rspec/rules/S5273/cfamily/rule.adoc

== Why is this an issue?

Size argument of ``++strncat++``, ``++strlcat++`` and ``++strlcpy++`` should define the size of the destination to prevent buffer overflow.


Moreover, ``++strncat++`` always adds a terminating null character at the end of the appended characters so the size argument should be smaller than the size of the destination to let enough space for it.


=== Noncompliant code example

[source,cpp]
----
void f(char* src) {
  char dest[10];
  strlcpy(dest, src, sizeof(src)); // Noncompliant; size argument is the size of the source instead of the size of the destination

  strncat(dest, src, sizeof(src)); // Noncompliant; size of the source instead of the size of the destination
  strncat(dest, src, sizeof(dest)); // Noncompliant; size argument is too large  
}
----


=== Compliant solution

[source,cpp]
----
void f(char* src) {
  char dest[10];
  strncat(dest, src, sizeof(dest) - 1); // Compliant  
}
----
 

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== Implementation Specification
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