hush: optimize parse_stream()

Since we check for '\' anyway when we determine whether we can look ahead,
we can just check for *and handle* it there.

function                                             old     new   delta
parse_stream                                        2751    2740     -11

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 31 insertions, 28 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 523fc1a31..735fbef27 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -5076,6 +5076,14 @@ static struct pipe *parse_stream(char **pstring,
                 }
                 nommu_addchr(&ctx.as_string, ch);
 
+                /* Handle "'" and "\" first, as they won't play nice with
+                 * i_peek_and_eat_bkslash_nl() anyway:
+                 *   echo z\\
+                 * and
+                 *   echo '\
+                 *   '
+                 * would break.
+                 */
                 if (ch == '\'') {
                         ctx.word.has_quoted_part = 1;
                         next = i_getch(input);
@@ -5101,19 +5109,34 @@ static struct pipe *parse_stream(char **pstring,
                         }
                         continue; /* get next char */
                 }
+                if (ch == '\\') {
+                        /*nommu_addchr(&ctx.as_string, '\\'); - already done */
+                        o_addchr(&ctx.word, '\\');
+                        ch = i_getch(input);
+                        if (ch == EOF) {
+                                /* Testcase: eval 'echo Ok\' */
 
-                next = '\0';
-                if (ch != '\n' && ch != '\\') {
-                        /* Not on '\': do not break the case of "echo z\\":
-                         * on 2nd '\', i_peek_and_eat_bkslash_nl()
-                         * would stop and try to read next line,
-                         * not letting the command to execute.
+#if 0 /* bash-4.3.43 was removing backslash, but 4.4.19 retains it, most other shells too */
+                                /* Remove trailing '\' from ctx.as_string */
+                                ctx.as_string.data[--ctx.as_string.length] = '\0';
+#endif
+                                continue; /* get next char */
+                        }
+                        /* Example: echo Hello \2>file
+                         * we need to know that word 2 is quoted
                          */
-                        next = i_peek_and_eat_bkslash_nl(input);
+                        ctx.word.has_quoted_part = 1;
+                        nommu_addchr(&ctx.as_string, ch);
+                        o_addchr(&ctx.word, ch);
+                        continue; /* get next char */
                 }
 
+                next = '\0';
+                if (ch != '\n')
+                        next = i_peek_and_eat_bkslash_nl(input);
+
                 is_special = "{}<>;&|()#" /* special outside of "str" */
-                                "\\$\"" IF_HUSH_TICK("`") /* always special */
+                                "$\"" IF_HUSH_TICK("`") /* always special */
                                 SPECIAL_VAR_SYMBOL_STR;
                 /* Are { and } special here? */
                 if (ctx.command->argv /* word [word]{... - non-special */
@@ -5401,26 +5424,6 @@ static struct pipe *parse_stream(char **pstring,
                         /* non-comment #: "echo a#b" etc */
                         o_addchr(&ctx.word, ch);
                         continue; /* get next char */
-                case '\\':
-                        /*nommu_addchr(&ctx.as_string, '\\'); - already done */
-                        o_addchr(&ctx.word, '\\');
-                        ch = i_getch(input);
-                        if (ch == EOF) {
-                                /* Testcase: eval 'echo Ok\' */
-
-#if 0 /* bash-4.3.43 was removing backslash, but 4.4.19 retains it, most other shells too */
-                                /* Remove trailing '\' from ctx.as_string */
-                                ctx.as_string.data[--ctx.as_string.length] = '\0';
-#endif
-                                continue; /* get next char */
-                        }
-                        /* Example: echo Hello \2>file
-                         * we need to know that word 2 is quoted
-                         */
-                        ctx.word.has_quoted_part = 1;
-                        nommu_addchr(&ctx.as_string, ch);
-                        o_addchr(&ctx.word, ch);
-                        continue; /* get next char */
                 case '$':
                         if (!parse_dollar(&ctx.as_string, &ctx.word, input, /*quote_mask:*/ 0)) {
                                 debug_printf_parse("parse_stream parse error: "