git: 621dae89f3c7 - main - loader: Document the lua loader table.
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Date: Sat, 10 Feb 2024 18:50:16 UTC
The branch main has been updated by imp: URL: https://cgit.FreeBSD.org/src/commit/?id=621dae89f3c70b86bef255a621a76bf553f733ff commit 621dae89f3c70b86bef255a621a76bf553f733ff Author: Warner Losh <imp@FreeBSD.org> AuthorDate: 2024-02-10 18:49:09 +0000 Commit: Warner Losh <imp@FreeBSD.org> CommitDate: 2024-02-10 18:49:09 +0000 loader: Document the lua loader table. Document all the public functions from the "loader" table. Sponsored by: Netflix Reviewed by: pauamma_gundo.com, tsoome, kevans Differential Revision: https://reviews.freebsd.org/D43701 --- stand/lua/Makefile | 1 + stand/lua/loader.lua.8 | 247 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 248 insertions(+) diff --git a/stand/lua/Makefile b/stand/lua/Makefile index 6b1064dc1815..e8fa16e6b589 100644 --- a/stand/lua/Makefile +++ b/stand/lua/Makefile @@ -8,6 +8,7 @@ MAN= loader.conf.lua.5 \ core.lua.8 \ drawer.lua.8 \ hook.lua.8 \ + loader.lua.8 \ menu.lua.8 \ password.lua.8 \ screen.lua.8 diff --git a/stand/lua/loader.lua.8 b/stand/lua/loader.lua.8 new file mode 100644 index 000000000000..cd436255d4a5 --- /dev/null +++ b/stand/lua/loader.lua.8 @@ -0,0 +1,247 @@ +.\" +.\" Copyright (c) 2024 Netflix, Inc. +.\" +.\" SPDX-License-Identifier: BSD-2-Clause +.\" +.Dd February 6, 2024 +.Dt LOADER.LUA 8 +.Os +.Sh NAME +.Nm loader.lua +.Nd Fx Lua loader module +.Sh DESCRIPTION +The built-in Lua bindings for the +.Fx +boot loaders using the Lua interpreter +are available via the +.Ic loader +table. +.Pp +The +.Ic loader +table is always available in Lua scripts. +There is no need to require it like other loader-specific modules. +.Ss Exported Variables +The following variables are provided by the Lua interpreter in the +.Nm loader +table: +.Bl -tag -width machine_arch +.It Ic machine +The target's +.Va hw.machine +.Xr sysctl 8 +value. +.It Ic machine_arch +The target's +.Va hw.machine_arch +.Xr sysctl 8 +value. +Some boot loaders are 32-bit applications that then load a 64-bit +kernel. +In these cases, +.Ic machine_arch +represents the 32-bit architecture, not the 64-bit architecture. +.It Ic lua_path +The current lua loading path. +.It Ic version +The version of the boot program. +.El +.Ss Exported Functions +The following functions are exported in the +.Nm loader +table. +.Bl -tag -width term_putimage +.It Fn delay usec +Delay for +.Va usec +microseconds. +.It Fn command_error +Returns the error string from the last command to fail. +.It Fn command argc argv +Like +.Fn perform +but the arguments are already parsed onto the stack. +.It Fn interpret str +Execute the loader builtin command +.Va str +as if it were typed by the user. +This will first try to execute +.Va str +as Lua. +If that fails, it will attempt to execute it as a cli command, +including those defined by the +.Xr cli.lua 8 +mechanism. +If that fails, it will attempt to execute it as a builtin command +and return the same values as +.Fn perform . +.It Fn parse str +Parses the command +.Va str +into its words and return those words on the stack. +.It Fn getenv name +Obtains the value of the environment variable +.Va name . +.It Fn has_command cmd +returns +.Va true +if +.Va commmand +is present in the interpreter as a builtin. +Otherwise it returns +.Va nil +and an error string. +It does not check the +.Dq cli +table to see if a user defined command has been created. +.It Fn has_feature feature +returns +.Va true +if the +.Va feature +is enabled. +Otherwise it returns +.Va nil +and an error string. +.It Fn perform str +Execute the loader builtin command +.Va str . +Returns the result of the command, one of the following values: +.Bl -tag -width loader -offset indent +.It loader.CMD_OK +The command completed successfully. +.It loader.CMD_WARN +The command was successful, but the user stopped its output +prematurely. +.It loader.CMD_ERROR +The command did not complete successfully. +Use +.Va command_error +to retrieve the error. +.It loader.CMD_CRIT +The command returned a critical error that was already printed. +.It loader.CMD_FATAL +The command determined continuation was not possible +and the loader panicked. +In practice, though, +.Fn panic +does not return. +.El +.It Fn printc str +Outputs the string using the loader's +.Fn putchar +function. +This function is also available globally as +.Fn printc . +.It Fn setenv name value +Insert or reset the environment variable +.Va name +into the loader's environment list. +If no environment variable with this name exists, one is created. +If one exists, its value is replaced. +.It Fn time +Returns the loader's notion of time, in seconds since 1970. +The value of loader's notion varies somewhat between different loading +environments. +.It Fn unsetenv name +Removes the environment variable +.Va name +from the loader's environment list. +.It Fn fb_bezier x0 y0 x1 y1 x2 y2 width +Draw a bezier curve through the points +.Pq Va x0 , Va y0 , +.Pq Va x1 , Va y1 , +and +.Pq Va x2 , Va y2 +of width +.Va width . +The units are in pixels and have an origin of +.Pq 0 , 0 . +.It Fn fb_drawrect x0 y0 x1 y1 fill +Fill in a rectangle with the pixel +.Va fill +with the corners +.Pq Va x0 , Va y0 +and +.Pq Va x1 , Va y1 . +The units are in pixels and have an origin of +.Pq 0 , 0 . +.It Fn fb_line x0 y0 x1 y1 width +Draw a line from +.Pq Va x0 , Va y0 +to +.Pq Va x1 , Va y1 +with a width of +.Va width . +The units are in pixels and have an origin of +.Pq 0 , 0 . +.It Fn fb_putimage name x0 y0 x1 y1 f +Load the PNG file +.Va name +and place it in the rectangle +with the corners +.Pq Va x0 , Va y0 +and +.Pq Va x1 , Va y1 +and fill with pixel +.Va f . +The units are in pixels and have an origin of +.Pq 0 , 0 . +.It Fn fb_set_pixel x y +Sets the pixel at +.Pq Va x , Va y . +The units are in pixels and have an origin of +.Pq 0 , 0 . +.It Fn term_drawrect x0 y0 x1 y1 +Draw the outline of a rectangle with the text coordinate corners of +.Pq Va x0 , Va y0 +and +.Pq Va x1 , Va y1 . +The units are in character cells and have an origin of +.Pq 1 , 1 . +.It Fn term_putimage name x0 y0 x1 y1 f +Load the PNG file +.Va name +and place it in the rectangle +with the text coordinate corners +.Pq Va x0 , Va y0 +and +.Pq Va x1 , Va y1 +and fill with pixel +.Va f . +The units are in character cells and have an origin of +.Pq 1 , 1 . +.El +.Pp +The functions starting with +.Fn fb_ +and +.Fn term_ +are optional. +They should only be used if they are non-nil and if +.Fn core.isFramebufferConsole +is true. +.Ss Default File +In addition, the Lua interpreters start with the file +.Pa /boot/lua/loader.lua +when they start to boot the system. +The default one will fixup the screen, load the configuration files, check for a +password, and then load the menu or load the kernel file and then return. +If autoboot is enabled, the loaded files will boot. +.Sh SEE ALSO +.Xr loader.conf 5 , +.Xr core.lua 8 , +.Xr loader 8 , +.Xr sysctl 8 +.Sh AUTHORS +The +.Nm +man page was written by +.An Warner Losh Aq Mt imp@FreeBSD.org . +.Sh BUGS +.Fn command +and +.Fn perform +should return a tuple when there's +.Va CMD_ERROR +or worse.