Skip to contentSkip to conversation

random.3: Update initstate() return value description to match glibc

PATCH In review W. Trevor King 2 participants 2 messages Sep 16, 2010 – Sep 19, 2010 Man-pages: manual pages for Linux -- Sections 2, 3, 4, 5, and 7

lore
Share & tools
lore
#0 lore raw

PATCH 1/1 random.3: Update initstate() return value description to match glibc

The glibc manual section on initstate
http://www.gnu.org/software/libc/manual/html_node/BSD-Random.html#index-initstate-2292
makes no mention of NULL on error (which it does mention for setstate).

As proof, the test code

  #include <stdlib.h>
  #include <stdio.h>
  #include <errno.h>
  
  int main(int argc, char **argv)
  {
    void *state = NULL;
    int arg_state = 0;
    printf("errno before %d\n", errno);
    state = (void *) initstate(1, (void *) &arg_state, 7);
    printf("errno after %d (EINVAL is %d)\n", errno, EINVAL);
    printf("state returned from bad initstate call: %p\n", state);
  
    return 0;

}

returns

errno before 0
errno after 22 (EINVAL is 22)
state returned from bad initstate call: 0xb781f040

not

errno before 0
errno after 22 (EINVAL is 22)
state returned from bad initstate call: (nil)

This makes sense because glibc's stdlib/random.c defines __initstate() to always return ostate (blank lines removed):

  char *
  __initstate (seed, arg_state, n)
       unsigned int seed;
       char *arg_state;
       size_t n;
  {
    int32_t *ostate;
    __libc_lock_lock (lock);
    ostate = &unsafe_state.state[-1];
    __initstate_r (seed, arg_state, n, &unsafe_state);
    __libc_lock_unlock (lock);
    return (char *) ostate;
  }

Personally, I think the behavior specified by the old man page makes more sense, but I don't imagine the glibc folks want to change their version.

This patch it against the current Git version of man-pages, and was generated with 'git format-patch -1' before I altered it to include the extra information the man-pages project suggested:
http://www.kernel.org/doc/man-pages/patches.html

W. Trevor King

---
 man3/random.3 |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
man3/random.3 +3 -2
index 7568dc1..6845b98 100644
@@ -120,9 +120,10 @@ The
 function returns no value.
 The
 .BR initstate ()
-and
+function returns a pointer to the previous state.
+The
 .BR setstate ()
-functions return a pointer to the previous state
+function returns a pointer to the previous state
 array, or NULL on error.
 .SH ERRORS
 .TP
Signature · 1 line
1.7.2.2.173.g515cc
#1 lore raw

Hello Trevor,

Quoted 56 lines · W. Trevor King

The glibc manual section on initstate
 http://www.gnu.org/software/libc/manual/html_node/BSD-Random.html#index-initstate-2292
makes no mention of NULL on error (which it does mention for setstate).

As proof, the test code

 #include <stdlib.h>
 #include <stdio.h>
 #include <errno.h>

 int main(int argc, char **argv)
 {
   void *state = NULL;
   int arg_state = 0;

   printf("errno before %d\n", errno);
   state = (void *) initstate(1, (void *) &arg_state, 7); printf("errno after %d (EINVAL is %d)\n", errno, EINVAL); printf("state returned from bad initstate call: %p\n", state);

   return 0;
 }

returns

 errno before 0
 errno after 22 (EINVAL is 22)
 state returned from bad initstate call: 0xb781f040

not

 errno before 0
 errno after 22 (EINVAL is 22)
 state returned from bad initstate call: (nil)

This makes sense because glibc's stdlib/random.c defines __initstate() to always return ostate (blank lines removed):

 char *
 __initstate (seed, arg_state, n)
      unsigned int seed;
      char *arg_state;
      size_t n;
 {
   int32_t *ostate;
   __libc_lock_lock (lock);
   ostate = &unsafe_state.state[-1]; __initstate_r (seed, arg_state, n, &unsafe_state); __libc_lock_unlock (lock);
   return (char *) ostate;
 }

Personally, I think the behavior specified by the old man page makes more sense, but I don't imagine the glibc folks want to change their version.

Quoted 6 lines

This patch it against the current Git version of man-pages, and was generated with 'git format-patch -1' before I altered it to include the extra information the man-pages project suggested:
 http://www.kernel.org/doc/man-pages/patches.html

W. Trevor King

Thanks for the detailed report. I applied the patch for man-pages-3.27.

Thanks,

Michael

Quoted 24 lines

---
 man3/random.3 |    5 +++--

 1 files changed, 3 insertions(+), 2 deletions(-)
man3/random.3 +0 -0
index 7568dc1..6845b98 100644
@@ -120,9 +120,10 @@ The

 function returns no value.
 The
 .BR initstate ()

man3/random.3 +2 -1
-and
+function returns a pointer to the previous state.
+The

 .BR setstate ()

man3/random.3 +1 -1
-functions return a pointer to the previous state
+function returns a pointer to the previous state

 array, or NULL on error.
 .SH ERRORS
 .TP
--
1.7.2.2.173.g515cc

Signature · 7 lines
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface"; http://man7.org/tlpi/
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html