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2019-06-17coccinelle: use COPY_ARRAY for copying arraysLibravatar René Scharfe1-15/+46
The current semantic patch for COPY_ARRAY transforms memcpy(3) calls on pointers, but Coccinelle distinguishes them from arrays. It already contains three rules to handle the options for sizeof (i.e. source, destination and type), and handling arrays as source and destination would require four times as many rules if we enumerated all cases. We also don't handle array subscripts, and supporting that would increase the number of rules by another factor of four. (An isomorphism telling Coccinelle that "sizeof x[...]" is equivalent to "sizeof *x" would be nice..) Support arrays and array subscripts, but keep the number of rules down by adding normalization steps: First turn array subscripts into derefences, then determine the types of expressions used with sizeof and replace them with these types, and then convert the different possible combinations of arrays and pointers with memcpy(3) to COPY_ARRAY. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-02coccinelle: remove parentheses that become unnecessaryLibravatar René Scharfe1-5/+5
Transformations that hide multiplications can end up with an pair of parentheses that is no longer needed. E.g. with a rule like this: @@ expression E; @@ - E * 2 + double(E) ... we might get a patch like this: - x = (a + b) * 2; + x = double((a + b)); Add a pair of parentheses to the preimage side of such rules. Coccinelle will generate patches that remove them if they are present, and it will still match expressions that lack them. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-17add MOVE_ARRAYLibravatar René Scharfe1-0/+17
Similar to COPY_ARRAY (introduced in 60566cbb58), add a safe and convenient helper for moving potentially overlapping ranges of array entries. It infers the element size, multiplies automatically and safely to get the size in bytes, does a basic type safety check by comparing element sizes and unlike memmove(3) it supports NULL pointers iff 0 elements are to be moved. Also add a semantic patch to demonstrate the helper's intended usage. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-02-27cocci: use ALLOC_ARRAYLibravatar René Scharfe1-0/+16
Add a semantic patch for using ALLOC_ARRAY to allocate arrays and apply the transformation on the current source tree. The macro checks for multiplication overflow and infers the element size automatically; the result is shorter and safer code. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-09-25use COPY_ARRAYLibravatar René Scharfe1-0/+26
Add a semantic patch for converting certain calls of memcpy(3) to COPY_ARRAY() and apply that transformation to the code base. The result is shorter and safer code. For now only consider calls where source and destination have the same type, or in other words: easy cases. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>