Break /proc/[pid]/{uid,gid}_map's dependence on seqfile.

In addition to simplifying the implementation, this fixes two bugs:

- seqfile.NewSeqFile unconditionally creates an inode with mode 0444,
  but {uid,gid}_map have mode 0644.

- idMapSeqFile.Write implements fs.FileOperations.Write ... but it
  doesn't implement any other fs.FileOperations methods and is never
  used as fs.FileOperations. idMapSeqFile.GetFile() =>
  seqfile.SeqFile.GetFile() uses seqfile.seqFileOperations instead,
  which rejects all writes.

PiperOrigin-RevId: 234638212
Change-Id: I4568f741ab07929273a009d7e468c8205a8541bc

1 files changed, 19 insertions, 0 deletions

diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD
index 75fa52a57..3c61c48ef 100644
--- a/test/syscalls/linux/BUILD
+++ b/test/syscalls/linux/BUILD
@@ -1445,6 +1445,25 @@ cc_binary(
 )
 
 cc_binary(
+    name = "proc_pid_uid_gid_map_test",
+    testonly = 1,
+    srcs = ["proc_pid_uid_gid_map.cc"],
+    linkstatic = 1,
+    deps = [
+        "//test/util:capability_util",
+        "//test/util:fs_util",
+        "//test/util:logging",
+        "//test/util:multiprocess_util",
+        "//test/util:posix_error",
+        "//test/util:save_util",
+        "//test/util:test_main",
+        "//test/util:test_util",
+        "@com_google_absl//absl/strings",
+        "@com_google_googletest//:gtest",
+    ],
+)
+
+cc_binary(
     name = "pselect_test",
     testonly = 1,
     srcs = ["pselect.cc"],