os: make executable() more robust

vlib/os/os.v

@@ -806,7 +806,7 @@ pub fn executable() string {
 		count := C.readlink('/proc/self/exe', result, MAX_PATH)
 		if count < 0 {
 			eprintln('os.executable() failed at reading /proc/self/exe to get exe path')
-			return os.args[0]
+			return executable_fallback()
 		}
 		return string(result)
 	}
@@ -822,7 +822,7 @@ pub fn executable() string {
 		ret := proc_pidpath(pid, result, MAX_PATH)
 		if ret <= 0 {
 			eprintln('os.executable() failed at calling proc_pidpath with pid: $pid . proc_pidpath returned $ret ')
-			return os.args[0]
+			return executable_fallback()
 		}
 		return string(result)
 	}
@@ -833,11 +833,8 @@ pub fn executable() string {
 		C.sysctl(mib.data, 4, result, &size, 0, 0)
 		return string(result)
 	}
-	$if openbsd {
-		// "Sadly there is no way to get the full path of the executed file in OpenBSD."
-		// lol
-		return os.args[0]
-	}
+	// "Sadly there is no way to get the full path of the executed file in OpenBSD."
+	$if openbsd {}
 	$if solaris {}
 	$if haiku {}
 	$if netbsd {
@@ -845,7 +842,7 @@ pub fn executable() string {
 		count := C.readlink('/proc/curproc/exe', result, MAX_PATH)
 		if count < 0 {
 			eprintln('os.executable() failed at reading /proc/curproc/exe to get exe path')
-			return os.args[0]
+			return executable_fallback()
 		}
 		return string(result,count)
 	}
@@ -854,11 +851,53 @@ pub fn executable() string {
 		count := C.readlink('/proc/curproc/file', result, MAX_PATH)
 		if count < 0 {
 			eprintln('os.executable() failed at reading /proc/curproc/file to get exe path')
-			return os.args[0]
+			return executable_fallback()
 		}
 		return string(result,count)
 	}
-	return os.args[0]
+	return executable_fallback()
+}
+
+// executable_fallback is used when there is not a more platform specific and accurate implementation
+// it relies on path manipulation of os.args[0] and os.wd_at_startup, so it may not work properly in
+// all cases, but it should be better, than just using os.args[0] directly.
+fn executable_fallback() string {
+	mut exepath := os.args[0]
+	if !os.is_abs_path(exepath) {
+		if exepath.contains( os.path_separator ) {
+			exepath = os.join_path(os.wd_at_startup, exepath)
+		}else{
+			// no choice but to try to walk the PATH folders :-| ...
+			foundpath := os.find_abs_path_of_executable(exepath) or { '' }
+			if foundpath.len > 0 {
+				exepath = foundpath
+			}
+		}
+	}
+	exepath = os.realpath(exepath)
+	return exepath
+}
+
+// find_exe_path walks the environment PATH, just like most shell do, it returns
+// the absolute path of the executable if found
+pub fn find_abs_path_of_executable(exepath string) ?string {
+	if os.is_abs_path(exepath) {
+		return exepath
+	}
+	mut res := ''
+	env_path_delimiter := if os.user_os() == 'windows' { ';' } else { ':' }
+	paths := os.getenv('PATH').split(env_path_delimiter)
+	for p in paths {
+		found_abs_path := os.join_path( p, exepath )
+		if os.exists( found_abs_path ) && os.is_executable( found_abs_path ) {
+			res = found_abs_path
+			break
+		}
+	}
+	if res.len>0 {
+		return res
+	}
+	return error('failed to find executable')
 }
 
 [deprecated]

vlib/v/table/table.v

@@ -3,10 +3,7 @@
 // that can be found in the LICENSE file.
 module table
 
-import (
-	strings
-	os
-)
+import os
 
 pub struct Table {
 	// struct_fields map[string][]string