binarybuffer: Fix str_to_buf() parsing function

The function str_to_buf() was too benevolent and did
not perform sufficient error checking on the input
string being parsed. Especially:

- Invalid numbers were silently ignored.
- Out-of-range numbers were silently truncated.

The following commands that use str_to_buf()
were affected:

- reg (when writing a register value)
- set_reg
- jtag drscan

This pull request fixes that by:

- Rewriting str_to_buf() to add the missing checks.
- Adding function command_parse_str_to_buf() which can
  be used in command handlers. It parses the input
  numbers and provides user-readable error messages
  in case of parsing errors.

Examples:

jtag drscan 10 huh10

- Old behavior: The string "huh10" is silently
  converted to 10 and the command is then executed.
  No warning error or warning is shown to the user.
- New behavior: Error message is shown:
  "'huh10' is not a valid number"

reg pc 0x123456789

Assuming the "pc" is 32 bits wide:

- Old behavior: The register value is silently
  truncated to 0x23456789 and the command is performed.
- New behavior: Error message is shown to the user:
  "Number 0x123456789 exceeds 32 bits"

Change-Id: I079e19cd153aec853a3c2eb66953024b8542d0f4
Signed-off-by: Jan Matyas <jan.matyas@codasip.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8315
Tested-by: jenkins
Reviewed-by: Marek Vrbka <marek.vrbka@codasip.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/helper/binarybuffer.h

@@ -14,6 +14,9 @@
 #include <helper/list.h>
 #include <helper/types.h>
 
+#define ERROR_INVALID_NUMBER         (-1700)
+#define ERROR_NUMBER_EXCEEDS_BUFFER  (-1701)
+
 /** @file
  * Support functions to access arbitrary bits in a byte array
  */
@@ -189,8 +192,18 @@ void *buf_set_ones(void *buf, unsigned size);
 void *buf_set_buf(const void *src, unsigned src_start,
 		  void *dst, unsigned dst_start, unsigned len);
 
-int str_to_buf(const char *str, unsigned len,
-		void *bin_buf, unsigned buf_size, unsigned radix);
+/**
+ * Parse an unsigned number (provided as a zero-terminated string)
+ * into a bit buffer whose size is buf_len bits.
+ * @param str Input number, zero-terminated string
+ * @param _buf Output buffer, allocated by the caller
+ * @param buf_len Output buffer size in bits
+ * @param radix Base of the input number - 16, 10, 8 or 0.
+ *              0 means auto-detect the radix.
+ */
+int str_to_buf(const char *str, void *_buf, unsigned int buf_len,
+	unsigned int radix, unsigned int *_detected_radix);
+
 char *buf_to_hex_str(const void *buf, unsigned size);
 
 /* read a uint32_t from a buffer in target memory endianness */