improve logging when ldconfig cannot be used, musl detection

don't run ldconfig when musl is in use, or when ldconfig -p does not
function. In this case, it will overwrite the included musl path, which
is generally harmless, but not helpful. In this case, simply writing the
library paths would be better.

Signed-off-by: Zen <[email protected]>

Author: desultory

src/ugrd/base/core.py

@@ -1,5 +1,5 @@
 __author__ = "desultory"
-__version__ = "4.6.0"
+__version__ = "4.7.0"
 
 from os import environ, makedev, mknod, uname
 from pathlib import Path
@@ -28,6 +28,12 @@ class DecompressorError(Exception):
     pass
 
 
+class LDConfigError(Exception):
+    """Custom exception for ldconfig errors."""
+
+    pass
+
+
 def get_tmpdir(self) -> None:
     """Reads TMPDIR from the environment, sets it as the temporary directory."""
     if tmpdir := environ.get("TMPDIR"):
@@ -303,35 +309,40 @@ def deploy_nodes(self) -> None:
             raise e
 
 
-@unset("musl_libc", "Skipping libgcc_s dependency resolution, musl_libc is enabled.", log_level=20)
-@contains("find_libgcc", "Skipping libgcc_s dependency resolution", log_level=20)
-def autodetect_libgcc(self) -> None:
-    """Finds libgcc.so, adds a 'dependencies' item for it.
-    Adds the parent directory to 'library_paths'
-    """
-    musl_warning = False
+def _get_ldconfig(self) -> list:
+    """Returns the ldconfig command if it exists, otherwise raise an LDConfigError."""
     try:
         cmd = self._run(["ldconfig", "-p"], fail_silent=True, fail_hard=False)
     except FileNotFoundError:
-        musl_warning = True
+        self.logger.warning("If musl libc is being used, `musl_libc = true` should be set in the config.")
+        raise LDConfigError("ldconfig not found, unable to resolve libraries.")
 
-    if not musl_warning and b"Unimplemented option: -p" in cmd.stderr:  # Probably musl libc
-        musl_warning = True
-
-    if musl_warning:
-        self.logger.warning(
-            "This check can be disabled by setting `musl_libc = true` or `find_libgcc = false` in the configuration."
-        )
-        return self.logger.warning("Unable to run ldconfig -p, if glibc is being used, this is fatal!")
+    if b"Unimplemented option: -p" in cmd.stderr:  # Probably musl libc
+        self.logger.warning("If musl libc is being used, `musl_libc = true` should be set in the config.")
+        raise LDConfigError("ldconfig -p not supported, musl libc is likely in use.")
 
     if cmd.returncode != 0:
-        return self.logger.critical("Unable to run ldconfig -p, if glibc is being used, this is fatal!")
+        raise LDConfigError("ldconfig failed to run: %s" % cmd.stderr.decode("utf-8"))
+
+    return cmd.stdout.decode("utf-8").splitlines()
 
-    ldconfig = cmd.stdout.decode("utf-8").splitlines()
+
+@unset("musl_libc", "Skipping libgcc_s dependency resolution, musl_libc is enabled.", log_level=20)
+@contains("find_libgcc", "Skipping libgcc_s dependency resolution", log_level=20)
+def autodetect_libgcc(self) -> None:
+    """Finds libgcc.so, adds a 'dependencies' item for it.
+    Adds the parent directory to 'library_paths'
+    """
+    try:
+        ldconfig = _get_ldconfig(self)
+    except LDConfigError:
+        self.logger.warning("Unable to run ldconfig -p, if glibc is being used, this is fatal!")
+        self.logger.warning("If libgcc_s is not required, set `find_libgcc = false` in the configuration.")
+        return
 
     libgcc = [lib for lib in ldconfig if "libgcc_s" in lib and "(libc6," in lib][0]
     source_path = Path(libgcc.partition("=> ")[-1])
-    self.logger.info("Source path for libgcc_s: %s" % source_path)
+    self.logger.info(f"Source path for libgcc_s: {c_(source_path, 'green')}")
 
     self["dependencies"] = source_path
     self["library_paths"] = str(source_path.parent)
@@ -344,15 +355,26 @@ def autodetect_musl(self) -> None:
     arch = uname().machine
     musl_path = Path(f"/etc/ld-musl-{arch}.path")
     if musl_path.exists():
-        self.logger.info("Detected musl search path: %s" % c_(musl_path, "cyan"))
+        self.logger.info(f"Detected musl search path: {c_(musl_path, 'green')}")
         self["dependencies"] = musl_path
     elif self["musl_libc"]:
         raise AutodetectError("Musl libc is enabled, but the musl search path was not found: %s" % musl_path)
 
 
 @unset("musl_libc", "Skipping ld.so.cache regeneration, musl_libc is enabled.", log_level=30)
 def regen_ld_so_cache(self) -> None:
-    """Regenerates the ld.so.cache file in the build dir. Uses defined library paths to generate the config"""
+    """
+    Checks if a 'real' ldconfig is available, if so, regenerates the ld.so.cache file in the build dir.
+    Uses defined library paths to generate the config file.
+
+    If ldconfig is not available, _get_ldconfiig will warn about setting `musl_libc` to true.
+    Here, warn about this and that this is a fatal error if glibc is being used.
+    """
+    try:
+        _get_ldconfig(self)
+    except LDConfigError:
+        return self.logger.warning("Unable to run ldconfig -p, if glibc is being used, this is fatal!")
+
     self.logger.info("Regenerating ld.so.cache")
     self._write("etc/ld.so.conf", self["library_paths"])
     build_path = self._get_build_path("/")