commit 42dda89dcb0407f6799dbfd0b9dab1529666ad51

Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>

Date:   Fri Dec 11 15:23:05 2020 -0300

    posix: Fix return value of system if shell can not be executed [BZ #27053]

    POSIX states that system returned code for failure to execute the shell

    shall be as if the shell had terminated using _exit(127).  This

    behaviour was removed with 5fb7fc96350575.

    Checked on x86_64-linux-gnu.

diff --git a/stdlib/tst-system.c b/stdlib/tst-system.c

index 194e09828dd5c206..8681584f15ef3b47 100644

--- a/stdlib/tst-system.c

+++ b/stdlib/tst-system.c

@@ -26,6 +26,7 @@

 #include <support/check.h>

 #include <support/temp_file.h>

 #include <support/support.h>

+#include <support/xunistd.h>

 static char *tmpdir;

 static long int namemax;

@@ -138,6 +139,22 @@ do_test (void)

     support_capture_subprocess_check (&result, "system", 0, sc_allow_none);

   }

+  {

+    struct stat64 st;

+    xstat (_PATH_BSHELL, &st);

+    mode_t mode = st.st_mode;

+    xchmod (_PATH_BSHELL, mode & ~(S_IXUSR | S_IXGRP | S_IXOTH));

+

+    struct support_capture_subprocess result;

+    result = support_capture_subprocess (call_system,

+					 &(struct args) {

+					   "exit 1", 127, 0

+					 });

+    support_capture_subprocess_check (&result, "system", 0, sc_allow_none);

+

+    xchmod (_PATH_BSHELL, st.st_mode);

+  }

+

   TEST_COMPARE (system (""), 0);

   return 0;

diff --git a/support/Makefile b/support/Makefile

index 4875f52495ef292d..09b41b0d57e9239a 100644

--- a/support/Makefile

+++ b/support/Makefile

@@ -86,6 +86,7 @@ libsupport-routines = \

   xchroot \

   xclone \

   xclose \

+  xchmod \

   xconnect \

   xcopy_file_range \

   xdlfcn \

diff --git a/sysdeps/posix/system.c b/sysdeps/posix/system.c

index 7db09a05c3fbca43..047ded4badfddcab 100644

--- a/sysdeps/posix/system.c

+++ b/sysdeps/posix/system.c

@@ -171,6 +171,10 @@ do_system (const char *line)

       __libc_cleanup_region_end (0);

 #endif

     }

+  else

+   /* POSIX states that failure to execute the shell should return

+      as if the shell had terminated using _exit(127).  */

+   status = W_EXITCODE (127, 0);

   DO_LOCK ();

   if (SUB_REF () == 0)