Reduce the use of grep

Avoid using the external command grep for simple string-based checks.
Prefer a case statement. This improves performance.

The performance improvement is moderate but noticeable when skipping
most tests. When a test is run, the cost of the associated grep calls
is negligible. In this commit, I focused on the uses of grep that can
be easily replaced and that are executed a large number of times.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

tests/ssl-opt.sh

@@ -178,6 +178,14 @@ case "$MBEDTLS_TEST_OUTCOME_FILE" in
         ;;
 esac
 
+# Read boolean configuration options from config.h for easy and quick
+# testing. Skip non-boolean options (with something other than spaces
+# and a comment after "#define SYMBOL"). The variable contains a
+# space-separated list of symbols.
+CONFIGS_ENABLED=" $(<"$CONFIG_H" \
+                    sed -n 's!^ *#define  *\([A-Za-z][0-9A-Z_a-z]*\) *\(/*\)*!\1!p' |
+                    tr '\n' ' ')"
+
 # Skip next test; use this macro to skip tests which are legitimate
 # in theory and expected to be re-introduced at some point, but
 # aren't expected to succeed at the moment due to problems outside
@@ -188,16 +196,17 @@ skip_next_test() {
 
 # skip next test if the flag is not enabled in config.h
 requires_config_enabled() {
-    if grep "^#define $1" $CONFIG_H > /dev/null; then :; else
-        SKIP_NEXT="YES"
-    fi
+    case $CONFIGS_ENABLED in
+        *" $1 "*) :;;
+        *) SKIP_NEXT="YES";;
+    esac
 }
 
 # skip next test if the flag is enabled in config.h
 requires_config_disabled() {
-    if grep "^#define $1" $CONFIG_H > /dev/null; then
-        SKIP_NEXT="YES"
-    fi
+    case $CONFIGS_ENABLED in
+        *" $1 "*) SKIP_NEXT="YES";;
+    esac
 }
 
 get_config_value_or_default() {
@@ -233,10 +242,16 @@ requires_config_value_at_most() {
     fi
 }
 
+# Space-separated list of ciphersuites supported by this build of
+# Mbed TLS.
+P_CIPHERSUITES=" $($P_CLI --help 2>/dev/null |
+                   grep TLS- |
+                   tr -s ' \n' ' ')"
 requires_ciphersuite_enabled() {
-    if [ -z "$($P_CLI --help 2>/dev/null | grep $1)" ]; then
-        SKIP_NEXT="YES"
-    fi
+    case $P_CIPHERSUITES in
+        *" $1 "*) :;;
+        *) SKIP_NEXT="YES";;
+    esac
 }
 
 # maybe_requires_ciphersuite_enabled CMD [RUN_TEST_OPTION...]
@@ -462,17 +477,21 @@ fail() {
 
 # is_polar <cmd_line>
 is_polar() {
-    echo "$1" | grep 'ssl_server2\|ssl_client2' > /dev/null
+    case "$1" in
+        *ssl_client2*) true;;
+        *ssl_server2*) true;;
+        *) false;;
+    esac
 }
 
 # openssl s_server doesn't have -www with DTLS
 check_osrv_dtls() {
-    if echo "$SRV_CMD" | grep 's_server.*-dtls' >/dev/null; then
-        NEEDS_INPUT=1
-        SRV_CMD="$( echo $SRV_CMD | sed s/-www// )"
-    else
-        NEEDS_INPUT=0
-    fi
+    case "$SRV_CMD" in
+        *s_server*-dtls*)
+            NEEDS_INPUT=1
+            SRV_CMD="$( echo $SRV_CMD | sed s/-www// )";;
+        *) NEEDS_INPUT=0;;
+    esac
 }
 
 # provide input to commands that need it
@@ -627,11 +646,10 @@ wait_client_done() {
 
 # check if the given command uses dtls and sets global variable DTLS
 detect_dtls() {
-    if echo "$1" | grep 'dtls=1\|-dtls1\|-u' >/dev/null; then
-        DTLS=1
-    else
-        DTLS=0
-    fi
+    case "$1" in
+        *dtls=1*|-dtls|-u) DTLS=1;;
+        *) DTLS=0;;
+    esac
 }
 
 # Usage: run_test name [-p proxy_cmd] srv_cmd cli_cmd cli_exit [option [...]]
@@ -657,10 +675,11 @@ run_test() {
     print_name "$NAME"
 
     # Do we only run numbered tests?
-    if [ "X$RUN_TEST_NUMBER" = "X" ]; then :
-    elif echo ",$RUN_TEST_NUMBER," | grep ",$TESTS," >/dev/null; then :
-    else
-        SKIP_NEXT="YES"
+    if [ -n "$RUN_TEST_NUMBER" ]; then
+        case ",$RUN_TEST_NUMBER," in
+            *",$TESTS,"*) :;;
+            *) SKIP_NEXT="YES";;
+        esac
     fi
 
     # does this test use a proxy?
@@ -678,10 +697,10 @@ run_test() {
     shift 3
 
     # Check if test uses files
-    TEST_USES_FILES=$(echo "$SRV_CMD $CLI_CMD" | grep "\.\(key\|crt\|pem\)" )
-    if [ ! -z "$TEST_USES_FILES" ]; then
-       requires_config_enabled MBEDTLS_FS_IO
-    fi
+    case "$SRV_CMD $CLI_CMD" in
+        *data_files/*)
+            requires_config_enabled MBEDTLS_FS_IO;;
+    esac
 
     # If the client or serve requires a ciphersuite, check that it's enabled.
     maybe_requires_ciphersuite_enabled "$SRV_CMD" "$@"