Quotearg part 3: add flag to control outer quote elision.

* lib/quotearg.h (c_maybe_quoting_style): New style.
(enum quoting_flags): Better documentation of flags.
* lib/quotearg.c (quoting_style_args, quoting_style_vals): Add
c-maybe style.
(quotearg_buffer_restyled): Handle new flag to elide outer
quotes.

Signed-off-by: Eric Blake <ebb9@byu.net>

diff --git a/ChangeLog b/ChangeLog
index 3f2ed9c..2da0617 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2008-02-07  Eric Blake  <ebb9@byu.net>
 
+       Quotearg part 3: add flag to control outer quote elision.
+       * lib/quotearg.h (c_maybe_quoting_style): New style.
+       (enum quoting_flags): Better documentation of flags.
+       * lib/quotearg.c (quoting_style_args, quoting_style_vals): Add
+       c-maybe style.
+       (quotearg_buffer_restyled): Handle new flag to elide outer
+       quotes.
+
        Quotearg part 2: add flag that can control NUL elision.
        * lib/quotearg.h (set_quoting_flags): New prototype.
        * lib/quotearg.c (struct quoting_options): Add flag field.

diff --git a/lib/quotearg.c b/lib/quotearg.c
index f9628e5..b6237b0 100644 (file)
--- a/lib/quotearg.c
+++ b/lib/quotearg.c
@@ -65,9 +65,7 @@ struct quoting_options
   /* Basic quoting style.  */
   enum quoting_style style;
 
-  /* Additional flags.  Behavior is altered according to these bits:
-     0x01: Elide null bytes rather than embed them unquoted.
-   */
+  /* Additional flags.  Bitwise combination of enum quoting_flags.  */
   int flags;
 
   /* Quote the characters indicated by this bit vector even if the
@@ -82,6 +80,7 @@ char const *const quoting_style_args[] =
   "shell",
   "shell-always",
   "c",
+  "c-maybe",
   "escape",
   "locale",
   "clocale",
@@ -95,6 +94,7 @@ enum quoting_style const quoting_style_vals[] =
   shell_quoting_style,
   shell_always_quoting_style,
   c_quoting_style,
+  c_maybe_quoting_style,
   escape_quoting_style,
   locale_quoting_style,
   clocale_quoting_style
@@ -149,10 +149,9 @@ set_char_quoting (struct quoting_options *o, char c, int i)
 }
 
 /* In O (or in the default if O is null),
-   set the value of the quoting options flag to I.
-   Return the old value.  Currently, the only values defined for I are
-   0 (the default) and 1 (which means to elide null bytes from styles
-   that would otherwise output them unquoted).  */
+   set the value of the quoting options flag to I, which can be a
+   bitwise combination of enum quoting_flags, or 0 for default
+   behavior.  Return the old value.  */
 int
 set_quoting_flags (struct quoting_options *o, int i)
 {
@@ -200,6 +199,7 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
   size_t quote_string_len = 0;
   bool backslash_escapes = false;
   bool unibyte_locale = MB_CUR_MAX == 1;
+  bool elide_outer_quotes = (flags & QA_ELIDE_OUTER_QUOTES) != 0;
 
 #define STORE(c) \
     do \
@@ -212,8 +212,13 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
 
   switch (quoting_style)
     {
+    case c_maybe_quoting_style:
+      quoting_style = c_quoting_style;
+      elide_outer_quotes = true;
+      /* Fall through.  */
     case c_quoting_style:
-      STORE ('"');
+      if (!elide_outer_quotes)
+       STORE ('"');
       backslash_escapes = true;
       quote_string = "\"";
       quote_string_len = 1;
@@ -221,6 +226,7 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
 
     case escape_quoting_style:
       backslash_escapes = true;
+      elide_outer_quotes = false;
       break;
 
     case locale_quoting_style:
@@ -248,22 +254,32 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
 
        char const *left = gettext_quote (N_("`"), quoting_style);
        char const *right = gettext_quote (N_("'"), quoting_style);
-       for (quote_string = left; *quote_string; quote_string++)
-         STORE (*quote_string);
+       if (!elide_outer_quotes)
+         for (quote_string = left; *quote_string; quote_string++)
+           STORE (*quote_string);
        backslash_escapes = true;
        quote_string = right;
        quote_string_len = strlen (quote_string);
       }
       break;
 
+    case shell_quoting_style:
+      quoting_style = shell_always_quoting_style;
+      elide_outer_quotes = true;
+      /* Fall through.  */
     case shell_always_quoting_style:
-      STORE ('\'');
+      if (!elide_outer_quotes)
+       STORE ('\'');
       quote_string = "'";
       quote_string_len = 1;
       break;
 
-    default:
+    case literal_quoting_style:
+      elide_outer_quotes = false;
       break;
+
+    default:
+      abort ();
     }
 
   for (i = 0;  ! (argsize == SIZE_MAX ? arg[i] == '\0' : i == argsize);  i++)
@@ -275,7 +291,11 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
          && quote_string_len
          && i + quote_string_len <= argsize
          && memcmp (arg + i, quote_string, quote_string_len) == 0)
-       STORE ('\\');
+       {
+         if (elide_outer_quotes)
+           goto force_outer_quoting_style;
+         STORE ('\\');
+       }
 
       c = arg[i];
       switch (c)
@@ -283,20 +303,24 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
        case '\0':
          if (backslash_escapes)
            {
+             if (elide_outer_quotes)
+               goto force_outer_quoting_style;
              STORE ('\\');
              STORE ('0');
              STORE ('0');
              c = '0';
            }
-         else if (flags & 0x1)
+         else if (flags & QA_ELIDE_NULL_BYTES)
            continue;
          break;
 
        case '?':
          switch (quoting_style)
            {
-           case shell_quoting_style:
-             goto use_shell_always_quoting_style;
+           case shell_always_quoting_style:
+             if (elide_outer_quotes)
+               goto force_outer_quoting_style;
+             break;
 
            case c_quoting_style:
              if (i + 2 < argsize && arg[i + 1] == '?')
@@ -307,6 +331,8 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
                  case '<': case '=': case '>':
                    /* Escape the second '?' in what would otherwise be
                       a trigraph.  */
+                   if (elide_outer_quotes)
+                     goto force_outer_quoting_style;
                    c = arg[i + 2];
                    i += 2;
                    STORE ('?');
@@ -334,8 +360,10 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
        case '\\': esc = c; goto c_and_shell_escape;
 
        c_and_shell_escape:
-         if (quoting_style == shell_quoting_style)
-           goto use_shell_always_quoting_style;
+         if (quoting_style == shell_always_quoting_style
+             && elide_outer_quotes)
+           goto force_outer_quoting_style;
+         /* Fall through.  */
        c_escape:
          if (backslash_escapes)
            {
@@ -365,24 +393,19 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
             be the first bytes of multibyte characters, which means
             we should check them with mbrtowc, but in practice this
             doesn't happen so it's not worth worrying about.  */
-         if (quoting_style == shell_quoting_style)
-           goto use_shell_always_quoting_style;
+         if (quoting_style == shell_always_quoting_style
+             && elide_outer_quotes)
+           goto force_outer_quoting_style;
          break;
 
        case '\'':
-         switch (quoting_style)
+         if (quoting_style == shell_always_quoting_style)
            {
-           case shell_quoting_style:
-             goto use_shell_always_quoting_style;
-
-           case shell_always_quoting_style:
+             if (elide_outer_quotes)
+               goto force_outer_quoting_style;
              STORE ('\'');
              STORE ('\\');
              STORE ('\'');
-             break;
-
-           default:
-             break;
            }
          break;
 
@@ -454,7 +477,8 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
                           that is really the 2nd byte of a multibyte character.
                           In practice the problem is limited to ASCII
                           chars >= '@' that are shell special chars.  */
-                       if ('[' == 0x5b && quoting_style == shell_quoting_style)
+                       if ('[' == 0x5b && elide_outer_quotes
+                           && quoting_style == shell_always_quoting_style)
                          {
                            size_t j;
                            for (j = 1; j < bytes; j++)
@@ -462,7 +486,7 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
                                {
                                case '[': case '\\': case '^':
                                case '`': case '|':
-                                 goto use_shell_always_quoting_style;
+                                 goto force_outer_quoting_style;
 
                                default:
                                  break;
@@ -487,6 +511,8 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
                  {
                    if (backslash_escapes && ! printable)
                      {
+                       if (elide_outer_quotes)
+                         goto force_outer_quoting_style;
                        STORE ('\\');
                        STORE ('0' + (c >> 6));
                        STORE ('0' + ((c >> 3) & 7));
@@ -508,16 +534,19 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
        goto store_c;
 
     store_escape:
+      if (elide_outer_quotes)
+       goto force_outer_quoting_style;
       STORE ('\\');
 
     store_c:
       STORE (c);
     }
 
-  if (i == 0 && quoting_style == shell_quoting_style)
-    goto use_shell_always_quoting_style;
+  if (i == 0 && quoting_style == shell_always_quoting_style
+      && elide_outer_quotes)
+    goto force_outer_quoting_style;
 
-  if (quote_string)
+  if (quote_string && !elide_outer_quotes)
     for (; *quote_string; quote_string++)
       STORE (*quote_string);
 
@@ -525,9 +554,10 @@ quotearg_buffer_restyled (char *buffer, size_t buffersize,
     buffer[len] = '\0';
   return len;
 
- use_shell_always_quoting_style:
+ force_outer_quoting_style:
   return quotearg_buffer_restyled (buffer, buffersize, arg, argsize,
-                                  shell_always_quoting_style, flags, o);
+                                  quoting_style,
+                                  flags & ~QA_ELIDE_OUTER_QUOTES, o);
 }
 
 /* Place into buffer BUFFER (of size BUFFERSIZE) a quoted version of
@@ -573,7 +603,7 @@ quotearg_alloc_mem (char const *arg, size_t argsize, size_t *size,
   struct quoting_options const *p = o ? o : &default_quoting_options;
   int e = errno;
   /* Elide embedded null bytes if we can't return a size.  */
-  int flags = p->flags | (size ? 0 : 0x1);
+  int flags = p->flags | (size ? 0 : QA_ELIDE_NULL_BYTES);
   size_t bufsize = quotearg_buffer_restyled (0, 0, arg, argsize, p->style,
                                             flags, p) + 1;
   char *buf = xcharalloc (bufsize);
@@ -663,9 +693,9 @@ quotearg_n_options (int n, char const *arg, size_t argsize,
     size_t size = sv[n].size;
     char *val = sv[n].val;
     /* Elide embedded null bytes since we don't return a size.  */
+    int flags = options->flags | QA_ELIDE_NULL_BYTES;
     size_t qsize = quotearg_buffer_restyled (val, size, arg, argsize,
-                                            options->style,
-                                            options->flags | 0x1, options);
+                                            options->style, flags, options);
 
     if (size <= qsize)
       {
@@ -674,7 +704,7 @@ quotearg_n_options (int n, char const *arg, size_t argsize,
          free (val);
        sv[n].val = val = xcharalloc (size);
        quotearg_buffer_restyled (val, size, arg, argsize, options->style,
-                                 options->flags | 0x1, options);
+                                 flags, options);
       }
 
     errno = e;

diff --git a/lib/quotearg.h b/lib/quotearg.h
index 501c856..5d3ca47 100644 (file)
--- a/lib/quotearg.h
+++ b/lib/quotearg.h
@@ -27,24 +27,34 @@
 enum quoting_style
   {
     /* Output names as-is (ls --quoting-style=literal).  Can result in
-       embedded null bytes in some cases.  */
+       embedded null bytes if QA_ELIDE_NULL_BYTES is not in
+       effect.  */
     literal_quoting_style,
 
     /* Quote names for the shell if they contain shell metacharacters
        or would cause ambiguous output (ls --quoting-style=shell).
-       Can result in embedded null bytes in some cases.  */
+       Can result in embedded null bytes if QA_ELIDE_NULL_BYTES is not
+       in effect.  */
     shell_quoting_style,
 
     /* Quote names for the shell, even if they would normally not
        require quoting (ls --quoting-style=shell-always).  Can result
-       in embedded null bytes in some cases.  */
+       in embedded null bytes if QA_ELIDE_NULL_BYTES is not in effect.
+       Behaves like shell_quoting_style if QA_ELIDE_OUTER_QUOTES is in
+       effect.  */
     shell_always_quoting_style,
 
-    /* Quote names as for a C language string (ls --quoting-style=c).  */
+    /* Quote names as for a C language string (ls --quoting-style=c).
+       Behaves like c_maybe_quoting_style if QA_ELIDE_OUTER_QUOTES is
+       in effect.  */
     c_quoting_style,
 
     /* Like c_quoting_style except omit the surrounding double-quote
-       characters (ls --quoting-style=escape).  */
+       characters if no quoted characters are encountered.  */
+    c_maybe_quoting_style,
+
+    /* Like c_quoting_style except always omit the surrounding
+       double-quote characters (ls --quoting-style=escape).  */
     escape_quoting_style,
 
     /* Like clocale_quoting_style, but quote `like this' instead of
@@ -56,6 +66,19 @@ enum quoting_style
     clocale_quoting_style
   };
 
+/* Flags for use in set_quoting_flags.  */
+enum quoting_flags
+  {
+    /* Always elide null bytes from styles that do not quote them,
+       even when the length of the result is available to the
+       caller.  */
+    QA_ELIDE_NULL_BYTES = 0x01,
+
+    /* Omit the surrounding quote characters if no escaped characters
+       are encountered.  */
+    QA_ELIDE_OUTER_QUOTES = 0x02
+  };
+
 /* For now, --quoting-style=literal is the default, but this may change.  */
 # ifndef DEFAULT_QUOTING_STYLE
 #  define DEFAULT_QUOTING_STYLE literal_quoting_style
@@ -90,10 +113,9 @@ void set_quoting_style (struct quoting_options *o, enum quoting_style s);
 int set_char_quoting (struct quoting_options *o, char c, int i);
 
 /* In O (or in the default if O is null),
-   set the value of the quoting options flag to I.
-   Return the old value.  Currently, the only values defined for I are
-   0 (the default) and 1 (which means to elide null bytes from styles
-   that would otherwise output them unquoted).  */
+   set the value of the quoting options flag to I, which can be a
+   bitwise combination of enum quoting_flags, or 0 for default
+   behavior.  Return the old value.  */
 int set_quoting_flags (struct quoting_options *o, int i);
 
 /* Place into buffer BUFFER (of size BUFFERSIZE) a quoted version of