user/sven/linux.git/scripts/kconfig/preprocess.c, branch v4.19.292

kconfig: let 'shell' return enough output for deep path names

2022-02-23T10:58:42Z

[ Upstream commit 8a4c5b2a6d8ea079fa36034e8167de87ab6f8880 ] The 'shell' built-in only returns the first 256 bytes of the command's output. In some cases, 'shell' is used to return a path; by bumping up the buffer size to 4096 this lets us capture up to PATH_MAX. The specific case where I ran into this was due to commit 1e860048c53e ("gcc-plugins: simplify GCC plugin-dev capability test"). After this change, we now use `$(shell,$(CC) -print-file-name=plugin)` to return a path; if the gcc path is particularly long, then the path ends up truncated at the 256 byte mark, which makes the HAVE_GCC_PLUGINS depends test always fail. Signed-off-by: Brenda Streiff Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

kconfig: fix return value of do_error_if()

2020-12-30T10:26:06Z

[ Upstream commit 135b4957eac43af2aedf8e2a277b9540f33c2558 ] $(error-if,...) is expanded to an empty string. Currently, it relies on eval_clause() returning xstrdup("") when all attempts for expansion fail, but the correct implementation is to make do_error_if() return xstrdup(""). Fixes: 1d6272e6fe43 ("kconfig: add 'info', 'warning-if', and 'error-if' built-in functions") Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

kconfig: loop boundary condition fix

2018-06-28T13:48:08Z

If buf[-1] just happens to hold the byte 0x0A, then nread can wrap around to (size_t)-1, leading to invalid memory accesses. This has caused segmentation faults when trying to build the latest kernel snapshots for i686 in Fedora: https://bugzilla.redhat.com/show_bug.cgi?id=1592374 Signed-off-by: Jerry James [alexpl@fedoraproject.org: reformatted patch for submission] Signed-off-by: Alexander Ploumistos Signed-off-by: Masahiro Yamada

kconfig: error out if a recursive variable references itself

2018-05-28T18:31:19Z

When using a recursively expanded variable, it is a common mistake to make circular reference. For example, Make terminates the following code: X = $(X) Y := $(X) Let's detect the circular expansion in Kconfig, too. On the other hand, a function that recurses itself is a commonly-used programming technique. So, Make does not check recursion in the reference with 'call'. For example, the following code continues running eternally: X = $(call X) Y := $(X) Kconfig allows circular expansion if one or more arguments are given, but terminates when the same function is recursively invoked 1000 times, assuming it is a programming mistake. Signed-off-by: Masahiro Yamada

kconfig: add 'filename' and 'lineno' built-in variables

2018-05-28T18:31:19Z

The special variables, $(filename) and $(lineno), are expanded to a file name and its line number being parsed, respectively. Suggested-by: Randy Dunlap Signed-off-by: Masahiro Yamada Reviewed-by: Kees Cook

kconfig: add 'info', 'warning-if', and 'error-if' built-in functions

2018-05-28T18:31:19Z

Syntax: $(info,) $(warning-if,,) $(error-if,, part is y. Kconfig does not implement the lazy expansion as used in the 'if' 'and, 'or' functions in Make. In other words, Kconfig does not support conditional expansion. The unconditional 'error' function would always terminate the parsing, hence would be useless in Kconfig. Signed-off-by: Masahiro Yamada Reviewed-by: Kees Cook

kconfig: support append assignment operator

2018-05-28T18:31:19Z

Support += operator. This appends a space and the text on the righthand side to a variable. The timing of the evaluation of the righthand side depends on the flavor of the variable. If the lefthand side was originally defined as a simple variable, the righthand side is expanded immediately. Otherwise, the expansion is deferred. Appending something to an undefined variable results in a recursive variable. To implement this, we need to remember the flavor of variables. Signed-off-by: Masahiro Yamada

kconfig: support simply expanded variable

2018-05-28T18:31:19Z

The previous commit added variable and user-defined function. They work similarly in the sense that the evaluation is deferred until they are used. This commit adds another type of variable, simply expanded variable, as we see in Make. The := operator defines a simply expanded variable, expanding the righthand side immediately. This works like traditional programming language variables. Signed-off-by: Masahiro Yamada

kconfig: support user-defined function and recursively expanded variable

2018-05-28T18:31:19Z

Now, we got a basic ability to test compiler capability in Kconfig. config CC_HAS_STACKPROTECTOR def_bool $(shell,($(CC) -Werror -fstack-protector -E -x c /dev/null -o /dev/null 2>/dev/null) && echo y || echo n) This works, but it is ugly to repeat this long boilerplate. We want to describe like this: config CC_HAS_STACKPROTECTOR bool default $(cc-option,-fstack-protector) It is straight-forward to add a new function, but I do not like to hard-code specialized functions like that. Hence, here is another feature, user-defined function. This works as a textual shorthand with parameterization. A user-defined function is defined by using the = operator, and can be referenced in the same way as built-in functions. A user-defined function in Make is referenced like $(call my-func,arg1,arg2), but I omitted the 'call' to make the syntax shorter. The definition of a user-defined function contains $(1), $(2), etc. in its body to reference the parameters. It is grammatically valid to pass more or fewer arguments when calling it. We already exploit this feature in our makefiles; scripts/Kbuild.include defines cc-option which takes two arguments at most, but most of the callers pass only one argument. By the way, a variable is supported as a subset of this feature since a variable is "a user-defined function with zero argument". In this context, I mean "variable" as recursively expanded variable. I will add a different flavored variable in the next commit. The code above can be written as follows: [Example Code] success = $(shell,($(1)) >/dev/null 2>&1 && echo y || echo n) cc-option = $(success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null) config CC_HAS_STACKPROTECTOR def_bool $(cc-option,-fstack-protector) [Result] $ make -s alldefconfig && tail -n 1 .config CONFIG_CC_HAS_STACKPROTECTOR=y Signed-off-by: Masahiro Yamada

kconfig: add 'shell' built-in function

2018-05-28T18:31:19Z

This accepts a single command to execute. It returns the standard output from it. [Example code] config HELLO string default "$(shell,echo hello world)" config Y def_bool $(shell,echo y) [Result] $ make -s alldefconfig && tail -n 2 .config CONFIG_HELLO="hello world" CONFIG_Y=y Caveat: Like environments, functions are expanded in the lexer. You cannot pass symbols to function arguments. This is a limitation to simplify the implementation. I want to avoid the dynamic function evaluation, which would introduce much more complexity. Signed-off-by: Masahiro Yamada