sysv: linux: Add 64-bit time_t variant for shmctl

To provide a y2038 safe interface a new symbol __shmctl64 is added
and __shmctl is change to call it instead (it adds some extra buffer
copying for the 32 bit time_t implementation).

Two new structures are added:

  1. kernel_shmid64_ds: used internally only on 32-bit architectures
     to issue the syscall.  A handful of architectures (hppa, i386,
     mips, powerpc32, and sparc32) require specific implementations
     due to their kernel ABI.

  2. shmid_ds64: this is only for __TIMESIZE != 64 to use along with
     the 64-bit shmctl.  It is different than the kernel struct because
     the exported 64-bit time_t might require different alignment
     depending on the architecture ABI.

So the resulting implementation does:

  1. For 64-bit architectures it assumes shmid_ds already contains
     64-bit time_t fields and will result in just the __shmctl symbol
     using the __shmctl64 code.  The shmid_ds argument is passed as-is
     to the syscall.

  2. For 32-bit architectures with default 64-bit time_t (newer ABIs
     such riscv32 or arc), it will also result in only one exported
     symbol but with the required high/low time handling.

  3. Finally for 32-bit architecture with both 32-bit and 64-bit time_t
     support we follow the already set way to provide one symbol with
     64-bit time_t support and implement the 32-bit time_t support
     using of the 64-bit one.

     The default 32-bit symbol will allocate and copy the shmid_ds
     over multiple buffers, but this should be deprecated in favor
     of the __shmctl64 anyway.

Checked on i686-linux-gnu and x86_64-linux-gnu.  I also did some sniff
tests on powerpc, powerpc64, mips, mips64, armhf, sparcv9, and
sparc64.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 147 insertions, 34 deletions

diff --git a/sysdeps/unix/sysv/linux/shmctl.c b/sysdeps/unix/sysv/linux/shmctl.c
index f41b359b8b..76d88441f1 100644
--- a/sysdeps/unix/sysv/linux/shmctl.c
+++ b/sysdeps/unix/sysv/linux/shmctl.c
@@ -24,16 +24,55 @@
 #include <errno.h>
 #include <linux/posix_types.h>  /* For __kernel_mode_t.  */
 
-#ifndef DEFAULT_VERSION
-# ifndef __ASSUME_SYSVIPC_BROKEN_MODE_T
-#  define DEFAULT_VERSION GLIBC_2_2
-# else
-#  define DEFAULT_VERSION GLIBC_2_31
-# endif
+/* POSIX states ipc_perm mode should have type of mode_t.  */
+_Static_assert (sizeof ((struct shmid_ds){0}.shm_perm.mode)
+		== sizeof (mode_t),
+		"sizeof (shmid_ds.shm_perm.mode) != sizeof (mode_t)");
+
+#if __IPC_TIME64 == 0
+typedef struct shmid_ds shmctl_arg_t;
+#else
+# include <struct_kernel_shmid64_ds.h>
+
+static void
+shmid64_to_kshmid64 (const struct __shmid64_ds *shmid64,
+		     struct kernel_shmid64_ds *kshmid)
+{
+  kshmid->shm_perm       = shmid64->shm_perm;
+  kshmid->shm_segsz      = shmid64->shm_segsz;
+  kshmid->shm_atime      = shmid64->shm_atime;
+  kshmid->shm_atime_high = shmid64->shm_atime >> 32;
+  kshmid->shm_dtime      = shmid64->shm_dtime;
+  kshmid->shm_dtime_high = shmid64->shm_dtime >> 32;
+  kshmid->shm_ctime      = shmid64->shm_ctime;
+  kshmid->shm_ctime_high = shmid64->shm_ctime >> 32;
+  kshmid->shm_cpid       = shmid64->shm_cpid;
+  kshmid->shm_lpid       = shmid64->shm_lpid;
+  kshmid->shm_nattch     = shmid64->shm_nattch;
+}
+
+static void
+kshmid64_to_shmid64 (const struct kernel_shmid64_ds *kshmid,
+		     struct __shmid64_ds *shmid64)
+{
+  shmid64->shm_perm   = kshmid->shm_perm;
+  shmid64->shm_segsz  = kshmid->shm_segsz;
+  shmid64->shm_atime  = kshmid->shm_atime
+		        | ((__time64_t) kshmid->shm_atime_high << 32);
+  shmid64->shm_dtime  = kshmid->shm_dtime
+		        | ((__time64_t) kshmid->shm_dtime_high << 32);
+  shmid64->shm_ctime  = kshmid->shm_ctime
+		        | ((__time64_t) kshmid->shm_ctime_high << 32);
+  shmid64->shm_cpid   = kshmid->shm_cpid;
+  shmid64->shm_lpid   = kshmid->shm_lpid;
+  shmid64->shm_nattch = kshmid->shm_nattch;
+}
+
+typedef struct kernel_shmid64_ds shmctl_arg_t;
 #endif
 
 static int
-shmctl_syscall (int shmid, int cmd, struct shmid_ds *buf)
+shmctl_syscall (int shmid, int cmd, shmctl_arg_t *buf)
 {
 #ifdef __ASSUME_DIRECT_SYSVIPC_SYSCALLS
   return INLINE_SYSCALL_CALL (shmctl, shmid, cmd | __IPC_64, buf);
@@ -45,46 +84,120 @@ shmctl_syscall (int shmid, int cmd, struct shmid_ds *buf)
 
 /* Provide operations to control over shared memory segments.  */
 int
-__new_shmctl (int shmid, int cmd, struct shmid_ds *buf)
+__shmctl64 (int shmid, int cmd, struct __shmid64_ds *buf)
 {
-  /* POSIX states ipc_perm mode should have type of mode_t.  */
-  _Static_assert (sizeof ((struct shmid_ds){0}.shm_perm.mode)
-		  == sizeof (mode_t),
-		  "sizeof (msqid_ds.msg_perm.mode) != sizeof (mode_t)");
-
-#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
-  struct shmid_ds tmpds;
-  if (cmd == IPC_SET)
+#if __IPC_TIME64
+  struct kernel_shmid64_ds kshmid, *arg = NULL;
+  if (buf != NULL)
     {
-      tmpds = *buf;
-      tmpds.shm_perm.mode *= 0x10000U;
-      buf = &tmpds;
+      shmid64_to_kshmid64 (buf, &kshmid);
+      arg = &kshmid;
     }
+# ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
+  if (cmd == IPC_SET)
+    arg->shm_perm.mode *= 0x10000U;
+# endif
+#else
+  shmctl_arg_t *arg = buf;
 #endif
 
-  int ret = shmctl_syscall (shmid, cmd, buf);
+  int ret = shmctl_syscall (shmid, cmd, arg);
+  if (ret < 0)
+    return ret;
 
-  if (ret >= 0)
+  switch (cmd)
     {
-      switch (cmd)
-	{
-        case IPC_STAT:
-        case SHM_STAT:
-        case SHM_STAT_ANY:
+      case IPC_INFO:
+      case IPC_STAT:
+      case SHM_STAT:
+      case SHM_STAT_ANY:
 #ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
-          buf->shm_perm.mode >>= 16;
+        arg->shm_perm.mode >>= 16;
 #else
-	  /* Old Linux kernel versions might not clear the mode padding.  */
-	  if (sizeof ((struct shmid_ds){0}.shm_perm.mode)
-	      != sizeof (__kernel_mode_t))
-	    buf->shm_perm.mode &= 0xFFFF;
+      /* Old Linux kernel versions might not clear the mode padding.  */
+      if (sizeof ((struct shmid_ds){0}.shm_perm.mode)
+	  != sizeof (__kernel_mode_t))
+	arg->shm_perm.mode &= 0xFFFF;
+#endif
+
+#if __IPC_TIME64
+      kshmid64_to_shmid64 (arg, buf);
 #endif
-	}
     }
 
   return ret;
 }
-versioned_symbol (libc, __new_shmctl, shmctl, DEFAULT_VERSION);
+#if __TIMESIZE != 64
+libc_hidden_def (__shmctl64)
+
+static void
+shmid_to_shmid64 (struct __shmid64_ds *shm64, const struct shmid_ds *shm)
+{
+  shm64->shm_perm   = shm->shm_perm;
+  shm64->shm_segsz  = shm->shm_segsz;
+  shm64->shm_atime  = shm->shm_atime
+		      | ((__time64_t) shm->__shm_atime_high << 32);
+  shm64->shm_dtime  = shm->shm_dtime
+		      | ((__time64_t) shm->__shm_dtime_high << 32);
+  shm64->shm_ctime  = shm->shm_ctime
+		      | ((__time64_t) shm->__shm_ctime_high << 32);
+  shm64->shm_cpid   = shm->shm_cpid;
+  shm64->shm_lpid   = shm->shm_lpid;
+  shm64->shm_nattch = shm->shm_nattch;
+}
+
+static void
+shmid64_to_shmid (struct shmid_ds *shm, const struct __shmid64_ds *shm64)
+{
+  shm->shm_perm         = shm64->shm_perm;
+  shm->shm_segsz        = shm64->shm_segsz;
+  shm->shm_atime        = shm64->shm_atime;
+  shm->__shm_atime_high = 0;
+  shm->shm_dtime        = shm64->shm_dtime;
+  shm->__shm_dtime_high = 0;
+  shm->shm_ctime        = shm64->shm_ctime;
+  shm->__shm_ctime_high = 0;
+  shm->shm_cpid         = shm64->shm_cpid;
+  shm->shm_lpid         = shm64->shm_lpid;
+  shm->shm_nattch       = shm64->shm_nattch;
+}
+
+int
+__shmctl (int shmid, int cmd, struct shmid_ds *buf)
+{
+  struct __shmid64_ds shmid64, *buf64 = NULL;
+  if (buf != NULL)
+    {
+      shmid_to_shmid64 (&shmid64, buf);
+      buf64 = &shmid64;
+    }
+
+  int ret = __shmctl64 (shmid, cmd, buf64);
+  if (ret < 0)
+    return ret;
+
+  switch (cmd)
+    {
+      case IPC_INFO:
+      case IPC_STAT:
+      case SHM_STAT:
+      case SHM_STAT_ANY:
+	shmid64_to_shmid (buf, buf64);
+    }
+
+  return ret;
+}
+#endif
+
+#ifndef DEFAULT_VERSION
+# ifndef __ASSUME_SYSVIPC_BROKEN_MODE_T
+#  define DEFAULT_VERSION GLIBC_2_2
+# else
+#  define DEFAULT_VERSION GLIBC_2_31
+# endif
+#endif
+
+versioned_symbol (libc, __shmctl, shmctl, DEFAULT_VERSION);
 
 #if defined __ASSUME_SYSVIPC_BROKEN_MODE_T \
     && SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_31)
@@ -92,7 +205,7 @@ int
 attribute_compat_text_section
 __shmctl_mode16 (int shmid, int cmd, struct shmid_ds *buf)
 {
-  return shmctl_syscall (shmid, cmd, buf);
+  return shmctl_syscall (shmid, cmd, (shmctl_arg_t *) buf);
 }
 compat_symbol (libc, __shmctl_mode16, shmctl, GLIBC_2_2);
 #endif