commit ee431112ff0d9bab8b4bd4259adc361d46f130cc
author Mark Salyzyn <salyzyn@google.com> Tue Aug 23 13:58:37 2016 -0700
committer Mark Salyzyn <salyzyn@google.com> Tue Aug 23 15:29:28 2016 -0700
tree dfbcb7bab11fa192955456df82236394f513f8a8
parent ad52cbb9ec16ecee443c72286845e0f3a336e350

libcutils: Add ashmem_valid() function

Bug: 30310689
Change-Id: I14c52c5d52745a725799652b87c86281ac214899

include/cutils/ashmem.h

diff --git a/include/cutils/ashmem.h b/include/cutils/ashmem.h
index acedf73..d80caa6 100644
--- a/include/cutils/ashmem.h
+++ b/include/cutils/ashmem.h
@@ -20,6 +20,7 @@
 extern "C" {
 #endif
 
+int ashmem_valid(int fd);
 int ashmem_create_region(const char *name, size_t size);
 int ashmem_set_prot_region(int fd, int prot);
 int ashmem_pin_region(int fd, size_t offset, size_t len);

libcutils/ashmem-dev.c

diff --git a/libcutils/ashmem-dev.c b/libcutils/ashmem-dev.c
index 4a07d66..09fa09a 100644
--- a/libcutils/ashmem-dev.c
+++ b/libcutils/ashmem-dev.c
@@ -85,7 +85,7 @@
 }
 
 /* Make sure file descriptor references ashmem, negative number means false */
-static int __ashmem_is_ashmem(int fd)
+static int __ashmem_is_ashmem(int fd, int fatal)
 {
     dev_t rdev;
     struct stat st;
@@ -117,22 +117,29 @@
         }
     }
 
-    if (rdev) {
-        LOG_ALWAYS_FATAL("illegal fd=%d mode=0%o rdev=%d:%d expected 0%o %d:%d",
-          fd, st.st_mode, major(st.st_rdev), minor(st.st_rdev),
-          S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IRGRP,
-          major(rdev), minor(rdev));
-    } else {
-        LOG_ALWAYS_FATAL("illegal fd=%d mode=0%o rdev=%d:%d expected 0%o",
-          fd, st.st_mode, major(st.st_rdev), minor(st.st_rdev),
-          S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IRGRP);
+    if (fatal) {
+        if (rdev) {
+            LOG_ALWAYS_FATAL("illegal fd=%d mode=0%o rdev=%d:%d expected 0%o %d:%d",
+              fd, st.st_mode, major(st.st_rdev), minor(st.st_rdev),
+              S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IRGRP,
+              major(rdev), minor(rdev));
+        } else {
+            LOG_ALWAYS_FATAL("illegal fd=%d mode=0%o rdev=%d:%d expected 0%o",
+              fd, st.st_mode, major(st.st_rdev), minor(st.st_rdev),
+              S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IRGRP);
+        }
+        /* NOTREACHED */
     }
-    /* NOTREACHED */
 
     errno = ENOTTY;
     return -1;
 }
 
+int ashmem_valid(int fd)
+{
+    return __ashmem_is_ashmem(fd, 0) >= 0;
+}
+
 /*
  * ashmem_create_region - creates a new ashmem region and returns the file
  * descriptor, or <0 on error
@@ -175,7 +182,7 @@
 
 int ashmem_set_prot_region(int fd, int prot)
 {
-    int ret = __ashmem_is_ashmem(fd);
+    int ret = __ashmem_is_ashmem(fd, 1);
     if (ret < 0) {
         return ret;
     }
@@ -187,7 +194,7 @@
 {
     struct ashmem_pin pin = { offset, len };
 
-    int ret = __ashmem_is_ashmem(fd);
+    int ret = __ashmem_is_ashmem(fd, 1);
     if (ret < 0) {
         return ret;
     }
@@ -199,7 +206,7 @@
 {
     struct ashmem_pin pin = { offset, len };
 
-    int ret = __ashmem_is_ashmem(fd);
+    int ret = __ashmem_is_ashmem(fd, 1);
     if (ret < 0) {
         return ret;
     }
@@ -209,7 +216,7 @@
 
 int ashmem_get_size_region(int fd)
 {
-    int ret = __ashmem_is_ashmem(fd);
+    int ret = __ashmem_is_ashmem(fd, 1);
     if (ret < 0) {
         return ret;
     }