diff --git a/modules/libcom/src/osi/os/Darwin/osdgetexec.c b/modules/libcom/src/osi/os/Darwin/osdgetexec.c
new file mode 100644
index 000000000..4e4961c59
--- /dev/null
+++ b/modules/libcom/src/osi/os/Darwin/osdgetexec.c
@@ -0,0 +1,50 @@
+
+#include <string.h>
+#include <stdlib.h>
+
+#include <mach-o/dyld.h>
+
+#define epicsExportSharedSymbols
+#include <osiFileName.h>
+
+char *epicsGetExecName(void)
+{
+    uint32_t max = 64u;
+    char *ret = NULL;
+
+    while(1) {
+        char *temp = realloc(ret, max);
+        if(!temp) {
+            /* we treat alloc failure as terminal */
+            free(ret);
+            ret = NULL;
+            break;
+        }
+        ret = temp;
+
+        /* cf. "man 3 dyld" */
+        if(_NSGetExecutablePath(ret, &max)==0) {
+            /* max left unchanged */
+            ret[max-1] = '\0';
+            break;
+        }
+        /* max has been updated with required size */
+    }
+
+    /* TODO: _NSGetExecutablePath() doesn't follow symlinks */
+
+    return ret;
+}
+
+char *epicsGetExecDir(void)
+{
+    char *ret = epicsGetExecName();
+    if(ret) {
+        char *sep = strrchr(ret, '/');
+        if(sep) {
+            /* nil the charactor after the / */
+            sep[1] = '\0';
+        }
+    }
+    return ret;
+}
diff --git a/modules/libcom/src/osi/os/Linux/osdgetexec.c b/modules/libcom/src/osi/os/Linux/osdgetexec.c
index 2ea8ca4ae..cba5d78a8 100644
--- a/modules/libcom/src/osi/os/Linux/osdgetexec.c
+++ b/modules/libcom/src/osi/os/Linux/osdgetexec.c
@@ -24,7 +24,11 @@ char *epicsGetExecName(void)
         ret = temp;
 
         n = readlink("/proc/self/exe", ret, max);
-        if(n < max) {
+        if(n == -1) {
+            free(ret);
+            ret = NULL;
+            break;
+        } else if(n < max) {
             /* readlink() never adds a nil */
             ret[n] = '\0';
             break;
diff --git a/modules/libcom/src/osi/os/WIN32/osdgetexec.c b/modules/libcom/src/osi/os/WIN32/osdgetexec.c
new file mode 100644
index 000000000..a46ce50cd
--- /dev/null
+++ b/modules/libcom/src/osi/os/WIN32/osdgetexec.c
@@ -0,0 +1,52 @@
+
+#include <string.h>
+#include <stdlib.h>
+#include <windows.h>
+
+#define epicsExportSharedSymbols
+#include <osiFileName.h>
+
+char *epicsGetExecName(void)
+{
+    size_t max = 128;
+    char *ret = NULL;
+    DWORD n;
+
+    while(1) {
+        char *temp = realloc(ret, max);
+        if(!temp) {
+            /* we treat alloc failure as terminal */
+            free(ret);
+            ret = NULL;
+            break;
+        }
+        ret = temp;
+
+        n = GetModuleFileName(NULL, ret, max);
+        if(n == 0) {
+            free(ret);
+            ret = NULL;
+            break;
+        } else if(n < max) {
+            ret[n] = '\0';
+            break;
+        }
+
+        max += 64;
+    }
+
+    return ret;
+}
+
+char *epicsGetExecDir(void)
+{
+    char *ret = epicsGetExecName();
+    if(ret) {
+        char *sep = strrchr(ret, '\\');
+        if(sep) {
+            /* nil the charactor after the / */
+            sep[1] = '\0';
+        }
+    }
+    return ret;
+}
diff --git a/modules/libcom/src/osi/os/freebsd/osdgetexec.c b/modules/libcom/src/osi/os/freebsd/osdgetexec.c
new file mode 100644
index 000000000..39c0a163d
--- /dev/null
+++ b/modules/libcom/src/osi/os/freebsd/osdgetexec.c
@@ -0,0 +1,68 @@
+
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <limits.h>
+
+#define epicsExportSharedSymbols
+#include <osiFileName.h>
+
+char *epicsGetExecName(void)
+{
+    size_t max = PATH_MAX;
+    char *ret = NULL;
+    ssize_t n;
+
+    while(1) {
+        char *temp = realloc(ret, max);
+        if(!temp) {
+            /* we treat alloc failure as terminal */
+            free(ret);
+            ret = NULL;
+            break;
+        }
+        ret = temp;
+
+        n = readlink("/proc/curproc/file", ret, max);
+        if(n == -1) {
+            free(ret);
+            ret = NULL;
+            break;
+        } else if(n < max) {
+            /* readlink() never adds a nil */
+            ret[n] = '\0';
+            break;
+        }
+
+        max += 64;
+    }
+
+    if(!ret) {
+        int mib[4];
+        mib[0] = CTL_KERN;
+        mib[1] = KERN_PROC;
+        mib[2] = KERN_PROC_PATHNAME;
+        mib[3] = -1;
+
+        ret = malloc(max);
+        if(ret) {
+            sysctl(mib, 4, ret, &cb, NULL, 0);
+            /* TODO: error check */
+        }
+    }
+
+    return ret;
+}
+
+char *epicsGetExecDir(void)
+{
+    char *ret = epicsGetExecName();
+    if(ret) {
+        char *sep = strrchr(ret, '/');
+        if(sep) {
+            /* nil the charactor after the / */
+            sep[1] = '\0';
+        }
+    }
+    return ret;
+}
diff --git a/modules/libcom/src/osi/os/solaris/osdgetexec.c b/modules/libcom/src/osi/os/solaris/osdgetexec.c
new file mode 100644
index 000000000..ff9739ca9
--- /dev/null
+++ b/modules/libcom/src/osi/os/solaris/osdgetexec.c
@@ -0,0 +1,30 @@
+
+#include <string.h>
+#include <stdlib.h>
+
+#define epicsExportSharedSymbols
+#include <osiFileName.h>
+
+char *epicsGetExecName(void)
+{
+    const char *raw = getexecname();
+    char *ret = NULL;
+    /* manpage says getexecname() might return a relative path.  we treat this as an error */
+    if(raw[0]=='/') {
+        ret = strdup(raw);
+    }
+    return ret;
+}
+
+char *epicsGetExecDir(void)
+{
+    char *ret = epicsGetExecName();
+    if(ret) {
+        char *sep = strrchr(ret, '/');
+        if(sep) {
+            /* nil the charactor after the / */
+            sep[1] = '\0';
+        }
+    }
+    return ret;
+}
diff --git a/modules/libcom/test/Makefile b/modules/libcom/test/Makefile
index 1c26c44b7..7e1ff1abc 100755
--- a/modules/libcom/test/Makefile
+++ b/modules/libcom/test/Makefile
@@ -232,6 +232,11 @@ osiSockTest_SRCS += osiSockTest.c
 testHarness_SRCS += osiSockTest.c
 TESTS += osiSockTest
 
+TESTPROD_HOST += testexecname
+testexecname_SRCS += testexecname.c
+# no point in including in testHarness.  Not implemented for RTEMS/vxWorks.
+TESTS += testexecname
+
 ifeq ($(BUILD_CLASS),HOST)
 ifneq ($(OS_CLASS),WIN32)
 # This test can only be run on a build host, and is broken on Windows
diff --git a/modules/libcom/test/testexecname.c b/modules/libcom/test/testexecname.c
new file mode 100644
index 000000000..87be847a0
--- /dev/null
+++ b/modules/libcom/test/testexecname.c
@@ -0,0 +1,24 @@
+
+#include <string.h>
+
+#include <epicsUnitTest.h>
+#include <testMain.h>
+
+#include <osiFileName.h>
+
+MAIN(testexecname)
+{
+    testPlan(1);
+
+    {
+        char *buf = epicsGetExecName();
+        if(!buf) {
+            testSkip(1, "epicsGetExecName() not available for this target");
+        } else {
+            char *loc = strstr(buf, "testexecname");
+            testOk(!!loc, "Find \"testexecname\" in \"%s\"", buf);
+        }
+    }
+
+    return testDone();
+}