If backup_label is removed from a restored backup then PostgreSQL will instead use checkpoint information from pg_control to attempt (what is thinks is) crash recovery. This will nearly always result in a corrupt cluster because the checkpoint will not be from the beginning of the backup, and even if it is, the end point will not be specified, which could lead to recovery stopping too early.
To prevent this, invalidate the checkpoint LSN in pg_control on restore. If backup_label is removed then recovery will still fail because PostgreSQL will not be able to find the invalid checkpoint. The LSN of the checkpoint is not logged but it will be visible in pg_controldata output as 0/DEAD. This value is invalid because PostgreSQL always skips the first WAL segment when initializing a cluster.
This serves as an additional sanity check to be sure the pg_control format is as expected. The field is useful for being all the way at the end and being four bytes that can only have one of two values. Something more distinctive than 0 and 1 would be better, but this is what we have to work with.
Convert PgControl.pageChecksum to unsigned int and rename to PgControl.pageChecksumVersion and make all downstream changes required for the new datatype.
Per our policy to support five EOL versions of PostgreSQL, 9.3 is no longer supported by pgBackRest.
Remove all logic associated with 9.3 and update the tests.
On certain file systems (e.g. ext4) pg_control may appear torn if there is a concurrent write while reading the file. To prevent an invalid read, retry until the checksum matches the control data.
Special handling is required for the pg-version-force feature since the offset of the checksum is not known. In this case, scan from the default position to the end of the data looking for a checksum match. This is a bit imprecise, but better than nothing, and the chance of a random collision in the control data seems very remote considering the ratio of data size (< 512 bytes) to checksum size (4 bytes).
This was discovered and a possible solution proposed for PostgreSQL in [1]. The proposed solution may work for backup, but pgBackRest needs to be able to read pg_control reliably outside of backup. So no matter what fix is adopted for PostgreSQL, pgBackRest need retries. Further adjustment may be required as the PostgreSQL fix evolves.
[1] https://www.postgresql.org/message-id/20221123014224.xisi44byq3cf5psi%40awork3.anarazel.de
Forks may update pg_control version or WAL magic without affecting the structures that pgBackRest depends on.
This option forces pgBackRest to treat a cluster as the specified version when it cannot be automatically identified.
Our new policy is to support ten versions of PostgreSQL, the five supported releases and the last five EOL releases. As of PostgreSQL 15, that means 9.0/9.1/9.2 are no longer supported by pgBackRest.
Remove all logic associated with 9.0/9.1/9.2 and update the tests.
Document the new support policy.
Update InfoPg to read/write control versions for the history in backup.info, since we can no longer rely on the mappings being available. In theory this could have been an issue after removing 8.3/8.4 if anybody was using a version that old.
Maintaining the version interfaces was complicated by the fact that each interface needed to be in separate compilation unit to avoid type conflicts. This also meant that various build/test files needed to be updated to add the new interfaces.
Solve these problems by auto-generating all the interfaces into a single file. This is made possible by parsing defines and types out of the header files and creating macros to rename the types. At the end of the version interface everything is undef'd. Another benefit is that the auto-generated interfaces can be static and included directly into postgres/interface.c.
Since some code generation is now always required for tests, change --no-gen to --min-gen in test.pl.
It would also make sense to auto-generate the version defines in postgres/version.h, but that will be left for a future commit.
There is no evidence that users need 8.3/8.4 anymore but it does cost us in terms of development and testing, especially now that we have a number of new backup/restore features planned.
It seems to make sense to remove this support now. If there are users who need to use/migrate from these versions they can use an older version of pgBackRest.
Add the following checks:
* Checkpoint is updated in pg_control after pg_start_backup(). This helps ensure that PostgreSQL and pgBackRest have a consistent view of the storage and that PGDATA paths match.
* Timeline of backup start WAL file matches pg_control. Hard to see how this one could get hit, but we have the power...
* Standby is on the same timeline as the primary. If not, this standby is not following the primary.
* Last standby checkpoint is not greater than the backup checkpoint. If so, this standby is not following the primary.
This also requires some additional plumbing to read/write timeline/checkpoint from pg_control and parse timelines from WAL filenames. There were some changes in the backup tests caused by the fact that pg_control now has different contents for each backup.
The check to ensure that the required checkpoint was reached on the standby should also be updated to use pg_control (it currently uses pg_control_checkpoint()), but that requires non-trivial changes to the test harness and will need to wait.
There are no code changes from PostgreSQL 13 so simply add the new version.
Add CATALOG_VERSION_NO_MAX to allow the catalog version to "float" during the PostgreSQL beta/rc period so new pgBackRest versions are not required when the catalog version changes.
Update the integration tests to handle new PostgreSQL startup messages.
Some version interface test functions were integrated into the core code because they relied on the PostgreSQL versioned interface. Even though they were compiled out for production builds they cluttered the core code and made it harder to determine what was required by core.
Create a PostgreSQL version interface in a test harness to contain these functions. This does require some duplication but the cleaner core code seems a good tradeoff. It is possible for some of this code to be auto-generated but since it is only updated once per year the matter is not pressing.
927d9adb changed the way CATALOG_VERSION_NO is used to identify PostgreSQL versions since PG_CONTROL_VERSION is generally bumped with each release. The goal was to make the beta/rc period less painful because any CATALOG_VERSION_NO bump renders pgBackRest inoperative.
This worked, but in fact we'd rather be stricter about which CATALOG_VERSION_NO we accept when identifying a version of PostgreSQL. It is not just about identifying a major version, but making sure the build contains all the functions and catalogs we expect to make pgBackRest work correctly. It is better to reject early dev/beta/rc builds that may not work.
Since 927d9adb was relatively recent the chance that this stricter checking will cause a problem seems minimal, so revert to checking CATALOG_VERSION_NO for every PostgreSQL version.
Leave in place the code that pulls CATALOG_VERSION_NO from pg_control rather than the internal constant since the plan is still to allow catalog versions to "float" during the PostgreSQL beta/rc phase, which will be the subject of a future commit.
Previously, catalog versions were fixed for all versions which made maintaining the catalog versions during PostgreSQL beta and release candidate cycles very painful. A version of pgBackRest which was functionally compatible was rendered useless by a catalog version bump in PostgreSQL.
Instead use only the control version to identify a PostgreSQL version when possible. Some older versions require a catalog version to positively identify a PostgreSQL version, so include them when required.
Since the catalog number is required to work with tablespaces it will need to be stored. There's already a copy of it in backup.info so use that (even though we have been ignoring it in the C versions).
Vendorized code is copied from another project when a library is not available and a git subproject won't work. Currently all the vendorized code is copied from PostgreSQL but it makes sense to have a more general mechanism for indicating vendorized code.
The .vendor extension will be used to denote vendorized code in the same way that .auto is used to denote auto-generated code.
Previously memNew() used memset() to initialize all struct members to 0, NULL, false, etc. While this appears to work in practice, it is a violation of the C specification. For instance, NULL == 0 must be true but neither NULL nor 0 must be represented with all zero bits.
Instead use designated initializers to initialize structs. These guarantee that struct members will be properly initialized even if they are not specified in the initializer. Note that due to a quirk in the C99 specification at least one member must be explicitly initialized even if it needs to be the default value.
Since pre-zeroed memory is no longer required, adjust memAllocInternal()/memReallocInternal() to return raw memory and update dependent functions accordingly. All instances of memset() have been removed except in debug/test code where needed.
Add memMewPtrArray() to allocate an array of pointers and automatically set all pointers to NULL.
Rename memGrowRaw() to the more logical memResize().
The control and catalog versions were stored a variety of places in the optimistic hope that they would be useful. In fact they never were.
We can't remove them from the backup.info and backup.manifest files due to backwards compatibility concerns, but we can at least avoid loading and storing them in C structures.
Add functions to the PostgreSQL interface which will return the control and catalog versions for any supported version of PostgreSQL to allow backwards compatibility for backup.info and backup.manifest. These functions will be useful in other ways, e.g. generating the tablespace identifier in PostgreSQL >= 9.0.
This was missed because the unit tests were reusing a buffer without resetting it to zero, so this flag ended up still set when the test function was called.
This was not a live issue since it only expressed in tests and this code is not used in master yet.
Having a copy per version worked well until it was time to add new features or modify existing functions. Then it was necessary to modify every version and try to keep them all in sync.
Consolidate all the PostgreSQL types into a single file using #if for type versions. Many types do not change or change infrequently so this cuts down on duplication. In addition, it is far easier to see what has changed when a new version is added.
Use macros to write the interface functions. There is still duplication here since some changes require a new copy of the macro, but it is far less than before.
