libbb: introduce and use strcpy_and_process_escape_sequences

function                                             old     new   delta
strcpy_and_process_escape_sequences                    -      50     +50
bb_process_escape_sequence                           148     138     -10
printf_main                                          789     776     -13
getty_main                                          1897    1831     -66
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/3 up/down: 50/-89)            Total: -39 bytes

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

2 files changed, 31 insertions, 27 deletions

diff --git a/libbb/parse_config.c b/libbb/parse_config.c
index 3fff9f212..9dbfaf5d7 100644
--- a/libbb/parse_config.c
+++ b/libbb/parse_config.c
@@ -187,19 +187,7 @@ again:
 
 #if 0 /* unused so far */
                 if (flags & PARSE_ESCAPE) {
-                        const char *from;
-                        char *to;
-
-                        from = to = tokens[t];
-                        while (*from) {
-                                if (*from == '\\') {
-                                        from++;
-                                        *to++ = bb_process_escape_sequence(&from);
-                                } else {
-                                        *to++ = *from++;
-                                }
-                        }
-                        *to = '\0';
+                        strcpy_and_process_escape_sequences(tokens[t], tokens[t]);
                 }
 #endif
                 /* Skip possible delimiters */
diff --git a/libbb/process_escape_sequence.c b/libbb/process_escape_sequence.c
index 82cbe10dc..dd6e076b0 100644
--- a/libbb/process_escape_sequence.c
+++ b/libbb/process_escape_sequence.c
@@ -31,14 +31,13 @@ char FAST_FUNC bb_process_escape_sequence(const char **ptr)
         unsigned num_digits;
         unsigned r;
         unsigned n;
-        unsigned d;
         unsigned base;
 
         num_digits = n = 0;
         base = 8;
         q = *ptr;
 
-#ifdef WANT_HEX_ESCAPES
+#if WANT_HEX_ESCAPES
         if (*q == 'x') {
                 ++q;
                 base = 16;
@@ -50,20 +49,21 @@ char FAST_FUNC bb_process_escape_sequence(const char **ptr)
          * \02 works, \2 does not (prints \ and 2).
          * We treat \2 as a valid octal escape sequence. */
         do {
-                d = (unsigned char)(*q) - '0';
-#ifdef WANT_HEX_ESCAPES
-                if (d >= 10) {
-                        d = (unsigned char)(_tolower(*q)) - 'a' + 10;
-                }
+#if !WANT_HEX_ESCAPES
+                unsigned d = (unsigned char)(*q) - '0';
+#else
+                unsigned d = (unsigned char)_tolower(*q) - '0';
+                if (d >= 10)
+                        d += ('0' - 'a' + 10);
 #endif
-
                 if (d >= base) {
-#ifdef WANT_HEX_ESCAPES
-                        if ((base == 16) && (!--num_digits)) {
-/*                              return '\\'; */
-                                --q;
+                        if (WANT_HEX_ESCAPES && base == 16) {
+                                --num_digits;
+                                if (num_digits == 0) {
+                                        /* \x<bad_char> */
+                                        --q; /* go back to x */
+                                }
                         }
-#endif
                         break;
                 }
 
@@ -85,7 +85,9 @@ char FAST_FUNC bb_process_escape_sequence(const char **ptr)
                         }
                 } while (*++p);
                 /* p points to found escape char or NUL,
-                 * advance it and find what it translates to */
+                 * 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;
         }
@@ -94,3 +96,17 @@ char FAST_FUNC bb_process_escape_sequence(const char **ptr)
 
         return (char) n;
 }
+
+char* FAST_FUNC strcpy_and_process_escape_sequences(char *dst, const char *src)
+{
+        while (1) {
+                char c, c1;
+                c = c1 = *src++;
+                if (c1 == '\\')
+                        c1 = bb_process_escape_sequence(&src);
+                *dst = c1;
+                if (c == '\0')
+                        return dst;
+                dst++;
+        }
+}