Support pg_read_[binary_]file (filename, missing_ok).

There wasn't an especially nice way to read all of a file while
passing missing_ok = true.  Add an additional overloaded variant
to support that use-case.

While here, refactor the C code to avoid a rats-nest of PG_NARGS
checks, instead handling the argument collection in the outer
wrapper functions.  It's a bit longer this way, but far more
straightforward.

(Upon looking at the code coverage report for genfile.c, I was
impelled to also add a test case for pg_stat_file() -- tgl)

Kyotaro Horiguchi

Discussion: https://postgr.es/m/20220607.160520.1984541900138970018.horikyota.ntt@gmail.com

2 files changed, 90 insertions, 0 deletions

diff --git a/src/test/regress/expected/misc_functions.out b/src/test/regress/expected/misc_functions.out
index 01d1ad0b9a..ca82d91f1a 100644
--- a/src/test/regress/expected/misc_functions.out
+++ b/src/test/regress/expected/misc_functions.out
@@ -372,6 +372,68 @@ select count(*) >= 0 as ok from pg_ls_archive_statusdir();
  t
 (1 row)
 
+-- pg_read_file()
+select length(pg_read_file('postgresql.auto.conf')) > 30;
+ ?column? 
+----------
+ t
+(1 row)
+
+select length(pg_read_file('postgresql.auto.conf', 1, 30));
+ length 
+--------
+     30
+(1 row)
+
+-- Test missing_ok
+select pg_read_file('does not exist'); -- error
+ERROR:  could not open file "does not exist" for reading: No such file or directory
+select pg_read_file('does not exist', true) IS NULL; -- ok
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test invalid argument
+select pg_read_file('does not exist', 0, -1); -- error
+ERROR:  requested length cannot be negative
+select pg_read_file('does not exist', 0, -1, true); -- error
+ERROR:  requested length cannot be negative
+-- pg_read_binary_file()
+select length(pg_read_binary_file('postgresql.auto.conf')) > 30;
+ ?column? 
+----------
+ t
+(1 row)
+
+select length(pg_read_binary_file('postgresql.auto.conf', 1, 30));
+ length 
+--------
+     30
+(1 row)
+
+-- Test missing_ok
+select pg_read_binary_file('does not exist'); -- error
+ERROR:  could not open file "does not exist" for reading: No such file or directory
+select pg_read_binary_file('does not exist', true) IS NULL; -- ok
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test invalid argument
+select pg_read_binary_file('does not exist', 0, -1); -- error
+ERROR:  requested length cannot be negative
+select pg_read_binary_file('does not exist', 0, -1, true); -- error
+ERROR:  requested length cannot be negative
+-- pg_stat_file()
+select size > 30, isdir from pg_stat_file('postgresql.auto.conf');
+ ?column? | isdir 
+----------+-------
+ t        | f
+(1 row)
+
+-- pg_ls_dir()
 select * from (select pg_ls_dir('.') a) a where a = 'base' limit 1;
   a   
 ------
@@ -401,12 +463,14 @@ select count(*) = 1 as dot_found
  f
 (1 row)
 
+-- pg_timezone_names()
 select * from (select (pg_timezone_names()).name) ptn where name='UTC' limit 1;
  name 
 ------
  UTC
 (1 row)
 
+-- pg_tablespace_databases()
 select count(*) > 0 from
   (select pg_tablespace_databases(oid) as pts from pg_tablespace
    where spcname = 'pg_default') pts
diff --git a/src/test/regress/sql/misc_functions.sql b/src/test/regress/sql/misc_functions.sql
index 072fc36a1f..30212103ca 100644
--- a/src/test/regress/sql/misc_functions.sql
+++ b/src/test/regress/sql/misc_functions.sql
@@ -123,6 +123,30 @@ from (select pg_ls_waldir() w) ss where length((w).name) = 24 limit 1;
 
 select count(*) >= 0 as ok from pg_ls_archive_statusdir();
 
+-- pg_read_file()
+select length(pg_read_file('postgresql.auto.conf')) > 30;
+select length(pg_read_file('postgresql.auto.conf', 1, 30));
+-- Test missing_ok
+select pg_read_file('does not exist'); -- error
+select pg_read_file('does not exist', true) IS NULL; -- ok
+-- Test invalid argument
+select pg_read_file('does not exist', 0, -1); -- error
+select pg_read_file('does not exist', 0, -1, true); -- error
+
+-- pg_read_binary_file()
+select length(pg_read_binary_file('postgresql.auto.conf')) > 30;
+select length(pg_read_binary_file('postgresql.auto.conf', 1, 30));
+-- Test missing_ok
+select pg_read_binary_file('does not exist'); -- error
+select pg_read_binary_file('does not exist', true) IS NULL; -- ok
+-- Test invalid argument
+select pg_read_binary_file('does not exist', 0, -1); -- error
+select pg_read_binary_file('does not exist', 0, -1, true); -- error
+
+-- pg_stat_file()
+select size > 30, isdir from pg_stat_file('postgresql.auto.conf');
+
+-- pg_ls_dir()
 select * from (select pg_ls_dir('.') a) a where a = 'base' limit 1;
 -- Test missing_ok (second argument)
 select pg_ls_dir('does not exist', false, false); -- error
@@ -133,8 +157,10 @@ select count(*) = 1 as dot_found
 select count(*) = 1 as dot_found
   from pg_ls_dir('.', false, false) as ls where ls = '.';
 
+-- pg_timezone_names()
 select * from (select (pg_timezone_names()).name) ptn where name='UTC' limit 1;
 
+-- pg_tablespace_databases()
 select count(*) > 0 from
   (select pg_tablespace_databases(oid) as pts from pg_tablespace
    where spcname = 'pg_default') pts