
directory was modified and would therefore generate a checkout conflict.

This reliance on read(2) is silly (and was most likely accidentally
giving us the behavior we wanted), we should be explicit about the
directory test.
Comment thread src/checkout.c

/* if the workdir item is a directory, it cannot be a modified file */
if (S_ISDIR(wditem->mode))
return false;
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@pks-t pks-t Sep 19, 2016

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Shouldn't we consider this as modified if !S_ISDIR(baseitem->mode)? E.g. something like

if (S_ISDIR(wditem->mode))
    return !S_ISDIR(baseitem->mode);

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@ethomson ethomson Sep 19, 2016

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That can't happen - we only process files in the checkout loop, not folders. (We'll make intermediate folders if we need them.) So we'll never see a baseitem (or newitem) that is a folder.

@ethomson ethomson merged commit 9fbbb0e into master Oct 2, 2016
@ethomson ethomson deleted the ethomson/checkout_dont_calculate_oid_for_dirs branch January 13, 2017 12:28
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2 participants