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Diffstat (limited to 'tools/magrathea/mg.scm')
| -rw-r--r-- | tools/magrathea/mg.scm | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/tools/magrathea/mg.scm b/tools/magrathea/mg.scm new file mode 100644 index 000000000000..a453da2ccd28 --- /dev/null +++ b/tools/magrathea/mg.scm @@ -0,0 +1,316 @@ +;; magrathea helps you build planets +;; +;; it is a tiny tool designed to ease workflows in monorepos that are +;; modeled after the tvl depot. +;; +;; users familiar with workflows from other, larger monorepos may be +;; used to having a build tool that can work in any tree location. +;; magrathea enables this, but with nix-y monorepos. + +(import (chicken base) + (chicken format) + (chicken irregex) + (chicken port) + (chicken file) + (chicken file posix) + (chicken process) + (chicken process-context) + (chicken string) + (matchable) + (only (chicken io) read-string)) + +(define usage #<<USAGE +usage: mg <command> [<target>] + +target: + a target specification with meaning inside of the repository. can + be absolute (starting with //) or relative to the current directory + (as long as said directory is inside of the repo). if no target is + specified, the current directory's physical target is built. + + for example: + + //tools/magrathea - absolute physical target + //foo/bar:baz - absolute virtual target + magrathea - relative physical target + :baz - relative virtual target + +commands: + build - build a target + shell - enter a shell with the target's build dependencies + path - print source folder for the target + run - build a target and execute its output + +file all feedback on b.tvl.fyi +USAGE +) + +;; parse target definitions. trailing slashes on physical targets are +;; allowed for shell autocompletion. +;; +;; component ::= any string without "/" or ":" +;; +;; physical-target ::= <component> +;; | <component> "/" +;; | <component> "/" <physical-target> +;; +;; virtual-target ::= ":" <component> +;; +;; relative-target ::= <physical-target> +;; | <virtual-target> +;; | <physical-target> <virtual-target> +;; +;; root-anchor ::= "//" +;; +;; target ::= <relative-target> | <root-anchor> <relative-target> + +;; read a path component until it looks like something else is coming +(define (read-component first port) + (let ((keep-reading? + (lambda () (not (or (eq? #\/ (peek-char port)) + (eq? #\: (peek-char port)) + (eof-object? (peek-char port))))))) + (let reader ((acc (list first)) + (condition (keep-reading?))) + (if condition (reader (cons (read-char port) acc) (keep-reading?)) + (list->string (reverse acc)))))) + +;; read something that started with a slash. what will it be? +(define (read-slash port) + (if (eq? #\/ (peek-char port)) + (begin (read-char port) + 'root-anchor) + 'path-separator)) + +;; read any target token and leave port sitting at the next one +(define (read-token port) + (match (read-char port) + [#\/ (read-slash port)] + [#\: 'virtual-separator] + [other (read-component other port)])) + +;; read a target into a list of target tokens +(define (read-target target-str) + (call-with-input-string + target-str + (lambda (port) + (let reader ((acc '())) + (if (eof-object? (peek-char port)) + (reverse acc) + (reader (cons (read-token port) acc))))))) + +(define-record target absolute components virtual) +(define (empty-target) (make-target #f '() #f)) + +(define-record-printer (target t out) + (fprintf out (conc (if (target-absolute t) "//" "") + (string-intersperse (target-components t) "/") + (if (target-virtual t) ":" "") + (or (target-virtual t) "")))) + +;; parse and validate a list of target tokens +(define parse-tokens + (lambda (tokens #!optional (mode 'root) (acc (empty-target))) + (match (cons mode tokens) + ;; absolute target + [('root . ('root-anchor . rest)) + (begin (target-absolute-set! acc #t) + (parse-tokens rest 'root acc))] + + ;; relative target minus potential garbage + [('root . (not ('path-separator . _))) + (parse-tokens tokens 'normal acc)] + + ;; virtual target + [('normal . ('virtual-separator . rest)) + (parse-tokens rest 'virtual acc)] + + [('virtual . ((? string? v))) + (begin + (target-virtual-set! acc v) + acc)] + + ;; chomp through all components and separators + [('normal . ('path-separator . rest)) (parse-tokens rest 'normal acc)] + [('normal . ((? string? component) . rest)) + (begin (target-components-set! + acc (append (target-components acc) (list component))) + (parse-tokens rest 'normal acc ))] + + ;; nothing more to parse and not in a weird state, all done, yay! + [('normal . ()) acc] + + ;; oh no, we ran out of input too early :( + [(_ . ()) `(error . ,(format "unexpected end of input while parsing ~s target" mode))] + + ;; something else was invalid :( + [_ `(error . ,(format "unexpected ~s while parsing ~s target" (car tokens) mode))]))) + +(define (parse-target target) + (parse-tokens (read-target target))) + +;; turn relative targets into absolute targets based on the current +;; directory +(define (normalise-target t) + (when (not (target-absolute t)) + (target-components-set! t (append (relative-repo-path) + (target-components t))) + (target-absolute-set! t #t)) + t) + +;; nix doesn't care about the distinction between physical and virtual +;; targets, normalise it away +(define (normalised-components t) + (if (target-virtual t) + (append (target-components t) (list (target-virtual t))) + (target-components t))) + +;; return the current repository root as a string +(define mg--repository-root #f) +(define (repository-root) + (or mg--repository-root + (begin + (set! mg--repository-root + (or (get-environment-variable "MG_ROOT") + (string-chomp + (call-with-input-pipe "git rev-parse --show-toplevel" + (lambda (p) (read-string #f p)))))) + mg--repository-root))) + +;; determine the current path relative to the root of the repository +;; and return it as a list of path components. +(define (relative-repo-path) + (string-split + (substring (current-directory) (string-length (repository-root))) "/")) + +;; escape a string for interpolation in nix code +(define (nix-escape str) + (string-translate* str '(("\"" . "\\\"") + ("${" . "\\${")))) + +;; create a nix expression to build the attribute at the specified +;; components +;; +;; an empty target will build the current folder instead. +;; +;; this uses builtins.getAttr explicitly to avoid problems with +;; escaping. +(define (nix-expr-for target) + (let nest ((parts (normalised-components (normalise-target target))) + (acc (conc "(import " (repository-root) " {})"))) + (match parts + [() (conc "with builtins; " acc)] + [_ (nest (cdr parts) + (conc "(getAttr \"" + (nix-escape (car parts)) + "\" " acc ")"))]))) + +;; exit and complain at the user if something went wrong +(define (mg-error message) + (format (current-error-port) "[mg] error: ~A~%" message) + (exit 1)) + +(define (guarantee-success value) + (match value + [('error . message) (mg-error message)] + [_ value])) + +(define (execute-build t) + (let ((expr (nix-expr-for t))) + (fprintf (current-error-port) "[mg] building target ~A~%" t) + (process-execute "nix-build" (list "-E" expr "--show-trace")))) + +(define (build args) + (match args + ;; simplest case: plain mg build with no target spec -> build + ;; the current folder's main target. + [() (execute-build (empty-target))] + + ;; single argument should be a target spec + [(arg) (execute-build + (guarantee-success (parse-target arg)))] + + [other (print "not yet implemented")])) + +(define (execute-shell t) + (let ((expr (nix-expr-for t)) + (user-shell (or (get-environment-variable "SHELL") "bash"))) + (fprintf (current-error-port) "[mg] entering shell for ~A~%" t) + (process-execute "nix-shell" + (list "-E" expr "--command" user-shell)))) + +(define (shell args) + (match args + [() (execute-shell (empty-target))] + [(arg) (execute-shell + (guarantee-success (parse-target arg)))] + [other (print "not yet implemented")])) + +(define (execute-run t #!optional cmd-args) + (fprintf (current-error-port) "[mg] building target ~A~%" t) + (let* ((expr (nix-expr-for t)) + (out (call-with-input-pipe + (apply string-append + ;; TODO(sterni): temporary gc root + (intersperse `("nix-build" "-E" ,(qs expr) "--no-out-link") + " ")) + (lambda (p) + (string-chomp (let ((s (read-string #f p))) + (if (eq? s #!eof) "" s))))))) + + ;; TODO(sterni): can we get the exit code of nix-build somehow? + (when (= (string-length out) 0) + (mg-error (string-append "Couldn't build target " (format "~A" t))) + (exit 1)) + + (fprintf (current-error-port) "[mg] running target ~A~%" t) + (process-execute + ;; If the output is a file, we assume it's an executable à la writeExecline, + ;; otherwise we look in the bin subdirectory and pick the only executable. + ;; Handling multiple executables is not possible at the moment, the choice + ;; could be made via a command line flag in the future. + (if (regular-file? out) + out + (let* ((dir-path (string-append out "/bin")) + (dir-contents (if (directory-exists? dir-path) + (directory dir-path #f) + '()))) + (case (length dir-contents) + ((0) (mg-error "no executables in build output") + (exit 1)) + ((1) (string-append dir-path "/" (car dir-contents))) + (else (mg-error "more than one executable in build output") + (exit 1))))) + cmd-args))) + +(define (run args) + (match args + [() (execute-run (empty-target))] + ;; TODO(sterni): flag for selecting binary name + [other (execute-run (guarantee-success (parse-target (car args))) + (cdr args))])) + +(define (path args) + (match args + [(arg) + (print (apply string-append + (intersperse + (cons (repository-root) + (target-components + (normalise-target + (guarantee-success (parse-target arg))))) + "/")))] + [() (mg-error "path command needs a target")] + [other (mg-error (format "unknown arguments: ~a" other))])) + +(define (main args) + (match args + [() (print usage)] + [("build" . _) (build (cdr args))] + [("shell" . _) (shell (cdr args))] + [("path" . _) (path (cdr args))] + [("run" . _) (run (cdr args))] + [other (begin (print "unknown command: mg " args) + (print usage))])) + +(main (command-line-arguments)) |