At Tue, 7 Jun 2022 16:33:53 +0900, Michael Paquier <mich...@paquier.xyz> wrote
in
> On Tue, Jun 07, 2022 at 04:05:20PM +0900, Kyotaro Horiguchi wrote:
> > If I want to read a file that I'm not sure of the existence but I want
> > to read the whole file if exists, I would call
> > pg_read_binary_file('path', 0, -1, true) but unfortunately this
> > doesn't work.
>
> Yeah, the "normal" cases that I have seen in the past just used an
> extra call to pg_stat_file() to retrieve the size of the file before
> reading it, but arguably it does not help if the file gets extended
> between the stat() call and the read() call (we don't need to care
> about this case with pg_rewind that has been the reason why the
> missing_ok argument was introduced first, for one, as file extensions
> don't matter as we'd replay from the LSN point where the rewind
> began, adding the new blocks at replay).
Sure.
> There is also an argument for supporting negative values rather than
> just -1. For example -2 could mean to read all the file except the
> last byte. Or you could have an extra flavor, as of
> pg_read_file(text, bool) to read the whole by default. Supporting
> just -1 as special value for the amount of data to read would be
> confusing IMO. So I would tend to choose for a set of arguments based
> on (text, bool).
I'm not sure about the negative length smaller than -1, since I don't
find an apprpriate offset that represents (last byte + 1).
pg_read_file(text, bool) makes sense to me, but it doesn't seem like
to be able to share C function with other variations.
pg_read_binary_file() need to accept some out-of-range value for
offset or length to signal that offset and length are not specified.
In the attached pg_read(_binary)_file_all() is modifiedf so that they
have the different body from pg_read(_binary)_file().
(function comments needs to be edited and docs are needed)
regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center
diff --git a/src/backend/utils/adt/genfile.c b/src/backend/utils/adt/genfile.c
index 2bf5219256..62e16b014e 100644
--- a/src/backend/utils/adt/genfile.c
+++ b/src/backend/utils/adt/genfile.c
@@ -349,7 +349,6 @@ pg_read_binary_file(PG_FUNCTION_ARGS)
PG_RETURN_NULL();
}
-
/*
* Wrapper functions for the 1 and 3 argument variants of pg_read_file_v2()
* and pg_read_binary_file().
@@ -367,7 +366,21 @@ pg_read_file_off_len(PG_FUNCTION_ARGS)
Datum
pg_read_file_all(PG_FUNCTION_ARGS)
{
- return pg_read_file_v2(fcinfo);
+ text *filename_t = PG_GETARG_TEXT_PP(0);
+ bool missing_ok = false;
+ char *filename;
+ text *result;
+
+ if (PG_NARGS() >= 2)
+ missing_ok = PG_GETARG_BOOL(1);
+
+ filename = convert_and_check_filename(filename_t);
+
+ result = read_text_file(filename, 0, -1, missing_ok);
+ if (result)
+ PG_RETURN_TEXT_P(result);
+ else
+ PG_RETURN_NULL();
}
Datum
@@ -379,7 +392,21 @@ pg_read_binary_file_off_len(PG_FUNCTION_ARGS)
Datum
pg_read_binary_file_all(PG_FUNCTION_ARGS)
{
- return pg_read_binary_file(fcinfo);
+ text *filename_t = PG_GETARG_TEXT_PP(0);
+ bool missing_ok = false;
+ char *filename;
+ bytea *result;
+
+ if (PG_NARGS() >= 2)
+ missing_ok = PG_GETARG_BOOL(1);
+
+ filename = convert_and_check_filename(filename_t);
+
+ result = read_binary_file(filename, 0, -1, missing_ok);
+ if (result)
+ PG_RETURN_BYTEA_P(result);
+ else
+ PG_RETURN_NULL();
}
/*
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 87aa571a33..e180286749 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6423,6 +6423,9 @@
{ oid => '3826', descr => 'read text from a file',
proname => 'pg_read_file', provolatile => 'v', prorettype => 'text',
proargtypes => 'text', prosrc => 'pg_read_file_all' },
+{ oid => '8530', descr => 'read text from a file',
+ proname => 'pg_read_file', provolatile => 'v', prorettype => 'text',
+ proargtypes => 'text bool', prosrc => 'pg_read_file_all' },
{ oid => '3827', descr => 'read bytea from a file',
proname => 'pg_read_binary_file', provolatile => 'v', prorettype => 'bytea',
proargtypes => 'text int8 int8', prosrc => 'pg_read_binary_file_off_len' },
@@ -6432,6 +6435,9 @@
{ oid => '3828', descr => 'read bytea from a file',
proname => 'pg_read_binary_file', provolatile => 'v', prorettype => 'bytea',
proargtypes => 'text', prosrc => 'pg_read_binary_file_all' },
+{ oid => '8529', descr => 'read bytea from a file',
+ proname => 'pg_read_binary_file', provolatile => 'v', prorettype => 'bytea',
+ proargtypes => 'text bool', prosrc => 'pg_read_binary_file_all' },
{ oid => '2625', descr => 'list all files in a directory',
proname => 'pg_ls_dir', prorows => '1000', proretset => 't',
provolatile => 'v', prorettype => 'text', proargtypes => 'text',
