Width-unspecified integer type
ID |
c.portability.fixed_width_integer |
Severity |
low |
Remediation Complexity |
medium |
Remediation Risk |
medium |
Remediation Effort |
medium |
Resource |
Portability |
Language |
C / C++ |
Description
This declares a variable with a width-unspecified integer type (short/long/long long). The size of these types differs across platforms and compilers (e.g. long is 32-bit on Windows LLP64 but 64-bit on Unix LP64), which breaks assumptions about ranges and struct layout. Prefer a fixed-width type from <stdint.h> such as int32_t, int64_t or uint64_t.
Rationale
This declares a variable with a width-unspecified integer type (short/long/long long). The size of these types differs across platforms and compilers (e.g. long is 32-bit on Windows LLP64 but 64-bit on Unix LP64), which breaks assumptions about ranges and struct layout. Prefer a fixed-width type from <stdint.h> such as int32_t, int64_t or uint64_t.
The following code illustrates the pattern detected by this rule:
void f(void)
{
// FLAGGED: Width-unspecified integer type
short a;
// FLAGGED: Width-unspecified integer type
long b;
// FLAGGED: Width-unspecified integer type
unsigned long c;
// FLAGGED: Width-unspecified integer type
long long d;
// FLAGGED: Width-unspecified integer type
unsigned short e;
// FLAGGED: Width-unspecified integer type
long g = 5;
int good;
int32_t better;
uint64_t best = 0;
(void)a; (void)b; (void)c; (void)d; (void)e; (void)g; (void)good; (void)better; (void)best;
}