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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2004-12-14 18:25:46 +0000 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2004-12-14 18:25:46 +0000 |
| commit | 898e9a87dfc1b74d9459cc7079f7df66bc2ca07c (patch) | |
| tree | 7d50be0bb00c343cf04bfe470d47a03c70f33691 /man3/printf.3 | |
| parent | 2d5e8aeb7359073791f4e2bef2c36e96325d7dd8 (diff) | |
| download | man-pages-898e9a87dfc1b74d9459cc7079f7df66bc2ca07c.tar.gz | |
Hello Joey,
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=205736
[[
This example contains the following line:
if ((p = realloc (p, size)) == NULL)
return NULL;
This is a very ill written code, since realloc returning
NULL do not deallocate the original memory block. Such a
statement has a potential to become significant memory
hole. I suggest to correct this example since:
1. It may trick naive programmers to write bad code
2. It may lead skeptic observers to the believe
the whole Linux is written in a similar style.
Regards Jan Kuznik
]]
This guy is right on the money!
I've changed that example, so that the above code has been replaced by:
char *np;
...
if ((np = realloc (p, size)) == NULL) {
free(p);
return NULL;
} else {
p = np;
}
Cheers,
Michael
Diffstat (limited to 'man3/printf.3')
| -rw-r--r-- | man3/printf.3 | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/man3/printf.3 b/man3/printf.3 index a5daac8717..f96630a37f 100644 --- a/man3/printf.3 +++ b/man3/printf.3 @@ -756,14 +756,17 @@ To allocate a sufficiently large string and print into it #include <stdio.h> #include <stdlib.h> #include <stdarg.h> + char * make_message(const char *fmt, ...) { /* Guess we need no more than 100 bytes. */ int n, size = 100; - char *p; + char *p, *np; va_list ap; + if ((p = malloc (size)) == NULL) return NULL; + while (1) { /* Try to print in the allocated space. */ va_start(ap, fmt); @@ -777,8 +780,12 @@ make_message(const char *fmt, ...) { size = n+1; /* precisely what is needed */ else /* glibc 2.0 */ size *= 2; /* twice the old size */ - if ((p = realloc (p, size)) == NULL) + if ((np = realloc (p, size)) == NULL) { + free(p); return NULL; + } else { + p = np; + } } } .fi |