[PATCH] fix compile failure with libc musl

[Hongxu Jia]

The lack of random_r in musl:
[snip]
|main.c:1393:7: warning: implicit declaration of function 'random_r';
did you mean 'random'? [-Wimplicit-function-declaration]
|  rv = random_r(&rand_data, &val);
|       ^~~~~~~~
|       random
|main.c:1408:30: error: invalid application of 'sizeof' to incomplete
type 'struct random_data'
|  memset(&rand_data, 0, sizeof(rand_data));
[snip]

s/random_r/random/, s/initstate_r/initstate/ and remove `static struct
random_data rand_data'

Here is the man of `random_r()':
[snip]
The random_r() function is like random(3), except that instead of using
state information maintained in a global variable
[snip]

So use random without state information is OK.

Signed-off-by: Hongxu Jia <hongxu.jia(a)windriver.com&gt;
---
 src/main.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/src/main.c b/src/main.c
index f60b4d3..602c400 100644
--- a/src/main.c
+++ b/src/main.c
@@ -84,7 +84,6 @@ static char command[COMMAND_MAX];
 static int cmd_argc;
 static char **cmd_argv;
 static struct thread_pool pool;
-static struct random_data rand_data;
 static char rand_state[32];
 static pthread_mutex_t rand_mutex = PTHREAD_MUTEX_INITIALIZER;
 static const char *run_dir = NULL;
@@ -1386,16 +1385,15 @@ int get_rand(int a, int b);
 
 int get_rand(int a, int b)
 {
-	int32_t val;
-	int rv;
+	long int rv;
 
 	pthread_mutex_lock(&rand_mutex);
-	rv = random_r(&rand_data, &val);
+	rv = random();
 	pthread_mutex_unlock(&rand_mutex);
 	if (rv < 0)
 		return rv;
 
-	return a + (int) (((float)(b - a + 1)) * val / (RAND_MAX+1.0));
+	return a + (int) (((float)(b - a + 1)) * rv / (RAND_MAX+1.0));
 }
 
 static void setup_host_name(void)
@@ -1405,9 +1403,7 @@ static void setup_host_name(void)
 	uuid_t uu;
 
 	memset(rand_state, 0, sizeof(rand_state));
-	memset(&rand_data, 0, sizeof(rand_data));
-
-	initstate_r(time(NULL), rand_state, sizeof(rand_state), &rand_data);
+	initstate(time(NULL), rand_state, sizeof(rand_state));
 
 	/* use host name from command line */
 
-- 
2.8.1

[Nir Soffer]

On Sun, Sep 9, 2018 at 2:47 PM Hongxu Jia <hongxu.jia(a)windriver.com&gt; wrote:

>  The lack of random_r in musl:
>  [snip]
>  |main.c:1393:7: warning: implicit declaration of function 'random_r';
>  did you mean 'random'? [-Wimplicit-function-declaration]
>  |  rv = random_r(&rand_data, &val);
>  |       ^~~~~~~~
>  |       random
>  |main.c:1408:30: error: invalid application of 'sizeof' to incomplete
>  type 'struct random_data'
>  |  memset(&rand_data, 0, sizeof(rand_data));
>  [snip]
>
>  s/random_r/random/, s/initstate_r/initstate/ and remove `static struct
>  random_data rand_data'
>
>  Here is the man of `random_r()':
>  [snip]
>  The random_r() function is like random(3), except that instead of using
>  state information maintained in a global variable
>  [snip]
>
>  So use random without state information is OK.
>  
But random(3) says:

The random() function should not be used in multithreaded programs
       where reproducible behavior is required.  Use random_r(3) for that
       purpose.


>  Signed-off-by: Hongxu Jia <hongxu.jia(a)windriver.com&gt;
>  ---
>   src/main.c | 12 ++++--------
>   1 file changed, 4 insertions(+), 8 deletions(-)
>
>  diff --git a/src/main.c b/src/main.c
>  index f60b4d3..602c400 100644
>  --- a/src/main.c
>  +++ b/src/main.c
>  @@ -84,7 +84,6 @@ static char command[COMMAND_MAX];
>   static int cmd_argc;
>   static char **cmd_argv;
>   static struct thread_pool pool;
>  -static struct random_data rand_data;
>   static char rand_state[32];
>   static pthread_mutex_t rand_mutex = PTHREAD_MUTEX_INITIALIZER;
>   static const char *run_dir = NULL;
>  @@ -1386,16 +1385,15 @@ int get_rand(int a, int b);
>
>   int get_rand(int a, int b)
>   {
>  -       int32_t val;
>  -       int rv;
>  +       long int rv;
>
>          pthread_mutex_lock(&rand_mutex);
>  -       rv = random_r(&rand_data, &val);
>  +       rv = random();
>          pthread_mutex_unlock(&rand_mutex); 
        if (rv < 0)
>                  return rv;
>  
But random_r() is accessed only via get_rand, using a mutex, so it looks
like we can replace it with random.

But why not use random() only when random_r() is not available?

Nir


>  -       return a + (int) (((float)(b - a + 1)) * val / (RAND_MAX+1.0));
>  +       return a + (int) (((float)(b - a + 1)) * rv / (RAND_MAX+1.0));
>   }
>
>   static void setup_host_name(void)
>  @@ -1405,9 +1403,7 @@ static void setup_host_name(void)
>          uuid_t uu;
>
>          memset(rand_state, 0, sizeof(rand_state));
>  -       memset(&rand_data, 0, sizeof(rand_data));
>  -
>  -       initstate_r(time(NULL), rand_state, sizeof(rand_state),
>  &rand_data);
>  +       initstate(time(NULL), rand_state, sizeof(rand_state));
>
>          /* use host name from command line */
>
>  --
>  2.8.1
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[Hongxu Jia]

>      +       rv = random();
>              pthread_mutex_unlock(&rand_mutex); 
>
>              if (rv < 0)
>                      return rv;
>
>
>  But random_r() is accessed only via get_rand, using a mutex, so it looks
>  like we can replace it with random.
>
>  But why not use random() only when random_r() is not available?
>  
The random_r family of functions and they seem to be a glibc extension.
There are random_r/random/, initstate_r/initstate and `static struct
random_data rand_data' required to be split by macro (such as
HAVE_RANDOM_R), and add AC_CHECK_FUNCS([random_r]) to configure.ac to
generate the macro HAVE_RANDOM_R according to the existence of random_r,
but we do not have configure.ac in sanlock :(

Or we can use  macro `__GLIBC__' to figure out glibc and other libc, but 
it also
make the source more complicated.

//Hongxu

>  Nir
>
>
>      -       return a + (int) (((float)(b - a + 1)) * val /
>      (RAND_MAX+1.0));
>      +       return a + (int) (((float)(b - a + 1)) * rv / (RAND_MAX+1.0));
>       }
>
>       static void setup_host_name(void)
>      @@ -1405,9 +1403,7 @@ static void setup_host_name(void)
>              uuid_t uu;
>
>              memset(rand_state, 0, sizeof(rand_state));
>      -       memset(&rand_data, 0, sizeof(rand_data));
>      -
>      -       initstate_r(time(NULL), rand_state, sizeof(rand_state),
>      &rand_data);
>      +       initstate(time(NULL), rand_state, sizeof(rand_state));
>
>              /* use host name from command line */
>
>      -- 
>      2.8.1
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