Initial project import

tools/v/vlib/os/environment.c.v

@@ -0,0 +1,123 @@
+// Copyright (c) 2019-2024 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+module os
+
+fn C.getenv(&char) &char
+
+// C.GetEnvironmentStringsW & C.FreeEnvironmentStringsW are defined only on windows
+fn C.GetEnvironmentStringsW() &u16
+
+fn C.FreeEnvironmentStringsW(&u16) i32
+
+// getenv returns the value of the environment variable named by the key.
+// If there is not one found, it returns an empty string ''.
+pub fn getenv(key string) string {
+	return getenv_opt(key) or { '' }
+}
+
+// getenv_opt returns the value of a given environment variable.
+// Returns `none` if the environment variable does not exist.
+@[manualfree]
+pub fn getenv_opt(key string) ?string {
+	unsafe {
+		$if windows {
+			kw := key.to_wide()
+			defer {
+				free(voidptr(kw))
+			}
+			s := C._wgetenv(kw)
+			if s == 0 {
+				return none
+			}
+			return string_from_wide(s)
+		} $else {
+			s := C.getenv(&char(key.str))
+			if s == nil {
+				return none
+			}
+			// Note: C.getenv *requires* that the result be copied.
+			return cstring_to_vstring(s)
+		}
+	}
+}
+
+// setenv sets the value of an environment variable with `name` to `value`.
+pub fn setenv(name string, value string, overwrite bool) int {
+	$if windows {
+		format := '${name}=${value}'.to_wide()
+		defer {
+			unsafe { free(voidptr(format)) }
+		}
+		if overwrite {
+			unsafe {
+				return C._wputenv(format)
+			}
+		} else {
+			if getenv(name).len == 0 {
+				unsafe {
+					return C._wputenv(format)
+				}
+			}
+		}
+		return -1
+	} $else {
+		unsafe {
+			return C.setenv(&char(name.str), &char(value.str), overwrite)
+		}
+	}
+}
+
+// unsetenv clears an environment variable with `name`.
+pub fn unsetenv(name string) int {
+	$if windows {
+		format := '${name}='.to_wide()
+		defer {
+			unsafe { free(voidptr(format)) }
+		}
+		return C._wputenv(format)
+	} $else {
+		return C.unsetenv(&char(name.str))
+	}
+}
+
+// environ returns a map of all the current environment variables.
+// See: https://linux.die.net/man/5/environ for Unix platforms.
+// See: https://docs.microsoft.com/bg-bg/windows/win32/api/processenv/nf-processenv-getenvironmentstrings
+// for Windows OS.
+pub fn environ() map[string]string {
+	// TODO how to declare Virtual C globals?
+	// const C.environ &&char
+	mut res := map[string]string{}
+	$if windows {
+		mut estrings := C.GetEnvironmentStringsW()
+		mut eline := ''
+		for c := estrings; *c != 0; {
+			eline = unsafe { string_from_wide(c) }
+			eq_index := eline.index_u8(`=`)
+			if eq_index > 0 {
+				res[eline[0..eq_index]] = eline[eq_index + 1..]
+			}
+			unsafe {
+				c = c + eline.len + 1
+			}
+		}
+		C.FreeEnvironmentStringsW(estrings)
+	} $else {
+		start := &&char(voidptr(C.environ))
+		mut i := 0
+		for {
+			x := unsafe { start[i] }
+			if x == 0 {
+				break
+			}
+			eline := unsafe { cstring_to_vstring(x) }
+			eq_index := eline.index_u8(`=`)
+			if eq_index > 0 {
+				res[eline[0..eq_index]] = eline[eq_index + 1..]
+			}
+			i++
+		}
+	}
+	return res
+}