Move include/ust/ to include/lttng/

[lttng-ust.git] / libringbuffer / shm.c

diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c
index 6a77af6462a61d93a3c5c1bfb8fff214f546de62..fc7fbfb2c0642ca0c410ddae0c6cd1a45b5a792e 100644 (file)
--- a/libringbuffer/shm.c
+++ b/libringbuffer/shm.c
@@ -13,7 +13,10 @@
 #include <sys/stat.h>  /* For mode constants */
 #include <fcntl.h>     /* For O_* constants */
 #include <assert.h>
-#include <ust/align.h>
+#include <stdio.h>
+#include <signal.h>
+#include <dirent.h>
+#include <lttng/align.h>
 
 struct shm_object_table *shm_object_table_create(size_t max_nb_obj)
 {
@@ -28,13 +31,15 @@ struct shm_object_table *shm_object_table_create(size_t max_nb_obj)
 struct shm_object *shm_object_table_append(struct shm_object_table *table,
                                           size_t memory_map_size)
 {
-       int shmfd, waitfd[2], ret, i;
+       int shmfd, waitfd[2], ret, i, sigblocked = 0;
        struct shm_object *obj;
        char *memory_map;
+       char tmp_name[NAME_MAX] = "ust-shm-tmp-XXXXXX";
+       sigset_t all_sigs, orig_sigs;
 
        if (table->allocated_len >= table->size)
                return NULL;
-       obj = &table->objects[table->allocated_len++];
+       obj = &table->objects[table->allocated_len];
 
        /* wait_fd: create pipe */
        ret = pipe(waitfd);
@@ -55,10 +60,23 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
                PERROR("fcntl");
                goto error_fcntl;
        }
-       *obj->wait_fd = *waitfd;
+       memcpy(obj->wait_fd, waitfd, sizeof(waitfd));
 
        /* shm_fd: create shm */
 
+       /*
+        * Theoretically, we could leak a shm if the application crashes
+        * between open and unlink. Disable signals on this thread for
+        * increased safety against this scenario.
+        */
+       sigfillset(&all_sigs);
+       ret = pthread_sigmask(SIG_BLOCK, &all_sigs, &orig_sigs);
+       if (ret == -1) {
+               PERROR("pthread_sigmask");
+               goto error_pthread_sigmask;
+       }
+       sigblocked = 1;
+
        /*
         * Allocate shm, and immediately unlink its shm oject, keeping
         * only the file descriptor as a reference to the object. If it
@@ -69,17 +87,32 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
         * the process (POSIX leaves this implementation-defined).
         */
        do {
-               shmfd = shm_open("ust-shm-tmp",
+               /*
+                * Using mktemp filename with O_CREAT | O_EXCL open
+                * flags.
+                */
+               mktemp(tmp_name);
+               if (tmp_name[0] == '\0') {
+                       PERROR("mktemp");
+                       goto error_shm_open;
+               }
+               shmfd = shm_open(tmp_name,
                                 O_CREAT | O_EXCL | O_RDWR, 0700);
-       } while (shmfd < 0 && errno == EEXIST);
+       } while (shmfd < 0 && (errno == EEXIST || errno == EACCES));
        if (shmfd < 0) {
                PERROR("shm_open");
                goto error_shm_open;
        }
-       ret = shm_unlink("ust-shm-tmp");
-       if (ret) {
+       ret = shm_unlink(tmp_name);
+       if (ret < 0 && errno != ENOENT) {
                PERROR("shm_unlink");
-               goto error_unlink;
+               goto error_shm_release;
+       }
+       sigblocked = 0;
+       ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL);
+       if (ret == -1) {
+               PERROR("pthread_sigmask");
+               goto error_sigmask_release;
        }
        ret = ftruncate(shmfd, memory_map_size);
        if (ret) {
@@ -98,17 +131,27 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
        obj->memory_map = memory_map;
        obj->memory_map_size = memory_map_size;
        obj->allocated_len = 0;
+       obj->index = table->allocated_len++;
+
        return obj;
 
 error_mmap:
 error_ftruncate:
-error_unlink:
+error_shm_release:
+error_sigmask_release:
        ret = close(shmfd);
        if (ret) {
                PERROR("close");
                assert(0);
        }
 error_shm_open:
+       if (sigblocked) {
+               ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL);
+               if (ret == -1) {
+                       PERROR("pthread_sigmask");
+               }
+       }
+error_pthread_sigmask:
 error_fcntl:
        for (i = 0; i < 2; i++) {
                ret = close(waitfd[i]);
@@ -118,11 +161,43 @@ error_fcntl:
                }
        }
 error_pipe:
-       free(obj);
        return NULL;
        
 }
 
+struct shm_object *shm_object_table_append_shadow(struct shm_object_table *table,
+                       int shm_fd, int wait_fd, size_t memory_map_size)
+{
+       struct shm_object *obj;
+       char *memory_map;
+
+       if (table->allocated_len >= table->size)
+               return NULL;
+       obj = &table->objects[table->allocated_len];
+
+       /* wait_fd: set read end of the pipe. */
+       obj->wait_fd[0] = wait_fd;
+       obj->wait_fd[1] = -1;   /* write end is unset. */
+       obj->shm_fd = shm_fd;
+
+       /* memory_map: mmap */
+       memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE,
+                         MAP_SHARED, shm_fd, 0);
+       if (memory_map == MAP_FAILED) {
+               PERROR("mmap");
+               goto error_mmap;
+       }
+       obj->memory_map = memory_map;
+       obj->memory_map_size = memory_map_size;
+       obj->allocated_len = memory_map_size;
+       obj->index = table->allocated_len++;
+
+       return obj;
+
+error_mmap:
+       return NULL;
+}
+
 static
 void shmp_object_destroy(struct shm_object *obj)
 {
@@ -139,6 +214,8 @@ void shmp_object_destroy(struct shm_object *obj)
                assert(0);
        }
        for (i = 0; i < 2; i++) {
+               if (obj->wait_fd[i] < 0)
+                       continue;
                ret = close(obj->wait_fd[i]);
                if (ret) {
                        PERROR("close");