Oihana PHP System

computeETag.php

Table of Contents

Functions

computeETag()  : string
Computes an HTTP entity tag (`ETag`) validator for a file.

Functions

computeETag()

Computes an HTTP entity tag (`ETag`) validator for a file.

computeETag(string $file[, bool $weak = false ][, bool $hashContent = false ]) : string

By default the tag is derived from the file metadata (mtime-size, in hexadecimal) so no content read is required — this keeps large-file streaming cheap. Pass $hashContent = true to build an exact, byte-level tag from md5_file() instead (reads the whole file).

The returned value is a quoted opaque tag, prefixed with W/ when $weak is true.

Parameters
$file : string

Absolute path of the file (must exist).

$weak : bool = false

Emit a weak validator (W/"...") instead of a strong one.

$hashContent : bool = false

Derive the tag from the file content (md5_file()) instead of its metadata.

Tags
author

Marc Alcaraz (ekameleon)

since
1.0.0
example 
computeETag( '/var/data/file.bin' ) ;                       // "<mtime-hex>-<size-hex>" (strong, metadata)
computeETag( '/var/data/file.bin' , weak: true ) ;          // W/"<mtime-hex>-<size-hex>"
computeETag( '/var/data/file.bin' , hashContent: true ) ;   // "<md5>" (strong, exact)
Return values
string —

The ETag value, e.g. "18f-3e8" or W/"18f-3e8".

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