No description
8a2a5b8f25
gcc compiles `p + length < p' into 'length < 0' since pointer overflow is undefined behavior in C. This breaks the check against a large `length'.
Use `length > pend - p' instead.
There's no need to check `length < 0' since `length' is from length_decode() and should be non-negative.
===
Try the simplified code.
void bar(void);
void foo(unsigned char *p, int length)
{
if (p + length < p)
bar();
}
$ gcc -S -o - t.c -O2
...
foo:
.LFB0:
.cfi_startproc
testl %esi, %esi
js .L4
rep
ret
.L4:
jmp bar
.cfi_endproc
Clearly `p' is not used at all.
R=rsc
CC=plan9port.codebot
https://codereview.appspot.com/7231069
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This is a port of many Plan 9 libraries and programs to Unix.
* Installation
To install, run ./INSTALL. It builds mk and then uses mk to
run the rest of the installation.
For more details, see install(1), at install.txt in this directory
and at http://swtch.com/plan9port/man/man1/install.html.
* Documentation
See http://swtch.com/plan9port/man/ for more documentation.
(Documentation is also in this tree, but you need to run
a successful install first. After that, "9 man 1 intro".)
Intro(1) contains a list of man pages that describe new features
or differences from Plan 9.
* Helping out
If you'd like to help out, great! The TODO file contains a small list.
If you port this code to other architectures, please share your changes
so others can benefit.
Please use diff -u or CVS (see below) to prepare patches.
* CVS
You can use CVS to keep your local copy up-to-date as we make
changes and fix bugs. See the cvs(1) man page here ("9 man cvs")
for details on using cvs.
* Contact
Russ Cox <rsc@swtch.com>