diff options
| author | Alejandro Colomar <alx@kernel.org> | 2023-02-05 15:36:07 +0100 |
|---|---|---|
| committer | Alejandro Colomar <alx@kernel.org> | 2023-02-05 15:36:46 +0100 |
| commit | 1f9949d11f499e5758f7e213e528b022cd8ad8f1 (patch) | |
| tree | 437a1d9eee10d9370ec6a1200f206290bca3c10c | |
| parent | 3aabcc0f7dda611dc2d2e43ede0a7a27b82f9be5 (diff) | |
sscanf.3: BUGS: Document the UB in some conversion specifiers
This is a bug in the standards, but implementation should not follow the
standard in this case.
Link: <https://lore.kernel.org/linux-man/20221208123454.13132-1-abbotti@mev.co.uk/T/#u>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Zack Weinberg <zack@owlfolio.org>
Cc: Joseph Myers <joseph@codesourcery.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: "G. Branden Robinson" <g.branden.robinson@gmail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
| -rw-r--r-- | man3/sscanf.3 | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/man3/sscanf.3 b/man3/sscanf.3 index 26a02521b..870c6f54b 100644 --- a/man3/sscanf.3 +++ b/man3/sscanf.3 @@ -653,6 +653,25 @@ floating-point conversion specifier (and is unaffected by .I gcc\~\-std=c99 etc.). .SH BUGS +.SS Numeric conversion specifiers +Use of the numeric conversion specifiers produces Undefined Behavior +for invalid input. +See +.UR https://port70.net/\:%7Ensz/\:c/\:c11/\:n1570.html\:#7.21.6.2p10 +C11 7.21.6.2/10 +.UE . +This is a bug in the ISO C standard, +and not an inherent design issue with the API. +However, +current implementations are not safe from that bug, +so it is not recommended to use them. +Instead, +programs should use functions such as +.BR strtol (3) +to parse numeric input. +This manual page deprecates use of the numeric conversion specifiers +until they are fixed by ISO C. +.SS Nonstandard modifiers These functions are fully C99 conformant, but provide the additional modifiers .B q |