Description:
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There are some functions that calculate hash from a file, e.g., md5_file() and sha1_file(), but they work only for whole files.

There's also a function (or a language construct?) __halt_compiler(), which is useful for making "installers", as it allows to mix PHP code and binary data (e.g., compressed archive) in a single file.

To make sure that whole "installer" is correctly downloaded, it would be worth to validate checksum of binary data by comparing it with value of checksum that is stored in PHP code part (i.e., before __halt_compiler()). Currently, checksum of binary data may be calculated by fully loading binary data and calling md5() or sha1() on a string. It is not a problem for smaller installers, but if installer is larger (e.g., because of having lots of images in it), it might require too much memory to be loaded into a string. In this case, it would be handy to use md5_file() or sha1_file() with 3rd parameter - $offset, something like md5_file($filename, false, __COMPILER_HALT_OFFSET__).

Any chance to see it implemented some day?