pg_dump: Fix incorrect parsing of object types in pg_dump --filter.

Previously, pg_dump --filter could misinterpret invalid object types
in the filter file as valid ones. For example, the invalid object type
"table-data" (likely a typo for the valid "table_data") could be
mistakenly recognized as "table", causing pg_dump to succeed
when it should have failed.

This happened because pg_dump identified keywords as sequences of
ASCII alphabetic characters, treating non-alphabetic characters
(like hyphens) as keyword boundaries. As a result, "table-data" was
parsed as "table".

To fix this, pg_dump --filter now treats keywords as strings of
non-whitespace characters, ensuring invalid types like "table-data"
are correctly rejected.

Back-patch to v17, where the --filter option was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com>
Reviewed-by: Srinath Reddy <srinath2133@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/CAHGQGwFzPKUwiV5C-NLBqz1oK1+z9K8cgrF+LcxFem-p3_Ftug@mail.gmail.com
Backpatch-through: 17

src/bin/pg_dump/filter.c

@@ -171,9 +171,8 @@ pg_log_filter_error(FilterStateData *fstate, const char *fmt,...)
 /*
  * filter_get_keyword - read the next filter keyword from buffer
  *
- * Search for keywords (limited to ascii alphabetic characters) in
- * the passed in line buffer. Returns NULL when the buffer is empty or the first
- * char is not alpha. The char '_' is allowed, except as the first character.
+ * Search for keywords (strings of non-whitespace characters) in the passed
+ * in line buffer. Returns NULL when the buffer is empty or no keyword exists.
  * The length of the found keyword is returned in the size parameter.
  */
 static const char *
@@ -182,6 +181,9 @@ filter_get_keyword(const char **line, int *size)
 	const char *ptr = *line;
 	const char *result = NULL;
 
+	/* The passed buffer must not be NULL */
+	Assert(*line != NULL);
+
 	/* Set returned length preemptively in case no keyword is found */
 	*size = 0;
 
@@ -189,11 +191,12 @@ filter_get_keyword(const char **line, int *size)
 	while (isspace((unsigned char) *ptr))
 		ptr++;
 
-	if (isalpha((unsigned char) *ptr))
+	/* Grab one keyword that's the string of non-whitespace characters */
+	if (*ptr != '\0' && !isspace((unsigned char) *ptr))
 	{
 		result = ptr++;
 
-		while (isalpha((unsigned char) *ptr) || *ptr == '_')
+		while (*ptr != '\0' && !isspace((unsigned char) *ptr))
 			ptr++;
 
 		*size = ptr - result;

src/bin/pg_dump/t/005_pg_dump_filterfile.pl

@@ -418,10 +418,16 @@ command_fails_like(
 	qr/invalid filter command/,
 	"invalid syntax: incorrect filter command");
 
-# Test invalid object type
+# Test invalid object type.
+#
+# This test also verifies that keywords are correctly recognized as strings of
+# non-whitespace characters. If the parser incorrectly treats non-whitespace
+# delimiters (like hyphens) as keyword boundaries, "table-data" might be
+# misread as the valid object type "table". To catch such issues,
+# "table-data" is used here as an intentionally invalid object type.
 open $inputfile, '>', "$tempdir/inputfile.txt"
   or die "unable to open filterfile for writing";
-print $inputfile "include xxx";
+print $inputfile "exclude table-data one";
 close $inputfile;
 
 command_fails_like(
@@ -432,8 +438,8 @@ command_fails_like(
 		'--filter' => "$tempdir/inputfile.txt",
 		'postgres'
 	],
-	qr/unsupported filter object type: "xxx"/,
-	"invalid syntax: invalid object type specified, should be table, schema, foreign_data or data"
+	qr/unsupported filter object type: "table-data"/,
+	"invalid syntax: invalid object type specified"
 );
 
 # Test missing object identifier pattern