[RFC PATCH] grep: provide sane default to grep_source struct

grep_buffer creates a struct grep_source gs and calls grep_source() with it. However, gs.name is null, which eventually produces a segmentation fault in grep_source()->grep_source_1()->show_line() when grep_opt.status_only is not set.

This seems to be unreachable from existing commands but is reachable in the event that someone rolls their own revision walk and neglects to set rev_info->grep_filter->status_only. Conceivably, someone might want to print all changed lines of all commits which match some regex.

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
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Hiya,

I ran into this issue while I was working on a tutorial on rolling your own revision walk. I didn't want to print all the lines associated with a matching change, but it didn't seem good that a seemingly-sane grep_filter config was segfaulting.

I don't know if adding a placeholder name is the right answer (hence RFC patch).

Jonathan Nieder proposed alternatively adding some check to grep_source() to ensure that if opt->status_only is unset, gs->name must be non-NULL (and yell about it if not), as well as some extra comments indicating what assumptions are made about the data coming into functions like grep_source(). I'm fine with that as well (although I'm not sure it makes sense semantically to require a name which the user probably can't easily set, or else ban the user from printing LOC during grep). Mostly I'm happy with any solution besides a segfault with no error logging :)

Thanks in advance for everyone's thoughts. Emily

 grep.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)