Test shmat() with a non-NULL address, both failure and success

diff --git a/regress/sys/kern/sysvshm/shmtest.c b/regress/sys/kern/sysvshm/shmtest.c
index 230fc87..39d1633 100644 (file)
--- a/regress/sys/kern/sysvshm/shmtest.c
+++ b/regress/sys/kern/sysvshm/shmtest.c
@@ -36,6 +36,7 @@
 
 #include <sys/param.h>
 #include <sys/ipc.h>
+#include <sys/mman.h>
 #include <sys/shm.h>
 #include <sys/wait.h>
 
@@ -288,6 +289,7 @@ receiver()
 {
        int shmid;
        void *shm_buf;
+       void *block;
 
        if ((shmid = shmget(shmkey, pgsize, 0)) == -1)
                err(1, "receiver: shmget");
@@ -296,9 +298,38 @@ receiver()
                err(1, "receiver: shmat");
 
        if (verbose)
-               printf("%s\n", (const char *)shm_buf);
+               printf("%.*s\n", (int)pgsize, (const char *)shm_buf);
        if (strcmp((const char *)shm_buf, m_str) != 0)
-               err(1, "receiver: data isn't correct");
+               errx(1, "receiver: data isn't correct");
+
+       /* mmap() a page to get a distinct, freeable address */
+       block = mmap(NULL, pgsize, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON,
+           -1, 0);
+       if (block == MAP_FAILED)
+               err(1, "receiver: mmap");
+
+       /* detach, then try to attach, conflicting with the mmap() */
+       if (shmdt(shm_buf) == -1)
+               err(1, "receiver: shmdt");
+       if ((shm_buf = shmat(shmid, block, 0)) != (void *) -1)
+               errx(1, "receiver: shmat(conflict) succeeded!");
+       if (errno != ENOMEM)
+               err(1, "receiver: shmat(conflict) wrong error");
+
+       /* free up that address and try again */
+       if (munmap(block, pgsize) == -1)
+               err(1, "receiver: munmap");
+       if ((shm_buf = shmat(shmid, block, 0)) == (void *) -1)
+               err(1, "receiver: shmat(fixed)");
+
+       if (shm_buf != block)
+               errx(1, "receiver: shmat not at expected address: %p != %p",
+                   shm_buf, block);
+
+       if (verbose)
+               printf("%.*s\n", (int)pgsize, (const char *)shm_buf);
+       if (strcmp((const char *)shm_buf, m_str) != 0)
+               errx(1, "receiver: data isn't correct second time");
 
        exit(0);
 }