This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.
This is just an experiment to cause a segfault in postgres, get a core dump and then analyze it with GDB.
- Enable core dumps in linux:
$ ulimit -c unlimited
$ mkdir -p /var/coredumps
$ chmod a+w /var/coredumps
$ sysctl kernel.core_pattern=/var/coredumps/core-%e-%p
- Add core files option to pg_ctl :
$ pg_ctl start -core-files
- Compile and exec this branch. Note: you need to compile pg with debug symbols
-genabled, by default this is the case withmeson.
$ nix-shell
$ meson
$ cd build
$ ninja && ninja install
& cd ..
$ with-pg psql
```bash
postgres=# create role blo;
2024-05-27 14:45:43.894 -05 [2402762] WARNING: Raising SIGSEGV purposefully for experimentation purposes..
WARNING: Raising SIGSEGV purposefully for experimentation purposes..
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Succeeded.
- Check the core dump
$ du -sh /var/coredumps/core-postgres-2394351
145M
$ file /var/coredumps/core-postgres-2394351
core-postgres-2394351: ELF 64-bit LSB core file, x86-64, version 1 (SYSV), SVR4-style, from 'postgres: postgres postgres [local] CREATE ROLE', real uid: 1000, effective uid: 1000, real gid
: 1000, effective gid: 1000, execfn: '/home/stevechavez/Projects/postgres/build/bin/postgres', platform: 'x86_64'
- Use gdb
$ gdb -c /var/coredumps/core-postgres-2394351 ./build/bin/postgres
(gdb) tui enable
(gdb) bt # get a backtrance
(gdb) f 3 # jump to func
(gdb) p *portal # print variables
$1 = {name = 0x131a290 "", prepStmtName = 0x0, portalContext = 0x12c4690, resowner = 0x12d39e0, cleanup = 0x66c774 <PortalCleanup>, createSubid = 1, activeSubid = 1, createLevel = 1,
sourceText = 0x129a618 "create role blo;", commandTag = CMDTAG_CREATE_ROLE, qc = {commandTag = CMDTAG_CREATE_ROLE, nprocessed = 0}, stmts = 0x129b400, cplan = 0x0, portalParams = 0x0,
queryEnv = 0x0, strategy = PORTAL_MULTI_QUERY, cursorOptions = 4, run_once = true, status = PORTAL_ACTIVE, portalPinned = false, autoHeld = false, queryDesc = 0x0, tupDesc = 0x0,
formats = 0x0, portalSnapshot = 0x12cc800, holdStore = 0x0, holdContext = 0x0, holdSnapshot = 0x0, atStart = true, atEnd = true, portalPos = 0, creation_time = 770152156020410,
visible = false}