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Improve mkstemp(3) random path generation.

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This commit is contained in:
Jonas 'Sortie' Termansen 2014-08-21 17:12:06 +02:00
parent 156e73d441
commit fb8221a381
1 changed files with 15 additions and 2 deletions
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17
libc/stdlib/mkstemp.cpp
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@ -27,12 +27,25 @@
#include <stdlib.h> #include <stdlib.h>
#include <string.h> #include <string.h>
const uint32_t NUM_CHARACTERS = 10 + 26 + 26;
static inline char get_character(uint32_t index)
{
if ( index < 10 )
return '0' + index;
if ( index < 10 + 26 )
return 'a' + index - 10;
if ( index < 10 + 26 + 26 )
return 'A' + index - (10 + 26);
__builtin_unreachable();
}
extern "C" int mkstemp(char* templ) extern "C" int mkstemp(char* templ)
{ {
size_t templ_length = strlen(templ); size_t templ_length = strlen(templ);
for ( size_t i = 0; i < 6; i++ ) for ( size_t i = 0; i < 6; i++ )
{ {
if ( templ_length - i == 0 ) if ( templ_length - i == 0 )
return errno = EINVAL, -1; return errno = EINVAL, -1;
if ( templ[templ_length - i - 1] != 'X' ) if ( templ[templ_length - i - 1] != 'X' )
return errno = EINVAL, -1; return errno = EINVAL, -1;
@ -42,7 +55,7 @@ extern "C" int mkstemp(char* templ)
do do
{ {
for ( size_t i = templ_length - 6; i < templ_length; i++ ) for ( size_t i = templ_length - 6; i < templ_length; i++ )
templ[i] = '0' + rand() % 10; templ[i] = get_character(arc4random_uniform(NUM_CHARACTERS));
} while ( (fd = open(templ, O_RDWR | O_EXCL | O_CREAT, 0600)) < 0 && } while ( (fd = open(templ, O_RDWR | O_EXCL | O_CREAT, 0600)) < 0 &&
(errno == EEXIST) ); (errno == EEXIST) );