git-version-string

#!/bin/sh
#
# **********************************************************************
#
# Author: Seth Underwood <Seth.Underwood@noaa.gov>
#
# **********************************************************************
#
# git-version-string reports on the git status of a file.  The string
# returned can be used in a CPP macro to set the file's version in the
# compiled source code, as in the following compile example:
#
# f90 -D_VERSION=`git version-string foo.F90` -c foo.F90
#
# or in a Makefile:
#
# foo.o : foo.F90
#      $(F90) -D_VERSION=$(shell git version-string foo.F90) -c foo.F90
#
# git-version-string will always print a string indicating the "known"
# status of a file to standard out.  The possible status lines are:
#
# 1. An unmodified file will only have the commit hash printed.
#    Example: ref:f6a0f81
#
# 2. A modified file will have the commit hash printed, a status string,
#    and the modified object hash.
#    Example: ref:f6a0f81 status:Modified blob:e50efe074c09a81d9041222a9976b4ef87758265
#
# 3. If the file is not in a git repository, or if any error occurs, the
#    string returned will be "UNKNOWN".  If possible, the hash of the
#    blob will also be printed.
#    Example: status:UNKNOWN
#             status:UNKNOWN blob:d86bac9de59abcc26bc7956c1e842237c7581859
#
# If git-version-string encounters any errors, the status line in 3
# will still be printed, along with an error message to stdout, and in
# some cases will have a non-zero exit status.
#
# To use with mkmf, use the following invocation:
#
# mkmf -t make_template -p foo -c '-D_VERSION="`git version-string $<`"' path_names
#
# That will add the following CPPDEFS make macro to the makefile:
#
# CPPDEFS = -d_VERSION="`git version-string $<`"
#
# **********************************************************************

usage () {
    printf "usage: %s <file>\n" $( basename $0 )  1>&2
    exit $1
}

error () {
    err_msg=$1
    exit_val=$2
    if [ $# -eq 3 ]; then
        blob_hash=" blob:$3"
    else
        blob_hash=""
    fi
    # $blob_hash will contain the leading space (if needed)
    # quoting $blob_hash will preserve the leading space.
    printf "'status:UNKNOWN%s'\n" "$blob_hash"

    printf "$err_msg\n" 1>&2
    exit $exit_val
}

git_status () {
    if [ $1 = '??' ]; then
        printf "Untracked"
    elif [ $1 = 'A' ]; then
        printf "Added"
    elif [ $1 = 'M' ]; then
        printf "Modified"
    elif [ $1 = 'D' ]; then
        printf "Deleted"
    elif [ $1 = 'R' ]; then
        printf "Renamed"
    elif [ $1 = 'C' ]; then
        printf "Copied"
    elif [ $1 = 'U' ]; then
        printf "Unmerged"
    else
        printf "UNKNOWN"
    fi
}

status () {
    if [ $# -ne 3 ]; then
	error "DEBUG: bad call to status" 1
    fi

    if [ ${#2} -eq 0 ]; then
        printf "'ref:%s'\n" $1
    else
        stat=$( git_status $2 )
        printf "'ref:%s status:%s blob:%s'\n" $1 $stat $3
    fi
}


# Parse opions
while getopts "h" opt; do
    case "$opt" in
        h)
            usage 0
            ;;
    esac
done
shift $((OPTIND-1))

# Verify git is in the path
git=$( which git 2>&1 )
if [ $? -ne 0 ]; then
    error "FATAL: git is not in PATH" 1
fi

if [ $# -eq 1 ]; then
    dir=$( dirname $1 )
    file=$( basename $1 )

    # Change into dir.
    if [ -e $dir ]; then
        if [ -d $dir ]; then
            cd $dir
        else
            error "FATAL: $dir is not a directory" 1
        fi
    else
        error "FATAL: Directory $dir does not exist" 1
    fi

    # Check if file exists
    if [ ! -e $file ]; then
        error "FATAL: File $file does not exist" 1
    elif [ ! -r $file ]; then
        error "FATAL: File $file is not readable" 1
    fi

    # File exists, can get the blob hash
    fileHash=$( git hash-object $file 2> /dev/null )
    errorStat=$?
    if [ $errorStat -ne 0 ]; then
        error "WARNING: Failed to get hash of $file" 0
    fi

    # Trap error if not in a git work directory
    repoHash=$( git rev-parse HEAD 2> /dev/null)
    errorStat=$?
    if [ $errorStat -eq 128 ]; then
        # Not in a git repository
        error "WARNING: Not in a git repository" 0 $fileHash
    elif [ $errorStat -ne 0 ]; then
        error "WARNING: Unknown 'git rev-parse' error $?" 0
    fi

    fileStatus=$( git status --porcelain $file | awk '{print $1}' )
    errorStat=$?
    if [ $errorStat -ne 0 ]; then
        error "WARNING: Unable to get status of $file" 0 $fileHash
    fi

    status "$repoHash" "$fileStatus" "$fileHash"
else
    usage 1
fi