[tamnd]

Summary

COPY ... FROM 'file' now reads a file of the server, as BeginCopyFrom of copyfrom.c opens it. The regression suite loads its tables with this form in test_setup.sql.

Changes

• The session holds the Io of the server and reads the whole file through it. The rows then go through the same path as COPY FROM STDIN, with the same line errors and context.
• A role that is not a superuser gets 42501 "permission denied to COPY from a file", with the detail and the hint of PostgreSQL.
• A directory gives 42809, and a file that cannot be opened gives "could not open file ... for reading" with the text of the OS error.
• The simple and the extended protocol both run the statement.

Known differences

• COPY FROM PROGRAM gives 0A000.
• The session reads the whole file before it parses the rows. PostgreSQL reads the file in parts.

Tests

• copy_from_file runs a file of rows, a file with a bad line, a file that does not exist, and the extended protocol, on a simulated file system.
• fmt, clippy, the workspace tests and the checks of xtask pass on server1.