Use xip --expand to open .xip archives

[EricFromCanada]

Although the xip man page has only mentioned the --expand option since macOS 10.14 Mojave, it's actually been available for use ever since xip first appeared in OS X 10.7 Lion. Using xip instead of Archive Utility saves some time in my testing, most likely due to less time spent on sandbox evaluation.

Before: 5:35.59 total for Xcode_8.3.3.xip

eric@iMac27-en1 xcodelegacy % time ./XcodeLegacy.sh -osx1012 buildpackages
*** Info: found Xcode >= 4.3 in /Applications/Xcode.app
Package "Xcode_8.3.3.xip":
   Status: signed Apple Software
   Signed with a trusted timestamp on: 2019-10-05 01:05:05 +0000
   Certificate Chain:
      1. Software Update
       Expires: 2029-04-14 21:28:23 +0000
       SHA256 Fingerprint:
           E0 74 D2 04 AC 24 98 E9 DC 90 4A 7B C7 CE D8 46 41 19 B7 9D 05 66
           80 28 92 05 83 B1 E8 96 EB B4
       \------------------------------------------------------------------------
      2. Apple Software Update Certification Authority
       Expires: 2031-10-15 00:00:00 +0000
       SHA256 Fingerprint:
           12 99 E9 BF E7 76 A2 9F F4 52 F8 C4 F5 E5 5F 3B 4D FD 29 34 34 9D
           D1 85 0B 82 74 F3 5C 71 74 5C
       \------------------------------------------------------------------------
      3. Apple Root CA
       Expires: 2035-02-09 21:40:36 +0000
       SHA256 Fingerprint:
           B0 B1 73 0E CB C7 FF 45 05 14 2C 49 F1 29 5E 6E DA 6B CA ED 7E 2C
           68 C5 BE 91 B5 A1 10 01 F0 24

Extracting Mac OS X 10.12 SDK from Xcode 8.3.3. Be patient - this will take some time
*** Created Xcode1012SDK.tar.gz in directory /Users/eric/Desktop/xcodelegacy
./XcodeLegacy.sh -osx1012 buildpackages  16.96s user 38.42s system 16% cpu 5:35.59 total

After: 5:26.57 total for Xcode_8.3.3.xip

eric@iMac27-en1 xcodelegacy % time ./XcodeLegacy.sh -osx1012 buildpackages
*** Info: found Xcode >= 4.3 in /Applications/Xcode.app
Package "Xcode_8.3.3.xip":
   Status: signed Apple Software
   Signed with a trusted timestamp on: 2019-10-05 01:05:05 +0000
   Certificate Chain:
      1. Software Update
       Expires: 2029-04-14 21:28:23 +0000
       SHA256 Fingerprint:
           E0 74 D2 04 AC 24 98 E9 DC 90 4A 7B C7 CE D8 46 41 19 B7 9D 05 66
           80 28 92 05 83 B1 E8 96 EB B4
       \------------------------------------------------------------------------
      2. Apple Software Update Certification Authority
       Expires: 2031-10-15 00:00:00 +0000
       SHA256 Fingerprint:
           12 99 E9 BF E7 76 A2 9F F4 52 F8 C4 F5 E5 5F 3B 4D FD 29 34 34 9D
           D1 85 0B 82 74 F3 5C 71 74 5C
       \------------------------------------------------------------------------
      3. Apple Root CA
       Expires: 2035-02-09 21:40:36 +0000
       SHA256 Fingerprint:
           B0 B1 73 0E CB C7 FF 45 05 14 2C 49 F1 29 5E 6E DA 6B CA ED 7E 2C
           68 C5 BE 91 B5 A1 10 01 F0 24

Extracting Mac OS X 10.12 SDK from Xcode 8.3.3. Be patient - this will take some time
xip: signing certificate was "Software Update" (validation not attempted)
xip: expanded items from "/Users/eric/Desktop/xcodelegacy/Xcode_8.3.3.xip"
*** Created Xcode1012SDK.tar.gz in directory /Users/eric/Desktop/xcodelegacy
./XcodeLegacy.sh -osx1012 buildpackages  664.02s user 214.47s system 269% cpu 5:26.57 total

Before: 6:14.00 total for Xcode_9.4.1.xip

eric@iMac27-en1 xcodelegacy % time ./XcodeLegacy.sh -osx1013 buildpackages
*** Info: found Xcode >= 4.3 in /Applications/Xcode.app
Package "Xcode_9.4.1.xip":
   Status: signed Apple Software
   Signed with a trusted timestamp on: 2019-10-05 01:06:26 +0000
   Certificate Chain:
      1. Software Update
       Expires: 2029-04-14 21:28:23 +0000
       SHA256 Fingerprint:
           E0 74 D2 04 AC 24 98 E9 DC 90 4A 7B C7 CE D8 46 41 19 B7 9D 05 66
           80 28 92 05 83 B1 E8 96 EB B4
       \------------------------------------------------------------------------
      2. Apple Software Update Certification Authority
       Expires: 2031-10-15 00:00:00 +0000
       SHA256 Fingerprint:
           12 99 E9 BF E7 76 A2 9F F4 52 F8 C4 F5 E5 5F 3B 4D FD 29 34 34 9D
           D1 85 0B 82 74 F3 5C 71 74 5C
       \------------------------------------------------------------------------
      3. Apple Root CA
       Expires: 2035-02-09 21:40:36 +0000
       SHA256 Fingerprint:
           B0 B1 73 0E CB C7 FF 45 05 14 2C 49 F1 29 5E 6E DA 6B CA ED 7E 2C
           68 C5 BE 91 B5 A1 10 01 F0 24

Extracting Mac OS X 10.13 SDK from Xcode 9.4.1. Be patient - this will take some time
*** Created Xcode1013SDK.tar.gz in directory /Users/eric/Desktop/xcodelegacy
./XcodeLegacy.sh -osx1013 buildpackages  16.94s user 50.63s system 18% cpu 6:14.00 total

After: 6:02.91 total for Xcode_9.4.1.xip

eric@iMac27-en1 xcodelegacy % time ./XcodeLegacy.sh -osx1013 buildpackages
*** Info: found Xcode >= 4.3 in /Applications/Xcode.app
Package "Xcode_9.4.1.xip":
   Status: signed Apple Software
   Signed with a trusted timestamp on: 2019-10-05 01:06:26 +0000
   Certificate Chain:
      1. Software Update
       Expires: 2029-04-14 21:28:23 +0000
       SHA256 Fingerprint:
           E0 74 D2 04 AC 24 98 E9 DC 90 4A 7B C7 CE D8 46 41 19 B7 9D 05 66
           80 28 92 05 83 B1 E8 96 EB B4
       \------------------------------------------------------------------------
      2. Apple Software Update Certification Authority
       Expires: 2031-10-15 00:00:00 +0000
       SHA256 Fingerprint:
           12 99 E9 BF E7 76 A2 9F F4 52 F8 C4 F5 E5 5F 3B 4D FD 29 34 34 9D
           D1 85 0B 82 74 F3 5C 71 74 5C
       \------------------------------------------------------------------------
      3. Apple Root CA
       Expires: 2035-02-09 21:40:36 +0000
       SHA256 Fingerprint:
           B0 B1 73 0E CB C7 FF 45 05 14 2C 49 F1 29 5E 6E DA 6B CA ED 7E 2C
           68 C5 BE 91 B5 A1 10 01 F0 24

Extracting Mac OS X 10.13 SDK from Xcode 9.4.1. Be patient - this will take some time
xip: signing certificate was "Software Update" (validation not attempted)
xip: expanded items from "/Users/eric/Desktop/xcodelegacy/Xcode_9.4.1.xip"
*** Created Xcode1013SDK.tar.gz in directory /Users/eric/Desktop/xcodelegacy
./XcodeLegacy.sh -osx1013 buildpackages  700.24s user 247.13s system 261% cpu 6:02.91 total