Improved allocation failure reporting

Now it reports file and line number of the function too.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/meson.build

@@ -4,7 +4,7 @@ deps = [
 	dependency('xcb', version: '>=1.9.2'),
 ]
 
-srcs = [ files('compton.c', 'win.c', 'c2.c', 'x.c', 'config.c', 'vsync.c',
+srcs = [ files('compton.c', 'win.c', 'c2.c', 'x.c', 'config.c', 'vsync.c', 'utils.c',
                'diagnostic.c', 'string_utils.c', 'render.c', 'kernel.c', 'log.c')]
 
 cflags = []

src/string_utils.h

@@ -11,6 +11,25 @@ char *
 mstrjoin3(const char *src1, const char *src2, const char *src3);
 void mstrextend(char **psrc1, const char *src2);
 
+static inline int uitostr(unsigned int n, char *buf) {
+  int ret = 0;
+  unsigned int tmp = n;
+  while (tmp > 0) {
+    tmp /= 10;
+    ret++;
+  }
+
+  if (ret == 0)
+    ret = 1;
+
+  int pos = ret;
+  while (pos--) {
+    buf[pos] = n%10 + '0';
+    n /= 10;
+  }
+  return ret;
+}
+
 static inline const char *
 skip_space_const(const char *src) {
   if (!src)

src/utils.c

@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <sys/uio.h>
+
+#include "compiler.h"
+#include "string_utils.h"
+#include "utils.h"
+
+/// Report allocation failure without allocating memory
+void report_allocation_failure(const char *func, const char *file, unsigned int line) {
+	// Since memory allocation failed, we try to print this error message without any
+	// memory allocation. Since logging framework allocates memory (and might even
+	// have not been initialized yet), so we can't use it.
+	char buf[11];
+	int llen = uitostr(line, buf);
+	const char msg1[] = " has failed to allocate memory, ";
+	const char msg2[] = ". Aborting...\n";
+	const struct iovec v[] = {
+	    {.iov_base = (void *)func, .iov_len = strlen(func)},
+	    {.iov_base = "()", .iov_len = 2},
+	    {.iov_base = (void *)msg1, .iov_len = sizeof(msg1) - 1},
+	    {.iov_base = "at ", .iov_len = 3},
+	    {.iov_base = (void *)file, .iov_len = strlen(file)},
+	    {.iov_base = ":", .iov_len = 1},
+	    {.iov_base = buf, .iov_len = llen},
+	    {.iov_base = (void *)msg2, .iov_len = sizeof(msg2) - 1},
+	};
+
+	writev(STDERR_FILENO, v, ARR_SIZE(v));
+	abort();
+
+	unreachable;
+}
+
+// vim: set noet sw=8 ts=8 :

src/utils.h

@@ -101,24 +101,21 @@ normalize_d(double d) {
   return normalize_d_range(d, 0.0, 1.0);
 }
 
+void report_allocation_failure(const char *func, const char *file, unsigned int line);
+
 /**
  * @brief Quit if the passed-in pointer is empty.
  */
 static inline void *
-allocchk_(const char *func_name, void *ptr) {
+allocchk_(const char *func_name, const char *file, unsigned int line, void *ptr) {
   if (unlikely(!ptr)) {
-    // Since memory allocation failed, we try to print
-    // this error message without any memory allocation.
-    const char msg[] = "(): Failed to allocate memory\n";
-    write(STDERR_FILENO, func_name, strlen(func_name));
-    write(STDERR_FILENO, msg, ARR_SIZE(msg));
-    abort();
+    report_allocation_failure(func_name, file, line);
   }
   return ptr;
 }
 
 /// @brief Wrapper of allocchk_().
-#define allocchk(ptr) allocchk_(__func__, ptr)
+#define allocchk(ptr) allocchk_(__func__, __FILE__, __LINE__, ptr)
 
 /// @brief Wrapper of malloc().
 #define cmalloc(type) ((type *) allocchk(malloc(sizeof(type))))