108 lines
3.9 KiB
Go
108 lines
3.9 KiB
Go
package sys
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import "io/fs"
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// Inode is the file serial number, or zero if unknown.
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//
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// Any constant value will invalidate functions that use this for
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// equivalence, such as os.SameFile (Stat_t.Ino).
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//
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// When zero is returned by a `readdir`, some compilers will attempt to
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// get a non-zero value with `lstat`. Those using this for darwin's definition
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// of `getdirentries` conflate zero `d_fileno` with a deleted file, so skip the
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// entry. See /RATIONALE.md for more on this.
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type Inode = uint64
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// ^-- Inode is a type alias to consolidate documentation and aid in reference
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// searches. While only Stat_t is exposed publicly at the moment, this is used
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// internally for Dirent and several function return values.
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// EpochNanos is a timestamp in epoch nanoseconds, or zero if unknown.
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//
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// This defines epoch time the same way as Walltime, except this value is
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// packed into an int64. Common conversions are detailed in the examples.
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type EpochNanos = int64
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// Stat_t is similar to syscall.Stat_t, except available on all operating
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// systems, including Windows.
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//
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// # Notes
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//
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// - This is used for WebAssembly ABI emulating the POSIX `stat` system call.
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// Fields included are required for WebAssembly ABI including wasip1
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// (a.k.a. wasix) and wasi-filesystem (a.k.a. wasip2). See
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// https://pubs.opengroup.org/onlinepubs/9699919799/functions/stat.html
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// - Fields here are required for WebAssembly ABI including wasip1
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// (a.k.a. wasix) and wasi-filesystem (a.k.a. wasip2).
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// - This isn't the same as syscall.Stat_t because wazero supports Windows,
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// which doesn't have that type. runtime.GOOS that has this already also
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// have inconsistent field lengths, which complicates wasm binding.
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// - Use NewStat_t to create this from an existing fs.FileInfo.
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// - For portability, numeric fields are 64-bit when at least one platform
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// defines it that large.
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type Stat_t struct {
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// Dev is the device ID of device containing the file.
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Dev uint64
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// Ino is the file serial number, or zero if not available. See Inode for
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// more details including impact returning a zero value.
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Ino Inode
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// Mode is the same as Mode on fs.FileInfo containing bits to identify the
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// type of the file (fs.ModeType) and its permissions (fs.ModePerm).
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Mode fs.FileMode
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// Nlink is the number of hard links to the file.
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//
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// Note: This value is platform-specific and often at least one. Linux will
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// return 1+N for a directory, where BSD (like Darwin) return 2+N, which
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// includes the dot entry.
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Nlink uint64
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// Size is the length in bytes for regular files. For symbolic links, this
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// is length in bytes of the pathname contained in the symbolic link.
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Size int64
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// Atim is the last data access timestamp in epoch nanoseconds.
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Atim EpochNanos
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// Mtim is the last data modification timestamp in epoch nanoseconds.
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Mtim EpochNanos
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// Ctim is the last file status change timestamp in epoch nanoseconds.
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Ctim EpochNanos
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}
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// NewStat_t fills a new Stat_t from `info`, including any runtime.GOOS-specific
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// details from fs.FileInfo `Sys`. When `Sys` is already a *Stat_t, it is
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// returned as-is.
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//
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// # Notes
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//
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// - When already in fs.FileInfo `Sys`, Stat_t must be a pointer.
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// - When runtime.GOOS is "windows" Stat_t.Ino will be zero.
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// - When fs.FileInfo `Sys` is nil or unknown, some fields not in fs.FileInfo
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// are defaulted: Stat_t.Atim and Stat_t.Ctim are set to `ModTime`, and
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// are set to ModTime and Stat_t.Nlink is set to 1.
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func NewStat_t(info fs.FileInfo) Stat_t {
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// Note: Pointer, not val, for parity with Go, which sets *syscall.Stat_t
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if st, ok := info.Sys().(*Stat_t); ok {
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return *st
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}
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return statFromFileInfo(info)
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}
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func defaultStatFromFileInfo(info fs.FileInfo) Stat_t {
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st := Stat_t{}
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st.Ino = 0
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st.Dev = 0
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st.Mode = info.Mode()
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st.Nlink = 1
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st.Size = info.Size()
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mtim := info.ModTime().UnixNano() // Set all times to the mod time
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st.Atim = mtim
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st.Mtim = mtim
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st.Ctim = mtim
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return st
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}
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