Documentation
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Overview ¶
Package atomicfile is the one way forge writes a file it generates or scaffolds.
os.WriteFile truncates the target and then writes it. A process that dies between the two — a sandbox restart in the middle of `forge generate` — leaves the file empty or partial, and a generated file that is empty is not "stale": it is a compile error in every package that imports it. WriteFile instead writes a sibling temp file, fsyncs it, and renames it over the target, so the target is always either the complete old bytes or the complete new bytes.
internal/writeguard fails the build on a direct os.WriteFile under internal/, so a new generator cannot reintroduce the truncating write.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
func MarkScratch ¶ added in v1.0.0
func MarkScratch(dir string) (unmark func())
MarkScratch declares dir a throwaway tree: WriteFile still writes atomically under it (readers never see a partial file) but skips the fsync, which on a busy disk dominates a render of hundreds of files. The returned function ends the declaration. Never mark a directory whose contents outlive the process.
func Replace ¶ added in v1.0.0
Replace renames oldPath over newPath, for a file the caller finished writing some other way (a `go install` into a staging dir). It is the rename WriteFile commits with: on Windows, where a replace is refused while any handle — a reader, a virus scanner — has newPath open, it retries for a moment, and a refusal that outlasts that leaves newPath's old content.
func WriteFile ¶
WriteFile writes data to path atomically. It is a drop-in for os.WriteFile: a new file gets perm (subject to the umask); an existing regular file keeps its current permission bits and perm is ignored; a symlink is written through to its target. A path that exists but is not a regular file (a device, a FIFO) cannot be replaced by rename and is written in place.
On any error the target is untouched and the temp file is removed.
Types ¶
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Source Files