[hci] Use dynamically allocated buffers for editable strings

Editable strings currently require a fixed-size buffer, which is
inelegant and limits the potential for creating interactive forms with
a variable number of edit box widgets.

Remove this limitation by switching to using a dynamically allocated
buffer for editable strings and edit box widgets.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 102 insertions, 42 deletions

diff --git a/src/hci/editstring.c b/src/hci/editstring.c
index 8cbce0767..b83916c6e 100644
--- a/src/hci/editstring.c
+++ b/src/hci/editstring.c
@@ -24,8 +24,10 @@
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #include <assert.h>
+#include <errno.h>
 #include <string.h>
 #include <ctype.h>
+#include <stdlib.h>
 #include <ipxe/keys.h>
 #include <ipxe/editstring.h>
 
@@ -35,17 +37,17 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  *
  */
 
-static void insert_delete ( struct edit_string *string, size_t delete_len,
-                            const char *insert_text ) 
-			    __attribute__ (( nonnull (1) ));
-static void insert_character ( struct edit_string *string,
-                               unsigned int character ) __nonnull;
-static void delete_character ( struct edit_string *string ) __nonnull;
-static void backspace ( struct edit_string *string ) __nonnull;
-static void previous_word ( struct edit_string *string ) __nonnull;
-static void kill_word ( struct edit_string *string ) __nonnull;
-static void kill_sol ( struct edit_string *string ) __nonnull;
-static void kill_eol ( struct edit_string *string ) __nonnull;
+static __attribute__ (( nonnull ( 1 ) )) int
+insert_delete ( struct edit_string *string, size_t delete_len,
+		const char *insert_text );
+static __nonnull int insert_character ( struct edit_string *string,
+					unsigned int character );
+static __nonnull void delete_character ( struct edit_string *string );
+static __nonnull void backspace ( struct edit_string *string );
+static __nonnull void previous_word ( struct edit_string *string );
+static __nonnull void kill_word ( struct edit_string *string );
+static __nonnull void kill_sol ( struct edit_string *string );
+static __nonnull void kill_eol ( struct edit_string *string );
 
 /**
  * Insert and/or delete text within an editable string
@@ -53,35 +55,56 @@ static void kill_eol ( struct edit_string *string ) __nonnull;
  * @v string		Editable string
  * @v delete_len	Length of text to delete from current cursor position
  * @v insert_text	Text to insert at current cursor position, or NULL
+ * @ret rc		Return status code
  */
-static void insert_delete ( struct edit_string *string, size_t delete_len,
-			    const char *insert_text ) {
-	size_t old_len, max_delete_len, insert_len, max_insert_len, new_len;
+static int insert_delete ( struct edit_string *string, size_t delete_len,
+			   const char *insert_text ) {
+	size_t old_len, max_delete_len, insert_len, new_len;
+	char *buf;
+	char *tmp;
 
 	/* Calculate lengths */
-	old_len = strlen ( string->buf );
+	buf = *(string->buf);
+	old_len = ( buf ? strlen ( buf ) : 0 );
 	assert ( string->cursor <= old_len );
 	max_delete_len = ( old_len - string->cursor );
 	if ( delete_len > max_delete_len )
 		delete_len = max_delete_len;
 	insert_len = ( insert_text ? strlen ( insert_text ) : 0 );
-	max_insert_len = ( ( string->len - 1 ) - ( old_len - delete_len ) );
-	if ( insert_len > max_insert_len )
-		insert_len = max_insert_len;
 	new_len = ( old_len - delete_len + insert_len );
 
+	/* Reallocate string, ignoring failures if shrinking */
+	tmp = realloc ( buf, ( new_len + 1 /* NUL */ ) );
+	if ( tmp ) {
+		buf = tmp;
+		*(string->buf) = buf;
+	} else if ( new_len > old_len ) {
+		return -ENOMEM;
+	}
+
 	/* Fill in edit history */
 	string->mod_start = string->cursor;
 	string->mod_end = ( ( new_len > old_len ) ? new_len : old_len );
 
 	/* Move data following the cursor */
-	memmove ( ( string->buf + string->cursor + insert_len ),
-		  ( string->buf + string->cursor + delete_len ),
-		  ( max_delete_len + 1 - delete_len ) );
+	memmove ( ( buf + string->cursor + insert_len ),
+		  ( buf + string->cursor + delete_len ),
+		  ( max_delete_len - delete_len ) );
 
 	/* Copy inserted text to cursor position */
-	memcpy ( ( string->buf + string->cursor ), insert_text, insert_len );
+	memcpy ( ( buf + string->cursor ), insert_text, insert_len );
 	string->cursor += insert_len;
+
+	/* Terminate string (if not NULL) */
+	if ( buf ) {
+		buf[new_len] = '\0';
+	} else {
+		assert ( old_len == 0 );
+		assert ( insert_len == 0 );
+		assert ( new_len == 0 );
+	}
+
+	return 0;
 }
 
 /**
@@ -89,11 +112,13 @@ static void insert_delete ( struct edit_string *string, size_t delete_len,
  *
  * @v string		Editable string
  * @v character		Character to insert
+ * @ret rc		Return status code
  */
-static void insert_character ( struct edit_string *string,
+static int insert_character ( struct edit_string *string,
 			      unsigned int character ) {
 	char insert_text[2] = { character, '\0' };
-	insert_delete ( string, 0, insert_text );
+
+	return insert_delete ( string, 0, insert_text );
 }
 
 /**
@@ -102,7 +127,10 @@ static void insert_character ( struct edit_string *string,
  * @v string		Editable string
  */
 static void delete_character ( struct edit_string *string ) {
-	insert_delete ( string, 1, NULL );
+	int rc;
+
+	rc = insert_delete ( string, 1, NULL );
+	assert ( ( rc == 0 ) || ( *(string->buf) == NULL ) );
 }
 
 /**
@@ -111,6 +139,7 @@ static void delete_character ( struct edit_string *string ) {
  * @v string		Editable string
  */
 static void backspace ( struct edit_string *string ) {
+
 	if ( string->cursor > 0 ) {
 		string->cursor--;
 		delete_character ( string );
@@ -123,14 +152,16 @@ static void backspace ( struct edit_string *string ) {
  * @v string		Editable string
  */
 static void previous_word ( struct edit_string *string ) {
-	while ( string->cursor &&
-		isspace ( string->buf[ string->cursor - 1 ] ) ) {
-		string->cursor--;
+	const char *buf = *(string->buf);
+	size_t cursor = string->cursor;
+
+	while ( cursor && isspace ( buf[ cursor - 1 ] ) ) {
+		cursor--;
 	}
-	while ( string->cursor &&
-		( ! isspace ( string->buf[ string->cursor - 1 ] ) ) ) {
-		string->cursor--;
+	while ( cursor && ( ! isspace ( buf[ cursor - 1 ] ) ) ) {
+		cursor--;
 	}
+	string->cursor = cursor;
 }
 
 /**
@@ -140,8 +171,11 @@ static void previous_word ( struct edit_string *string ) {
  */
 static void kill_word ( struct edit_string *string ) {
 	size_t old_cursor = string->cursor;
+	int rc;
+
 	previous_word ( string );
-	insert_delete ( string, ( old_cursor - string->cursor ), NULL );
+	rc = insert_delete ( string, ( old_cursor - string->cursor ), NULL );
+	assert ( ( rc == 0 ) || ( *(string->buf) == NULL ) );
 }
 
 /**
@@ -151,8 +185,11 @@ static void kill_word ( struct edit_string *string ) {
  */
 static void kill_sol ( struct edit_string *string ) {
 	size_t old_cursor = string->cursor;
+	int rc;
+
 	string->cursor = 0;
-	insert_delete ( string, old_cursor, NULL );
+	rc = insert_delete ( string, old_cursor, NULL );
+	assert ( ( rc == 0 ) || ( *(string->buf) == NULL ) );
 }
 
 /**
@@ -161,18 +198,36 @@ static void kill_sol ( struct edit_string *string ) {
  * @v string		Editable string
  */
 static void kill_eol ( struct edit_string *string ) {
-	insert_delete ( string, ~( ( size_t ) 0 ), NULL );
+	int rc;
+
+	rc = insert_delete ( string, ~( ( size_t ) 0 ), NULL );
+	assert ( ( rc == 0 ) || ( *(string->buf) == NULL ) );
 }
 
 /**
  * Replace editable string
  *
  * @v string		Editable string
- * @v replacement	Replacement string
+ * @v replacement	Replacement string, or NULL to empty the string
+ * @ret rc		Return status code
+ *
+ * Replace the entire content of the editable string and update the
+ * edit history to allow the caller to bring the display into sync
+ * with the string content.
+ *
+ * This function does not itself update the display in any way.
+ *
+ * Upon success, the string buffer is guaranteed to be non-NULL (even
+ * if the replacement string is NULL or empty).
+ *
+ * Errors may safely be ignored if it is deemed that subsequently
+ * failing to update the display will provide sufficient feedback to
+ * the user.
  */
-void replace_string ( struct edit_string *string, const char *replacement ) {
+int replace_string ( struct edit_string *string, const char *replacement ) {
+
 	string->cursor = 0;
-	insert_delete ( string, ~( ( size_t ) 0 ), replacement );
+	return insert_delete ( string, ~( ( size_t ) 0 ), replacement );
 }
 
 /**
@@ -180,21 +235,26 @@ void replace_string ( struct edit_string *string, const char *replacement ) {
  *
  * @v string		Editable string
  * @v key		Key pressed by user
- * @ret key		Key returned to application, or zero
+ * @ret key		Key returned to application, zero, or negative error
  *
  * Handles keypresses and updates the content of the editable string.
  * Basic line editing facilities (delete/insert/cursor) are supported.
  * If edit_string() understands and uses the keypress it will return
  * zero, otherwise it will return the original key.
  *
- * This function does not update the display in any way.
- *
  * The string's edit history will be updated to allow the caller to
  * efficiently bring the display into sync with the string content.
+ *
+ * This function does not itself update the display in any way.
+ *
+ * Errors may safely be ignored if it is deemed that subsequently
+ * failing to update the display will provide sufficient feedback to
+ * the user.
  */
 int edit_string ( struct edit_string *string, int key ) {
+	const char *buf = *(string->buf);
+	size_t len = ( buf ? strlen ( buf ) : 0 );
 	int retval = 0;
-	size_t len = strlen ( string->buf );
 
 	/* Prepare edit history */
 	string->last_cursor = string->cursor;
@@ -204,7 +264,7 @@ int edit_string ( struct edit_string *string, int key ) {
 	/* Interpret key */
 	if ( ( key >= 0x20 ) && ( key <= 0x7e ) ) {
 		/* Printable character; insert at current position */
-		insert_character ( string, key );
+		retval = insert_character ( string, key );
 	} else switch ( key ) {
 	case KEY_BACKSPACE:
 		/* Backspace */