misc: add find_program

misc/find_program.h

@@ -0,0 +1,69 @@
+/**
+ * @file find_program.h
+ * @author Ambroz Bizjak <ambrop7@gmail.com>
+ * 
+ * @section LICENSE
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the author nor the
+ *    names of its contributors may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ * @section DESCRIPTION
+ * 
+ * Function that finds the absolute path of a program by checking a predefined
+ * list of directories.
+ */
+
+#ifndef BADVPN_FIND_PROGRAM_H
+#define BADVPN_FIND_PROGRAM_H
+
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <misc/concat_strings.h>
+#include <misc/debug.h>
+
+static char * badvpn_find_program (const char *name);
+
+static char * badvpn_find_program (const char *name)
+{
+    ASSERT(name)
+    
+    const char *dirs[] = {"/usr/sbin", "/usr/bin", "/sbin", "/bin", NULL};
+    
+    for (size_t i = 0; dirs[i]; i++) {
+        char *path = concat_strings(3, dirs[i], "/", name);
+        if (!path) {
+            goto fail;
+        }
+        
+        if (access(path, X_OK) == 0) {
+            return path;
+        }
+        
+        free(path);
+    }
+    
+fail:
+    return NULL;
+}
+
+#endif