diff options
| -rw-r--r-- | drivers/firmware/efi/libstub/vsprintf.c | 61 |
1 files changed, 40 insertions, 21 deletions
diff --git a/drivers/firmware/efi/libstub/vsprintf.c b/drivers/firmware/efi/libstub/vsprintf.c index b7316ab9f8b4..0e6f2c1158fd 100644 --- a/drivers/firmware/efi/libstub/vsprintf.c +++ b/drivers/firmware/efi/libstub/vsprintf.c @@ -231,7 +231,20 @@ int get_flags(const char **fmt) } while (1); } -int vsprintf(char *buf, const char *fmt, va_list args) +static +int get_int(const char **fmt, va_list *ap) +{ + if (isdigit(**fmt)) + return skip_atoi(fmt); + if (**fmt == '*') { + ++(*fmt); + /* it's the next argument */ + return va_arg(*ap, int); + } + return 0; +} + +int vsprintf(char *buf, const char *fmt, va_list ap) { int len; unsigned long long num; @@ -246,6 +259,24 @@ int vsprintf(char *buf, const char *fmt, va_list args) number of chars for from string */ int qualifier; /* 'h', 'hh', 'l' or 'll' for integer fields */ + va_list args; + + /* + * We want to pass our input va_list to helper functions by reference, + * but there's an annoying edge case. If va_list was originally passed + * to us by value, we could just pass &ap down to the helpers. This is + * the case on, for example, X86_32. + * However, on X86_64 (and possibly others), va_list is actually a + * size-1 array containing a structure. Our function parameter ap has + * decayed from T[1] to T*, and &ap has type T** rather than T(*)[1], + * which is what will be expected by a function taking a va_list * + * parameter. + * One standard way to solve this mess is by creating a copy in a local + * variable of type va_list and then passing a pointer to that local + * copy instead, which is what we do here. + */ + va_copy(args, ap); + for (str = buf; *fmt; ++fmt) { if (*fmt != '%' || *++fmt == '%') { *str++ = *fmt; @@ -256,32 +287,17 @@ int vsprintf(char *buf, const char *fmt, va_list args) flags = get_flags(&fmt); /* get field width */ - field_width = -1; - if (isdigit(*fmt)) { - field_width = skip_atoi(&fmt); - } else if (*fmt == '*') { - ++fmt; - /* it's the next argument */ - field_width = va_arg(args, int); - if (field_width < 0) { - field_width = -field_width; - flags |= LEFT; - } + field_width = get_int(&fmt, &args); + if (field_width < 0) { + field_width = -field_width; + flags |= LEFT; } /* get the precision */ precision = -1; if (*fmt == '.') { ++fmt; - if (isdigit(*fmt)) { - precision = skip_atoi(&fmt); - } else if (*fmt == '*') { - ++fmt; - /* it's the next argument */ - precision = va_arg(args, int); - } else { - precision = 0; - } + precision = get_int(&fmt, &args); if (precision >= 0) flags &= ~ZEROPAD; } @@ -392,6 +408,9 @@ int vsprintf(char *buf, const char *fmt, va_list args) str = number(str, num, base, field_width, precision, flags); } *str = '\0'; + + va_end(args); + return str - buf; } |