gnulib-tool.py: Handle absolute path checks consistently.

[Collin Funk]

A few functions in constants.py check for drive prefixes where other
code does not. Lets just use os.path.isabs() and let it deal with
platform related stuff. I suppose path.startswith('/') would probably
work too but it is less clear and would make Windows (without Cygwin)
support harder in the future.

* pygnulib/GLImport.py (GLImport.relative_to_destdir)
(GLImport.relative_to_currdir): Use os.path.isabs() instead of checking
for a slash.
* pygnulib/constants.py (symlink_relative, as_link_value_at_dest)
(hardlink): Use os.path.isabs() instead of checking for a slash or drive
prefix.
---
 ChangeLog             | 10 ++++++++++
 pygnulib/GLImport.py  |  8 ++++----
 pygnulib/constants.py | 11 +++++------
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 8e67f0a816..3d34109399 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2024-06-09  Collin Funk  <collin.funk1@gmail.com>
+
+       gnulib-tool.py: Handle absolute path checks consistently.
+       * pygnulib/GLImport.py (GLImport.relative_to_destdir)
+       (GLImport.relative_to_currdir): Use os.path.isabs() instead of checking
+       for a slash.
+       * pygnulib/constants.py (symlink_relative, as_link_value_at_dest)
+       (hardlink): Use os.path.isabs() instead of checking for a slash or drive
+       prefix.
+
 2024-06-09  Bruno Haible  <bruno@clisp.org>
 
        c32width tests: Avoid a test failure on Solaris 11 OpenIndiana, OmniOS.
diff --git a/pygnulib/GLImport.py b/pygnulib/GLImport.py
index df541a8b77..5f090d4ea1 100644
--- a/pygnulib/GLImport.py
+++ b/pygnulib/GLImport.py
@@ -418,10 +418,10 @@ def relative_to_destdir(self, dir: str) -> str:
         directory, to a filename relative to destdir.
         GLConfig: destdir.'''
         destdir = self.config['destdir']
-        if dir.startswith('/'):
+        if os.path.isabs(dir):
             return dir
         else:
-            if destdir.startswith('/'):
+            if os.path.isabs(destdir):
                 # XXX This doesn't look right.
                 return dir
             else:
@@ -433,10 +433,10 @@ def relative_to_currdir(self, dir: str) -> str:
         to a filename relative to the current directory.
         GLConfig: destdir.'''
         destdir = self.config['destdir']
-        if dir.startswith('/'):
+        if os.path.isabs(dir):
             return dir
         else:
-            if destdir.startswith('/'):
+            if os.path.isabs(destdir):
                 # XXX This doesn't look right.
                 return joinpath(destdir, dir)
             else:
diff --git a/pygnulib/constants.py b/pygnulib/constants.py
index 4890e2129f..71811576da 100644
--- a/pygnulib/constants.py
+++ b/pygnulib/constants.py
@@ -362,7 +362,7 @@ def symlink_relative(src: str, dest: str) -> None:
         os.symlink(src, dest)
     except PermissionError:
         sys.stderr.write('%s: ln -s failed; falling back on cp -p\n' % 
APP['name'])
-        if src.startswith('/') or (len(src) >= 2 and src[1] == ':'):
+        if os.path.isabs(src):
             # src is absolute.
             cp_src = src
         else:
@@ -384,12 +384,11 @@ def as_link_value_at_dest(src: str, dest: str) -> str:
         raise TypeError('src must be a string, not %s' % (type(src).__name__))
     if type(dest) is not str:
         raise TypeError('dest must be a string, not %s' % 
(type(dest).__name__))
-    if src.startswith('/') or (len(src) >= 2 and src[1] == ':'):
+    if os.path.isabs(src):
         return src
     else:  # if src is not absolute
-        if dest.startswith('/') or (len(dest) >= 2 and dest[1] == ':'):
-            cwd = os.getcwd()
-            return joinpath(cwd, src)
+        if os.path.isabs(dest):
+            return joinpath(os.getcwd(), src)
         else:  # if dest is not absolute
             destdir = os.path.dirname(dest)
             if not destdir:
@@ -427,7 +426,7 @@ def hardlink(src: str, dest: str) -> None:
         os.link(src, dest)
     except PermissionError:
         sys.stderr.write('%s: ln failed; falling back on cp -p\n' % 
APP['name'])
-        if src.startswith('/') or (len(src) >= 2 and src[1] == ':'):
+        if os.path.isabs(src):
             # src is absolute.
             cp_src = src
         else:
-- 
2.45.2