sprintf_trunc() is a function similar to strscpy(). It truncates the string, and returns an error code on truncation or error. On success, it returns the length of the new string.
Cc: Kees Cook <[email protected]> Cc: Christopher Bazley <[email protected]> Cc: Rasmus Villemoes <[email protected]> Cc: Marco Elver <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Al Viro <[email protected]> Signed-off-by: Alejandro Colomar <[email protected]> --- include/linux/sprintf.h | 2 ++ lib/vsprintf.c | 53 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 55 insertions(+) diff --git a/include/linux/sprintf.h b/include/linux/sprintf.h index 51cab2def9ec..5ea6ec9c2e59 100644 --- a/include/linux/sprintf.h +++ b/include/linux/sprintf.h @@ -13,6 +13,8 @@ __printf(3, 4) int snprintf(char *buf, size_t size, const char *fmt, ...); __printf(3, 0) int vsnprintf(char *buf, size_t size, const char *fmt, va_list args); __printf(3, 4) int scnprintf(char *buf, size_t size, const char *fmt, ...); __printf(3, 0) int vscnprintf(char *buf, size_t size, const char *fmt, va_list args); +__printf(3, 4) int sprintf_trunc(char *buf, size_t size, const char *fmt, ...); +__printf(3, 0) int vsprintf_trunc(char *buf, size_t size, const char *fmt, va_list args); __printf(2, 3) __malloc char *kasprintf(gfp_t gfp, const char *fmt, ...); __printf(2, 0) __malloc char *kvasprintf(gfp_t gfp, const char *fmt, va_list args); __printf(2, 0) const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list args); diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 01699852f30c..15e780942c56 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -2923,6 +2923,34 @@ int vscnprintf(char *buf, size_t size, const char *fmt, va_list args) } EXPORT_SYMBOL(vscnprintf); +/** + * vsprintf_trunc - va_list string truncate print formatted + * @buf: The buffer to place the result into + * @size: The size of the buffer, including the trailing null space + * @fmt: The format string to use + * @args: Arguments for the format string + * + * The return value is the length of the string. + * If the string is truncated, the function returns -E2BIG. + * If @size is invalid, the function returns -EOVERFLOW. + * + * See the vsnprintf() documentation for format string extensions over C99. + */ +int vsprintf_trunc(char *buf, size_t size, const char *fmt, va_list args) +{ + int len; + + if (WARN_ON_ONCE(size == 0 || size > INT_MAX)) + return -EOVERFLOW; + + len = vsnprintf(buf, size, fmt, args); + if (unlikely(len >= size)) + return -E2BIG; + + return len; +} +EXPORT_SYMBOL(vsprintf_trunc); + /** * snprintf - Format a string and place it in a buffer * @buf: The buffer to place the result into @@ -2974,6 +3002,31 @@ int scnprintf(char *buf, size_t size, const char *fmt, ...) } EXPORT_SYMBOL(scnprintf); +/** + * sprintf_trunc - string truncate print formatted + * @buf: The buffer to place the result into + * @size: The size of the buffer, including the trailing null space + * @fmt: The format string to use + * @...: Arguments for the format string + * + * The return value is the length of the string. + * If the string is truncated, the function returns -E2BIG. + * If @size is invalid, the function returns -EOVERFLOW. + */ + +int sprintf_trunc(char *buf, size_t size, const char *fmt, ...) +{ + int len; + va_list args; + + va_start(args, fmt); + len = vsprintf_trunc(buf, size, fmt, args); + va_end(args); + + return len; +} +EXPORT_SYMBOL(sprintf_trunc); + /** * vsprintf - Format a string and place it in a buffer * @buf: The buffer to place the result into -- 2.50.0
