Add os:unsetenv/1

New BIF os:unsetenv/1 which deletes an environment variable and
returns 'true'.

Does not change any old functionality.

Calls the libc function unsetenv(3) on UNIX and
SetEnvironmentVariableW(key, NULL) on Windows. The unicode support
is the same as for os:getenv and os:putenv.

2 files changed, 28 insertions, 0 deletions

diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
index 401b37b9d2..61f9f6a59a 100644
--- a/erts/emulator/sys/unix/sys.c
+++ b/erts/emulator/sys/unix/sys.c
@@ -2489,6 +2489,16 @@ erts_sys_getenv(char *key, char *value, size_t *size)
     return res;
 }
 
+int
+erts_sys_unsetenv(char *key)
+{
+    int res;
+    erts_smp_rwmtx_rwlock(&environ_rwmtx);
+    res = unsetenv(key);
+    erts_smp_rwmtx_rwunlock(&environ_rwmtx);
+    return res;
+}
+
 void
 sys_init_io(void)
 {
diff --git a/erts/emulator/sys/win32/sys_env.c b/erts/emulator/sys/win32/sys_env.c
index 754f4c6e4c..9f977ad6c8 100644
--- a/erts/emulator/sys/win32/sys_env.c
+++ b/erts/emulator/sys/win32/sys_env.c
@@ -141,6 +141,24 @@ void fini_getenv_state(GETENV_STATE *state)
     erts_smp_rwmtx_runlock(&environ_rwmtx);

 }

 

+int erts_sys_unsetenv(char *key)

+{

+    int res = 0;

+    WCHAR *wkey = (WCHAR *) key;

+

+    SetLastError(0);

+    erts_smp_rwmtx_rlock(&environ_rwmtx);

+    GetEnvironmentVariableW(wkey,

+                            NULL,

+                            0);

+    if (GetLastError() != ERROR_ENVVAR_NOT_FOUND) {

+        res = (SetEnvironmentVariableW(wkey,

+                                       NULL) ? 0 : 1);

+    }

+    erts_smp_rwmtx_runlock(&environ_rwmtx);

+    return res;

+}

+

 char*

 win_build_environment(char* new_env)

 {