diff options
| author |   jaredy <jaredy@openbsd.org> | 2005-07-26 03:30:25 +0000 |
|---|---|---|
| committer | jaredy <jaredy@openbsd.org> | 2005-07-26 03:30:25 +0000 |
| commit | 2f2ed4fb1c1c50ba362ab9d8bcbb47d714c9eecd (patch) | |
| tree | 083f8216358973290d0918f833b769ce5465dc87 /lib/libc/stdio/printf.3 | |
| parent | clarify description of 'c' conversion; ok millert, jmc (diff) | |
| download | wireguard-openbsd-2f2ed4fb1c1c50ba362ab9d8bcbb47d714c9eecd.tar.xz wireguard-openbsd-2f2ed4fb1c1c50ba362ab9d8bcbb47d714c9eecd.zip | |
- typos, punctuation, spacing, macro, layout, etc. fixes
- avoid first person
ok jmc
Diffstat (limited to 'lib/libc/stdio/printf.3')
| -rw-r--r-- | lib/libc/stdio/printf.3 | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/lib/libc/stdio/printf.3 b/lib/libc/stdio/printf.3 index f138476201c..0678581bff4 100644 --- a/lib/libc/stdio/printf.3 +++ b/lib/libc/stdio/printf.3 @@ -1,4 +1,4 @@ -.\" $OpenBSD: printf.3,v 1.48 2005/07/26 03:23:14 jaredy Exp $ +.\" $OpenBSD: printf.3,v 1.49 2005/07/26 03:30:25 jaredy Exp $ .\" .\" Copyright (c) 1990, 1991, 1993 .\" The Regents of the University of California. All rights reserved. @@ -653,7 +653,7 @@ to five decimal places: fprintf(stdout, "pi = %.5f\en", 4 * atan(1.0)); .Ed .Pp -To allocate a 128 byte string and print into it: +To allocate a 128-byte string and print into it: .Bd -literal -offset indent #include <stdarg.h> #include <stdio.h> @@ -749,9 +749,9 @@ interface is not portable. It is important never to pass a string with user-supplied data as a format without using .Ql %s . -An attacker can put format specifiers in the string to mangle your stack, +An attacker can put format specifiers in the string to mangle the stack, leading to a possible security hole. -This holds true even if you have built the string +This holds true even if the string has been built .Dq by hand using a function like .Fn snprintf , @@ -764,8 +764,11 @@ Be sure to use the proper secure idiom: snprintf(buffer, sizeof(buffer), "%s", string); .Ed .Pp -There is no way for printf to know the size of each argument passed. -If you use positional arguments you must ensure that all parameters, up to the +There is no way for +.Fn printf +to know the size of each argument passed. +If positional arguments are used, care must be taken to ensure that all +parameters, up to the last positionally specified parameter, are used in the format string. This allows for the format string to be parsed for this information. -Failure to do this will mean your code is non-portable and liable to fail. +Failure to do this will mean the code is non-portable and liable to fail. |