Improve pg_regress.c's infrastructure for issuing psql commands.

Support issuing more than one "-c command" switch to a single psql invocation. This allows combining some things that formerly required two or more backend launches into a single session. In particular, we can issue DROP DATABASE as one of the -c commands without getting "DROP DATABASE cannot run inside a transaction block". In addition to reducing the number of sessions needed, this patch also suppresses "NOTICE: database "foo" does not exist, skipping" chatter that was formerly generated during pg_regress's DROP DATABASE (or ROLE) IF NOT EXISTS calls. That moves us another step closer to the ideal of not seeing any messages during successful build/test. This also eliminates some hard-coded restrictions on the length of the commands issued. I don't think we were anywhere near hitting those, but getting rid of the limit is comforting. Patch by me, but thanks to Nathan Bossart for starting the discussion. Discussion: https://postgr.es/m/DCBAE0E4-BD56-482F-8A70-7FD0DC0860BE@amazon.com

Author: tglsfdc

src/test/regress/pg_regress.c

@@ -122,7 +122,9 @@ static void make_directory(const char *dir);
 
 static void header(const char *fmt,...) pg_attribute_printf(1, 2);
 static void status(const char *fmt,...) pg_attribute_printf(1, 2);
-static void psql_command(const char *database, const char *query,...) pg_attribute_printf(2, 3);
+static StringInfo psql_start_command(void);
+static void psql_add_command(StringInfo buf, const char *query,...) pg_attribute_printf(2, 3);
+static void psql_end_command(StringInfo buf, const char *database);
 
 /*
  * allow core files if possible.
@@ -1136,51 +1138,94 @@ config_sspi_auth(const char *pgdata, const char *superuser_name)
 #endif/* ENABLE_SSPI */
 
 /*
- * Issue a command via psql, connecting to the specified database
+ * psql_start_command, psql_add_command, psql_end_command
+ *
+ * Issue one or more commands within one psql call.
+ * Set up with psql_start_command, then add commands one at a time
+ * with psql_add_command, and finally execute with psql_end_command.
  *
  * Since we use system(), this doesn't return until the operation finishes
  */
+static StringInfo
+psql_start_command(void)
+{
+StringInfobuf = makeStringInfo();
+
+appendStringInfo(buf,
+ "\"%s%spsql\" -X",
+ bindir ? bindir : "",
+ bindir ? "/" : "");
+return buf;
+}
+
 static void
-psql_command(const char *database, const char *query,...)
+psql_add_command(StringInfo buf, const char *query,...)
 {
-charquery_formatted[1024];
-charquery_escaped[2048];
-charpsql_cmd[MAXPGPATH + 2048];
-va_listargs;
-char *s;
-char *d;
+StringInfoData cmdbuf;
+const char *cmdptr;
+
+/* Add each command as a -c argument in the psql call */
+appendStringInfoString(buf, " -c \"");
 
 /* Generate the query with insertion of sprintf arguments */
-va_start(args, query);
-vsnprintf(query_formatted, sizeof(query_formatted), query, args);
-va_end(args);
+initStringInfo(&cmdbuf);
+for (;;)
+{
+va_listargs;
+intneeded;
+
+va_start(args, query);
+needed = appendStringInfoVA(&cmdbuf, query, args);
+va_end(args);
+if (needed == 0)
+break;/* success */
+enlargeStringInfo(&cmdbuf, needed);
+}
 
 /* Now escape any shell double-quote metacharacters */
-d = query_escaped;
-for (s = query_formatted; *s; s++)
+for (cmdptr = cmdbuf.data; *cmdptr; cmdptr++)
 {
-if (strchr("\\\"$`", *s))
-*d++ = '\\';
-*d++ = *s;
+if (strchr("\\\"$`", *cmdptr))
+appendStringInfoChar(buf, '\\');
+appendStringInfoChar(buf, *cmdptr);
 }
-*d = '\0';
 
-/* And now we can build and execute the shell command */
-snprintf(psql_cmd, sizeof(psql_cmd),
- "\"%s%spsql\" -X -c \"%s\" \"%s\"",
- bindir ? bindir : "",
- bindir ? "/" : "",
- query_escaped,
- database);
+appendStringInfoChar(buf, '"');
+
+pfree(cmdbuf.data);
+}
+
+static void
+psql_end_command(StringInfo buf, const char *database)
+{
+/* Add the database name --- assume it needs no extra escaping */
+appendStringInfo(buf,
+ " \"%s\"",
+ database);
 
-if (system(psql_cmd) != 0)
+/* And now we can execute the shell command */
+if (system(buf->data) != 0)
 {
 /* psql probably already reported the error */
-fprintf(stderr, _("command failed: %s\n"), psql_cmd);
+fprintf(stderr, _("command failed: %s\n"), buf->data);
 exit(2);
 }
+
+/* Clean up */
+pfree(buf->data);
+pfree(buf);
 }
 
+/*
+ * Shorthand macro for the common case of a single command
+ */
+#define psql_command(database, ...) \
+do { \
+StringInfo cmdbuf = psql_start_command(); \
+psql_add_command(cmdbuf, __VA_ARGS__); \
+psql_end_command(cmdbuf, database); \
+} while (0)
+
 /*
  * Spawn a process to execute the given shell command; don't wait for it
  *
@@ -2012,13 +2057,19 @@ open_result_files(void)
 static void
 drop_database_if_exists(const char *dbname)
 {
+StringInfobuf = psql_start_command();
+
 header(_("dropping database \"%s\""), dbname);
-psql_command("postgres", "DROP DATABASE IF EXISTS \"%s\"", dbname);
+/* Set warning level so we don't see chatter about nonexistent DB */
+psql_add_command(buf, "SET client_min_messages = warning");
+psql_add_command(buf, "DROP DATABASE IF EXISTS \"%s\"", dbname);
+psql_end_command(buf, "postgres");
 }
 
 static void
 create_database(const char *dbname)
 {
+StringInfobuf = psql_start_command();
 _stringlist *sl;
 
 /*
@@ -2027,19 +2078,20 @@ create_database(const char *dbname)
  */
 header(_("creating database \"%s\""), dbname);
 if (encoding)
-psql_command("postgres", "CREATE DATABASE \"%s\" TEMPLATE=template0 ENCODING='%s'%s", dbname, encoding,
- (nolocale) ? " LC_COLLATE='C' LC_CTYPE='C'" : "");
+psql_add_command(buf, "CREATE DATABASE \"%s\" TEMPLATE=template0 ENCODING='%s'%s", dbname, encoding,
+ (nolocale) ? " LC_COLLATE='C' LC_CTYPE='C'" : "");
 else
-psql_command("postgres", "CREATE DATABASE \"%s\" TEMPLATE=template0%s", dbname,
- (nolocale) ? " LC_COLLATE='C' LC_CTYPE='C'" : "");
-psql_command(dbname,
- "ALTER DATABASE \"%s\" SET lc_messages TO 'C';"
- "ALTER DATABASE \"%s\" SET lc_monetary TO 'C';"
- "ALTER DATABASE \"%s\" SET lc_numeric TO 'C';"
- "ALTER DATABASE \"%s\" SET lc_time TO 'C';"
- "ALTER DATABASE \"%s\" SET bytea_output TO 'hex';"
- "ALTER DATABASE \"%s\" SET timezone_abbreviations TO 'Default';",
- dbname, dbname, dbname, dbname, dbname, dbname);
+psql_add_command(buf, "CREATE DATABASE \"%s\" TEMPLATE=template0%s", dbname,
+ (nolocale) ? " LC_COLLATE='C' LC_CTYPE='C'" : "");
+psql_add_command(buf,
+ "ALTER DATABASE \"%s\" SET lc_messages TO 'C';"
+ "ALTER DATABASE \"%s\" SET lc_monetary TO 'C';"
+ "ALTER DATABASE \"%s\" SET lc_numeric TO 'C';"
+ "ALTER DATABASE \"%s\" SET lc_time TO 'C';"
+ "ALTER DATABASE \"%s\" SET bytea_output TO 'hex';"
+ "ALTER DATABASE \"%s\" SET timezone_abbreviations TO 'Default';",
+ dbname, dbname, dbname, dbname, dbname, dbname);
+psql_end_command(buf, "postgres");
 
 /*
  * Install any requested extensions. We use CREATE IF NOT EXISTS so that
@@ -2055,20 +2107,28 @@ create_database(const char *dbname)
 static void
 drop_role_if_exists(const char *rolename)
 {
+StringInfobuf = psql_start_command();
+
 header(_("dropping role \"%s\""), rolename);
-psql_command("postgres", "DROP ROLE IF EXISTS \"%s\"", rolename);
+/* Set warning level so we don't see chatter about nonexistent role */
+psql_add_command(buf, "SET client_min_messages = warning");
+psql_add_command(buf, "DROP ROLE IF EXISTS \"%s\"", rolename);
+psql_end_command(buf, "postgres");
 }
 
 static void
 create_role(const char *rolename, const _stringlist *granted_dbs)
 {
+StringInfobuf = psql_start_command();
+
 header(_("creating role \"%s\""), rolename);
-psql_command("postgres", "CREATE ROLE \"%s\" WITH LOGIN", rolename);
+psql_add_command(buf, "CREATE ROLE \"%s\" WITH LOGIN", rolename);
 for (; granted_dbs != NULL; granted_dbs = granted_dbs->next)
 {
-psql_command("postgres", "GRANT ALL ON DATABASE \"%s\" TO \"%s\"",
- granted_dbs->str, rolename);
+psql_add_command(buf, "GRANT ALL ON DATABASE \"%s\" TO \"%s\"",
+ granted_dbs->str, rolename);
 }
+psql_end_command(buf, "postgres");
 }
 
 static void