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| CodeSonar® 9.0p0 Hot Tips | CONFIDENTIAL | CodeSecure Inc |
An attempt to use a negative number as a file descriptor.
| Class Name | Negative file descriptor | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Significance | reliability | |||||||||
| Mnemonic | IO.NEGFD | |||||||||
| Categories |
|
|||||||||
| Availability | Available for C and C++. |
|||||||||
| Enabling | Checks for this warning class are enabled by
default. To disable them, add the following WARNING_FILTER rule to the
project configuration file.
WARNING_FILTER += discard class="Negative file descriptor" |
| CWE:252 | Unchecked Return Value |
|---|
Japanese (ja)
#include <fcntl.h>
#include <unistd.h>
int negfd_nocheck(void){
return close(open("myfile.txt",O_RDONLY)); /* 'Negative file descriptor' warning issued here
* - open() returns -1 on error
*/
}
int negfd_check(void){
int rv;
rv = open("myfile.txt",O_RDONLY);
if (rv < 0){
return -1;
}
return close(rv);
}
CodeSonar ships with library models that allow it to recognize a large number of functions that take a file descriptor or socket descriptor argument. Some examples are shown in the table below. If one of these functions is called with a negative value in the file/socket descriptor parameter position, a warning will be issued.
If you have created a custom library model for some function f() in terms of one of these existing models, calls to f() will also be capable of triggering Negative file descriptor warnings.
| Functions that can trigger warnings include... | |
|---|---|
| libc | dup(), fdopen(), sendmsg(), |
| Win32 | _dup(), _fstat64(), _write() |
The following configuration file parameters affect checks for this warning class.