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glibc: Add an environment variable for specifying an NSS search path #111194

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glibc: Add an environment variable for specifying an NSS search path #111194

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2 changes: 1 addition & 1 deletion nixos/modules/services/system/nscd.nix
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@ in

wantedBy = [ "nss-lookup.target" "nss-user-lookup.target" ];

environment = { LD_LIBRARY_PATH = nssModulesPath; };
environment = { NIX_GLIBC_NSS_PATH = nssModulesPath; };

restartTriggers = [
config.environment.etc.hosts.source
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2 changes: 2 additions & 0 deletions pkgs/development/libraries/glibc/common.nix
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Expand Up @@ -119,6 +119,8 @@ stdenv.mkDerivation ({
})

./fix-x64-abi.patch

./nss-path.patch
]
++ lib.optional stdenv.hostPlatform.isMusl ./fix-rpc-types-musl-conflicts.patch
++ lib.optional stdenv.buildPlatform.isDarwin ./darwin-cross-build.patch;
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6 changes: 6 additions & 0 deletions pkgs/development/libraries/glibc/default.nix
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Expand Up @@ -62,6 +62,12 @@ callPackage ./common.nix { inherit stdenv; } {
])
]);

preHook =
''
outName=$(basename $out)
NIX_CFLAGS_COMPILE+=" -DDEFAULT_NSS_PATH=\"${dirOf builtins.storeDir}/run/glibc-nss-path/''${outName:0:32}:${dirOf builtins.storeDir}/run/glibc-nss-path\"";
'';

# When building glibc from bootstrap-tools, we need libgcc_s at RPATH for
# any program we run, because the gcc will have been placed at a new
# store path than that determined when built (as a source for the
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50 changes: 50 additions & 0 deletions pkgs/development/libraries/glibc/nss-path.patch
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Original file line number Diff line number Diff line change
@@ -0,0 +1,50 @@
diff -ru -x '*~' glibc-2.32-orig/nss/nsswitch.c glibc-2.32/nss/nsswitch.c
--- glibc-2.32-orig/nss/nsswitch.c 2020-08-05 04:17:00.000000000 +0200
+++ glibc-2.32/nss/nsswitch.c 2021-01-29 19:40:50.730883061 +0100
@@ -349,6 +349,35 @@
__nss_shlib_revision);

ni->library->lib_handle = __libc_dlopen (shlib_name);
+
+ if (ni->library->lib_handle == NULL)
+ {
+ const char *nss_path = __libc_secure_getenv ("NIX_GLIBC_NSS_PATH");
+ if (!nss_path)
+ nss_path = DEFAULT_NSS_PATH;
+
+ const char *pos = nss_path;
+
+ while (*pos)
+ {
+ const char *end = __strchrnul(pos, ':');
+ if (pos != end)
+ {
+ char shlib_path[1024];
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How about:

Suggested change
+ char shlib_path[1024];
+ char shlib_path[PATH_MAX];

Not that it PATH_MAX is not a lie..

+ size_t shlib_pathlen = (end - pos) + 1 + strlen (shlib_name) + 1;
+ if (shlib_pathlen < sizeof(shlib_path))
+ {
+ __stpcpy (__stpcpy (__stpncpy (shlib_path, pos, end - pos), "/"), shlib_name);
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Is memcpy not better here given that we already calulate the string length?

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Alternative would be good old snprintf...

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I'm just following the surrounding code here, didn't want to deviate from the coding style.

+ ni->library->lib_handle = __libc_dlopen (shlib_path);
+ if (ni->library->lib_handle != NULL)
+ break;
+ }
+ if (!*end) break;
+ pos = end + 1;
+ }
+ }
+ }
+
if (ni->library->lib_handle == NULL)
{
/* Failed to load the library. */
diff -ru -x '*~' glibc-2.32-orig/sysdeps/generic/unsecvars.h glibc-2.32/sysdeps/generic/unsecvars.h
--- glibc-2.32-orig/sysdeps/generic/unsecvars.h 2020-08-05 04:17:00.000000000 +0200
+++ glibc-2.32/sysdeps/generic/unsecvars.h 2021-01-29 15:38:37.067684060 +0100
@@ -27,6 +27,7 @@
"LOCPATH\0" \
"MALLOC_TRACE\0" \
"NIS_PATH\0" \
+ "NIX_GLIBC_NSS_PATH\0" \
"NLSPATH\0" \
"RESOLV_HOST_CONF\0" \
"RES_OPTIONS\0" \