[binutils-gdb] ELF/BFD: Fix padding in `elf_external_linux_prpsinfo64'

[Maciej W.Rozycki]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=72bc1bb934ba99bc9182179a866c0d2c77d027c8

commit 72bc1bb934ba99bc9182179a866c0d2c77d027c8
Author: Maciej W. Rozycki <macro@imgtec.com>
Date:   Wed Oct 11 15:01:40 2017 +0100

    ELF/BFD: Fix padding in `elf_external_linux_prpsinfo64'
    
    Fix commit 70a38d42c5b3 ("New entry points for writing Linux NT_PRPSINFO
    notes."), <https://sourceware.org/ml/binutils/2013-02/msg00023.html>,
    and move the padding of the `elf_external_linux_prpsinfo64' structure to
    match the corresponding 64-bit Linux kernel `elf_prpsinfo' structure.
    
    The 64-bit kernel structure is defined as follows:
    
    (gdb) ptype struct elf_prpsinfo
    type = struct elf_prpsinfo {
        char pr_state;
        char pr_sname;
        char pr_zomb;
        char pr_nice;
        unsigned long pr_flag;
        __kernel_uid_t pr_uid;
        __kernel_gid_t pr_gid;
        pid_t pr_pid;
        pid_t pr_ppid;
        pid_t pr_pgrp;
        pid_t pr_sid;
        char pr_fname[16];
        char pr_psargs[80];
    }
    (gdb) print /x &((struct elf_prpsinfo *)0)->pr_nice
    $1 = 0x3
    (gdb) print /x &((struct elf_prpsinfo *)0)->pr_flag
    $2 = 0x8
    (gdb) print /x &((struct elf_prpsinfo *)0)->pr_uid
    $3 = 0x10
    (gdb) print sizeof(((struct elf_prpsinfo *)0)->pr_flag)
    $4 = 8
    (gdb)
    
    with implicit padding present before the `pr_flag' member, to correctly
    align it to a multiple of 8.  Conversely `elf_external_linux_prpsinfo64'
    has padding after its `pr_flag' member:
    
    (top-gdb) ptype struct elf_external_linux_prpsinfo64
    type = struct elf_external_linux_prpsinfo64 {
        char pr_state;
        char pr_sname;
        char pr_zomb;
        char pr_nice;
        char pr_flag[8];
        char gap[4];
        char pr_uid[4];
        char pr_gid[4];
        char pr_pid[4];
        char pr_ppid[4];
        char pr_pgrp[4];
        char pr_sid[4];
        char pr_fname[16];
        char pr_psargs[80];
    }
    (top-gdb) print /x &((struct elf_external_linux_prpsinfo64 *)0)->pr_nice
    $1 = 0x3
    (top-gdb) print /x &((struct elf_external_linux_prpsinfo64 *)0)->pr_flag
    $2 = 0x4
    (top-gdb) print /x &((struct elf_external_linux_prpsinfo64 *)0)->pr_uid
    $3 = 0x10
    (top-gdb)
    
    and consequently `pr_flag' is misplaced.  Move `gap' ahead of `pr_flag'
    then.
    
    	bfd/
    	* elf-linux-core.h (elf_external_linux_prpsinfo64): Move the
    	`gap' member ahead of `pr_flag'.

Diff:
---
 bfd/ChangeLog        | 5 +++++
 bfd/elf-linux-core.h | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 82bcbf2..f2ad127 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,8 @@
+2017-10-11  Maciej W. Rozycki  <macro@imgtec.com>
+
+	* elf-linux-core.h (elf_external_linux_prpsinfo64): Move the
+	`gap' member ahead of `pr_flag'.
+
 2017-10-11  Pedro Alves  <palves@redhat.com>
 
 	* bfd.c (_doprnt): Rename to ...
diff --git a/bfd/elf-linux-core.h b/bfd/elf-linux-core.h
index 4dcc488..e904939 100644
--- a/bfd/elf-linux-core.h
+++ b/bfd/elf-linux-core.h
@@ -85,8 +85,8 @@ struct elf_external_linux_prpsinfo64
     char pr_sname;			/* Char for pr_state.  */
     char pr_zomb;			/* Zombie.  */
     char pr_nice;			/* Nice val.  */
-    char pr_flag[8];			/* Flags.  */
     char gap[4];
+    char pr_flag[8];			/* Flags.  */
     char pr_uid[4];
     char pr_gid[4];
     char pr_pid[4];