+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+#include <limits.h>
+#include <stdlib.h>
+
+#include "libi3.h"
+
+/*
+ * This function returns the absolute path to the executable it is running in.
+ *
+ * The implementation follows http://stackoverflow.com/a/933996/712014
+ *
+ */
+const char *get_exe_path(const char *argv0) {
+ static char destpath[PATH_MAX];
+ char tmp[PATH_MAX];
+
+#if defined(__linux__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+ /* Linux and Debian/kFreeBSD provide /proc/self/exe */
+#if defined(__linux__) || defined(__FreeBSD_kernel__)
+ const char *exepath = "/proc/self/exe";
+#elif defined(__FreeBSD__)
+ const char *exepath = "/proc/curproc/file";
+#endif
+ ssize_t linksize;
+
+ if ((linksize = readlink(exepath, destpath, sizeof(destpath))) != -1) {
+ /* readlink() does not NULL-terminate strings, so we have to. */
+ destpath[linksize] = '\0';
+
+ return destpath;
+ }
+#endif
+
+ /* argv[0] is most likely a full path if it starts with a slash. */
+ if (argv0[0] == '/')
+ return argv0;
+
+ /* if argv[0] contains a /, prepend the working directory */
+ if (strchr(argv0, '/') != NULL &&
+ getcwd(tmp, sizeof(tmp)) != NULL) {
+ snprintf(destpath, sizeof(destpath), "%s/%s", tmp, argv0);
+ return destpath;
+ }
+
+ /* Fall back to searching $PATH (or _CS_PATH in absence of $PATH). */
+ char *path = getenv("PATH");
+ size_t pathlen;
+ if (path == NULL) {
+ /* _CS_PATH is typically something like "/bin:/usr/bin" */
+ pathlen = confstr(_CS_PATH, tmp, sizeof(tmp));
+ sasprintf(&path, ":%s", tmp);
+ } else {
+ pathlen = strlen(path);
+ path = strdup(path);
+ }
+ const char *component;
+ char *str = path;
+ while (1) {
+ if ((component = strtok(str, ":")) == NULL)
+ break;
+ str = NULL;
+ snprintf(destpath, sizeof(destpath), "%s/%s", component, argv0);
+ /* Of course this is not 100% equivalent to actually exec()ing the
+ * binary, but meh. */
+ if (access(destpath, X_OK) == 0) {
+ free(path);
+ return destpath;
+ }
+ }
+ free(path);
+
+ /* Last resort: maybe it’s in /usr/bin? */
+ return "/usr/bin/i3bar";
+}