zip: read all non-zip data from --preamble_from file
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The `zip` command's `--preamble_from` option, as used by Please's python-rules plugin, has strange semantics. The help text says it reads the first line from the given file and uses it as the preamble for the generated zip file, which is true unless the first line is `#!/bin/sh`, in which case the second line will also be read. The second line of "main" pex files generated by python-rules contain an `exec` command, allowing them to self-execute with more arguments than would otherwise be supported in a traditional shebang. Genericise the behaviour of `--preamble_from` so that it is useful for more than just files that begin with 1 or 2-line shell commands - assume the input is a zip file (a tacit assumption until now), and read all non-zip data from the start of the file and use it as the preamble for the generated zip file. Because python-rules' pex files are either pure zip files or zip files prepended with a 1 or 2-line shell command, this does not break backwards compatibility with python-rules.
peterebden
approved these changes
Oct 21, 2024
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The
zipcommand's--preamble_fromoption, as used by Please's python-rules plugin, has strange semantics. The help text says it reads the first line from the given file and uses it as the preamble for the generated zip file, which is true unless the first line is#!/bin/sh, in which case the second line will also be read. The second line of "main" pex files generated by python-rules contain anexeccommand, allowing them to self-execute with more arguments than would otherwise be supported in a traditional shebang.Genericise the behaviour of
--preamble_fromso that it is useful for more than just files that begin with 1 or 2-line shell commands - assume the input is a zip file (a tacit assumption until now), and read all non-zip data from the start of the file and use it as the preamble for the generated zip file.Because python-rules' pex files are either pure zip files or zip files prepended with a 1 or 2-line shell command, this does not break backwards compatibility with python-rules.