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Zero-length C string operations should not yield pointer checks #2276

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Merged
merged 1 commit into from
Jun 5, 2018
Merged

Zero-length C string operations should not yield pointer checks #2276

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22 changes: 11 additions & 11 deletions src/ansi-c/library/string.c
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Original file line number Diff line number Diff line change
Expand Up @@ -597,11 +597,11 @@ void *memcpy(void *dst, const void *src, size_t n)
__CPROVER_precondition(__CPROVER_POINTER_OBJECT(dst)!=
__CPROVER_POINTER_OBJECT(src),
"memcpy src/dst overlap");
(void)*(char *)dst; // check that the memory is accessible
(void)*(const char *)src; // check that the memory is accessible

if(n > 0)
{
(void)*(char *)dst; // check that the memory is accessible
(void)*(const char *)src; // check that the memory is accessible
(void)*(((char *)dst) + n - 1); // check that the memory is accessible
(void)*(((const char *)src) + n - 1); // check that the memory is accessible
//for(__CPROVER_size_t i=0; i<n ; i++) ((char *)dst)[i]=((const char *)src)[i];
Expand Down Expand Up @@ -639,12 +639,12 @@ void *__builtin___memcpy_chk(void *dst, const void *src, __CPROVER_size_t n, __C
__CPROVER_precondition(__CPROVER_POINTER_OBJECT(dst)!=
__CPROVER_POINTER_OBJECT(src),
"memcpy src/dst overlap");
(void)*(char *)dst; // check that the memory is accessible
(void)*(const char *)src; // check that the memory is accessible
(void)size;

if(n > 0)
{
(void)*(char *)dst; // check that the memory is accessible
(void)*(const char *)src; // check that the memory is accessible
(void)*(((char *)dst) + n - 1); // check that the memory is accessible
(void)*(((const char *)src) + n - 1); // check that the memory is accessible
//for(__CPROVER_size_t i=0; i<n ; i++) ((char *)dst)[i]=((const char *)src)[i];
Expand Down Expand Up @@ -685,10 +685,10 @@ void *memset(void *s, int c, size_t n)
else
__CPROVER_is_zero_string(s)=0;
#else
(void)*(char *)s; // check that the memory is accessible

if(n > 0)
{
(void)*(char *)s; // check that the memory is accessible
(void)*(((char *)s) + n - 1); // check that the memory is accessible
//char *sp=s;
//for(__CPROVER_size_t i=0; i<n ; i++) sp[i]=c;
Expand Down Expand Up @@ -724,10 +724,10 @@ void *__builtin_memset(void *s, int c, __CPROVER_size_t n)
__CPROVER_is_zero_string(s)=0;
}
#else
(void)*(char *)s; // check that the memory is accessible

if(n > 0)
{
(void)*(char *)s; // check that the memory is accessible
(void)*(((char *)s) + n - 1); // check that the memory is accessible
//char *sp=s;
//for(__CPROVER_size_t i=0; i<n ; i++) sp[i]=c;
Expand Down Expand Up @@ -763,11 +763,11 @@ void *__builtin___memset_chk(void *s, int c, __CPROVER_size_t n, __CPROVER_size_
else
__CPROVER_is_zero_string(s)=0;
#else
(void)*(char *)s; // check that the memory is accessible
(void)size;

if(n > 0)
{
(void)*(char *)s; // check that the memory is accessible
(void)*(((char *)s) + n - 1); // check that the memory is accessible
//char *sp=s;
//for(__CPROVER_size_t i=0; i<n ; i++) sp[i]=c;
Expand Down Expand Up @@ -804,11 +804,11 @@ void *memmove(void *dest, const void *src, size_t n)
else
__CPROVER_is_zero_string(dest)=0;
#else
(void)*(char *)dest; // check that the memory is accessible
(void)*(const char *)src; // check that the memory is accessible

if(n > 0)
{
(void)*(char *)dest; // check that the memory is accessible
(void)*(const char *)src; // check that the memory is accessible
(void)*(((char *)dest) + n - 1); // check that the memory is accessible
(void)*(((const char *)src) + n - 1); // check that the memory is accessible
char src_n[n];
Expand Down Expand Up @@ -848,12 +848,12 @@ void *__builtin___memmove_chk(void *dest, const void *src, size_t n, __CPROVER_s
__CPROVER_is_zero_string(dest)=0;
}
#else
(void)*(char *)dest; // check that the memory is accessible
(void)*(const char *)src; // check that the memory is accessible
(void)size;

if(n > 0)
{
(void)*(char *)dest; // check that the memory is accessible
(void)*(const char *)src; // check that the memory is accessible
(void)*(((char *)dest) + n - 1); // check that the memory is accessible
(void)*(((const char *)src) + n - 1); // check that the memory is accessible
char src_n[n];
Expand Down