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LibC: Fix off-by-one in snprintf()

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snprintf is supposed to *always* NUL-terminate its output, so it has to write one
output byte fewer.

And yes, I *did* check all existing usages; this shouldn't break anything.
This commit is contained in:
Ben Wiederhake 2020-08-16 07:47:33 +02:00 • committed by Andreas Kling
parent 499e953380
commit 2d34f0f93a
1 changed files with 7 additions and 1 deletions
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8
Libraries/LibC/stdio.cpp
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@ -889,10 +889,16 @@ ALWAYS_INLINE void sized_buffer_putch(char*& bufptr, char ch)
int vsnprintf(char* buffer, size_t size, const char* fmt, va_list ap) int vsnprintf(char* buffer, size_t size, const char* fmt, va_list ap)
{ {
__vsnprintf_space_remaining = size; if (size) {
__vsnprintf_space_remaining = size - 1;
} else {
__vsnprintf_space_remaining = 0;
}
int ret = printf_internal(sized_buffer_putch, buffer, fmt, ap); int ret = printf_internal(sized_buffer_putch, buffer, fmt, ap);
if (__vsnprintf_space_remaining) { if (__vsnprintf_space_remaining) {
buffer[ret] = '\0'; buffer[ret] = '\0';
} else if (size > 0) {
buffer[size - 1] = '\0';
} }
return ret; return ret;
} }