From 1874938c0d35990f95e494a7fef066bf97001d8f Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@gmail.com>
Date: Tue, 29 Jun 2010 21:17:39 -0600
Subject: Move platform-specific stuff in libdimension into platform.c.

---
 libdimension/error.c    | 27 +++++----------------------
 libdimension/platform.c | 33 +++++++++++++++++++++++++++++++--
 libdimension/platform.h | 11 +++++++++++
 libdimension/png.c      |  3 +--
 4 files changed, 48 insertions(+), 26 deletions(-)

diff --git a/libdimension/error.c b/libdimension/error.c
index 49b1d8d..bc0e3e2 100644
--- a/libdimension/error.c
+++ b/libdimension/error.c
@@ -18,15 +18,10 @@
  * <http://www.gnu.org/licenses/>.                                       *
  *************************************************************************/
 
-#define _GNU_SOURCE
-#include <unistd.h>
-#include <sys/syscall.h> /* For gettid() where supported */
-#include <execinfo.h>    /* For backtrace() etc. */
-
-#include "dimension.h"
+#include "dimension_impl.h"
 #include <pthread.h>
-#include <stdio.h>       /* For fprintf() */
-#include <stdlib.h>      /* For exit() */
+#include <stdio.h>     /* For fprintf() */
+#include <stdlib.h>    /* For exit() */
 
 static void dmnsn_default_fatal_error_fn();
 static dmnsn_fatal_error_fn *dmnsn_fatal = &dmnsn_default_fatal_error_fn;
@@ -139,18 +134,9 @@ void dmnsn_set_fatal_error_fn(dmnsn_fatal_error_fn *fatal)
 static void
 dmnsn_default_fatal_error_fn()
 {
-  const unsigned int size = 64;
-  void *buffer[size];
-
-  int nptrs = backtrace(buffer, size);
-  /* buffer + 1 to hide this static function */
-  backtrace_symbols_fd(buffer + 1, nptrs - 1, STDERR_FILENO);
-
-#ifdef SYS_gettid
-  pid_t pid = getpid(),
-        tid = syscall(SYS_gettid);
+  dmnsn_backtrace(stderr);
 
-  if (pid == tid) {
+  if (dmnsn_is_main_thread()) {
     exit(EXIT_FAILURE);
   } else {
     int *ret = malloc(sizeof(int)); /* Don't use dmnsn_malloc */
@@ -158,7 +144,4 @@ dmnsn_default_fatal_error_fn()
       *ret = 1;
     pthread_exit(ret);
   }
-#else
-  exit(EXIT_FAILURE);
-#endif
 }
diff --git a/libdimension/platform.c b/libdimension/platform.c
index 6ac15c0..be7e7a8 100644
--- a/libdimension/platform.c
+++ b/libdimension/platform.c
@@ -19,8 +19,37 @@
  *************************************************************************/
 
 #include "dimension_impl.h"
-#include <unistd.h> /* For sysconf() */
-#include <sched.h>  /* For sched_getaffinity() */
+#include <unistd.h>      /* For sysconf() */
+#include <arpa/inet.h>   /* For htonl() */
+#include <execinfo.h>    /* For backtrace() etc. */
+#include <sys/syscall.h> /* For gettid() where supported */
+#include <sched.h>       /* For sched_getaffinity() */
+
+void
+dmnsn_backtrace(FILE *file)
+{
+  const size_t size = 128;
+  void *buffer[size];
+
+  int nptrs = backtrace(buffer, size);
+  backtrace_symbols_fd(buffer, nptrs, fileno(file));
+}
+
+bool
+dmnsn_is_main_thread()
+{
+#ifdef SYS_gettid
+  return getpid() == syscall(SYS_gettid);
+#else
+  return true;
+#endif
+}
+
+bool
+dmnsn_is_little_endian()
+{
+  return htonl(1) != 1;
+}
 
 size_t
 dmnsn_ncpus()
diff --git a/libdimension/platform.h b/libdimension/platform.h
index bda83dd..a2bcd39 100644
--- a/libdimension/platform.h
+++ b/libdimension/platform.h
@@ -21,7 +21,18 @@
 #ifndef DIMENSION_IMPL_UTILITIES_H
 #define DIMENSION_IMPL_UTILITIES_H
 
+#include <stdbool.h>
 #include <stddef.h>
+#include <stdio.h>
+
+/* Provide a stack trace if possible */
+void dmnsn_backtrace(FILE *file);
+
+/* Return whether this is the main execution thread, if we can tell */
+bool dmnsn_is_main_thread();
+
+/* Return true if we are little-endian */
+bool dmnsn_is_little_endian();
 
 /* Return the number of CPUs available to dimension */
 size_t dmnsn_ncpus();
diff --git a/libdimension/png.c b/libdimension/png.c
index 9bece58..7c21475 100644
--- a/libdimension/png.c
+++ b/libdimension/png.c
@@ -21,7 +21,6 @@
 #include "dimension_impl.h"
 #include <pthread.h>
 #include <png.h>
-#include <arpa/inet.h>
 #include <errno.h>
 #include <setjmp.h>
 #include <stdlib.h>
@@ -245,7 +244,7 @@ dmnsn_png_write_canvas_thread(void *ptr)
   /* Write the info struct */
   png_write_info(png_ptr, info_ptr);
 
-  if (htonl(1) != 1) {
+  if (dmnsn_is_little_endian()) {
     /* We are little-endian; swap the byte order of the pixels */
     png_set_swap(png_ptr);
   }
-- 
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