unix: Enable sys.executable.

Gives the absolute path to the unix micropython binary.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Signed-off-by: Damien George <damien@micropython.org>

Author: jimmo

ports/unix/main.c

@@ -43,6 +43,7 @@
 #include "py/builtin.h"
 #include "py/repl.h"
 #include "py/gc.h"
+#include "py/objstr.h"
 #include "py/stackctrl.h"
 #include "py/mphal.h"
 #include "py/mpthread.h"
@@ -435,6 +436,17 @@ STATIC void set_sys_argv(char *argv[], int argc, int start_arg) {
     }
 }
 
+#if MICROPY_PY_SYS_EXECUTABLE
+extern mp_obj_str_t mp_sys_executable_obj;
+STATIC char executable_path[MICROPY_ALLOC_PATH_MAX];
+
+STATIC void sys_set_excecutable(char *argv0) {
+    if (realpath(argv0, executable_path)) {
+        mp_obj_str_set_data(&mp_sys_executable_obj, (byte *)executable_path, strlen(executable_path));
+    }
+}
+#endif
+
 #ifdef _WIN32
 #define PATHLIST_SEP_CHAR ';'
 #else
@@ -598,6 +610,10 @@ MP_NOINLINE int main_(int argc, char **argv) {
     printf("    peak  %d\n", m_get_peak_bytes_allocated());
     */
 
+    #if MICROPY_PY_SYS_EXECUTABLE
+    sys_set_excecutable(argv[0]);
+    #endif
+
     const int NOTHING_EXECUTED = -2;
     int ret = NOTHING_EXECUTED;
     bool inspect = false;

ports/unix/mpconfigport.h

@@ -154,6 +154,9 @@ typedef long mp_off_t;
 // Don't default sys.argv because we do that in main.
 #define MICROPY_PY_SYS_PATH_ARGV_DEFAULTS (0)
 
+// Enable sys.executable.
+#define MICROPY_PY_SYS_EXECUTABLE (1)
+
 #define MICROPY_PY_USOCKET_LISTEN_BACKLOG_DEFAULT (SOMAXCONN < 128 ? SOMAXCONN : 128)
 
 // Bare-metal ports don't have stderr. Printing debug to stderr may give tests

tests/unix/extra_coverage.py.exp

@@ -62,10 +62,11 @@ ime
 utime           utimeq
 
 argv            atexit          byteorder       exc_info
-exit            getsizeof       implementation  maxsize
-modules         path            platform        print_exception
-ps1             ps2             stderr          stdin
-stdout          tracebacklimit  version         version_info
+executable      exit            getsizeof       implementation
+maxsize         modules         path            platform
+print_exception                 ps1             ps2
+stderr          stdin           stdout          tracebacklimit
+version         version_info
 ementation
 # attrtuple
 (start=1, stop=2, step=3)