awk: fix breakage in last commit

While at it, made bb_process_escape_sequence faster (same size)

function                                             old     new   delta
nextchar                                              49      53      +4
bb_process_escape_sequence                           138     140      +2
next_token                                           838     839      +1
static.charmap                                        20      18      -2
is_assignment                                        143     135      -8
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/2 up/down: 7/-10)              Total: -3 bytes

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

2 files changed, 38 insertions, 35 deletions

diff --git a/editors/awk.c b/editors/awk.c
index fb3bf6b47..9646cedd6 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -684,8 +684,11 @@ static char nextchar(char **s)
         pps = *s;
         if (c == '\\')
                 c = bb_process_escape_sequence((const char**)s);
-        if (c == '\\' && *s == pps)
-                c = *(*s)++;
+        if (c == '\\' && *s == pps) { /* unrecognized \z? */
+                c = *(*s); /* yes, fetch z */
+                if (c)
+                        (*s)++; /* advance unless z = NUL */
+        }
         return c;
 }
 
@@ -1007,9 +1010,10 @@ static uint32_t next_token(uint32_t expected)
                         /* it's a string */
                         t_string = s = ++p;
                         while (*p != '\"') {
-                                char *pp = p;
+                                char *pp;
                                 if (*p == '\0' || *p == '\n')
                                         syntax_error(EMSG_UNEXP_EOS);
+                                pp = p;
                                 *s++ = nextchar(&pp);
                                 p = pp;
                         }
@@ -2926,22 +2930,21 @@ static int awk_exit(int r)
  * otherwise return 0 */
 static int is_assignment(const char *expr)
 {
-        char *exprc, *s, *s0, *s1;
+        char *exprc, *val, *s, *s1;
 
-        if (!isalnum_(*expr) || (s0 = strchr(expr, '=')) == NULL) {
+        if (!isalnum_(*expr) || (val = strchr(expr, '=')) == NULL) {
                 return FALSE;
         }
 
         exprc = xstrdup(expr);
-        s0 = exprc + (s0 - expr);
-        *s++ = '\0';
+        val = exprc + (val - expr);
+        *val++ = '\0';
 
-        s = s1 = s0;
-        while (*s)
-                *s1++ = nextchar(&s);
-        *s1 = '\0';
+        s = s1 = val;
+        while ((*s1 = nextchar(&s)) != '\0')
+                s1++;
 
-        setvar_u(newvar(exprc), s0);
+        setvar_u(newvar(exprc), val);
         free(exprc);
         return TRUE;
 }
diff --git a/libbb/process_escape_sequence.c b/libbb/process_escape_sequence.c
index dd6e076b0..7b1d97f9c 100644
--- a/libbb/process_escape_sequence.c
+++ b/libbb/process_escape_sequence.c
@@ -18,18 +18,8 @@
 
 char FAST_FUNC bb_process_escape_sequence(const char **ptr)
 {
-        /* bash builtin "echo -e '\ec'" interprets \e as ESC,
-         * but coreutils "/bin/echo -e '\ec'" does not.
-         * manpages tend to support coreutils way.
-         * Update: coreutils added support for \e on 28 Oct 2009. */
-        static const char charmap[] ALIGN1 = {
-                'a',  'b', 'e', 'f',  'n',  'r',  't',  'v',  '\\', 0,
-                '\a', '\b', 27, '\f', '\n', '\r', '\t', '\v', '\\', '\\' };
-
-        const char *p;
         const char *q;
         unsigned num_digits;
-        unsigned r;
         unsigned n;
         unsigned base;
 
@@ -37,18 +27,17 @@ char FAST_FUNC bb_process_escape_sequence(const char **ptr)
         base = 8;
         q = *ptr;
 
-#if WANT_HEX_ESCAPES
-        if (*q == 'x') {
+        if (WANT_HEX_ESCAPES && *q == 'x') {
                 ++q;
                 base = 16;
                 ++num_digits;
         }
-#endif
 
         /* bash requires leading 0 in octal escapes:
          * \02 works, \2 does not (prints \ and 2).
          * We treat \2 as a valid octal escape sequence. */
         do {
+                unsigned r;
 #if !WANT_HEX_ESCAPES
                 unsigned d = (unsigned char)(*q) - '0';
 #else
@@ -60,8 +49,9 @@ char FAST_FUNC bb_process_escape_sequence(const char **ptr)
                         if (WANT_HEX_ESCAPES && base == 16) {
                                 --num_digits;
                                 if (num_digits == 0) {
-                                        /* \x<bad_char> */
-                                        --q; /* go back to x */
+                                        /* \x<bad_char>: return '\',
+                                         * leave ptr pointing to x */
+                                        return '\\';
                                 }
                         }
                         break;
@@ -76,20 +66,30 @@ char FAST_FUNC bb_process_escape_sequence(const char **ptr)
                 ++q;
         } while (++num_digits < 3);
 
-        if (num_digits == 0) {  /* mnemonic escape sequence? */
-                p = charmap;
+        if (num_digits == 0) {
+                /* Not octal or hex escape sequence.
+                 * Is it one-letter one? */
+
+                /* bash builtin "echo -e '\ec'" interprets \e as ESC,
+                 * but coreutils "/bin/echo -e '\ec'" does not.
+                 * Manpages tend to support coreutils way.
+                 * Update: coreutils added support for \e on 28 Oct 2009. */
+                static const char charmap[] ALIGN1 = {
+                        'a',  'b', 'e', 'f',  'n',  'r',  't',  'v',  '\\',
+                        '\a', '\b', 27, '\f', '\n', '\r', '\t', '\v', '\\',
+                };
+                const char *p = charmap;
                 do {
                         if (*p == *q) {
                                 q++;
                                 break;
                         }
-                } while (*++p);
-                /* p points to found escape char or NUL,
+                } while (*++p != '\\');
+                /* p points to found escape char or '\',
                  * advance it and find what it translates to.
-                 * Note that unrecognized sequence \z returns '\'
-                 * and leaves ptr pointing to z. */
-                p += sizeof(charmap) / 2;
-                n = *p;
+                 * Note that \NUL and unrecognized sequence \z return '\'
+                 * and leave ptr pointing to NUL or z. */
+                n = p[sizeof(charmap) / 2];
         }
 
         *ptr = q;