Implementation of 'build-git' command.

This command acts as an alias for 'build dev', that is introduces
the special version 'dev' to instrument the build process to download
the source tree via git instead of getting a tarball.

If the 'dev' version has never been created, than a complete checkout
is performed; otherwise a fetch is done.
The build process continues as usual, with patching, make, and etc.

At the end, the 'pgenv-dev' directory will be in place to indicate the
new version of PostgreSQL.

It is possible to configure the git process via two special variables, that
have not been introduced in the configuration mechanism because they
represent developer tweaks; they can be manually added in any case.

Documentation updated.

See theory#25

README.md

@@ -15,6 +15,9 @@ Synopsis
     # Build PostgreSQL server
     pgenv build 10.4
 
+    # Build from git
+    pgenv build-git
+
     # Use PostgreSQL version
     pgenv use 10.4
 
@@ -110,7 +113,8 @@ $ git pull
 *   curl - Used to download files
 *   sed, grep, cat, tar, sort, tr, uname - General Unix command line utilities
 *   patch - For patching versions that need patching
-*   make -  Builds PostgreSQL
+*   make - Builds PostgreSQL
+*   git - Used to download the current source tree
 
 Optional dependencies:
 
@@ -270,6 +274,38 @@ file. As an example
 
 
 
+### pgenv build-git
+
+This command fetches the current source tree from the official PostgreSQL git repository
+and builds it as special version `dev`. This is an option aimed to help developers
+to keep a version up-to-date with the current PostgreSQL source tree.
+
+Actually, the command is an *alias* for `build dev`, meaning that the following
+two commands are identical:
+    
+    $ pgenv build-git
+    $ pgenv build dev
+    
+The first time the command is called a source directory `dev` is created and the
+default branch is checked out. On a further execution, the command
+will fetch updates from the repository.
+
+It is possible to configure both the repository and the branch to fetch
+using the variables:
+- `PGENV_GIT_REPO` which defaults to `https://git.postgresql.org/git/postgresql.git`;
+- `PGENV_GIT_CHECKOUT_BRANCH` which if not set defaults to fetching the `master` branch, while
+  if set creates a tracking branch.
+
+The above variable have not been included in the configuration mechanism because they
+represent advanced tweaks. It is however possible to include them in the configuration file
+for this particular version (`.pgenv.dev.conf`) or in the global configuration file
+to drive the checkout and fetch process.
+
+Patching of the special `dev` version happens as for regular versions, but using the special
+`dev` version identifier, and therefore the patch index is searched with such string
+in place of a regular version number.
+
+
 ### pgenv remove
 
 Removes the specified version of PostgreSQL unless it is the currently-active

bin/pgenv

@@ -181,6 +181,8 @@ pgenv_input_version_or_exit() {
     local verbose=$2
     local hint=$3
 
+    echo "version $version"
+
     if [ -z "$version" ]; then
         if [ ! -z "$hint" ]; then
             # count the versions
@@ -214,6 +216,8 @@ pgenv_input_version_or_exit() {
         return # versions 9.5.4 or 10.1 and alike
     elif [[ $version =~ ^[1-9][1-9](beta|rc)[1-9]?$ ]]; then
         return # versions 11beta1 and alike
+    elif [ $version = 'dev' ]; then
+         return # building from git or alike
     else
         echo "Value \"$version\" does not appear to be a PostgreSQL valid version number"
         exit 1
@@ -685,8 +689,17 @@ case $1 in
         exit
         ;;
 
-    build)
-        v=$2
+    build|build-git)
+
+        # in the case of 'build-git'
+        # the version defaults to 'dev'
+        case $1 in
+            build)     v=$2    ;;
+            build-git) v='dev'
+                       shift # remove the command
+                       ;;
+        esac
+
         # sanity checks before building
         pgenv_input_version_or_exit "$v"
         pgenv_configuration_load $v
@@ -705,40 +718,76 @@ case $1 in
         fi
         cd src
 
-        # Download the source if wee don't already have it.
-        # WARNING: older PostgreSQL used .tar.gz instead of .tar.bz2,
-        # so if the version is behind 8 use the first format, otherwise
-        # try to get the most compressed archive
-        if [[ $v =~ ^[1-7]\. ]]; then
-            PG_TARBALL="postgresql-$v.tar.gz"
-            TAR_OPTS="zxf"
+
+        if [ "$v" != 'dev' ]; then
+            # Download the source if wee don't already have it.
+            # WARNING: older PostgreSQL used .tar.gz instead of .tar.bz2,
+            # so if the version is behind 8 use the first format, otherwise
+            # try to get the most compressed archive
+            if [[ $v =~ ^[1-7]\. ]]; then
+                PG_TARBALL="postgresql-$v.tar.gz"
+                TAR_OPTS="zxf"
+            else
+                PG_TARBALL="postgresql-$v.tar.bz2"
+                TAR_OPTS="jxf"
+            fi
+
+            if [ ! -f $PG_TARBALL ]; then
+                $PGENV_CURL -fLO ${PGENV_DOWNLOAD_ROOT}/v$v/${PG_TARBALL}
+            fi
+
+
+            # warn if no configuration was loaded
+            if [ -z "$PGENV_CONFIGURATION_FILE" ]; then
+                echo "WARNING: no configuration file found for version $v"
+                echo "HINT: if you wish to customize the build process please"
+                echo "stop the execution within 5 seconds (CTRL-c) and run "
+                echo "    pgenv config write $v && pgenv config edit $v"
+                echo "adjust 'configure' and 'make' options and flags and run again"
+                echo "    pgenv build $v"
+                echo
+                sleep 5
+            fi
+
+
+            # Unpack the source.
+            rm -rf "postgresql-$v"
+            $PGENV_TAR $TAR_OPTS $PG_TARBALL
+            cd postgresql-$v
+
+
         else
-            PG_TARBALL="postgresql-$v.tar.bz2"
-            TAR_OPTS="jxf"
-        fi
+            # here there is the build from git for 'dev'
 
-        if [ ! -f $PG_TARBALL ]; then
-            $PGENV_CURL -fLO ${PGENV_DOWNLOAD_ROOT}/v$v/${PG_TARBALL}
-        fi
+            # initialize variables if not explicitly set
+            if [ -z "$PGENV_GIT_REPO" ]; then
+                PGENV_GIT_REPO="https://git.postgresql.org/git/postgresql.git"
+            fi
 
+            # if the user wants a specific branch, build the
+            # command line options
+            if [ ! -z "$PGENV_GIT_CHECKOUT_BRANCH" ]; then
+                PGENV_GIT_CHECKOUT="-b $PGENV_GIT_CHECKOUT_BRANCH --track origin/$PGENV_GIT_CHECKOUT_BRANCH"
+            else
+                # avoid tainting
+                PGENV_GIT_CHECKOUT=""
+            fi
+
+            pgenv_debug "Checking out [$PGENV_GIT_REPO] @ [$PGENV_GIT_CHECKOUT]"
 
-        # warn if no configuration was loaded
-        if [ -z "$PGENV_CONFIGURATION_FILE" ]; then
-            echo "WARNING: no configuration file found for version $v"
-            echo "HINT: if you wish to customize the build process please"
-            echo "stop the execution within 5 seconds (CTRL-c) and run "
-            echo "    pgenv config write $v && pgenv config edit $v"
-            echo "adjust 'configure' and 'make' options and flags and run again"
-            echo "    pgenv build $v"
-            echo
-            sleep 5
+            # download the sources
+            if [ -d 'dev' ]; then
+                # directory already existing, fetch new sources
+                cd dev
+                git fetch $PGENV_GIT_REPO
+            else
+                # first checkout
+                git clone $PGENV_GIT_REPO $PGENV_GIT_CHECKOUT dev
+                cd dev
+            fi
         fi
 
 
-        # Unpack the source.
-        rm -rf "postgresql-$v"
-        $PGENV_TAR $TAR_OPTS $PG_TARBALL
-        cd postgresql-$v
 
         # patch the source tree if required
         pgenv_debug "Patching version $v"
@@ -748,7 +797,7 @@ case $1 in
         pgenv_debug "configure command line [--prefix=$PGENV_ROOT/pgsql-$v] + [$PGENV_CONFIGURE_OPTS]"
         # need to keep a single string to pass to configure or
         # will get an 'invalid package'
-        ./configure --prefix=$PGENV_ROOT/pgsql-$v $PGENV_CONFIGURE_OPTS
+        ./configure --prefix=$PGENV_ROOT/pgsql-$v $PGENV_CONFIGURE_OPTS --without-readline
 
         # make and make install
         if [[ $v =~ ^[1-8]\. ]]; then
@@ -758,6 +807,8 @@ case $1 in
             cd contrib
             $PGENV_MAKE $PGENV_MAKE_OPTS
             $PGENV_MAKE install
+        elif [ "$v" = 'dev' ]; then
+            $PGENV_MAKE world $PGENV_MAKE_OPTS
         else
             # Yay, make world!
             $PGENV_MAKE world $PGENV_MAKE_OPTS