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From 3574b567c486d264d680a37586436c3b5a8cb978 Mon Sep 17 00:00:00 2001
From: Philip McGrath <philip@philipmcgrath.com>
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)
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