Bug 3330205 Thread safety for bignum powers of 5

Change-Id: I739a06f9037a9fb643276f61601f0f3e192581b8

diff --git a/libc/stdlib/strtod.c b/libc/stdlib/strtod.c
index 2851506..ab637a1 100644 (file)
--- a/libc/stdlib/strtod.c
+++ b/libc/stdlib/strtod.c
@@ -754,6 +754,7 @@ mult
 }
 
  static Bigint *p5s;
+ static pthread_mutex_t p5s_mutex = PTHREAD_MUTEX_INITIALIZER;
 
  static Bigint *
 pow5mult
@@ -775,11 +776,13 @@ pow5mult
 
        if (!(k = (unsigned int) k >> 2))
                return b;
+       mutex_lock(&p5s_mutex);
        if (!(p5 = p5s)) {
                /* first time */
                p5 = i2b(625);
                if (p5 == BIGINT_INVALID) {
                        Bfree(b);
+                       mutex_unlock(&p5s_mutex);
                        return p5;
                }
                p5s = p5;
@@ -797,6 +800,7 @@ pow5mult
                        p51 = mult(p5,p5);
                        if (p51 == BIGINT_INVALID) {
                                Bfree(b);
+                               mutex_unlock(&p5s_mutex);
                                return p51;
                        }
                        p5->next = p51;
@@ -804,6 +808,7 @@ pow5mult
                }
                p5 = p51;
        }
+       mutex_unlock(&p5s_mutex);
        return b;
 }