Commit Graph

340 Commits (v2.48.2)

Author SHA1 Message Date
René Scharfe e4981ed1e7 reftable: handle realloc error in parse_names()
Check the final reallocation for adding the terminating NULL and handle
it just like those in the loop.  Simply use REFTABLE_ALLOC_GROW instead
of keeping the REFTABLE_REALLOC_ARRAY call and adding code to preserve
the original pointer value around it.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-28 08:00:44 -08:00
René Scharfe 2cca185e85 reftable: fix allocation count on realloc error
When realloc(3) fails, it returns NULL and keeps the original allocation
intact.  REFTABLE_ALLOC_GROW overwrites both the original pointer and
the allocation count variable in that case, simultaneously leaking the
original allocation and misrepresenting the number of storable items.

parse_names() avoids the leak by keeping the original pointer if
reallocation fails, but still increase the allocation count in such a
case as if it succeeded.  That's OK, because the error handling code
just frees everything and doesn't look at names_cap anymore.

reftable_buf_add() does the same, but here it is a problem as it leaves
the reftable_buf in a broken state, with ->alloc being roughly twice as
big as the actually allocated memory, allowing out-of-bounds writes in
subsequent calls.

Reimplement REFTABLE_ALLOC_GROW to avoid leaks, keep allocation counts
in sync and still signal failures to callers while avoiding code
duplication in callers.  Make it an expression that evaluates to 0 if no
reallocation is needed or it succeeded and 1 on failure while keeping
the original pointer and allocation counter values.

Adjust REFTABLE_ALLOC_GROW_OR_NULL to the new calling convention for
REFTABLE_ALLOC_GROW, but keep its support for non-size_t alloc variables
for now.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-28 08:00:44 -08:00
René Scharfe 8db127d43f reftable: avoid leaks on realloc error
When realloc(3) fails, it returns NULL and keeps the original allocation
intact.  REFTABLE_ALLOC_GROW overwrites both the original pointer and
the allocation count variable in that case, simultaneously leaking the
original allocation and misrepresenting the number of storable items.

parse_names() and reftable_buf_add() avoid leaking by restoring the
original pointer value on failure, but all other callers seem to be OK
with losing the old allocation.  Add a new variant of the macro,
REFTABLE_ALLOC_GROW_OR_NULL, which plugs the leak and zeros the
allocation counter.  Use it for those callers.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-28 08:00:44 -08:00
Junio C Hamano 4156b6a741 Merge branch 'ps/build-sign-compare'
Start working to make the codebase buildable with -Wsign-compare.

* ps/build-sign-compare:
  t/helper: don't depend on implicit wraparound
  scalar: address -Wsign-compare warnings
  builtin/patch-id: fix type of `get_one_patchid()`
  builtin/blame: fix type of `length` variable when emitting object ID
  gpg-interface: address -Wsign-comparison warnings
  daemon: fix type of `max_connections`
  daemon: fix loops that have mismatching integer types
  global: trivial conversions to fix `-Wsign-compare` warnings
  pkt-line: fix -Wsign-compare warning on 32 bit platform
  csum-file: fix -Wsign-compare warning on 32-bit platform
  diff.h: fix index used to loop through unsigned integer
  config.mak.dev: drop `-Wno-sign-compare`
  global: mark code units that generate warnings with `-Wsign-compare`
  compat/win32: fix -Wsign-compare warning in "wWinMain()"
  compat/regex: explicitly ignore "-Wsign-compare" warnings
  git-compat-util: introduce macros to disable "-Wsign-compare" warnings
2024-12-23 09:32:11 -08:00
Junio C Hamano f7c607fac3 Merge branch 'kn/reftable-writer-log-write-verify'
Reftable backend adds check for upper limit of log's update_index.

* kn/reftable-writer-log-write-verify:
  reftable/writer: ensure valid range for log's update_index
2024-12-23 09:32:08 -08:00
Junio C Hamano 3151e6a121 Merge branch 'ps/reftable-alloc-failures-zalloc-fix'
Recent reftable updates mistook a NULL return from a request for
0-byte allocation as OOM and died unnecessarily, which has been
corrected.

* ps/reftable-alloc-failures-zalloc-fix:
  reftable/basics: return NULL on zero-sized allocations
  reftable/stack: fix zero-sized allocation when there are no readers
  reftable/merged: fix zero-sized allocation when there are no readers
  reftable/stack: don't perform auto-compaction with less than two tables
2024-12-23 09:32:06 -08:00
Patrick Steinhardt d7282891f5 reftable/basics: return NULL on zero-sized allocations
In the preceding commits we have fixed a couple of issues when
allocating zero-sized objects. These issues were masked by
implementation-defined behaviour. Quoting malloc(3p):

  If size is 0, either:

    * A null pointer shall be returned and errno may be set to an
      implementation-defined value, or

    * A pointer to the allocated space shall be returned. The
      application shall ensure that the pointer is not used to access an
      object.

So it is perfectly valid that implementations of this function may or
may not return a NULL pointer in such a case.

Adapt both `reftable_malloc()` and `reftable_realloc()` so that they
return NULL pointers on zero-sized allocations. This should remove any
implementation-defined behaviour in our allocators and thus allows us to
detect such platform-specific issues more easily going forward.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-22 00:58:23 -08:00
Patrick Steinhardt 2d3cb4b4b5 reftable/stack: fix zero-sized allocation when there are no readers
Similar as the preceding commit, we may try to do a zero-sized
allocation when reloading a reftable stack that ain't got any tables.
It is implementation-defined whether malloc(3p) returns a NULL pointer
in that case or a zero-sized object. In case it does return a NULL
pointer though it causes us to think we have run into an out-of-memory
situation, and thus we return an error.

Fix this by only allocating arrays when they have at least one entry.

Reported-by: Randall S. Becker <rsbecker@nexbridge.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-22 00:58:23 -08:00
Patrick Steinhardt 5ab83521cf reftable/merged: fix zero-sized allocation when there are no readers
It was reported [1] that Git started to fail with an out-of-memory error
when initializing repositories with the reftable backend on NonStop
platforms. A bisect led to 802c0646ac (reftable/merged: handle
allocation failures in `merged_table_init_iter()`, 2024-10-02), which
changed how we allocate memory when initializing a merged table.

The root cause of this seems to be that NonStop returns a `NULL` pointer
when doing a zero-sized allocation. This would've already happened
before the above change, but we never noticed because we did not check
the result. Now we do notice and thus return an out-of-memory error to
the caller.

Fix the issue by skipping the allocation altogether in case there are no
readers.

[1]: <00ad01db5017$aa9ce340$ffd6a9c0$@nexbridge.com>

Reported-by: Randall S. Becker <rsbecker@nexbridge.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-22 00:58:23 -08:00
Patrick Steinhardt 8e27ee9220 reftable/stack: don't perform auto-compaction with less than two tables
In order to compact tables we need at least two tables. Bail out early
from `reftable_stack_auto_compact()` in case we have less than two
tables.

In the original, `stack_table_sizes_for_compaction()` yields an array
that has the same length as the number of tables. This array is then
passed on to `suggest_compaction_segment()`, which returns an empty
segment in case we have less than two tables. The segment is then passed
to `segment_size()`, which will return `0` because both start and end of
the segment are `0`. And because we only call `stack_compact_range()` in
case we have a positive segment size we don't perform auto-compaction at
all. Consequently, this change does not result in a user-visible change
in behaviour when called with a single table.

But when called with no tables this protects us against a potential
out-of-memory error: `stack_table_sizes_for_compaction()` would try to
allocate a zero-byte object when there aren't any tables, and that may
lead to a `NULL` pointer on some platforms like NonStop which causes us
to bail out with an out-of-memory error.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-22 00:58:23 -08:00
Junio C Hamano 7041902dfa Merge branch 'ps/reftable-iterator-reuse'
Optimize reading random references out of the reftable backend by
allowing reuse of iterator objects.

* ps/reftable-iterator-reuse:
  refs/reftable: reuse iterators when reading refs
  reftable/merged: drain priority queue on reseek
  reftable/stack: add mechanism to notify callers on reload
  refs/reftable: refactor reflog expiry to use reftable backend
  refs/reftable: refactor reading symbolic refs to use reftable backend
  refs/reftable: read references via `struct reftable_backend`
  refs/reftable: figure out hash via `reftable_stack`
  reftable/stack: add accessor for the hash ID
  refs/reftable: handle reloading stacks in the reftable backend
  refs/reftable: encapsulate reftable stack
2024-12-10 10:04:58 +09:00
Junio C Hamano de9278127e Merge branch 'ps/reftable-detach'
Isolates the reftable subsystem from the rest of Git's codebase by
using fewer pieces of Git's infrastructure.

* ps/reftable-detach:
  reftable/system: provide thin wrapper for lockfile subsystem
  reftable/stack: drop only use of `get_locked_file_path()`
  reftable/system: provide thin wrapper for tempfile subsystem
  reftable/stack: stop using `fsync_component()` directly
  reftable/system: stop depending on "hash.h"
  reftable: explicitly handle hash format IDs
  reftable/system: move "dir.h" to its only user
2024-12-10 10:04:56 +09:00
Karthik Nayak 49c6b912e2 reftable/writer: ensure valid range for log's update_index
Each reftable addition has an associated update_index. While writing
refs, the update_index is verified to be within the range of the
reftable writer, i.e. `writer.min_update_index <= ref.update_index` and
`writer.max_update_index => ref.update_index`.

The corresponding check for reflogs in `reftable_writer_add_log` is
however missing. Add a similar check, but only check for the upper
limit. This is because reflogs are treated a bit differently than refs.
Each reflog entry in reftable has an associated update_index and we also
allow expiring entries in the middle, which is done by simply writing a
new reflog entry with the same update_index. This means, writing reflog
entries with update_index lesser than the writer's update_index is an
expected scenario.

Add a new unit test to check for the limits and fix some of the existing
tests, which were setting arbitrary values for the update_index by
ensuring they stay within the now checked limits.

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-07 08:04:46 +09:00
Patrick Steinhardt 41f43b8243 global: mark code units that generate warnings with `-Wsign-compare`
Mark code units that generate warnings with `-Wsign-compare`. This
allows for a structured approach to get rid of all such warnings over
time in a way that can be easily measured.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-06 20:20:02 +09:00
Patrick Steinhardt 9d471b9dfe reftable/merged: drain priority queue on reseek
In 5bf96e0c39 (reftable/generic: move seeking of records into the
iterator, 2024-05-13) we have refactored the reftable codebase such that
iterators can be initialized once and then re-seeked multiple times.
This feature is used by 1869525066 (refs/reftable: wire up support for
exclude patterns, 2024-09-16) in order to skip records based on exclude
patterns provided by the caller.

The logic to re-seek the merged iterator is insufficient though because
we don't drain the priority queue on a re-seek. This means that the
queue may contain stale entries and thus reading the next record in the
queue will return the wrong entry. While this is an obvious bug, it is
harmless in the context of above exclude patterns:

  - If the queue contained stale entries that match the pattern then the
    caller would already know to filter out such refs. This is because
    our codebase is prepared to handle backends that don't have a way to
    efficiently implement exclude patterns.

  - If the queue contained stale entries that don't match the pattern
    we'd eventually filter out any duplicates. This is because the
    reftable code discards items with the same ref name and sorts any
    remaining entries properly.

So things happen to work in this context regardless of the bug, and
there is no other use case yet where we re-seek iterators. We're about
to introduce a caching mechanism though where iterators are reused by
the reftable backend, and that will expose the bug.

Fix the issue by draining the priority queue when seeking and add a
testcase that surfaces the issue.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-26 17:18:38 +09:00
Patrick Steinhardt eb22c1b46b reftable/stack: add mechanism to notify callers on reload
Reftable stacks are reloaded in two cases:

  - When calling `reftable_stack_reload()`, if the stat-cache tells us
    that the stack has been modified.

  - When committing a reftable addition.

While callers can figure out the second case, they do not have a
mechanism to figure out whether `reftable_stack_reload()` led to an
actual reload of the on-disk data. All they can do is thus to assume
that data is always being reloaded in that case.

Improve the situation by introducing a new `on_reload()` callback to the
reftable options. If provided, the function will be invoked every time
the stack has indeed been reloaded. This allows callers to invalidate
data that depends on the current stack data.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-26 17:18:38 +09:00
Patrick Steinhardt c9f76fc7d1 reftable/stack: add accessor for the hash ID
Add an accessor function that allows callers to access the hash ID of a
reftable stack. This function will be used in a subsequent commit.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-26 17:18:36 +09:00
Patrick Steinhardt ef46ad0815 reftable: rename scratch buffer
Both `struct block_writer` and `struct reftable_writer` have a `buf`
member that is being reused to optimize the number of allocations.
Rename the variable to `scratch` to clarify its intend and provide a
comment explaining why it exists.

Suggested-by: Christian Couder <christian.couder@gmail.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-26 08:39:38 +09:00
Patrick Steinhardt d94ac23d3b reftable/block: optimize allocations by using scratch buffer
The block writer needs to compute the key for every record that one adds
to the writer. The buffer for this key is stored on the stack and thus
reallocated on every call to `block_writer_add()`, which is inefficient.

Refactor the code so that we store the buffer in the `block_writer`
struct itself so that we can reuse it. This reduces the number of
allocations when writing many refs, e.g. when migrating one million refs
from the "files" backend to the "reftable backend. Before this change:

    HEAP SUMMARY:
        in use at exit: 80,048 bytes in 49 blocks
      total heap usage: 3,025,864 allocs, 3,025,815 frees, 372,746,291 bytes allocated

After this change:

    HEAP SUMMARY:
        in use at exit: 80,048 bytes in 49 blocks
      total heap usage: 2,013,250 allocs, 2,013,201 frees, 347,543,583 bytes allocated

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-21 07:59:17 +09:00
Patrick Steinhardt aa248b8ab2 reftable/block: rename `block_writer::buf` variable
Adapt the name of the `block_writer::buf` variable to instead be called
`block`. This aligns it with the existing `block_len` variable, which
tracks the length of this buffer, and is generally a bit more tied to
the actual context where this variable gets used.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-21 07:59:17 +09:00
Patrick Steinhardt 66ed011bf7 reftable/writer: optimize allocations by using a scratch buffer
Both `writer_add_record()` and `reftable_writer_add_ref()` get executed
for every single ref record we're adding to the reftable writer. And as
both functions use a local buffer to write data, the allocations we have
to do here add up during larger transactions.

Refactor the code to use a scratch buffer part of the `reftable_writer`
itself such that we can reuse it. This signifcantly reduces the number
of allocations during large transactions, e.g. when migrating refs from
the "files" backend to the "reftable" backend. Before this change:

    HEAP SUMMARY:
        in use at exit: 80,048 bytes in 49 blocks
      total heap usage: 5,032,171 allocs, 5,032,122 frees, 418,792,092 bytes allocated

After this change:

    HEAP SUMMARY:
        in use at exit: 80,048 bytes in 49 blocks
      total heap usage: 3,025,864 allocs, 3,025,815 frees, 372,746,291 bytes allocated

This also translate into a small speedup:

    Benchmark 1: migrate files:reftable (refcount = 1000000, revision = HEAD~)
      Time (mean ± σ):     827.2 ms ±  16.5 ms    [User: 689.4 ms, System: 124.9 ms]
      Range (min … max):   809.0 ms … 924.7 ms    50 runs

    Benchmark 2: migrate files:reftable (refcount = 1000000, revision = HEAD)
      Time (mean ± σ):     813.6 ms ±  11.6 ms    [User: 679.0 ms, System: 123.4 ms]
      Range (min … max):   786.7 ms … 833.5 ms    50 runs

    Summary
      migrate files:reftable (refcount = 1000000, revision = HEAD) ran
        1.02 ± 0.02 times faster than migrate files:reftable (refcount = 1000000, revision = HEAD~)

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-21 07:59:16 +09:00
Patrick Steinhardt 988e7f5e95 reftable/system: provide thin wrapper for lockfile subsystem
We use the lockfile subsystem to write lockfiles for "tables.list". As
with the tempfile subsystem, the lockfile subsystem also hooks into our
infrastructure to prune stale locks via atexit(3p) or signal handlers.

Furthermore, the lockfile subsystem also handles locking timeouts, which
do add quite a bit of logic. Having to reimplement that in the context
of Git wouldn't make a whole lot of sense, and it is quite likely that
downstream users of the reftable library may have a better idea for how
exactly to implement timeouts.

So again, provide a thin wrapper for the lockfile subsystem instead such
that the compatibility shim is fully self-contained.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-19 12:23:11 +09:00
Patrick Steinhardt 6361226b79 reftable/stack: drop only use of `get_locked_file_path()`
We've got a single callsite where we call `get_locked_file_path()`. As
we're about to convert our usage of the lockfile subsystem to instead be
used via a compatibility shim we'd have to implement more logic for this
single callsite. While that would be okay if Git was the only supposed
user of the reftable library, it's a bit more awkward when considering
that we have to reimplement this functionality for every user of the
library eventually.

Refactor the code such that we don't call `get_locked_file_path()`
anymore.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-19 12:23:10 +09:00
Patrick Steinhardt 01e49941d6 reftable/system: provide thin wrapper for tempfile subsystem
We use the tempfile subsystem to write temporary tables, but given that
we're in the process of converting the reftable library to become
standalone we cannot use this subsystem directly anymore. While we could
in theory convert the code to use mkstemp(3p) instead, we'd lose access
to our infrastructure that automatically prunes tempfiles via atexit(3p)
or signal handlers.

Provide a thin wrapper for the tempfile subsystem instead. Like this,
the compatibility shim is fully self-contained in "reftable/system.c".
Downstream users of the reftable library would have to implement their
own tempfile shims by replacing "system.c" with a custom version.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-19 12:23:10 +09:00
Patrick Steinhardt 86b770b0bb reftable/stack: stop using `fsync_component()` directly
We're executing `fsync_component()` directly in the reftable library so
that we can fsync data to disk depending on "core.fsync". But as we're
in the process of converting the reftable library to become standalone
we cannot use that function in the library anymore.

Refactor the code such that users of the library can inject a custom
fsync function via the write options. This allows us to get rid of the
dependency on "write-or-die.h".

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-19 12:23:10 +09:00
Patrick Steinhardt c2f08236ed reftable/system: stop depending on "hash.h"
We include "hash.h" in "reftable/system.h" such that we can use hash
format IDs as well as the raw size of SHA1 and SHA256. As we are in the
process of converting the reftable library to become standalone we of
course cannot rely on those constants anymore.

Introduce a new `enum reftable_hash` to replace internal uses of the
hash format IDs and new constants that replace internal uses of the hash
size. Adapt the reftable backend to set up the correct hash function.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-19 12:23:10 +09:00
Patrick Steinhardt 88e297275b reftable: explicitly handle hash format IDs
The hash format IDs are used for two different things across the
reftable codebase:

  - They are used as a 32 bit unsigned integer when reading and writing
    the header in order to identify the hash function.

  - They are used internally to identify which hash function is in use.

When one only considers the second usecase one might think that one can
easily change the representation of those hash IDs. But because those
IDs end up in the reftable header and footer on disk it is important
that those never change.

Create separate constants `REFTABLE_FORMAT_ID_*` and use them in
contexts where we read or write reftable headers. This serves multiple
purposes:

  - It allows us to more easily discern cases where we actually use
    those constants for the on-disk format.

  - It detangles us from the same constants that are defined in
    libgit.a, which is another required step to convert the reftable
    library to become standalone.

  - It makes the next step easier where we stop using `GIT_*_FORMAT_ID`
    constants in favor of a custom enum.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-19 12:23:09 +09:00
Patrick Steinhardt 17e8039878 reftable/system: move "dir.h" to its only user
We still include "dir.h" in "reftable/system.h" even though it is not
used by anything but by a single unit test. Move it over into that unit
test so that we don't accidentally use any functionality provided by it
in the reftable codebase.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-19 12:23:08 +09:00
Patrick Steinhardt 20590cd287 reftable: handle trivial `reftable_buf` errors
Convert the reftable library such that we handle failures with the
new `reftable_buf` interfaces.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-10-17 16:59:56 -04:00
Patrick Steinhardt 591c6a600e reftable/stack: adapt `stack_filename()` to handle allocation failures
The `stack_filename()` function cannot pass any errors to the caller as it
has a `void` return type. Adapt it and its callers such that we can
handle errors and start handling allocation failures.

There are two interesting edge cases in `reftable_stack_destroy()` and
`reftable_addition_close()`. Both of these are trying to tear down their
respective structures, and while doing so they try to unlink some of the
tables they have been keeping alive. Any earlier attempts to do that may
fail on Windows because it keeps us from deleting such tables while they
are still open, and thus we re-try on close. It's okay and even expected
that this can fail when the tables are still open by another process, so
we handle the allocation failures gracefully and just skip over any file
whose name we couldn't figure out.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-10-17 16:59:56 -04:00
Patrick Steinhardt 4abc8022ff reftable/record: adapt `reftable_record_key()` to handle allocation failures
The `reftable_record_key()` function cannot pass any errors to the
caller as it has a `void` return type. Adapt it and its callers such
that we can handle errors and start handling allocation failures.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-10-17 16:59:56 -04:00
Patrick Steinhardt e693ccf2c9 reftable/stack: adapt `format_name()` to handle allocation failures
The `format_name()` function cannot pass any errors to the caller as it
has a `void` return type. Adapt it and its callers such that we can
handle errors and start handling allocation failures.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-10-17 16:59:56 -04:00
Patrick Steinhardt f177d49163 reftable/blocksource: adapt interface name
Adapt the name of the `strbuf` block source to no longer relate to this
interface, but instead to the `reftable_buf` interface.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-10-17 16:59:56 -04:00
Patrick Steinhardt be4c070a3c reftable: convert from `strbuf` to `reftable_buf`
Convert the reftable library to use the `reftable_buf` interface instead
of the `strbuf` interface. This is mostly a mechanical change via sed(1)
with some manual fixes where functions for `strbuf` and `reftable_buf`
differ. The converted code does not yet handle allocation failures. This
will be handled in subsequent commits.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-10-17 16:59:56 -04:00
Patrick Steinhardt 81eddda540 reftable/basics: provide new `reftable_buf` interface
Implement a new `reftable_buf` interface that will replace Git's own
`strbuf` interface. This is done due to three reasons:

  - The `strbuf` interfaces do not handle memory allocation failures and
    instead causes us to die. This is okay in the context of Git, but is
    not in the context of the reftable library, which is supposed to be
    usable by third-party applications.

  - The `strbuf` interface is quite deeply tied into Git, which makes it
    hard to use the reftable library as a standalone library. Any
    dependent would have to carefully extract the relevant parts of it
    to make things work, which is not all that sensible.

  - The `strbuf` interface does not use the pluggable allocators that
    can be set up via `reftable_set_alloc()`.

So we have good reasons to use our own type, and the implementation is
rather trivial. Implement our own type. Conversion of the reftable
library will be handled in subsequent commits.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-10-17 16:59:55 -04:00
Patrick Steinhardt 7fa7e14ebe reftable: stop using `strbuf_addf()`
We're about to introduce our own `reftable_buf` type to replace
`strbuf`. One function we'll have to convert is `strbuf_addf()`, which
is used in a handful of places. This function uses `snprintf()`
internally, which makes porting it a bit more involved:

  - It is not available on all platforms.

  - Some platforms like Windows have broken implementations.

So by using `snprintf()` we'd also push the burden on downstream users
of the reftable library to make available a properly working version of
it.

Most callsites of `strbuf_addf()` are trivial to convert to not using
it. We do end up using `snprintf()` in our unit tests, but that isn't
much of a problem for downstream users of the reftable library.

While at it, remove a useless call to `strbuf_reset()` in
`t_reftable_stack_auto_compaction_with_locked_tables()`. We don't write
to the buffer before this and initialize it with `STRBUF_INIT`, so there
is no need to reset anything.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-10-17 16:59:55 -04:00
Patrick Steinhardt 409f04995e reftable: stop using `strbuf_addbuf()`
We're about to introduce our own `reftable_buf` type to replace
`strbuf`. Get rid of the seldomly-used `strbuf_addbuf()` function such
that we have to reimplement one less function.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-10-17 16:59:55 -04:00
Junio C Hamano 5575c713c2 Merge branch 'ps/reftable-alloc-failures'
The reftable library is now prepared to expect that the memory
allocation function given to it may fail to allocate and to deal
with such an error.

* ps/reftable-alloc-failures: (26 commits)
  reftable/basics: fix segfault when growing `names` array fails
  reftable/basics: ban standard allocator functions
  reftable: introduce `REFTABLE_FREE_AND_NULL()`
  reftable: fix calls to free(3P)
  reftable: handle trivial allocation failures
  reftable/tree: handle allocation failures
  reftable/pq: handle allocation failures when adding entries
  reftable/block: handle allocation failures
  reftable/blocksource: handle allocation failures
  reftable/iter: handle allocation failures when creating indexed table iter
  reftable/stack: handle allocation failures in auto compaction
  reftable/stack: handle allocation failures in `stack_compact_range()`
  reftable/stack: handle allocation failures in `reftable_new_stack()`
  reftable/stack: handle allocation failures on reload
  reftable/reader: handle allocation failures in `reader_init_iter()`
  reftable/reader: handle allocation failures for unindexed reader
  reftable/merged: handle allocation failures in `merged_table_init_iter()`
  reftable/writer: handle allocation failures in `reftable_new_writer()`
  reftable/writer: handle allocation failures in `writer_index_hash()`
  reftable/record: handle allocation failures when decoding records
  ...
2024-10-10 14:22:25 -07:00
Junio C Hamano 4861bbf85a Merge branch 'ak/typofix-2.46-maint'
Typofixes.

* ak/typofix-2.46-maint:
  perl: fix a typo
  mergetool: fix a typo
  reftable: fix a typo
  trace2: fix typos
2024-10-04 14:21:40 -07:00
Patrick Steinhardt 2179b5c831 reftable/basics: fix segfault when growing `names` array fails
When growing the `names` array fails we would end up with a `NULL`
pointer. This causes two problems:

  - We would run into a segfault because we try to free names that we
    have assigned to the array already.

  - We lose track of the old array and cannot free its contents.

Fix this issue by using a temporary variable. Like this we do not
clobber the old array that we tried to reallocate, which will remain
valid when a call to realloc(3P) fails.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-04 07:59:31 -07:00
Andrew Kreimer a54601c38b reftable: fix a typo
Fix a typo in comments.

Signed-off-by: Andrew Kreimer <algonell@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-03 12:06:51 -07:00
Patrick Steinhardt 35730302e9 reftable/basics: ban standard allocator functions
The reftable library uses pluggable allocators, which means that we
shouldn't ever use the standard allocator functions. But it is an easy
mistake to make to accidentally use e.g. free(3P) instead of the
reftable-specific `reftable_free()` function, and we do not have any
mechanism to detect this misuse right now.

Introduce a couple of macros that ban the standard allocators, similar
to how we do it in "banned.h".

Note that we do not ban the following two classes of functions:

  - Macros like `FREE_AND_NULL()` or `REALLOC_ARRAY()`. As those expand
    to code that contains already-banned functions we'd get a compiler
    error even without banning those macros explicitly.

  - Git-specific allocators like `xmalloc()` and friends. The primary
    reason is that there are simply too many of them, so we're rather
    aiming for best effort here. Furthermore, the eventual goal is to
    make them unavailable in the reftable library place by not pulling
    them in via "git-compat-utils.h" anymore.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-02 07:53:56 -07:00
Patrick Steinhardt 24e0ade65b reftable: introduce `REFTABLE_FREE_AND_NULL()`
We have several calls to `FREE_AND_NULL()` in the reftable library,
which of course uses free(3P). As the reftable allocators are pluggable
we should rather call the reftable specific function, which is
`reftable_free()`.

Introduce a new macro `REFTABLE_FREE_AND_NULL()` and adapt the callsites
accordingly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-02 07:53:56 -07:00
Patrick Steinhardt daa59e9c43 reftable: fix calls to free(3P)
There are a small set of calls to free(3P) in the reftable library. As
the reftable allocators are pluggable we should rather call the reftable
specific function, which is `reftable_free()`.

Convert the code accordingly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-02 07:53:56 -07:00
Patrick Steinhardt 12b9078066 reftable: handle trivial allocation failures
Handle trivial allocation failures in the reftable library and its unit
tests.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-02 07:53:55 -07:00
Patrick Steinhardt 51afc709dc reftable/tree: handle allocation failures
The tree interfaces of the reftable library handle both insertion and
searching of tree nodes with a single function, where the behaviour is
altered between the two via an `insert` bit. This makes it quit awkward
to handle allocation failures because on inserting we'd have to check
for `NULL` pointers and return an error, whereas on searching entries we
don't have to handle it as an allocation error.

Split up concerns of this function into two separate functions, one for
inserting entries and one for searching entries. This makes it easy for
us to check for allocation errors as `tree_insert()` should never return
a `NULL` pointer now. Adapt callers accordingly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-02 07:53:55 -07:00
Patrick Steinhardt d0501c8c9d reftable/pq: handle allocation failures when adding entries
Handle allocation failures when adding entries to the pqueue. Adapt its
only caller accordingly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-02 07:53:55 -07:00
Patrick Steinhardt 2d5dbb37b2 reftable/block: handle allocation failures
Handle allocation failures in `block_writer_init()` and
`block_reader_init()`. This requires us to bubble up error codes into
`writer_reinit_block_writer()`. Adapt call sites accordingly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-02 07:53:55 -07:00
Patrick Steinhardt cd6a47167e reftable/blocksource: handle allocation failures
Handle allocation failures in the blocksource code.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-02 07:53:54 -07:00
Patrick Steinhardt cc6a9af5d7 reftable/iter: handle allocation failures when creating indexed table iter
Handle allocation failures in `new_indexed_table_ref_iter()`. While at
it, rename the function to match our coding style.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-02 07:53:54 -07:00