libsysprof-capture: Use malloc() rather than g_new0() and friends

Another step away from GLib. This changes the OOM behaviour of the
library — previously it would immediately `abort()` on OOM. However, it
seems likely that given the small number of allocations
libsysprof-capture does, it should be able to recover from an OOM
situation more gracefully than larger libraries can — so the new
implementation tries to do that.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Helps: #40

src/libsysprof-capture/mapped-ring-buffer.c

@@ -203,7 +203,10 @@ mapped_ring_buffer_new_reader (size_t buffer_size)
   header->offset = page_size;
   header->size = buffer_size - page_size;
 
-  self = g_slice_new0 (MappedRingBuffer);
+  self = sysprof_malloc0 (sizeof (MappedRingBuffer));
+  if (self == NULL)
+    return NULL;
+
   self->ref_count = 1;
   self->mode = MODE_READER;
   self->body_size = buffer_size - page_size;
@@ -301,7 +304,14 @@ mapped_ring_buffer_new_writer (int fd)
       return NULL;
     }
 
-  self = g_slice_new0 (MappedRingBuffer);
+  self = sysprof_malloc0 (sizeof (MappedRingBuffer));
+  if (self == NULL)
+    {
+      munmap (map, page_size + ((buffer_size - page_size) * 2));
+      close (fd);
+      return NULL;
+    }
+
   self->ref_count = 1;
   self->mode = MODE_WRITER;
   self->fd = fd;

src/libsysprof-capture/sysprof-capture-condition.c

@@ -63,6 +63,7 @@
 #include <string.h>
 
 #include "sysprof-capture-condition.h"
+#include "sysprof-capture-util-private.h"
 #include "sysprof-macros-internal.h"
 
 /**
@@ -204,7 +205,10 @@ sysprof_capture_condition_init (void)
 {
   SysprofCaptureCondition *self;
 
-  self = g_slice_new0 (SysprofCaptureCondition);
+  self = sysprof_malloc0 (sizeof (SysprofCaptureCondition));
+  if (self == NULL)
+    return NULL;
+
   self->ref_count = 1;
 
   return g_steal_pointer (&self);
@@ -294,7 +298,7 @@ sysprof_capture_condition_finalize (SysprofCaptureCondition *self)
       break;
     }
 
-  g_slice_free (SysprofCaptureCondition, self);
+  free (self);
 }
 
 SysprofCaptureCondition *

src/libsysprof-capture/sysprof-capture-cursor.c

@@ -63,6 +63,7 @@
 #include "sysprof-capture-condition.h"
 #include "sysprof-capture-cursor.h"
 #include "sysprof-capture-reader.h"
+#include "sysprof-capture-util-private.h"
 
 #define READ_DELEGATE(f) ((ReadDelegate)(f))
 
@@ -81,7 +82,7 @@ sysprof_capture_cursor_finalize (SysprofCaptureCursor *self)
 {
   g_clear_pointer (&self->conditions, g_ptr_array_unref);
   g_clear_pointer (&self->reader, sysprof_capture_reader_unref);
-  g_slice_free (SysprofCaptureCursor, self);
+  free (self);
 }
 
 static SysprofCaptureCursor *
@@ -89,7 +90,10 @@ sysprof_capture_cursor_init (void)
 {
   SysprofCaptureCursor *self;
 
-  self = g_slice_new0 (SysprofCaptureCursor);
+  self = sysprof_malloc0 (sizeof (SysprofCaptureCursor));
+  if (self == NULL)
+    return NULL;
+
   self->conditions = g_ptr_array_new_with_free_func ((GDestroyNotify) sysprof_capture_condition_unref);
   self->ref_count = 1;
 

src/libsysprof-capture/sysprof-capture-reader.c

@@ -126,9 +126,9 @@ sysprof_capture_reader_finalize (SysprofCaptureReader *self)
   if (self != NULL)
     {
       close (self->fd);
-      g_free (self->buf);
+      free (self->buf);
       g_free (self->filename);
-      g_free (self);
+      free (self);
     }
 }
 
@@ -216,10 +216,23 @@ sysprof_capture_reader_new_from_fd (int      fd,
 
   assert (fd > -1);
 
-  self = g_new0 (SysprofCaptureReader, 1);
+  self = sysprof_malloc0 (sizeof (SysprofCaptureReader));
+  if (self == NULL)
+    {
+      g_set_error_literal (error, G_FILE_ERROR, G_FILE_ERROR_NOMEM, "No memory");
+      return NULL;
+    }
+
   self->ref_count = 1;
   self->bufsz = USHRT_MAX * 2;
-  self->buf = g_malloc (self->bufsz);
+  self->buf = sysprof_malloc0 (self->bufsz);
+  if (self->buf == NULL)
+    {
+      free (self);
+      g_set_error_literal (error, G_FILE_ERROR, G_FILE_ERROR_NOMEM, "No memory");
+      return NULL;
+    }
+
   self->len = 0;
   self->pos = 0;
   self->fd = fd;
@@ -1156,7 +1169,12 @@ sysprof_capture_reader_copy (SysprofCaptureReader *self)
   if (-1 == (fd = dup (self->fd)))
     return NULL;
 
-  copy = g_new0 (SysprofCaptureReader, 1);
+  copy = sysprof_malloc0 (sizeof (SysprofCaptureReader));
+  if (copy == NULL)
+    {
+      close (fd);
+      return NULL;
+    }
 
   *copy = *self;
 
@@ -1167,7 +1185,15 @@ sysprof_capture_reader_copy (SysprofCaptureReader *self)
   copy->st_buf = self->st_buf;
   copy->st_buf_set = self->st_buf_set;
 
-  copy->buf = g_malloc (self->bufsz);
+  copy->buf = malloc (self->bufsz);
+  if (copy->buf == NULL)
+    {
+      close (fd);
+      g_free (copy->filename);
+      free (copy);
+      return NULL;
+    }
+
   memcpy (copy->buf, self->buf, self->bufsz);
 
   return copy;

src/libsysprof-capture/sysprof-capture-util-private.h

@@ -62,8 +62,20 @@
 # include <sys/sendfile.h>
 #endif
 
+#include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
+static inline void *
+sysprof_malloc0 (size_t size)
+{
+  void *ptr = malloc (size);
+  if (ptr == NULL)
+    return NULL;
+  memset (ptr, 0, size);
+  return ptr;
+}
+
 #ifdef __linux__
 # define _sysprof_getpagesize()     getpagesize()
 # define _sysprof_pread(a,b,c,d)    pread(a,b,c,d)

src/libsysprof-capture/sysprof-capture-writer.c

@@ -181,8 +181,8 @@ sysprof_capture_writer_finalize (SysprofCaptureWriter *self)
           self->fd = -1;
         }
 
-      g_free (self->buf);
+      free (self->buf);
-      g_free (self);
+      free (self);
     }
 }
 
@@ -483,10 +483,18 @@ sysprof_capture_writer_new_from_fd (int    fd,
   /* This is only useful on files, memfd, etc */
   if (ftruncate (fd, 0) != 0) { /* Do Nothing */ }
 
-  self = g_new0 (SysprofCaptureWriter, 1);
+  self = sysprof_malloc0 (sizeof (SysprofCaptureWriter));
+  if (self == NULL)
+    return NULL;
+
   self->ref_count = 1;
   self->fd = fd;
-  self->buf = (guint8 *)g_malloc0 (buffer_size);
+  self->buf = (uint8_t *) sysprof_malloc0 (buffer_size);
+  if (self->buf == NULL)
+    {
+      free (self);
+      return NULL;
+    }
   self->len = buffer_size;
   self->next_counter_id = 1;
 

src/libsysprof-capture/sysprof-collector.c

@@ -75,6 +75,7 @@
 
 #include "mapped-ring-buffer.h"
 
+#include "sysprof-capture-util-private.h"
 #include "sysprof-collector.h"
 
 #define MAX_UNWIND_DEPTH 128
@@ -214,7 +215,7 @@ sysprof_collector_free (void *data)
           mapped_ring_buffer_unref (buffer);
         }
 
-      g_free (collector);
+      free (collector);
     }
 }
 
@@ -238,9 +239,12 @@ sysprof_collector_get (void)
 
     g_private_replace (&collector_key, COLLECTOR_INVALID);
 
+    self = sysprof_malloc0 (sizeof (SysprofCollector));
+    if (self == NULL)
+      return COLLECTOR_INVALID;
+
     G_LOCK (control_fd);
 
-    self = g_new0 (SysprofCollector, 1);
     self->pid = getpid ();
 #ifdef __linux__
     self->tid = syscall (__NR_gettid, 0);