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JDK-8310265: (process) jspawnhelper should not use argv[0] #14531

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JDK-8310265: (process) jspawnhelper should not use argv[0] #14531

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JDK-8310265-jspawnhelper-argv0
tstuefe Jun 17, 2023
1ee05c0
correct comment
tstuefe Jun 19, 2023
8f83fa2
feedback Volker and Roger
tstuefe Jun 20, 2023
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2 changes: 1 addition & 1 deletion src/java.base/unix/native/jspawnhelper/jspawnhelper.c
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Original file line number Diff line number Diff line change
@@ -136,7 +136,7 @@ void initChildStuff (int fdin, int fdout, ChildStuff *c) {
int main(int argc, char *argv[]) {
ChildStuff c;
struct stat buf;
/* argv[0] contains the fd number to read all the child info */
/* argv[1] contains the fd number to read all the child info */
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I would prefer to also fix the use of argc-1 below to match. Its a pretty odd form and might trip someone later.

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I wondered about this, it looked so deliberate. So I wondered whether jspawnhelper is used outside of the posix_spawn context, but cannot find anything. Maybe historic?

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I'm not aware of any other uses either; its not intended to be used outside of ProcessImpl especially since the addition of the new protocol to communicate parameters and confirm launching of the child.

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This curiosity has been present since Rob's first version:
https://mail.openjdk.org/pipermail/core-libs-dev/2012-November/012417.html

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I assumed that at some point in its life, maybe just in the first unpublished versions, the jspawnhelper had a variable number of arguments, possibly from different callers. But the fd-string was always supposed to be the last one. Then this would have made perfect sense.

int r, fdinr, fdinw, fdout;
sigset_t unblock_signals;