On 01.11.22 06:52, Tom Lane wrote:
I think there are two issues here. POSIX saysUpon successful return, pclose() shall return the termination status of the command language interpreter. Otherwise, pclose() shall return -1 and set errno to indicate the error. That is, first you need to make sure that pclose returned a valid child process status, and then you need to decode that status. It's not obvious to me that -1 is disjoint from the set of possible child statuses. Do we need to add some logic that clears and then checks errno?
This return convention is also used by system() and is widely used. So I don't think we need to be concerned about this.
In practice, int is 4 bytes and WEXITSTATUS() and WTERMSIG() are one byte each, so they are probably in the lower bytes, and wouldn't accidentally make up a -1.
Also, we have a number of places --- at least FreeDesc() and ClosePipeStream() --- that consider pclose()'s return value to be perfectly equivalent to that of close() etc, because they'll return either one without telling the caller which is which. It seems like we have to fix that if we want to issue sane error reports.
I think this works. FreeDesc() returns the pclose() exit status to ClosePipeStream(), which returns it directly. No interpretation is done within these functions.
