[gcc r12-3106] Fix a few problems with download_prerequisites.

[gcc r12-3106] Fix a few problems with download_prerequisites.

[Andrew Pinski]

https://gcc.gnu.org/g:0deabebedd16c9519bfb1dfbff303c2d9bd701ee

commit r12-3106-g0deabebedd16c9519bfb1dfbff303c2d9bd701ee
Author: Andrew Pinski <apinski@marvell.com>
Date:   Tue Aug 24 05:56:59 2021 +0000

    Fix a few problems with download_prerequisites.
    
    There are a few problems with download_prerequisites are
    described in PR 82704.  The first is on busy-box version of
    shasum and md5sum the extended option --check don't exist
    so just use -c.  The second issue is the code for which
    shasum program to use is included twice and is different.
    So move which program to use for the checksum after argument
    parsing.  The last issue is --md5 option has been broken for
    sometime now as the program is named md5sum and not just md5.
    Nobody updated switch table to be correct.
    
    contrib/ChangeLog:
    
            PR other/82704
            * download_prerequisites: Fix issues with --md5 and
            --sha512 options.

Diff:
---
 contrib/download_prerequisites | 59 +++++++++++++++++++++---------------------
 1 file changed, 30 insertions(+), 29 deletions(-)

diff --git a/contrib/download_prerequisites b/contrib/download_prerequisites
index 51e715f69e1..8f69b61f5a9 100755
--- a/contrib/download_prerequisites
+++ b/contrib/download_prerequisites
@@ -46,18 +46,6 @@ verify=1
 force=0
 OS=$(uname)
 
-case $OS in
-  "Darwin"|"FreeBSD"|"DragonFly"|"AIX")
-    chksum='shasum -a 512 --check'
-  ;;
-  "OpenBSD")
-    chksum='sha512 -c'
-  ;;
-  *)
-    chksum='sha512sum -c'
-  ;;
-esac
-
 if type wget > /dev/null ; then
   fetch='wget'
 else
@@ -113,7 +101,7 @@ do
 done
 unset arg
 
-# Emulate Linux's 'md5 --check' on macOS
+# Emulate Linux's 'md5sum --check' on macOS
 md5_check() {
   # Store the standard input: a line from contrib/prerequisites.md5:
   md5_checksum_line=$(cat -)
@@ -162,26 +150,10 @@ do
                 verify=0
                 ;;
             --sha512)
-                case $OS in
-                  "Darwin")
-                    chksum='shasum -a 512 --check'
-                  ;;
-                  *)
-                    chksum='sha512sum --check'
-                  ;;
-                esac
                 chksum_extension='sha512'
                 verify=1
                 ;;
             --md5)
-                case $OS in
-                  "Darwin")
-                    chksum='md5_check'
-                  ;;
-                  *)
-                    chksum='md5 --check'
-                  ;;
-                esac
                 chksum_extension='md5'
                 verify=1
                 ;;
@@ -212,6 +184,35 @@ done
 [ "x${argnext}" = x ] || die "Missing argument for option --${argnext}"
 unset arg argnext
 
+case $chksum_extension in
+  sha512)
+    case $OS in
+      "Darwin"|"FreeBSD"|"DragonFly"|"AIX")
+        chksum='shasum -a 512 --check'
+      ;;
+      "OpenBSD")
+        chksum='sha512 -c'
+      ;;
+      *)
+        chksum='sha512sum -c'
+      ;;
+    esac
+  ;;
+  md5)
+    case $OS in
+      "Darwin")
+        chksum='md5_check'
+      ;;
+      *)
+        chksum='md5sum -c'
+      ;;
+    esac
+    ;;
+  *)
+    die "Unkown checksum $chksum_extension"
+  ;;
+esac
+
 [ -e ./gcc/BASE-VER ]                                                         \
     || die "You must run this script in the top-level GCC source directory"