Re: add --match argument to git-version-gen

[Andy Wingo]

Hi Jim,

On Fri 06 Jul 2012 16:32, Jim Meyering <address@hidden> writes:

> It'd be nice to say "why" this change is useful.
> At worst, just refer to the URL for this mailing list thread.

OK.

> Protecting against envvars by those names is a good idea.
> That's a fix that merits mention in the ChangeLog, if not
> a separate commit.
> However, please don't use "unset" and rather just set them to
> the empty string as is done just below -- oh, and also initialize
> tarball_version_file:

OK.

>>  # directory, and "git describe" output looks sensible, use that to
>>  # derive a version string.
>>  elif test "`git log -1 --pretty=format:x . 2>&1`" = x \
>> -    && v=`git describe --abbrev=4 --match="$prefix*" HEAD 2>/dev/null \
>> -          || git describe --abbrev=4 HEAD 2>/dev/null` \
>> +    && v=`git describe --abbrev=4 --match="$match" HEAD 2>/dev/null` \
>
> Why remove the second git invocation here?
> I can see why you'd do that when --match has been specified,
> but what about all of us who use the default (no --match option).
> Do you really want to add the "feature" that git-version-gen now
> fails when there is no "v*" tag, whereas before that worked fine?

Fixed to only match strictly when --match is passed.  I couldn't figure
out a way to do it without the gymnastics.

Andy

>From 1994935abc52afb85eb71232075ce06a9c83bf1b Mon Sep 17 00:00:00 2001
From: Andy Wingo <address@hidden>
Date: Fri, 6 Jul 2012 17:27:37 +0200
Subject: [PATCH] git-version-gen: add --match argument.

* build-aux/git-version-gen (Options): Add --match argument.
  (match):
  (tag_sed_script):
  (tarball_version_file): Protect against ambient values of these
  variables.
  (massage_git_version): Contort the tests to require a match in the
  --match case, and otherwise have our previous behavior.

Using --match can prevent a merge from e.g. a version 2 branch to a 3
branch from causing the 3 branch to show a 2 version, if the 2 version
released more recently than the 3 version.
---
 build-aux/git-version-gen |   65 +++++++++++++++++++++++++++++++--------------
 1 file changed, 45 insertions(+), 20 deletions(-)

diff --git a/build-aux/git-version-gen b/build-aux/git-version-gen
index 0fa9063..c7ed287 100755
--- a/build-aux/git-version-gen
+++ b/build-aux/git-version-gen
@@ -1,6 +1,6 @@
 #!/bin/sh
 # Print a version string.
-scriptversion=2012-03-18.17; # UTC
+scriptversion=2012-07-06.15; # UTC
 
 # Copyright (C) 2007-2012 Free Software Foundation, Inc.
 #
@@ -85,20 +85,27 @@ Print a version string.
 
 Options:
 
-   --prefix           prefix of git tags (default 'v')
+   --prefix     prefix of git tags to strip from version (default 'v')
+   --match      pattern for git tags to match
 
-   --help             display this help and exit
-   --version          output version information and exit
+   --help       display this help and exit
+   --version    output version information and exit
 
-Running without arguments will suffice in most cases."
+Running without arguments will suffice in most cases.  If no --match
+argument is given, try to match tags that begin with the --prefix,
+falling back to the first tag that git-describe finds."
 
 prefix=v
+match=
+tag_sed_script=
+tarball_version_file=
 
 while test $# -gt 0; do
   case $1 in
     --help) echo "$usage"; exit 0;;
     --version) echo "$version"; exit 0;;
     --prefix) shift; prefix="$1";;
+    --match) shift; match="$1";;
     -*)
       echo "$0: Unknown option '$1'." >&2
       echo "$0: Try '--help' for more information." >&2
@@ -144,21 +151,7 @@ then
         && echo "$0: WARNING: $tarball_version_file is missing or damaged" 1>&2
 fi
 
-if test -n "$v"
-then
-    : # use $v
-# Otherwise, if there is at least one git commit involving the working
-# directory, and "git describe" output looks sensible, use that to
-# derive a version string.
-elif test "`git log -1 --pretty=format:x . 2>&1`" = x \
-    && v=`git describe --abbrev=4 --match="$prefix*" HEAD 2>/dev/null \
-          || git describe --abbrev=4 HEAD 2>/dev/null` \
-    && v=`printf '%s\n' "$v" | sed "$tag_sed_script"` \
-    && case $v in
-         $prefix[0-9]*) ;;
-         *) (exit 1) ;;
-       esac
-then
+function massage_git_version() {
     # Is this a new git that lists number of commits since the last
     # tag or the previous older version that did not?
     #   Newer: v6.10-77-g0f8faeb
@@ -184,6 +177,38 @@ then
     # Remove the "g" in git describe's output string, to save a byte.
     v=`echo "$v" | sed 's/-/./;s/\(.*\)-g/\1-/'`;
     v_from_git=1
+}
+
+if test -n "$v"
+then
+    : # use $v
+# Otherwise, if the user specified --match, look for a matching tag.
+elif test -n "$match"
+then
+    if  test "`git log -1 --pretty=format:x . 2>&1`" = x \
+        && v=`git describe --abbrev=4 --match="$match" HEAD 2>/dev/null` \
+        && v=`printf '%s\n' "$v" | sed "$tag_sed_script"` \
+        && case $v in
+             $prefix[0-9]*) ;;
+             *) (exit 1) ;;
+           esac
+    then
+        massage_git_version
+    else
+        v=UNKNOWN
+    fi
+# Otherwise, look for a tag starting with --prefix, or the first tag we
+# find, sed it, and see if it looks like a version.
+elif test "`git log -1 --pretty=format:x . 2>&1`" = x \
+    && v=`git describe --abbrev=4 --match="$prefix*" HEAD 2>/dev/null \
+          || git describe --abbrev=4 HEAD 2>/dev/null` \
+    && v=`printf '%s\n' "$v" | sed "$tag_sed_script"` \
+    && case $v in
+         $prefix[0-9]*) ;;
+         *) (exit 1) ;;
+       esac
+then
+    massage_git_version
 else
     v=UNKNOWN
 fi
-- 
1.7.10

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