From 7151fbe498a3dd47a6d3e3dcb2f6e2a3ff5625da Mon Sep 17 00:00:00 2001
From: Dirk Zimoch <dirk.zimoch@psi.ch>
Date: Wed, 3 Oct 2018 15:03:11 +0200
Subject: [PATCH] implement epicsEnvUnset

---
 src/libCom/iocsh/libComRegister.c  | 16 ++++++++++++++++
 src/libCom/osi/os/Darwin/osdEnv.c  | 10 ++++++++++
 src/libCom/osi/os/default/osdEnv.c | 12 ++++++++++++
 src/libCom/osi/os/iOS/osdEnv.c     | 10 ++++++++++
 src/libCom/osi/os/vxWorks/osdEnv.c | 19 +++++++++++++++++++
 5 files changed, 67 insertions(+)

diff --git a/src/libCom/iocsh/libComRegister.c b/src/libCom/iocsh/libComRegister.c
index d3a5cfac4..d8429fa9f 100644
--- a/src/libCom/iocsh/libComRegister.c
+++ b/src/libCom/iocsh/libComRegister.c
@@ -110,6 +110,21 @@ static void epicsEnvSetCallFunc(const iocshArgBuf *args)
     epicsEnvSet (name, value);
 }
 
+/* epicsEnvUnset */
+static const iocshArg epicsEnvUnsetArg0 = { "name",iocshArgString};
+static const iocshArg * const epicsEnvUnsetArgs[1] = {&epicsEnvUnsetArg0};
+static const iocshFuncDef epicsEnvUnsetFuncDef = {"epicsEnvUnset",1,epicsEnvUnsetArgs};
+static void epicsEnvUnsetCallFunc(const iocshArgBuf *args)
+{
+    char *name = args[0].sval;
+
+    if (name == NULL) {
+        fprintf(stderr, "Missing environment variable name argument.\n");
+        return;
+    }
+    epicsEnvUnset (name);
+}
+
 /* epicsParamShow */
 static const iocshFuncDef epicsParamShowFuncDef = {"epicsParamShow",0,NULL};
 static void epicsParamShowCallFunc(const iocshArgBuf *args)
@@ -367,6 +382,7 @@ void epicsShareAPI libComRegister(void)
     iocshRegister(&pwdFuncDef, pwdCallFunc);
 
     iocshRegister(&epicsEnvSetFuncDef, epicsEnvSetCallFunc);
+    iocshRegister(&epicsEnvUnsetFuncDef, epicsEnvUnsetCallFunc);
     iocshRegister(&epicsParamShowFuncDef, epicsParamShowCallFunc);
     iocshRegister(&epicsPrtEnvParamsFuncDef, epicsPrtEnvParamsCallFunc);
     iocshRegister(&epicsEnvShowFuncDef, epicsEnvShowCallFunc);
diff --git a/src/libCom/osi/os/Darwin/osdEnv.c b/src/libCom/osi/os/Darwin/osdEnv.c
index ab3f93644..f7ff12ced 100644
--- a/src/libCom/osi/os/Darwin/osdEnv.c
+++ b/src/libCom/osi/os/Darwin/osdEnv.c
@@ -39,6 +39,16 @@ epicsShareFunc void epicsShareAPI epicsEnvSet (const char *name, const char *val
     setenv(name, value, 1);
 }
 
+/*
+ * Unset an environment variable
+ */
+
+epicsShareFunc void epicsShareAPI epicsEnvUnset (const char *name)
+{
+    iocshEnvClear(name);
+    unsetenv(name);
+}
+
 /*
  * Show the value of the specified, or all, environment variables
  */
diff --git a/src/libCom/osi/os/default/osdEnv.c b/src/libCom/osi/os/default/osdEnv.c
index 682bcc934..27cb1efd2 100644
--- a/src/libCom/osi/os/default/osdEnv.c
+++ b/src/libCom/osi/os/default/osdEnv.c
@@ -55,6 +55,18 @@ epicsShareFunc void epicsShareAPI epicsEnvSet (const char *name, const char *val
 	}
 }
 
+/*
+ * Unset an environment variable
+ * Using putenv with a an exsiting name but without "=..." deletes the variable.
+ */
+
+epicsShareFunc void epicsShareAPI epicsEnvUnset (const char *name)
+{
+    iocshEnvClear(name);
+    if (getenv(name) != NULL)
+        putenv(name);
+}
+
 /*
  * Show the value of the specified, or all, environment variables
  */
diff --git a/src/libCom/osi/os/iOS/osdEnv.c b/src/libCom/osi/os/iOS/osdEnv.c
index a32cce5ef..0c256725c 100644
--- a/src/libCom/osi/os/iOS/osdEnv.c
+++ b/src/libCom/osi/os/iOS/osdEnv.c
@@ -36,6 +36,16 @@ epicsShareFunc void epicsShareAPI epicsEnvSet (const char *name, const char *val
     setenv(name, value, 1);
 }
 
+/*
+ * Unset an environment variable
+ */
+
+epicsShareFunc void epicsShareAPI epicsEnvUnset (const char *name)
+{
+    iocshEnvClear(name);
+    unsetenv(name);
+}
+
 /*
  * Show the value of the specified, or all, environment variables
  */
diff --git a/src/libCom/osi/os/vxWorks/osdEnv.c b/src/libCom/osi/os/vxWorks/osdEnv.c
index c81f49316..f09897681 100644
--- a/src/libCom/osi/os/vxWorks/osdEnv.c
+++ b/src/libCom/osi/os/vxWorks/osdEnv.c
@@ -51,6 +51,25 @@ epicsShareFunc void epicsShareAPI epicsEnvSet (const char *name, const char *val
     }
 }
 
+/*
+ * Unset an environment variable
+ * Basically destroy the name of that variable because vxWorks does not
+ * support to really uset an environment variable.
+ */
+
+epicsShareFunc void epicsShareAPI epicsEnvUnset (const char *name)
+{
+    char* var;
+
+    if (!name) return;
+    iocshEnvClear(name);
+    var = getenv(name);
+    if (!var) return;
+    var -= strlen(name);
+    var --;
+    *var = 0;
+}
+
 /*
  * Show the value of the specified, or all, environment variables
  */