Add whichp() predicate function to which()

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

README.md

@@ -288,10 +288,12 @@ Generic Functions
   optional listing of file and directory permissions if `show_perms` is
   set.  The `path` argument should be a directory.
 
-- `which(cmd)`
+- `which(cmd)`, `whichp(cmd)`
 
   C implementation of UNIX which(1).  Returns a malloc'ed string with the
   full path to `cmd` on success, otherwise `NULL`.
+  
+  `whichp()` is a predicate function, returns `TRUE` or `FALSE`.
 
 
 GNU Functions

lite.h

@@ -86,6 +86,7 @@ void    progress       (int percent, int max_width);
 void    progress_simple(int percent);
 
 char   *which      (const char *cmd);
+int     whichp     (const char *cmd);
 
 #ifndef touch
 #include <sys/stat.h>		/* utimensat() */

which.c

@@ -81,6 +81,22 @@ char *which(const char *cmd)
 	return NULL;
 }
 
+/*
+ * Like which(), above, but only answers TRUE(1)/FALSE(0)
+ */
+int whichp(const char *cmd)
+{
+	char *path;
+
+	path = which(cmd);
+	if (path) {
+		free(path);
+		return 1;
+	}
+
+	return 0;
+}
+
 /**
  * Local Variables:
  *  indent-tabs-mode: t