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Add ABI extra field to fmgr magic block

This allows derived products to intentionally make their fmgr ABIincompatible, with a clean error message.Discussion:https://www.postgresql.org/message-id/flat/55215fda-db31-a045-d6b7-d6f2d2dc9920%40enterprisedb.com

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Lines changed: 15 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -330,6 +330,21 @@ incompatible_module_error(const char *libname,`
`330`	`330`	`magic_data.version /100,library_version)));`
`331`	`331`	`}`
`332`	`332`
	`333`	`+/*`
	`334`	`+ * Similarly, if the ABI extra field doesn't match, error out. Other`
	`335`	`+ * fields below might also mismatch, but that isn't useful information if`
	`336`	`+ * you're using the wrong product altogether.`
	`337`	`+ */`
	`338`	`+if (strcmp(module_magic_data->abi_extra,magic_data.abi_extra)!=0)`
	`339`	`+{`
	`340`	`+ereport(ERROR,`
	`341`	`+(errmsg("incompatible library \"%s\": ABI mismatch",`
	`342`	`+libname),`
	`343`	`+errdetail("Server has ABI \"%s\", library has \"%s\".",`
	`344`	`+magic_data.abi_extra,`
	`345`	`+module_magic_data->abi_extra)));`
	`346`	`+}`
	`347`	`+`
`333`	`348`	`/*`
`334`	`349`	`* Otherwise, spell out which fields don't agree.`
`335`	`350`	`*`

Lines changed: 6 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -458,6 +458,7 @@ typedef struct`
`458`	`458`	`intindexmaxkeys;/* INDEX_MAX_KEYS */`
`459`	`459`	`intnamedatalen;/* NAMEDATALEN */`
`460`	`460`	`intfloat8byval;/* FLOAT8PASSBYVAL */`
	`461`	`+charabi_extra[32];/* see pg_config_manual.h */`
`461`	`462`	`}Pg_magic_struct;`
`462`	`463`
`463`	`464`	`/* The actual data block contents */`
`@@ -468,9 +469,13 @@ typedef struct`
`468`	`469`	`FUNC_MAX_ARGS, \`
`469`	`470`	`INDEX_MAX_KEYS, \`
`470`	`471`	`NAMEDATALEN, \`
`471`		`-FLOAT8PASSBYVAL \`
	`472`	`+FLOAT8PASSBYVAL, \`
	`473`	`+FMGR_ABI_EXTRA, \`
`472`	`474`	`}`
`473`	`475`
	`476`	`+StaticAssertDecl(sizeof(FMGR_ABI_EXTRA) <=sizeof(((Pg_magic_struct*)0)->abi_extra),`
	`477`	`+"FMGR_ABI_EXTRA too long");`
	`478`	`+`
`474`	`479`	`/*`
`475`	`480`	`* Declare the module magic function. It needs to be a function as the dlsym`
`476`	`481`	`* in the backend is only guaranteed to work on functions, not data`

Lines changed: 17 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -42,6 +42,23 @@`
`42`	`42`	`*/`
`43`	`43`	`#defineFUNC_MAX_ARGS100`
`44`	`44`
	`45`	`+/*`
	`46`	`+ * When creating a product derived from PostgreSQL with changes that cause`
	`47`	`+ * incompatibilities for loadable modules, it is recommended to change this`
	`48`	`+ * string so that dfmgr.c can refuse to load incompatible modules with a clean`
	`49`	`+ * error message. Typical examples that cause incompatibilities are any`
	`50`	`+ * changes to node tags or node structures. (Note that dfmgr.c already`
	`51`	`+ * detects common sources of incompatibilities due to major version`
	`52`	`+ * differences and due to some changed compile-time constants. This setting`
	`53`	`+ * is for catching anything that cannot be detected in a straightforward way.)`
	`54`	`+ *`
	`55`	`+ * There is no prescribed format for the string. The suggestion is to include`
	`56`	`+ * product or company name, and optionally any internally-relevant ABI`
	`57`	`+ * version. Example: "ACME Postgres/1.2". Note that the string will appear`
	`58`	`+ * in a user-facing error message if an ABI mismatch is detected.`
	`59`	`+ */`
	`60`	`+#defineFMGR_ABI_EXTRA"PostgreSQL"`
	`61`	`+`
`45`	`62`	`/*`
`46`	`63`	`* Maximum number of columns in an index. There is little point in making`
`47`	`64`	`* this anything but a multiple of 32, because the main cost is associated`

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