From 3574b567c486d264d680a37586436c3b5a8cb978 Mon Sep 17 00:00:00 2001 From: Philip McGrath Date: Thu, 4 Mar 2021 04:11:50 -0500 Subject: [PATCH] patch rktio_process for "/bin/sh" on Guix Racket provides the functions `system` and `process`, which execute shell commands using `sh` (or `cmd` on Windows). Racket assumes that `sh` can be found at "/bin/sh", which is not necessarily true on Guix. This patch adds a special case for "/bin/sh" to `rktio_process`, the C function that implements the core of `system`, `process`, and related Racket functions. Guix should enable the special case by defining the C preprocessor macro `GUIX_RKTIO_PATCH_BIN_SH` with the path to `sh` in the store. If: 1. The `GUIX_RKTIO_PATCH_BIN_SH` macro is defined; and 2. `rktio_process` is called with the exact path "/bin/sh"; and 3. The path specified by `GUIX_RKTIO_PATCH_BIN_SH` does exists; then `rktio_process` will execute the file specified by `GUIX_RKTIO_PATCH_BIN_SH` instead of "/bin/sh". Compared to previous attempts to patch the Racket sources, making this change at the C level is both: - More comprehensive: it catches all attempts to execute "/bin/sh", without having to track down the source of every occurance; and - Less intrusive: by guarding the special case with a C preprocessor conditional and a runtime check that the file in the store exists, we make it much less likely that it will "leak" out of Guix. --- src/rktio/rktio_process.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/src/rktio/rktio_process.c b/src/rktio/rktio_process.c index 89202436c0..465ebdd5c5 100644 --- a/src/rktio/rktio_process.c +++ b/src/rktio/rktio_process.c @@ -1224,12 +1224,14 @@ int rktio_process_allowed_flags(rktio_t *rktio) /*========================================================================*/ rktio_process_result_t *rktio_process(rktio_t *rktio, - const char *command, int argc, rktio_const_string_t *argv, + /* PATCHED for Guix (next line) */ + const char *_guix_orig_command, int argc, rktio_const_string_t *argv, rktio_fd_t *stdout_fd, rktio_fd_t *stdin_fd, rktio_fd_t *stderr_fd, rktio_process_t *group_proc, const char *current_directory, rktio_envvars_t *envvars, int flags) { + const char *command; /* PATCHED for Guix */ rktio_process_result_t *result; intptr_t to_subprocess[2], from_subprocess[2], err_subprocess[2]; int pid; @@ -1255,6 +1257,23 @@ rktio_process_result_t *rktio_process(rktio_t *rktio, int i; #endif +/* BEGIN PATCH for Guix */ +#if defined(GUIX_RKTIO_PATCH_BIN_SH) +# define GUIX_AS_a_STR_HELPER(x) #x +# define GUIX_AS_a_STR(x) GUIX_AS_a_STR_HELPER(x) + /* A level of indirection makes `#` work as needed: */ + command = + ((0 == strcmp(_guix_orig_command, "/bin/sh")) + && rktio_file_exists(rktio, GUIX_AS_a_STR(GUIX_RKTIO_PATCH_BIN_SH))) + ? GUIX_AS_a_STR(GUIX_RKTIO_PATCH_BIN_SH) + : _guix_orig_command; +# undef GUIX_AS_a_STR +# undef GUIX_AS_a_STR_HELPER +#else + command = _guix_orig_command; +#endif +/* END PATCH for Guix */ + /* avoid compiler warnings: */ to_subprocess[0] = -1; to_subprocess[1] = -1; -- 2.21.1 (Apple Git-122.3)