Changeset 1ed69dc for lib

Timestamp:

06/28/18 11:26:07 (3 years ago)

Author:

Shane Alcock <salcock@…>

Branches:

cachetimestamps, develop, master, rc-4.0.4, ringdecrementfix, ringperformance

Children:

055a2c9, b06b894

Parents:

47d4f8c

Message:

Be less casual with error checking in SCB data structure

• ftruncate can fail, so actually check for that during init.
• If this does happen, return an error from libtrace_scb_init() -- this means that libtrace_scb_init() now returns an int rather than void.
• Update other API functions to make sure that they don't die horribly if the error returned by init is ignored.

Location:

lib/data-struct

Files:

• simple_circular_buffer.c (modified) (5 diffs)
• simple_circular_buffer.h (modified) (1 diff)

lib/data-struct/simple_circular_buffer.c

@@ -10 +10 @@
 #include <fcntl.h>
 #include <sys/socket.h>
+#include <errno.h>
 
 #include "simple_circular_buffer.h"
 
-DLLEXPORT void libtrace_scb_init(libtrace_scb_t *buf, uint32_t size,
+DLLEXPORT int libtrace_scb_init(libtrace_scb_t *buf, uint32_t size,
                 uint16_t id) {
 
@@ -28 +29 @@
         buf->fd = shm_open(anonname, O_RDWR | O_CREAT, 0600);
 #endif
-        ftruncate(buf->fd, size);
-
-        buf->address = mmap(NULL, 2 * size, PROT_NONE,
-                        MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-        mmap(buf->address, size, PROT_READ | PROT_WRITE,
-                        MAP_SHARED | MAP_FIXED, buf->fd, 0);
-        mmap(buf->address + size, size, PROT_READ | PROT_WRITE,
-                        MAP_SHARED | MAP_FIXED, buf->fd, 0);
+        if (ftruncate(buf->fd, size) < 0) {
+                perror("ftruncate in libtrace_scb_init");
+                close(buf->fd);
+                buf->fd = -1;
+                buf->address = NULL;
+        } else {
+                buf->address = mmap(NULL, 2 * size, PROT_NONE,
+                                MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+                mmap(buf->address, size, PROT_READ | PROT_WRITE,
+                                MAP_SHARED | MAP_FIXED, buf->fd, 0);
+                mmap(buf->address + size, size, PROT_READ | PROT_WRITE,
+                                MAP_SHARED | MAP_FIXED, buf->fd, 0);
+        }
         buf->read_offset = 0;
         buf->write_offset = 0;
         buf->count_bytes = size;
+
+        if (buf->address) {
+                return 0;
+        }
+        return -1;
 }
 
@@ -44 +55 @@
         /* TODO shm_unlink the file name if we used shm_open? */
 
-        munmap(buf->address, buf->count_bytes * 2);
-        close(buf->fd);
+        if (buf->address) {
+                munmap(buf->address, buf->count_bytes * 2);
+        }
+        if (buf->fd != -1) {
+                close(buf->fd);
+        }
 }
 
@@ -52 +67 @@
         int space = buf->count_bytes - (buf->write_offset - buf->read_offset);
         int ret;
+
+        if (buf->address == NULL) {
+                return -1;
+        }
 
         if (space == 0) {
@@ -68 +87 @@
                 uint32_t *available) {
 
+        if (buf->address == NULL) {
+                return NULL;
+        }
         *available = buf->write_offset - buf->read_offset;
         return buf->address + buf->read_offset;

lib/data-struct/simple_circular_buffer.h

@@ -13 +13 @@
 
 
-DLLEXPORT void libtrace_scb_init(libtrace_scb_t *buf, uint32_t size,
+DLLEXPORT int libtrace_scb_init(libtrace_scb_t *buf, uint32_t size,
                 uint16_t id);
 DLLEXPORT void libtrace_scb_destroy(libtrace_scb_t *buf);