33 lines
1.5 KiB
Plaintext
33 lines
1.5 KiB
Plaintext
Spawn.cc in cygwin handles spawn, vfork and exec calls. It does this via
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a mode parameter that determines its behaviour with respect to the
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child.
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Of particular interest is the exec behaviour.
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In general spawn_guts (where the action happens) does the following:
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* Finds the actual program being run (which may include path searching).
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* Determines the type (.exe, shell script, perl etc) and for non binary
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programs finds the correct interpreter.
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* Creates a commandline (based on the type and the user parameters).
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* Guesses at whether the binary that will be invoked is a cygwin program
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or not (if (real_path.iscygexec ())) and uses that information to copy
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the argv table, or to translate it for win32 program usage.
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* passes a handle to the parent to the child (note: this handle should
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have it's rights restricted the daemon is merged).
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* Start the process.
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* if the mode is _P_OVERLAY (we are doing an exec)
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wait for the child to
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a) if it's a cygwin process, signal us via an event.
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b) if it's a win32 process, exit.
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c) exit.
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If a) occurs, we 'reparent' the child which makes it look to the current
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process's parent in the pid and process group chains.
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b) is where the cygwin process hangs around as a 'stub' presenting it's
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pid as the win32 process's pid, to allow cygwin tools to kill the win32
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process.
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once a-c has occured, execution resumes.
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* If the mode is _P_OVERLAY, this process exits, otherwise it's
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behaviour depends on the mode parameter. See the last block of
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spawn_guts.
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