improve the argument parser

[project/uci.git] / util.c

diff --git a/util.c b/util.c
index bcf65aa..4713c74 100644 (file)
--- a/util.c
+++ b/util.c
@@ -59,19 +59,32 @@ static char *uci_strdup(struct uci_context *ctx, const char *str)
        return ptr;
 }
 
-static bool uci_validate_name(const char *str)
+/*
+ * validate strings for names and types, reject special characters
+ * for names, only alphanum and _ is allowed (shell compatibility)
+ * for types, we allow more characters
+ */
+static bool uci_validate_str(const char *str, bool name)
 {
        if (!*str)
                return false;
 
        while (*str) {
-               if (!isalnum(*str) && (*str != '_'))
-                       return false;
+               char c = *str;
+               if (!isalnum(c) && c != '_') {
+                       if (name || (c < 33) || (c > 126))
+                               return false;
+               }
                str++;
        }
        return true;
 }
 
+static inline bool uci_validate_name(const char *str)
+{
+       return uci_validate_str(str, true);
+}
+
 static void uci_alloc_parse_context(struct uci_context *ctx)
 {
        ctx->pctx = (struct uci_parse_context *) uci_malloc(ctx, sizeof(struct uci_parse_context));
@@ -176,6 +189,191 @@ static void uci_getln(struct uci_context *ctx, int offset)
        } while (1);
 }
 
+/* 
+ * parse a character escaped by '\'
+ * returns true if the escaped character is to be parsed
+ * returns false if the escaped character is to be ignored
+ */
+static inline bool parse_backslash(struct uci_context *ctx, char **str)
+{
+       /* skip backslash */
+       *str += 1;
+
+       /* undecoded backslash at the end of line, fetch the next line */
+       if (!**str) {
+               *str += 1;
+               uci_getln(ctx, *str - ctx->pctx->buf);
+               return false;
+       }
+
+       /* FIXME: decode escaped char, necessary? */
+       return true;
+}
+
+/*
+ * move the string pointer forward until a non-whitespace character or
+ * EOL is reached
+ */
+static void skip_whitespace(struct uci_context *ctx, char **str)
+{
+restart:
+       while (**str && isspace(**str))
+               *str += 1;
+
+       if (**str == '\\') {
+               if (!parse_backslash(ctx, str))
+                       goto restart;
+       }
+}
+
+static inline void addc(char **dest, char **src)
+{
+       **dest = **src;
+       *dest += 1;
+       *src += 1;
+}
+
+/*
+ * parse a double quoted string argument from the command line
+ */
+static void parse_double_quote(struct uci_context *ctx, char **str, char **target)
+{
+       char c;
+
+       /* skip quote character */
+       *str += 1;
+
+       while ((c = **str)) {
+               switch(c) {
+               case '"':
+                       **target = 0;
+                       *str += 1;
+                       return;
+               case '\\':
+                       if (!parse_backslash(ctx, str))
+                               continue;
+                       /* fall through */
+               default:
+                       addc(target, str);
+                       break;
+               }
+       }
+       uci_parse_error(ctx, *str, "unterminated \"");
+}
+
+/*
+ * parse a single quoted string argument from the command line
+ */
+static void parse_single_quote(struct uci_context *ctx, char **str, char **target)
+{
+       char c;
+       /* skip quote character */
+       *str += 1;
+
+       while ((c = **str)) {
+               switch(c) {
+               case '\'':
+                       **target = 0;
+                       *str += 1;
+                       return;
+               default:
+                       addc(target, str);
+               }
+       }
+       uci_parse_error(ctx, *str, "unterminated '");
+}
+
+/*
+ * parse a string from the command line and detect the quoting style
+ */
+static void parse_str(struct uci_context *ctx, char **str, char **target)
+{
+       do {
+               switch(**str) {
+               case '\'':
+                       parse_single_quote(ctx, str, target);
+                       break;
+               case '"':
+                       parse_double_quote(ctx, str, target);
+                       break;
+               case '#':
+                       **str = 0;
+                       /* fall through */
+               case 0:
+                       goto done;
+               case '\\':
+                       if (!parse_backslash(ctx, str))
+                               continue;
+                       /* fall through */
+               default:
+                       addc(target, str);
+                       break;
+               }
+       } while (**str && !isspace(**str));
+done:
+
+       /* 
+        * if the string was unquoted and we've stopped at a whitespace
+        * character, skip to the next one, because the whitespace will
+        * be overwritten by a null byte here
+        */
+       if (**str)
+               *str += 1;
+
+       /* terminate the parsed string */
+       **target = 0;
+}
+
+/*
+ * extract the next argument from the command line
+ */
+static char *next_arg(struct uci_context *ctx, char **str, bool required, bool name)
+{
+       char *val;
+       char *ptr;
+
+       val = ptr = *str;
+       skip_whitespace(ctx, str);
+       parse_str(ctx, str, &ptr);
+       if (!*val) {
+               if (required)
+                       uci_parse_error(ctx, *str, "insufficient arguments");
+               goto done;
+       }
+
+       if (name && !uci_validate_name(val))
+               uci_parse_error(ctx, val, "invalid character in field");
+
+done:
+       return val;
+}
+
+int uci_parse_argument(struct uci_context *ctx, FILE *stream, char **str, char **result)
+{
+       UCI_HANDLE_ERR(ctx);
+       UCI_ASSERT(ctx, str != NULL);
+       UCI_ASSERT(ctx, result != NULL);
+
+       if (ctx->pctx) {
+               if (ctx->pctx->file != stream) {
+                       ctx->internal = true;
+                       uci_cleanup(ctx);
+               }
+       } else {
+               uci_alloc_parse_context(ctx);
+               ctx->pctx->file = stream;
+       }
+       if (!*str) {
+               uci_getln(ctx, 0);
+               *str = ctx->pctx->buf;
+       }
+
+       *result = next_arg(ctx, str, false, false);
+
+       return 0;
+}
+
+
 /*
  * open a stream and go to the right position
  *