https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87096
Bug ID: 87096
Summary: "Optimised" snprintf is not POSIX conformant
Product: gcc
Version: 6.4.0
URL: http://pubs.opengroup.org/onlinepubs/9699919799/functi
ons/snprintf.html
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: awilfox at adelielinux dot org
Target Milestone: ---
POSIX Issue 7, 2018 edition (see URL)
The snprintf() function shall fail if:
[EOVERFLOW]
The value of n is greater than {INT_MAX}.
This behaviour may or may not be ISO C compatible: C99 WG14 and C11
specifically state that intending the printf family of functions to return
larger than INT_MAX is undefined behaviour: J.2. I am unclear on the status of
this behaviour with regards to C89. It is definitely required by POSIX.
The following line of C, which is the minimum reproduction case:
snprintf(buf, (size_t)INT_MAX + 1, "");
returns 0 when compiled with GCC unless -fno-builtin is passed.
