Fix pg_truncate() on Windows.

macdice · macdice · commit 72aea955d497 · 2023-01-06T16:42:47.000+13:00
Commit 57faaf3 added pg_truncate(const char *path, off_t length), but "length" was ignored under WIN32 and the file was unconditionally truncated to 0. There was no live bug, since the only caller passes 0. Fix, and back-patch to 14 where the function arrived. Author: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20230106031652.GR3109%40telsasoft.com
diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
@@ -638,7 +638,7 @@ pg_truncate(const char *path, off_t length)
 	fd = OpenTransientFile(path, O_RDWR | PG_BINARY);
 	if (fd >= 0)
 	{
-		ret = ftruncate(fd, 0);
+		ret = ftruncate(fd, length);
 		save_errno = errno;
 		CloseTransientFile(fd);
 		errno = save_errno;

Original file line number	Diff line number	Diff line change
`@@ -638,7 +638,7 @@ pg_truncate(const char *path, off_t length)`
`638`	`638`	`fd = OpenTransientFile(path, O_RDWR \| PG_BINARY);`
`639`	`639`	`if (fd >= 0)`
`640`	`640`	`{`
`641`		`- ret = ftruncate(fd, 0);`
	`641`	`+ ret = ftruncate(fd, length);`
`642`	`642`	`save_errno = errno;`
`643`	`643`	`CloseTransientFile(fd);`
`644`	`644`	`errno = save_errno;`