Merged revisions 298905 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

........
  r298905 | tilghman | 2010-12-17 15:40:56 -0600 (Fri, 17 Dec 2010) | 6 lines
  
  Let Asterisk find better backtrace information with libbfd.
  
  The menuselect option BETTER_BACKTRACES, if enabled, will use libbfd to search
  for better symbol information within both the Asterisk binary, as well as
  loaded modules, to assist when using inline backtraces to track down problems.
........


git-svn-id: http://svn.digium.com/svn/asterisk/branches/1.6.2@298957 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 152 insertions, 4 deletions

diff --git a/main/logger.c b/main/logger.c
index 6425183b3..9849a595c 100644
--- a/main/logger.c
+++ b/main/logger.c
@@ -46,8 +46,12 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include <sys/stat.h>
 #include <fcntl.h>
 #ifdef HAVE_BKTR
-#include <execinfo.h>
-#define MAX_BACKTRACE_FRAMES 20
+#  include <execinfo.h>
+#  define MAX_BACKTRACE_FRAMES 20
+#  if defined(HAVE_DLADDR) && defined(HAVE_BFD) && defined(BETTER_BACKTRACES)
+#    include <dlfcn.h>
+#    include <bfd.h>
+#  endif
 #endif
 
 #define SYSLOG_NAMES /* so we can map syslog facilities names to their numeric values,
@@ -1214,6 +1218,150 @@ void *ast_bt_destroy(struct ast_bt *bt)
 	return NULL;
 }
 
+char **ast_bt_get_symbols(void **addresses, size_t num_frames)
+{
+	char **strings = NULL;
+#if defined(BETTER_BACKTRACES)
+	int stackfr;
+	bfd *bfdobj;           /* bfd.h */
+	Dl_info dli;           /* dlfcn.h */
+	long allocsize;
+	asymbol **syms = NULL; /* bfd.h */
+	bfd_vma offset;        /* bfd.h */
+	const char *lastslash;
+	asection *section;
+	const char *file, *func;
+	unsigned int line;
+	char address_str[128];
+	char msg[1024];
+	size_t strings_size;
+	size_t *eachlen;
+#endif
+
+#if defined(BETTER_BACKTRACES)
+	strings_size = num_frames * sizeof(*strings);
+	eachlen = ast_calloc(num_frames, sizeof(*eachlen));
+
+	if (!(strings = ast_calloc(num_frames, sizeof(*strings)))) {
+		return NULL;
+	}
+
+	for (stackfr = 0; stackfr < num_frames; stackfr++) {
+		int found = 0, symbolcount;
+
+		msg[0] = '\0';
+
+		if (!dladdr(addresses[stackfr], &dli)) {
+			continue;
+		}
+
+		if (strcmp(dli.dli_fname, "asterisk") == 0) {
+			char asteriskpath[256];
+			if (!(dli.dli_fname = ast_utils_which("asterisk", asteriskpath, sizeof(asteriskpath)))) {
+				/* This will fail to find symbols */
+				ast_log(LOG_DEBUG, "Failed to find asterisk binary for debug symbols.\n");
+				dli.dli_fname = "asterisk";
+			}
+		}
+
+		lastslash = strrchr(dli.dli_fname, '/');
+		if (	(bfdobj = bfd_openr(dli.dli_fname, NULL)) &&
+				bfd_check_format(bfdobj, bfd_object) &&
+				(allocsize = bfd_get_symtab_upper_bound(bfdobj)) > 0 &&
+				(syms = ast_malloc(allocsize)) &&
+				(symbolcount = bfd_canonicalize_symtab(bfdobj, syms))) {
+
+			if (bfdobj->flags & DYNAMIC) {
+				offset = addresses[stackfr] - dli.dli_fbase;
+			} else {
+				offset = addresses[stackfr] - (void *) 0;
+			}
+
+			for (section = bfdobj->sections; section; section = section->next) {
+				if (	!bfd_get_section_flags(bfdobj, section) & SEC_ALLOC ||
+						section->vma > offset ||
+						section->size + section->vma < offset) {
+					continue;
+				}
+
+				if (!bfd_find_nearest_line(bfdobj, section, syms, offset - section->vma, &file, &func, &line)) {
+					continue;
+				}
+
+				/* Stack trace output */
+				found++;
+				if ((lastslash = strrchr(file, '/'))) {
+					const char *prevslash;
+					for (prevslash = lastslash - 1; *prevslash != '/' && prevslash >= file; prevslash--);
+					if (prevslash >= file) {
+						lastslash = prevslash;
+					}
+				}
+				if (dli.dli_saddr == NULL) {
+					address_str[0] = '\0';
+				} else {
+					snprintf(address_str, sizeof(address_str), " (%p+%lX)",
+						dli.dli_saddr,
+						(unsigned long) (addresses[stackfr] - dli.dli_saddr));
+				}
+				snprintf(msg, sizeof(msg), "%s:%u %s()%s",
+					lastslash ? lastslash + 1 : file, line,
+					S_OR(func, "???"),
+					address_str);
+
+				break; /* out of section iteration */
+			}
+		}
+		if (bfdobj) {
+			bfd_close(bfdobj);
+			if (syms) {
+				ast_free(syms);
+			}
+		}
+
+		/* Default output, if we cannot find the information within BFD */
+		if (!found) {
+			if (dli.dli_saddr == NULL) {
+				address_str[0] = '\0';
+			} else {
+				snprintf(address_str, sizeof(address_str), " (%p+%lX)",
+					dli.dli_saddr,
+					(unsigned long) (addresses[stackfr] - dli.dli_saddr));
+			}
+			snprintf(msg, sizeof(msg), "%s %s()%s",
+				lastslash ? lastslash + 1 : dli.dli_fname,
+				S_OR(dli.dli_sname, "<unknown>"),
+				address_str);
+		}
+
+		if (!ast_strlen_zero(msg)) {
+			char **tmp;
+			eachlen[stackfr] = strlen(msg);
+			if (!(tmp = ast_realloc(strings, strings_size + eachlen[stackfr] + 1))) {
+				ast_free(strings);
+				strings = NULL;
+				break; /* out of stack frame iteration */
+			}
+			strings = tmp;
+			strings[stackfr] = (char *) strings + strings_size;
+			ast_copy_string(strings[stackfr], msg, eachlen[stackfr] + 1);
+			strings_size += eachlen[stackfr] + 1;
+		}
+	}
+
+	if (strings) {
+		/* Recalculate the offset pointers */
+		strings[0] = (char *) strings + num_frames * sizeof(*strings);
+		for (stackfr = 1; stackfr < num_frames; stackfr++) {
+			strings[stackfr] = strings[stackfr - 1] + eachlen[stackfr - 1] + 1;
+		}
+	}
+#else /* !defined(BETTER_BACKTRACES) */
+	strings = backtrace_symbols(addresses, num_frames);
+#endif /* defined(BETTER_BACKTRACES) */
+	return strings;
+}
+
 #endif /* HAVE_BKTR */
 
 void ast_backtrace(void)
@@ -1228,7 +1376,7 @@ void ast_backtrace(void)
 		return;
 	}
 
-	if ((strings = backtrace_symbols(bt->addresses, bt->num_frames))) {
+	if ((strings = ast_bt_get_symbols(bt->addresses, bt->num_frames))) {
 		ast_debug(1, "Got %d backtrace record%c\n", bt->num_frames, bt->num_frames != 1 ? 's' : ' ');
 		for (i = 0; i < bt->num_frames; i++) {
 			ast_log(LOG_DEBUG, "#%d: [%p] %s\n", i, bt->addresses[i], strings[i]);
@@ -1240,7 +1388,7 @@ void ast_backtrace(void)
 	ast_bt_destroy(bt);
 #else
 	ast_log(LOG_WARNING, "Must run configure with '--with-execinfo' for stack backtraces.\n");
-#endif
+#endif /* defined(HAVE_BKTR) */
 }
 
 void __ast_verbose_ap(const char *file, int line, const char *func, const char *fmt, va_list ap)