dependencies: Fix parsing of shebangs with spaces

While finding an external program, we should only split the shebang
once since that is what Linux and BSD also do. This is also why
everyone uses #!/usr/bin/env in their shebangs since that allows
you to run an interpreter in a path with spaces in it.

See `man execve` for more details, specifically the sections for
interpreter scripts.

1 files changed, 5 insertions, 1 deletions

diff --git a/mesonbuild/dependencies/base.py b/mesonbuild/dependencies/base.py
index 682182c..a720232 100644
--- a/mesonbuild/dependencies/base.py
+++ b/mesonbuild/dependencies/base.py
@@ -560,7 +560,11 @@ class ExternalProgram:
             with open(script) as f:
                 first_line = f.readline().strip()
             if first_line.startswith('#!'):
-                commands = first_line[2:].split('#')[0].strip().split()
+                # In a shebang, everything before the first space is assumed to
+                # be the command to run and everything after the first space is
+                # the single argument to pass to that command. So we must split
+                # exactly once.
+                commands = first_line[2:].split('#')[0].strip().split(maxsplit=1)
                 if mesonlib.is_windows():
                     # Windows does not have UNIX paths so remove them,
                     # but don't remove Windows paths