Functions to quote and unquote pathnames in C-style.

Following the list discussion, define two functions, quote_c_style and
unquote_c_style, to help adopting the proposed way for quoting funny
pathname letters for GNU patch.  The rule is described in:

    http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2

Currently we do not support the leading '!', but we probably should
barf upon seeing it.  Rule B4. is interpreted to require always 3
octal digits in \XYZ notation.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/quote.c b/quote.c
index 9d5d0bc..7df05a9 100644 (file)
--- a/quote.c
+++ b/quote.c
@@ -12,6 +12,7 @@
  *  a'b      ==> a'\''b    ==> 'a'\''b'
  *  a!b      ==> a'\!'b    ==> 'a'\!'b'
  */
+#undef EMIT
 #define EMIT(x) ( (++len < n) && (*bp++ = (x)) )
 
 size_t sq_quote_buf(char *dst, size_t n, const char *src)
@@ -51,3 +52,167 @@ char *sq_quote(const char *src)
        return buf;
 }
 
+/*
+ * C-style name quoting.
+ *
+ * Does one of three things:
+ *
+ * (1) if outbuf and outfp are both NULL, inspect the input name and
+ *     counts the number of bytes that are needed to hold c_style
+ *     quoted version of name, counting the double quotes around
+ *     it but not terminating NUL, and returns it.  However, if name
+ *     does not need c_style quoting, it returns 0.
+ *
+ * (2) if outbuf is not NULL, it must point at a buffer large enough
+ *     to hold the c_style quoted version of name, enclosing double
+ *     quotes, and terminating NUL.  Fills outbuf with c_style quoted
+ *     version of name enclosed in double-quote pair.  Return value
+ *     is undefined.
+ *
+ * (3) if outfp is not NULL, outputs c_style quoted version of name,
+ *     but not enclosed in double-quote pair.  Return value is undefined.
+ */
+
+int quote_c_style(const char *name, char *outbuf, FILE *outfp, int no_dq)
+{
+#undef EMIT
+#define EMIT(c) \
+       (outbuf ? (*outbuf++ = (c)) : outfp ? fputc(c, outfp) : (count++))
+
+#define EMITQ() EMIT('\\')
+
+       const char *sp;
+       int ch, count = 0, needquote = 0;
+
+       if (!no_dq)
+               EMIT('"');
+       for (sp = name; (ch = *sp++); ) {
+
+               if ((ch <= ' ') || (ch == '"') ||
+                   (ch == '\\') || (ch == 0177)) {
+                       needquote = 1;
+                       switch (ch) {
+                       case '\a': EMITQ(); ch = 'a'; break;
+                       case '\b': EMITQ(); ch = 'b'; break;
+                       case '\f': EMITQ(); ch = 'f'; break;
+                       case '\n': EMITQ(); ch = 'n'; break;
+                       case '\r': EMITQ(); ch = 'r'; break;
+                       case '\t': EMITQ(); ch = 't'; break;
+                       case '\v': EMITQ(); ch = 'v'; break;
+
+                       case '\\': /* fallthru */
+                       case '"': EMITQ(); break;
+                       case ' ':
+                               break;
+                       default:
+                               /* octal */
+                               EMITQ();
+                               EMIT(((ch >> 6) & 03) + '0');
+                               EMIT(((ch >> 3) & 07) + '0');
+                               ch = (ch & 07) + '0';
+                               break;
+                       }
+               }
+               EMIT(ch);
+       }
+       if (!no_dq)
+               EMIT('"');
+       if (outbuf)
+               *outbuf = 0;
+
+       return needquote ? count : 0;
+}
+
+/*
+ * C-style name unquoting.
+ *
+ * Quoted should point at the opening double quote.  Returns
+ * an allocated memory that holds unquoted name, which the caller
+ * should free when done.  Updates endp pointer to point at
+ * one past the ending double quote if given.
+ */
+
+char *unquote_c_style(const char *quoted, const char **endp)
+{
+       const char *sp;
+       char *name = NULL, *outp = NULL;
+       int count = 0, ch, ac;
+
+#undef EMIT
+#define EMIT(c) (outp ? (*outp++ = (c)) : (count++))
+
+       if (*quoted++ != '"')
+               return NULL;
+
+       while (1) {
+               /* first pass counts and allocates, second pass fills */
+               for (sp = quoted; (ch = *sp++) != '"'; ) {
+                       if (ch == '\\') {
+                               switch (ch = *sp++) {
+                               case 'a': ch = '\a'; break;
+                               case 'b': ch = '\b'; break;
+                               case 'f': ch = '\f'; break;
+                               case 'n': ch = '\n'; break;
+                               case 'r': ch = '\r'; break;
+                               case 't': ch = '\t'; break;
+                               case 'v': ch = '\v'; break;
+
+                               case '\\': case '"':
+                                       break; /* verbatim */
+
+                               case '0'...'7':
+                                       /* octal */
+                                       ac = ((ch - '0') << 6);
+                                       if ((ch = *sp++) < '0' || '7' < ch)
+                                               return NULL;
+                                       ac |= ((ch - '0') << 3);
+                                       if ((ch = *sp++) < '0' || '7' < ch)
+                                               return NULL;
+                                       ac |= (ch - '0');
+                                       ch = ac;
+                                       break;
+                               default:
+                                       return NULL; /* malformed */
+                               }
+                       }
+                       EMIT(ch);
+               }
+
+               if (name) {
+                       *outp = 0;
+                       if (endp)
+                               *endp = sp;
+                       return name;
+               }
+               outp = name = xmalloc(count + 1);
+       }
+}
+
+void write_name_quoted(const char *prefix, const char *name,
+                      int quote, FILE *out)
+{
+       int needquote;
+
+       if (!quote) {
+       no_quote:
+               if (prefix && prefix[0])
+                       fputs(prefix, out);
+               fputs(name, out);
+               return;
+       }
+
+       needquote = 0;
+       if (prefix && prefix[0])
+               needquote = quote_c_style(prefix, NULL, NULL, 0);
+       if (!needquote)
+               needquote = quote_c_style(name, NULL, NULL, 0);
+       if (needquote) {
+               fputc('"', out);
+               if (prefix && prefix[0])
+                       quote_c_style(prefix, NULL, out, 1);
+               quote_c_style(name, NULL, out, 1);
+               fputc('"', out);
+       }
+       else
+               goto no_quote;
+}

diff --git a/quote.h b/quote.h
index 50ce1df..2fdde3b 100644 (file)
--- a/quote.h
+++ b/quote.h
@@ -2,6 +2,7 @@
 #define QUOTE_H
 
 #include <stddef.h>
+#include <stdio.h>
 
 /* Help to copy the thing properly quoted for the shell safety.
  * any single quote is replaced with '\'', any exclamation point
@@ -27,7 +28,14 @@
  * excluding the final null regardless of the buffer size.
  */
 
-char *sq_quote(const char *src);
-size_t sq_quote_buf(char *dst, size_t n, const char *src);
+extern char *sq_quote(const char *src);
+extern size_t sq_quote_buf(char *dst, size_t n, const char *src);
+
+extern int quote_c_style(const char *name, char *outbuf, FILE *outfp,
+                        int nodq);
+extern char *unquote_c_style(const char *quoted, const char **endp);
+
+extern void write_name_quoted(const char *prefix, const char *name,
+                             int quote, FILE *out);
 
 #endif