std.process: adding hasNonEmptyEnvVar() and using for NO_COLOR

1 files changed, 35 insertions, 0 deletions

diff --git a/lib/std/process.zig b/lib/std/process.zig
index 34072a4d31..bc798e68e0 100644
--- a/lib/std/process.zig
+++ b/lib/std/process.zig
@@ -431,6 +431,20 @@ pub fn hasEnvVarConstant(comptime key: []const u8) bool {
     }
 }
 
+/// On Windows, `key` must be valid UTF-8.
+pub fn hasNonEmptyEnvVarConstant(comptime key: []const u8) bool {
+    if (native_os == .windows) {
+        const key_w = comptime unicode.utf8ToUtf16LeStringLiteral(key);
+        const value = getenvW(key_w) orelse return false;
+        return value.len != 0;
+    } else if (native_os == .wasi and !builtin.link_libc) {
+        @compileError("hasNonEmptyEnvVarConstant is not supported for WASI without libc");
+    } else {
+        const value = posix.getenv(key) orelse return false;
+        return value.len != 0;
+    }
+}
+
 pub const ParseEnvVarIntError = std.fmt.ParseIntError || error{EnvironmentVariableNotFound};
 
 /// Parses an environment variable as an integer.
@@ -477,6 +491,27 @@ pub fn hasEnvVar(allocator: Allocator, key: []const u8) HasEnvVarError!bool {
     }
 }
 
+/// On Windows, if `key` is not valid [WTF-8](https://simonsapin.github.io/wtf-8/),
+/// then `error.InvalidWtf8` is returned.
+pub fn hasNonEmptyEnvVar(allocator: Allocator, key: []const u8) HasEnvVarError!bool {
+    if (native_os == .windows) {
+        var stack_alloc = std.heap.stackFallback(256 * @sizeOf(u16), allocator);
+        const stack_allocator = stack_alloc.get();
+        const key_w = try unicode.wtf8ToWtf16LeAllocZ(stack_allocator, key);
+        defer stack_allocator.free(key_w);
+        const value = getenvW(key_w) orelse return false;
+        return value.len != 0;
+    } else if (native_os == .wasi and !builtin.link_libc) {
+        var envmap = getEnvMap(allocator) catch return error.OutOfMemory;
+        defer envmap.deinit();
+        const value = envmap.getPtr(key) orelse return false;
+        return value.len != 0;
+    } else {
+        const value = posix.getenv(key) orelse return false;
+        return value.len != 0;
+    }
+}
+
 /// Windows-only. Get an environment variable with a null-terminated, WTF-16 encoded name.
 ///
 /// This function performs a Unicode-aware case-insensitive lookup using RtlEqualUnicodeString.