winansi: more robust handling of invalid escape sequences

Commit 399b1dd64 (winansi: support escape sequence to set window
title) failed to handle some invalid escape sequences correctly.
Make the code more robust.

Fixes GitHub issue #153.

1 files changed, 46 insertions, 34 deletions

diff --git a/win32/winansi.c b/win32/winansi.c
index 018b05c76..098b57c5d 100644
--- a/win32/winansi.c
+++ b/win32/winansi.c
@@ -213,12 +213,36 @@ static void move_cursor(int x, int y)
         SetConsoleCursorPosition(console, pos);
 }
 
-static const char *set_attr(const char *str)
+/* On input pos points to the start of a suspected escape sequence.
+ * If a valid sequence is found return a pointer to the character
+ * following it, otherwise return the original pointer. */
+static char *process_escape(char *pos)
 {
-        const char *func;
-        size_t len = strspn(str, "0123456789;");
-        func = str + len;
+        const char *str, *func;
+        char *bel;
+        size_t len;
+
+        switch (pos[1]) {
+        case '[':
+                /* go ahead and process "\033[" sequence */
+                break;
+        case ']':
+                if ((pos[2] == '0' || pos[2] == '2') && pos[3] == ';' &&
+                                (bel=strchr(pos+4, '\007')) && bel - pos < 260) {
+                        /* set console title */
+                        *bel++ = '\0';
+                        CharToOem(pos+4, pos+4);
+                        SetConsoleTitle(pos+4);
+                        return bel;
+                }
+                /* invalid "\033]" sequence, fall through */
+        default:
+                return pos;
+        }
 
+        str = pos + 2;
+        len = strspn(str, "0123456789;");
+        func = str + len;
         switch (*func) {
         case 'm':
                 do {
@@ -344,7 +368,7 @@ static const char *set_attr(const char *str)
                                 break;
                         default:
                                 /* Unsupported code */
-                                break;
+                                return pos;
                         }
                         str++;
                 } while (*(str-1) == ';');
@@ -391,10 +415,10 @@ static const char *set_attr(const char *str)
                 break;
         default:
                 /* Unsupported code */
-                break;
+                return pos;
         }
 
-        return func + 1;
+        return (char *)func + 1;
 }
 
 #if ENABLE_FEATURE_EURO
@@ -465,28 +489,6 @@ static BOOL winansi_OemToCharBuff(LPCSTR s, LPSTR d, DWORD len)
 # define OemToCharBuff winansi_OemToCharBuff
 #endif
 
-static char *check_escapes(char *pos)
-{
-        char *str = pos+1;
-
-        switch (pos[1]) {
-        case '[':
-                str = (char *)set_attr(pos+2);
-                break;
-        case ']':
-                if ((pos[2] == '0' || pos[2] == '2') && pos[3] == ';' &&
-                                (str=strchr(pos, '\007')) && str - pos < 260) {
-                        *str = '\0';
-                        CharToOem(pos+4, pos+4);
-                        SetConsoleTitle(pos+4);
-                        ++str;
-                }
-                break;
-        }
-
-        return str;
-}
-
 static int ansi_emulate(const char *s, FILE *stream)
 {
         int rv = 0;
@@ -529,7 +531,7 @@ static int ansi_emulate(const char *s, FILE *stream)
                         size_t len = pos - str;
 
                         if (len) {
-                                *pos = '\0';
+                                *pos = '\0';    /* NB, '\033' has been overwritten */
                                 CharToOem(str, str);
                                 if (fputs(str, stream) == EOF)
                                         return EOF;
@@ -539,8 +541,13 @@ static int ansi_emulate(const char *s, FILE *stream)
                         if (fflush(stream) == EOF)
                                 return EOF;
 
-                        str = check_escapes(pos);
-                        rv += pos - str;
+                        str = process_escape(pos);
+                        if (str == pos) {
+                                if (fputc('\033', stream) == EOF)
+                                        return EOF;
+                                ++str;
+                        }
+                        rv += str - pos;
                         pos = str;
 
                         if (fflush(stream) == EOF)
@@ -785,8 +792,13 @@ static int ansi_emulate_write(int fd, const void *buf, size_t count)
                                 rv += out_len;
                         }
 
-                        str = check_escapes(pos);
-                        rv += pos - str;
+                        str = process_escape(pos);
+                        if (str == pos) {
+                                if (write(fd, pos, 1) == -1)
+                                        return -1;
+                                ++str;
+                        }
+                        rv += str - pos;
                         pos = str;
                 } else {
                         len = strlen(str);