Rewrite Unique thingy again

This time it first uses config file path for ftok, if present. If not
present, it tries to obtain executable path via different methods.

Relying on argv[0] was a bad idea, because:

* some programs that launch gsimplecal may not set it properly;
* when launched from $PATH, it contains only file name, no path.

Hopefully, this fixes #17 this time.

configure.ac

@@ -60,6 +60,7 @@ AC_CHECK_HEADERS([iostream \
                   sys/types.h \
                   sys/ipc.h \
                   sys/sem.h \
+                  sys/sysctl.h \
                   signal.h \
                   limits.h])
 
@@ -72,14 +73,16 @@ AC_CHECK_FUNCS([atexit \
                 execl \
                 fork \
                 ftok \
+                getexecname \
                 gettimeofday \
                 kill \
                 readlink \
                 semctl \
                 semget \
                 setenv \
                 signal \
-                strlcpy])
+                strlcpy \
+                sysctl])
 
 
 # Flags

src/Unique.cpp

@@ -1,33 +1,31 @@
 #include <stdlib.h>
 #include <unistd.h>
-#include <stdio.h>
 #include <string.h>
-#include <sys/types.h>
-#include <sys/ipc.h>
 #include <limits.h>
-#include <sys/sem.h>
 #include <signal.h>
+#include <sys/sem.h>
+#include <sys/sysctl.h>
+#include <sys/types.h>
 
 #include "Unique.hpp"
 #include "config.h"
 
 
-Unique::Unique(const char* const cmd)
+Unique::Unique(const char *const path)
 {
-    char* filename = new char[PATH_MAX + 1];
-#if HAVE_STRLCPY
-    strlcpy(filename, cmd, PATH_MAX);
-#else
-    strncpy(filename, cmd, PATH_MAX);
-    filename[PATH_MAX] = '\0';
-#endif
+    char pathname[PATH_MAX + 1];
+
+    if (path) {
+        getPathnameFromFile(path, *&pathname);
+    } else {
+        getPathnameFromExe(*&pathname);
+    }
 
     // Get unique key for semaphore.
-    semaphore_key = ftok(filename, 1);
+    semaphore_key = ftok(pathname, 1);
     if (semaphore_key == -1) {
         throw new UniqueException("ftok failed");
     }
-    delete[] filename;
 }
 
 Unique::~Unique()
@@ -97,3 +95,50 @@ void Unique::stop()
         semctl(semid, 0, IPC_RMID, 0);
     }
 }
+
+void Unique::getPathnameFromFile(const char *const path, char* pathname)
+{
+#if HAVE_STRLCPY
+    strlcpy(pathname, path, PATH_MAX + 1);
+#else
+    strncpy(pathname, path, PATH_MAX);
+    pathname[PATH_MAX] = '\0';
+#endif
+}
+
+void Unique::getPathnameFromExe(char* pathname)
+{
+#if HAVE_GETEXECNAME && HAVE_STRLCPY
+    // Try getexecname (Solaris).
+    const char* execname = getexecname();
+    strlcpy(pathname, execname, PATH_MAX + 1);
+#elif HAVE_SYSCTL && defined(CTL_KERN) && defined(KERN_PROC) && defined(KERN_PROC_PATHNAME)
+    // Try sysctl call (FreeBSD).
+    int mib[4];
+    mib[0] = CTL_KERN;
+    mib[1] = KERN_PROC;
+    mib[2] = KERN_PROC_PATHNAME;
+    mib[3] = -1;
+    size_t cb = PATH_MAX;
+    sysctl(mib, 4, pathname, &cb, NULL, 0);
+#else
+    // Try reading procfs links.
+    const char *const paths[] = {
+        "/proc/self/exe",     // Linux
+        "/proc/curproc/exe",  // NetBSD
+        "/proc/curproc/file", // FreeBSD with procfs
+        NULL
+    };
+    for (const char *const *path = paths; *path; path++) {
+        pathname[0] = 0;
+        int bytes = readlink(*path, pathname, sizeof(*pathname) * PATH_MAX);
+        if (bytes > 0) {
+            if (bytes > PATH_MAX - 1) {
+                bytes = PATH_MAX;
+            }
+            pathname[bytes] = '\0';
+            break;
+        }
+    }
+#endif
+}

src/Unique.hpp

@@ -25,7 +25,7 @@ class UniqueException : public exception
 class Unique
 {
 public:
-    Unique(const char* const cmd);
+    Unique(const char* const path);
     ~Unique();
 
     bool isRunning();
@@ -38,6 +38,9 @@ class Unique
 protected:
     key_t semaphore_key;
 
+private:
+    void getPathnameFromFile(const char *const path, char* pathname);
+    void getPathnameFromExe(char* pathname);
 };
 
 #endif

src/gsimplecal.cpp

@@ -70,7 +70,9 @@ int main(int argc, char *argv[])
         }
     }
 
-    Unique* unique = new Unique(argv[0]);
+    Config* config = Config::getInstance();
+
+    Unique* unique = new Unique(config->getPath());
     if (unique->isRunning()) {
         try {
             if (argc >= 2 && strcmp(argv[1], "next_month") == 0) {
@@ -96,7 +98,6 @@ int main(int argc, char *argv[])
     signal(SIGUSR2, &signal_handler);
     signal(SIGCHLD, SIG_IGN);
 
-    Config* config = Config::getInstance();
     if (config->force_lang.length()) {
         // Must be done before gtk_init call.
         setenv("LANG", config->force_lang.c_str(), 1);