Add support for generating backtraces on Windows

This commit adds support for generating backtraces on Windows and
refactors the isc_backtrace API to match the Linux/BSD API (without
the isc_ prefix)

 * isc_backtrace_gettrace() was renamed to isc_backtrace(), the third
   argument was removed and the return type was changed to int
 * isc_backtrace_symbols() was added
 * isc_backtrace_symbols_fd() was added and used as appropriate

bin/named/main.c

@@ -205,8 +205,6 @@ assertion_failed(const char *file, int line, isc_assertiontype_t type,
 		 const char *cond) {
 	void *tracebuf[BACKTRACE_MAXFRAME];
 	int nframes;
-	isc_result_t result;
-	const char *logsuffix = "";
 
 	/*
 	 * Handle assertion failures.
@@ -219,32 +217,23 @@ assertion_failed(const char *file, int line, isc_assertiontype_t type,
 		 */
 		isc_assertion_setcallback(NULL);
 
-		result = isc_backtrace_gettrace(tracebuf, BACKTRACE_MAXFRAME,
-						&nframes);
-		if (result == ISC_R_SUCCESS && nframes > 0) {
-			logsuffix = ", back trace";
-		}
+		nframes = isc_backtrace(tracebuf, BACKTRACE_MAXFRAME);
 		isc_log_write(named_g_lctx, NAMED_LOGCATEGORY_GENERAL,
 			      NAMED_LOGMODULE_MAIN, ISC_LOG_CRITICAL,
 			      "%s:%d: %s(%s) failed%s", file, line,
-			      isc_assertion_typetotext(type), cond, logsuffix);
-		if (result == ISC_R_SUCCESS) {
-#if HAVE_BACKTRACE_SYMBOLS
-			char **strs = backtrace_symbols(tracebuf, nframes);
-			for (int i = 0; i < nframes; i++) {
-				isc_log_write(named_g_lctx,
-					      NAMED_LOGCATEGORY_GENERAL,
-					      NAMED_LOGMODULE_MAIN,
-					      ISC_LOG_CRITICAL, "%s", strs[i]);
+			      isc_assertion_typetotext(type), cond,
+			      (nframes > 0) ? ", back trace" : "");
+		if (nframes > 0) {
+			char **strs = isc_backtrace_symbols(tracebuf, nframes);
+			if (strs != NULL) {
+				for (int i = 0; i < nframes; i++) {
+					isc_log_write(named_g_lctx,
+						      NAMED_LOGCATEGORY_GENERAL,
+						      NAMED_LOGMODULE_MAIN,
+						      ISC_LOG_CRITICAL, "%s",
+						      strs[i]);
+				}
 			}
-#else  /* HAVE_BACKTRACE_SYMBOLS */
-			for (int i = 0; i < nframes; i++) {
-				isc_log_write(
-					named_g_lctx, NAMED_LOGCATEGORY_GENERAL,
-					NAMED_LOGMODULE_MAIN, ISC_LOG_CRITICAL,
-					"#%d %p in ??", i, tracebuf[i]);
-			}
-#endif /* HAVE_BACKTRACE_SYMBOLS */
 		}
 		isc_log_write(named_g_lctx, NAMED_LOGCATEGORY_GENERAL,
 			      NAMED_LOGMODULE_MAIN, ISC_LOG_CRITICAL,

configure.ac

@@ -975,10 +975,8 @@ AC_SUBST([ZLIB_LIBS])
 # Check if the system supports glibc-compatible backtrace() function.
 #
 AC_CHECK_HEADERS([execinfo.h],
-		 [AC_SEARCH_LIBS([backtrace], [execinfo],
-				 [AC_CHECK_FUNCS([backtrace backtrace_symbols])])])
-
-AM_CONDITIONAL([HAVE_BACKTRACE], [test "$ac_cv_func_backtrace" = "yes"])
+		 [AC_SEARCH_LIBS([backtrace_symbols], [execinfo],
+				 [AC_CHECK_FUNCS([backtrace_symbols])])])
 
 #
 # We do the IPv6 compilation checking after libtool so that we can put

lib/isc/assertions.c

@@ -16,8 +16,14 @@
 
 #include <isc/assertions.h>
 #include <isc/backtrace.h>
+#include <isc/platform.h>
 #include <isc/print.h>
 #include <isc/result.h>
+#include <isc/strerr.h>
+
+#if _WIN32
+#include <dbghelp.h>
+#endif
 
 /*
  * The maximum number of stack frames to dump on assertion failure.
@@ -95,30 +101,15 @@ static void
 default_callback(const char *file, int line, isc_assertiontype_t type,
 		 const char *cond) {
 	void *tracebuf[BACKTRACE_MAXFRAME];
-	int nframes;
-	bool have_backtrace = false;
-	isc_result_t result;
-
-	result = isc_backtrace_gettrace(tracebuf, BACKTRACE_MAXFRAME, &nframes);
-	if (result == ISC_R_SUCCESS && nframes > 0) {
-		have_backtrace = true;
-	}
+	int nframes = isc_backtrace(tracebuf, BACKTRACE_MAXFRAME);
 
 	fprintf(stderr, "%s:%d: %s(%s) failed%s\n", file, line,
 		isc_assertion_typetotext(type), cond,
-		(have_backtrace) ? ", back trace" : ".");
+		(nframes > 0) ? ", back trace" : ".");
 
-	if (result == ISC_R_SUCCESS) {
-#if HAVE_BACKTRACE_SYMBOLS
-		char **strs = backtrace_symbols(tracebuf, nframes);
-		for (int i = 0; i < nframes; i++) {
-			fprintf(stderr, "%s\n", strs[i]);
-		}
-#else  /* HAVE_BACKTRACE_SYMBOLS */
-		for (int i = 0; i < nframes; i++) {
-			fprintf(stderr, "#%d %p in ??\n", i, tracebuf[i]);
-		}
-#endif /* HAVE_BACKTRACE_SYMBOLS */
+	if (nframes > 0) {
+		isc_backtrace_symbols_fd(tracebuf, nframes, fileno(stderr));
 	}
+
 	fflush(stderr);
 }

lib/isc/backtrace.c

@@ -13,46 +13,245 @@
 
 #include <stdlib.h>
 #include <string.h>
-#ifdef HAVE_BACKTRACE
+#ifdef HAVE_BACKTRACE_SYMBOLS
 #include <execinfo.h>
-#endif /* HAVE_BACKTRACE */
+#endif /* HAVE_BACKTRACE_SYMBOLS */
 
 #include <isc/backtrace.h>
+#include <isc/platform.h>
+#include <isc/print.h>
 #include <isc/result.h>
 #include <isc/util.h>
 
-#ifdef HAVE_BACKTRACE
-isc_result_t
-isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes) {
+#if defined(_WIN32) && defined(_DEBUG)
+
+#include <dbghelp.h>
+
+int
+isc_backtrace(void **addrs, int maxaddrs, int *nframes) {
+	USHORT n = CaptureStackBackTrace(1, maxaddrs, addrs, NULL);
+
+	return (n);
+}
+
+#define TRACE_MAX_DEPTH		       128
+#define TRACE_MAX_FUNCTION_NAME_LENGTH 1024
+
+int
+vasprintf(char **strp, const char *format, va_list ap) {
+	int len, retval;
+	char *str = NULL;
+
+	len = _vscprintf(format, ap);
+	if (len == -1) {
+		return (-1);
+	}
+
+	str = malloc((size_t)len + 1);
+	if (str == NULL) {
+		return (-1);
+	}
+
+	retval = vsnprintf(str, len + 1, format, ap);
+	if (retval == -1) {
+		free(str);
+		return (-1);
+	}
+
+	*strp = str;
+	return (retval);
+}
+
+int
+asprintf(char **strp, const char *format, ...) {
+	va_list ap;
+	int retval;
+
+	va_start(ap, format);
+	retval = vasprintf(strp, format, ap);
+	va_end(ap);
+
+	return (retval);
+}
+
+static char **
+_backtrace_symbols(void *const *buffer, size_t size, bool add_cr) {
+	HANDLE process = GetCurrentProcess();
+	DWORD displacement;
+	uint8_t symbol_storage[sizeof(SYMBOL_INFO) +
+			       (TRACE_MAX_FUNCTION_NAME_LENGTH - 1) *
+				       sizeof(TCHAR)];
+	SYMBOL_INFO *symbol = (SYMBOL_INFO *)symbol_storage;
+	uint8_t line_storage[sizeof(IMAGEHLP_LINE64)];
+	IMAGEHLP_LINE64 *line = (IMAGEHLP_LINE64 *)line_storage;
+	char **lines = NULL;
+	char **outbuf = NULL;
+	char *cur = NULL;
+	size_t outsize = 0;
+
+	if (buffer == NULL || size <= 0) {
+		return (NULL);
+	}
+
+	lines = malloc(size * sizeof(*lines));
+	if (lines == NULL) {
+		return (NULL);
+	}
+
+	/* Initialize symbol_info */
+	symbol->MaxNameLen = TRACE_MAX_FUNCTION_NAME_LENGTH;
+	symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
+
+	line->SizeOfStruct = sizeof(IMAGEHLP_LINE64);
+
+	SymInitialize(process, NULL, TRUE);
+
+	/* adjust for the char ** array size */
+	outsize = size * sizeof(char *);
+	for (size_t i = 0; i < size; i++) {
+		DWORD64 address = (DWORD64)(buffer[i]);
+		BOOL r;
+		char *file = NULL;
+		unsigned int lineno;
+		int len;
+
+		if (SymFromAddr(process, address, NULL, symbol) &&
+		    SymGetLineFromAddr64(process, address, &displacement, line))
+		{
+			file = line->FileName;
+			lineno = line->LineNumber;
+		} else {
+			file = "??";
+			lineno = 0;
+		}
+
+		len = asprintf(&lines[i], "#%-2d %p in %s at %s:%lu%s", i,
+			       (void *)symbol->Address, symbol->Name,
+			       line->FileName, line->LineNumber,
+			       (add_cr) ? "\n" : "");
+		if (len == -1) {
+			goto cleanup;
+		}
+
+		outsize += strlen(lines[i]) + 1;
+	}
+
+	outbuf = malloc(outsize);
+	if (outbuf == NULL) {
+		goto cleanup;
+	}
+
+	cur = (char *)&outbuf[size];
+	for (size_t i = 0; i < size; i++) {
+		size_t remaining = outsize - (cur - (char *)outbuf);
+		size_t copied = strlcpy(cur, lines[i], remaining);
+		if (copied >= remaining) {
+			free(outbuf);
+			outbuf = NULL;
+			goto cleanup;
+		}
+
+		outbuf[i] = cur;
+		cur += copied + 1;
+	}
+
+cleanup:
+	for (size_t i = 0; i < size; i++) {
+		free(lines[i]);
+	}
+	free(lines);
+
+	return (outbuf);
+}
+
+char **
+isc_backtrace_symbols(void *const *buffer, int size) {
+	if (buffer == NULL || size <= 0) {
+		return (NULL);
+	}
+	return (_backtrace_symbols(buffer, size, false));
+}
+
+void
+isc_backtrace_symbols_fd(void *const *buffer, int size, int fd) {
+	char **strings = NULL;
+	size_t sz;
+
+	strings = _backtrace_symbols(buffer, size, true);
+	if (strings == NULL) {
+		return;
+	}
+
+	for (size_t i = 0; i < (size_t)size; i++) {
+		sz = strlen(strings[i]);
+		if (write(fd, strings[i], sz) == -1) {
+			return;
+		}
+	}
+
+	free(strings);
+}
+
+#elif HAVE_BACKTRACE_SYMBOLS
+int
+isc_backtrace(void **addrs, int maxaddrs) {
+	int n;
+
 	/*
 	 * Validate the arguments: intentionally avoid using REQUIRE().
 	 * See notes in backtrace.h.
 	 */
-	if (addrs == NULL || nframes == NULL) {
-		return (ISC_R_FAILURE);
+	if (addrs == NULL || maxaddrs <= 0) {
+		return (-1);
 	}
 
 	/*
 	 * backtrace(3) includes this function itself in the address array,
 	 * which should be eliminated from the returned sequence.
 	 */
-	int n = backtrace(addrs, maxaddrs);
+	n = backtrace(addrs, maxaddrs);
 	if (n < 2) {
-		return (ISC_R_NOTFOUND);
+		return (-1);
 	}
 	n--;
 	memmove(addrs, &addrs[1], sizeof(addrs[0]) * n);
-	*nframes = n;
-	return (ISC_R_SUCCESS);
+
+	return (n);
 }
 
-#else  /* HAVE_BACKTRACE */
-isc_result_t
-isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes) {
+char **
+isc_backtrace_symbols(void *const *buffer, int size) {
+	return (backtrace_symbols(buffer, size));
+}
+
+void
+isc_backtrace_symbols_fd(void *const *buffer, int size, int fd) {
+	backtrace_symbols_fd(buffer, size, fd);
+}
+
+#else /* HAVE_BACKTRACE_SYMBOLS */
+
+int
+isc_backtrace(void **addrs, int maxaddrs) {
 	UNUSED(addrs);
 	UNUSED(maxaddrs);
-	UNUSED(nframes);
 
-	return (ISC_R_NOTIMPLEMENTED);
+	return (-1);
 }
-#endif /* HAVE_BACKTRACE */
+
+char **
+isc_backtrace_symbols(void *const *buffer, int size) {
+	UNUSED(buffer);
+	UNUSED(size);
+
+	return (NULL);
+}
+
+void
+isc_backtrace_symbols_fd(void *const *buffer, int size, int fd) {
+	UNUSED(buffer);
+	UNUSED(size);
+	UNUSED(fd);
+}
+
+#endif /* HAVE_BACKTRACE_SYMBOLS */

lib/isc/include/isc/backtrace.h

@@ -22,25 +22,14 @@
  * dumping a back trace on a fatal error, normally followed by self termination,
  * functions defined in this module generally doesn't employ assertion checks
  * (if it did, a program bug could cause infinite recursive calls to a
- * backtrace function).  These functions still perform minimal checks and return
- * ISC_R_FAILURE if they detect an error, but the caller should therefore be
- * very careful about the use of these functions, and generally discouraged to
- * use them except in an exit path.  The exception is
- * isc_backtrace_getsymbolfromindex(), which is expected to be used in a
- * non-error-handling context and validates arguments with assertion checks.
+ * backtrace function).
  */
 
-#ifndef ISC_BACKTRACE_H
-#define ISC_BACKTRACE_H 1
+#pragma once
 
 /***
  ***	Imports
  ***/
-
-#if HAVE_BACKTRACE_SYMBOLS
-#include <execinfo.h>
-#endif /* HAVE_BACKTRACE_SYMBOLS */
-
 #include <isc/types.h>
 
 /***
@@ -48,8 +37,8 @@
  ***/
 
 ISC_LANG_BEGINDECLS
-isc_result_t
-isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes);
+int
+isc_backtrace(void **addrs, int maxaddrs);
 /*%<
  * Get a back trace of the running process above this function itself.  On
  * success, addrs[i] will store the address of the call point of the i-th
@@ -69,6 +58,42 @@ isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes);
  *\li	#ISC_R_NOTFOUND
  *\li	#ISC_R_NOTIMPLEMENTED
  */
-ISC_LANG_ENDDECLS
 
-#endif /* ISC_BACKTRACE_H */
+char **
+isc_backtrace_symbols(void *const *buffer, int size);
+/*
+ * isc_backtrace_symbols() attempts to transform a call stack obtained by
+ * backtrace() into an array of human-readable strings using dladdr().  The
+ * array of strings returned has size elements.  It is allocated using
+ * malloc() and should be released using free().  There is no need to free
+ * the individual strings in the array.
+ *
+ * Notes:
+ *
+ *\li	On Windows, this is shim implementation using SymFromAddr()
+ *\li	On systems with backtrace_symbols(), it's just a thin wrapper
+ *\li	Otherwise, it returns NULL
+ *\li	See platform NOTES for backtrace_symbols
+ *
+ * Returns:
+ *
+ *\li	On success, backtrace_symbols() returns a pointer to the array
+ *\li	On error, NULL is returned.
+ */
+
+void
+isc_backtrace_symbols_fd(void *const *buffer, int size, int fd);
+/*
+ * isc_backtrace_symbols_fd() performs the same operation as
+ * isc_backtrace_symbols(), but the resulting strings are immediately written to
+ * the file descriptor fd, and are not returned.  isc_backtrace_symbols_fd()
+ * does not call malloc(3), and so can be employed in situations where the
+ * latter function might fail.
+ *
+ * Notes:
+ *
+ *\li	See isc_backtrace_symbols() notes
+ *\li	See platform NOTES for backtrace_symbols_fd for caveats
+ */
+
+ISC_LANG_ENDDECLS

lib/isc/netmgr/netmgr.c

@@ -14,6 +14,7 @@
 #include <uv.h>
 
 #include <isc/atomic.h>
+#include <isc/backtrace.h>
 #include <isc/buffer.h>
 #include <isc/condition.h>
 #include <isc/errno.h>
@@ -39,16 +40,6 @@
 #include "openssl_shim.h"
 #include "uv-compat.h"
 
-#if NETMGR_TRACE
-#if HAVE_BACKTRACE
-#include <execinfo.h>
-#else /* HAVE_BACKTRACE */
-#define backtrace(buffer, size) 0
-#define backtrace_symbols_fd(buffer, size, fd) \
-	fprintf(stderr, "<not available>");
-#endif /* HAVE_BACKTRACE */
-#endif /* NETMGR_TRACE */
-
 /*%
  * How many isc_nmhandles and isc_nm_uvreqs will we be
  * caching for reuse in a socket.
@@ -1358,7 +1349,7 @@ isc___nmsocket_init(isc_nmsocket_t *sock, isc_nm_t *mgr, isc_nmsocket_type type,
 					  mgr->mctx, ISC_NM_REQS_STACK_SIZE) };
 
 #if NETMGR_TRACE
-	sock->backtrace_size = backtrace(sock->backtrace, TRACE_SIZE);
+	sock->backtrace_size = isc_backtrace(sock->backtrace, TRACE_SIZE);
 	ISC_LINK_INIT(sock, active_link);
 	ISC_LIST_INIT(sock->active_handles);
 	LOCK(&mgr->lock);
@@ -1506,7 +1497,7 @@ isc___nmhandle_get(isc_nmsocket_t *sock, isc_sockaddr_t *peer,
 	isc___nmsocket_attach(sock, &handle->sock FLARG_PASS);
 
 #if NETMGR_TRACE
-	handle->backtrace_size = backtrace(handle->backtrace, TRACE_SIZE);
+	handle->backtrace_size = isc_backtrace(handle->backtrace, TRACE_SIZE);
 #endif
 
 	if (peer != NULL) {
@@ -3096,8 +3087,8 @@ nmhandle_dump(isc_nmhandle_t *handle) {
 	fprintf(stderr, "Active handle %p, refs %" PRIuFAST32 "\n", handle,
 		isc_refcount_current(&handle->references));
 	fprintf(stderr, "Created by:\n");
-	backtrace_symbols_fd(handle->backtrace, handle->backtrace_size,
-			     STDERR_FILENO);
+	isc_backtrace_symbols_fd(handle->backtrace, handle->backtrace_size,
+				 STDERR_FILENO);
 	fprintf(stderr, "\n\n");
 }
 
@@ -3121,8 +3112,8 @@ nmsocket_dump(isc_nmsocket_t *sock) {
 		atomic_load(&sock->connecting) ? " connecting" : "",
 		sock->accepting ? " accepting" : "");
 	fprintf(stderr, "Created by:\n");
-	backtrace_symbols_fd(sock->backtrace, sock->backtrace_size,
-			     STDERR_FILENO);
+	isc_backtrace_symbols_fd(sock->backtrace, sock->backtrace_size,
+				 STDERR_FILENO);
 	fprintf(stderr, "\n");
 
 	for (handle = ISC_LIST_HEAD(sock->active_handles); handle != NULL;

lib/isc/win32/libisc.def.in

@@ -131,7 +131,9 @@ isc_appctx_destroy
 isc_assertion_failed
 isc_assertion_setcallback
 isc_assertion_typetotext
-isc_backtrace_gettrace
+isc_backtrace
+isc_backtrace_symbols
+isc_backtrace_symbols_fd
 isc_base32_decoderegion
 isc_base32_decodestring
 isc_base32_tobuffer

lib/isc/win32/libisc.vcxproj.in

@@ -80,7 +80,7 @@
       <SubSystem>Console</SubSystem>
       <GenerateDebugInformation>true</GenerateDebugInformation>
       <OutputFile>..\..\..\Build\$(Configuration)\$(TargetName)$(TargetExt)</OutputFile>
-      <AdditionalDependencies>@OPENSSL_LIBCRYPTO@@OPENSSL_LIBSSL@@LIBUV_LIB@@NGHTTP2_LIB@@LIBXML2_LIB@@ZLIB_LIB@ws2_32.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <AdditionalDependencies>@OPENSSL_LIBCRYPTO@@OPENSSL_LIBSSL@@LIBUV_LIB@@NGHTTP2_LIB@@LIBXML2_LIB@@ZLIB_LIB@ws2_32.lib;Dbghelp.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <ModuleDefinitionFile>$(ProjectName).def</ModuleDefinitionFile>
       <ImportLibrary>.\$(Configuration)\$(ProjectName).lib</ImportLibrary>
     </Link>
@@ -168,7 +168,7 @@ copy InstallFiles ..\Build\Debug\
       <ForcedIncludeFiles>..\..\..\config.h</ForcedIncludeFiles>
       <AdditionalIncludeDirectories>.\;..\..\..\;@LIBXML2_INC@@LIBUV_INC@@NGHTTP2_INC@@OPENSSL_INC@@ZLIB_INC@include;..\include;..\;win32;..\..\isccfg\include;..\..\dns\win32\include;..\..\dns\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
 @ELSE PKCS11
-      <PreprocessorDefinitions>BIND9;WIN32;_DEBUG;_WINDOWS;_USRDLL;LIBISC_EXPORTS;%(PreprocessorDefinitions);%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>BIND9;WIN32;NDEBUG;_WINDOWS;_USRDLL;LIBISC_EXPORTS;%(PreprocessorDefinitions);%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <ForcedIncludeFiles>..\..\..\config.h</ForcedIncludeFiles>
       <AdditionalIncludeDirectories>.\;..\..\..\;@LIBXML2_INC@@LIBUV_INC@@NGHTTP2_INC@@OPENSSL_INC@@ZLIB_INC@include;..\include;..\;win32;..\..\isccfg\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
 @END PKCS11