Move relpath() to libpgcommon

This enables non-backend code, such as pg_xlogdump, to use it easily.
The previous location, in src/backend/catalog/catalog.c, made that
essentially impossible because that file depends on many backend-only
facilities; so this needs to live separately.

1 files changed, 162 insertions, 0 deletions

diff --git a/src/common/relpath.c b/src/common/relpath.c
new file mode 100644
index 00000000000..18fe4d1fe36
--- /dev/null
+++ b/src/common/relpath.c
@@ -0,0 +1,162 @@
+/*-------------------------------------------------------------------------
+ * relpath.c
+ * 		Shared frontend/backend code to find out pathnames of relation files
+ *
+ * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *    src/common/relpath.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include "catalog/pg_tablespace.h"
+#include "common/relpath.h"
+#include "storage/backendid.h"
+
+#define FORKNAMECHARS	4		/* max chars for a fork name */
+
+/*
+ * Lookup table of fork name by fork number.
+ *
+ * If you add a new entry, remember to update the errhint below, and the
+ * documentation for pg_relation_size(). Also keep FORKNAMECHARS above
+ * up-to-date.
+ */
+const char *forkNames[] = {
+	"main",						/* MAIN_FORKNUM */
+	"fsm",						/* FSM_FORKNUM */
+	"vm",						/* VISIBILITYMAP_FORKNUM */
+	"init"						/* INIT_FORKNUM */
+};
+
+/*
+ * forkname_chars
+ *		We use this to figure out whether a filename could be a relation
+ *		fork (as opposed to an oddly named stray file that somehow ended
+ *		up in the database directory).	If the passed string begins with
+ *		a fork name (other than the main fork name), we return its length,
+ *		and set *fork (if not NULL) to the fork number.  If not, we return 0.
+ *
+ * Note that the present coding assumes that there are no fork names which
+ * are prefixes of other fork names.
+ */
+int
+forkname_chars(const char *str, ForkNumber *fork)
+{
+	ForkNumber	forkNum;
+
+	for (forkNum = 1; forkNum <= MAX_FORKNUM; forkNum++)
+	{
+		int			len = strlen(forkNames[forkNum]);
+
+		if (strncmp(forkNames[forkNum], str, len) == 0)
+		{
+			if (fork)
+				*fork = forkNum;
+			return len;
+		}
+	}
+	return 0;
+}
+
+/*
+ * relpathbackend - construct path to a relation's file
+ *
+ * Result is a palloc'd string.
+ */
+char *
+relpathbackend(RelFileNode rnode, BackendId backend, ForkNumber forknum)
+{
+	int			pathlen;
+	char	   *path;
+
+	if (rnode.spcNode == GLOBALTABLESPACE_OID)
+	{
+		/* Shared system relations live in {datadir}/global */
+		Assert(rnode.dbNode == 0);
+		Assert(backend == InvalidBackendId);
+		pathlen = 7 + OIDCHARS + 1 + FORKNAMECHARS + 1;
+		path = (char *) palloc(pathlen);
+		if (forknum != MAIN_FORKNUM)
+			snprintf(path, pathlen, "global/%u_%s",
+					 rnode.relNode, forkNames[forknum]);
+		else
+			snprintf(path, pathlen, "global/%u", rnode.relNode);
+	}
+	else if (rnode.spcNode == DEFAULTTABLESPACE_OID)
+	{
+		/* The default tablespace is {datadir}/base */
+		if (backend == InvalidBackendId)
+		{
+			pathlen = 5 + OIDCHARS + 1 + OIDCHARS + 1 + FORKNAMECHARS + 1;
+			path = (char *) palloc(pathlen);
+			if (forknum != MAIN_FORKNUM)
+				snprintf(path, pathlen, "base/%u/%u_%s",
+						 rnode.dbNode, rnode.relNode,
+						 forkNames[forknum]);
+			else
+				snprintf(path, pathlen, "base/%u/%u",
+						 rnode.dbNode, rnode.relNode);
+		}
+		else
+		{
+			/* OIDCHARS will suffice for an integer, too */
+			pathlen = 5 + OIDCHARS + 2 + OIDCHARS + 1 + OIDCHARS + 1
+				+ FORKNAMECHARS + 1;
+			path = (char *) palloc(pathlen);
+			if (forknum != MAIN_FORKNUM)
+				snprintf(path, pathlen, "base/%u/t%d_%u_%s",
+						 rnode.dbNode, backend, rnode.relNode,
+						 forkNames[forknum]);
+			else
+				snprintf(path, pathlen, "base/%u/t%d_%u",
+						 rnode.dbNode, backend, rnode.relNode);
+		}
+	}
+	else
+	{
+		/* All other tablespaces are accessed via symlinks */
+		if (backend == InvalidBackendId)
+		{
+			pathlen = 9 + 1 + OIDCHARS + 1
+				+ strlen(TABLESPACE_VERSION_DIRECTORY) + 1 + OIDCHARS + 1
+				+ OIDCHARS + 1 + FORKNAMECHARS + 1;
+			path = (char *) palloc(pathlen);
+			if (forknum != MAIN_FORKNUM)
+				snprintf(path, pathlen, "pg_tblspc/%u/%s/%u/%u_%s",
+						 rnode.spcNode, TABLESPACE_VERSION_DIRECTORY,
+						 rnode.dbNode, rnode.relNode,
+						 forkNames[forknum]);
+			else
+				snprintf(path, pathlen, "pg_tblspc/%u/%s/%u/%u",
+						 rnode.spcNode, TABLESPACE_VERSION_DIRECTORY,
+						 rnode.dbNode, rnode.relNode);
+		}
+		else
+		{
+			/* OIDCHARS will suffice for an integer, too */
+			pathlen = 9 + 1 + OIDCHARS + 1
+				+ strlen(TABLESPACE_VERSION_DIRECTORY) + 1 + OIDCHARS + 2
+				+ OIDCHARS + 1 + OIDCHARS + 1 + FORKNAMECHARS + 1;
+			path = (char *) palloc(pathlen);
+			if (forknum != MAIN_FORKNUM)
+				snprintf(path, pathlen, "pg_tblspc/%u/%s/%u/t%d_%u_%s",
+						 rnode.spcNode, TABLESPACE_VERSION_DIRECTORY,
+						 rnode.dbNode, backend, rnode.relNode,
+						 forkNames[forknum]);
+			else
+				snprintf(path, pathlen, "pg_tblspc/%u/%s/%u/t%d_%u",
+						 rnode.spcNode, TABLESPACE_VERSION_DIRECTORY,
+						 rnode.dbNode, backend, rnode.relNode);
+		}
+	}
+	return path;
+}
+