Program names on platforms without __progname in libc

Makefile

@@ -89,7 +89,8 @@ distclean: clean
 # ----------------------------------------------------------------------------
 
 SOURCES = $(SRC)/smax.c $(SRC)/smax-easy.c $(SRC)/smax-lazy.c $(SRC)/smax-queue.c \
-          $(SRC)/smax-meta.c $(SRC)/smax-messages.c $(SRC)/smax-resilient.c $(SRC)/smax-util.c
+          $(SRC)/smax-meta.c $(SRC)/smax-messages.c $(SRC)/smax-resilient.c \
+          $(SRC)/smax-util.c $(SRC)/procname.c
 
 # Generate a list of object (obj/*.o) files from the input sources
 OBJECTS := $(subst $(SRC),$(OBJ),$(SOURCES))

README.md

@@ -113,7 +113,7 @@ prior to invoking `make`. The following build variables can be configured:
 
  - `WEXTRA`: If set to 1, `-Wextra` is added to `CFLAGS` automatically.
 
- - `LDFLAGS`: Extra linker flags (default: _not set_). Note, `-lm -lredisx -lxchange -pthread` will be added 
+ - `LDFLAGS`: Extra linker flags (default: _not set_). Note, `-lm  -lpthread -lredisx -lxchange` will be added 
    automatically.
 
  - `CHECKEXTRA`: Extra options to pass to `cppcheck` for the `make check` target

config.mk

@@ -45,12 +45,15 @@ ifeq ($(WEXTRA), 1)
   CFLAGS += -Wextra
 endif
 
+# On some old platforms __progname is not provided by libc. We have a 
+# workaround in place for LynxOS/PowerPCs. For other platforms without
+# __progname, uncomment the line below to use a default program name
+# instead.
+#NO_PROCNAME = 1
+
 # Extra link flags (if any)
 #LDFLAGS =
 
-# Link flags to use for threading with pthread
-THREADS ?= -pthread
-
 # Link flags required for network functions (if any) to include in LDFLAGS
 #NETFLAGS = -lnsl
 
@@ -76,6 +79,10 @@ CHECKOPTS += --inline-suppr $(CHECKEXTRA)
 # Below are some generated constants based on the one that were set above
 # ============================================================================
 
+ifeq ($(NO_PROCNAME),1)
+  CPPFLAGS += -DNO_PROCNAME=1
+endif
+
 ifdef OSFLAGS
   LDFLAGS += $(OSFLAGS)
 endif
@@ -84,8 +91,8 @@ ifdef NETFLAGS
   LDFLAGS += $(NETFLAGS)
 endif
 
-# Links against pthread and dependencies
-LDFLAGS += $(THREADS) -lredisx -lxchange 
+# Link against pthread and dependencies
+LDFLAGS += -lpthread -lredisx -lxchange 
 
 # Search for libraries under LIB
 ifneq ($(findstring $(LIB),$(LD_LIBRARY_PATH)),$LIB)

include/procname.h

@@ -0,0 +1,31 @@
+/**
+ *
+ * @date Created on: May 12, 2020
+ * @author Attila Kovacs
+ *
+ *  Obtain the process name on platforms where the `__progname` is not defined by libc
+ *  such as on LynxOS 3.1 / PowerPC...
+ */
+
+#ifndef LYNXOS_PROCNAME_H_
+#define LYNXOS_PROCNAME_H_
+
+#define DEFAULT_PROCESS_NAME    "anonymous"
+
+#if __Lynx__ && __powerpc__
+/**
+ * Gets the process name for a given pid on LynxOS, by parsing process tables from /dev/mem.
+ *
+ * \param[in]   pid       Process ID, such as returned by getpid().
+ * \param[out]  procName  String to return process name in (terminated, and with path stripped)
+ * \param[in]   length    The maximum number of characters to print into procName.
+ *
+ * \return      0   if the process was successfully identified (i.e. alive)
+ *              1   if there is no live process with that ID (returns default name)
+ *             -1   if there was an error trying to look up the process name (return redault name).
+ */
+int getProcessName(int pid, char *procName, const int length);
+
+#endif
+
+#endif /* LYNXOS_PROCNAME_H_ */

src/procname.c

@@ -0,0 +1,63 @@
+/**
+ *
+ * @date Created on: May 12, 2020
+ * @author Attila Kovacs
+ *
+ *  Obtain the process name on LynxOS 3.1 / PowerPC, where the `__progname` macro does
+ *  not exists...
+ */
+
+#include "procname.h"
+
+#if __Lynx__ && __powerpc__
+
+#include <errno.h>
+#include <info.h>
+#include <mem.h>
+#include <proc.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+
+// We'll parse the process table to match the PID to a process name...
+int getProcessName(int pid, char *procName, const int length) {
+  int fd, status;
+  char *shortName;
+  __pentry proc;
+
+  // Default process name
+  strncpy(procName, DEFAULT_PROCESS_NAME, length-1);
+  procName[length-1] = '\0';
+
+  if(pid <= 0 || pid > info(_I_NPROCTAB)) {
+    errno = EINVAL;
+    return -1;
+  }
+
+  fd = open("/dev/mem", O_RDONLY);
+  if (fd < 0) return -1;
+
+  lseek(fd, info(_I_PROCTAB) + pid * sizeof(struct pentry), 0);
+  status = read(fd, &proc, sizeof(struct pentry));
+  close(fd);
+
+  if(status < 0) return -1;
+
+  /* Ignore if slot is marked as free   */
+  if(proc.pstate & PRFREE) return 1;
+
+  shortName = strrchr(proc.pname, '/');
+  if(shortName == NULL) shortName = proc.pname;
+  else shortName++;
+
+  strncpy(procName, shortName, length-1);
+  procName[length-1] = '\0';    // Failsafe terminate.
+
+  return 0;
+}
+
+
+#endif

src/smax.c

@@ -29,10 +29,7 @@
 #include <sys/utsname.h>
 
 #include "smax-private.h"
-
-#if __Lynx__
 #include "procname.h"
-#endif
 
 
 
@@ -349,18 +346,18 @@ void smaxSetHostName(const char *name) {
  *
  */
 char *smaxGetProgramID() {
-#if __Lynx__ && __powerpc__
+#if (__Lynx__ && __powerpc__)
   char procName[40];
 #else
-  const char *procName;
+  const char *procName = DEFAULT_PROCESS_NAME;
   extern char *__progname;
 #endif
 
   const char *host;
 
   if(programID) return programID;
 
-#if __Lynx__ && __powerpc__
+#if (__Lynx__ && __powerpc__)
   getProcessName(getpid(), procName, 40);
 #else
   procName = __progname;