Trac #30128: enforce sourcing of sage-env-config before src/bin/sage-env.

All callers within sage now source sage-env-config before sage-env, so
this commit removes the bashism within sage-env that tries to find and
source sage-env-config on its own. Since sage-env still morally
depends on sage-env-config for the values of some variables, we now
throw an error in sage-env is sage-env-config was not previously
sourced. This should prevent future misuse from creeping in.

Author: orlitzky

src/bin/sage-env

@@ -13,7 +13,6 @@
 #    they won't be available in child programs.
 #  - This script has a version number such that a newer version of
 #    sage-env can be sourced when upgrading.  See below.
-#  - It uses bash features, so it cannot be used with other shells.
 #
 #  If you want to set all environment variables for your shell like
 #  they are during the build of Sage packages, type
@@ -27,6 +26,16 @@
 #
 ##########################################################################
 
+if [ "${SAGE_ENV_CONFIG_SOURCED}" -ne 1 ]; then
+    # This script uses sage-env-config to find the ./configured value
+    # of SAGE_ROOT, but ironically, it doesn't know how to find
+    # sage-env-config because it doesn't know SAGE_ROOT yet!
+    # Fortunately, anyone that knows how to source sage-env must know
+    # how to source sage-env-config, so the issue is avoided by
+    # requiring sage-env-config to be sourced before sage-env.
+    echo 'must source sage-env-config before sage-env' >&2
+    return 3
+fi
 
 # Resolve all symbolic links in a filename.  This more or less behaves
 # like "readlink -f" except that it does not convert the filename to an
@@ -109,25 +118,6 @@ resolvelinks() {
     echo "$out"
 }
 
-# See if we can obtain SAGE_SCRIPTS_DIR before determining SAGE_ROOT
-if [ -z "$SAGE_SCRIPTS_DIR" ]; then
-    ## Find the directory of this script (sage-env).
-    ## Note that it is *sourced* by various other scripts,
-    ## which is why `dirname $0` would not work ($0 is /bin/bash).
-    ## Instead we use a solution from
-    ## http://stackoverflow.com/questions/59895/can-a-bash-script-tell-which-directory-it-is-stored-in
-    ## It uses a bash feature: BASH_SOURCE[0] gives the source of
-    ## the "currently running function". See
-    ## https://www.gnu.org/software/bash/manual/html_node/Bash-Variables.html
-    ## (entries for FUNCNAME and BASH_SOURCE).
-    SAGE_SCRIPTS_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
-fi
-
-if [ -n "$SAGE_SCRIPTS_DIR" -a -r "$SAGE_SCRIPTS_DIR/sage-env-config" ]; then
-    # Set environment variables (like SAGE_LOCAL and SAGE_ROOT) depending on ./configure
-    . "$SAGE_SCRIPTS_DIR/sage-env-config"
-fi
-
 # New value for SAGE_ROOT: either SAGE_ROOT (if given)
 # or a guessed value based on pwd.
 if [ -n "$SAGE_ROOT" ]; then
@@ -137,7 +127,7 @@ elif [ -f sage -a -d build ]; then
 elif [ -f ../../sage -a -d ../../build ]; then
     NEW_SAGE_ROOT="../.."
 else
-    # No idea what SAGE_ROOT should be...
+    # No idea what SAGE_ROOT should be... it should have been set by sage-env-config.
     echo >&2 "Error: You must set the SAGE_ROOT or SAGE_SCRIPTS_DIR environment variables or run this"
     echo >&2 "script from the SAGE_ROOT or SAGE_ROOT/local/bin/ directory."
     return 1
@@ -203,15 +193,6 @@ elif [ ! -f "$SAGE_SCRIPTS_DIR/sage-env-config" ]; then
     return 1
 fi
 
-if [ -n $SAGE_ENV_CONFIG_SOURCED ]; then
-    # Set environment variables (like SAGE_LOCAL) depending on ./configure
-    . "$SAGE_SCRIPTS_DIR/sage-env-config"
-    if [ $? -ne 0 ]; then
-        echo >&2 "Error: failed to source $SAGE_SCRIPTS_DIR/sage-env-config"
-        return 1
-    fi
-fi
-
 # The compilers are set in order of priority by
 # 1) environment variables
 # 2) compiler installed by sage