[PATCH v2 09/14] Print backtrace in a signal-safe manner
Chase Douglas
chase.douglas at canonical.com
Mon Apr 9 11:17:35 PDT 2012
Backtraces are often printed in signal context, such as when a segfault
occurs.
Signed-off-by: Chase Douglas <chase.douglas at canonical.com>
---
os/backtrace.c | 88 ++++++++++++++++++++++++++++++++++++++++---------------
1 files changed, 64 insertions(+), 24 deletions(-)
diff --git a/os/backtrace.c b/os/backtrace.c
index 81348f4..9c825fb 100644
--- a/os/backtrace.c
+++ b/os/backtrace.c
@@ -45,29 +45,52 @@ xorg_backtrace(void)
int size, i;
Dl_info info;
- ErrorF("\n");
- ErrorF("Backtrace:\n");
+ LogMessageVerbSigSafe(X_NONE, -1, "\n");
+ LogMessageVerbSigSafe(X_NONE, -1, "Backtrace:\n");
size = backtrace(array, 64);
for (i = 0; i < size; i++) {
int rc = dladdr(array[i], &info);
+ char string[20];
+ long unsigned int offset;
if (rc == 0) {
- ErrorF("%d: ?? [%p]\n", i, array[i]);
+ FormatUInt64(i, string);
+ LogMessageVerbSigSafe(X_NONE, -1, string);
+ LogMessageVerbSigSafe(X_NONE, -1, ": ?? [0x");
+ FormatUInt64((unsigned long)array[i], string);
+ LogMessageVerbSigSafe(X_NONE, -1, string);
+ LogMessageVerbSigSafe(X_NONE, -1, "]\n");
continue;
}
+
mod = (info.dli_fname && *info.dli_fname) ? info.dli_fname : "(vdso)";
+
if (info.dli_saddr)
- ErrorF("%d: %s (%s+0x%lx) [%p]\n", i, mod,
- info.dli_sname,
- (long unsigned int) ((char *) array[i] -
- (char *) info.dli_saddr), array[i]);
+ offset = (char *) array[i] - (char *) info.dli_saddr;
else
- ErrorF("%d: %s (%p+0x%lx) [%p]\n", i, mod,
- info.dli_fbase,
- (long unsigned int) ((char *) array[i] -
- (char *) info.dli_fbase), array[i]);
+ offset = (char *) array[i] - (char *) info.dli_fbase;
+
+ FormatUInt64(i, string);
+ LogMessageVerbSigSafe(X_NONE, -1, string);
+ LogMessageVerbSigSafe(X_NONE, -1, ": ");
+ LogMessageVerbSigSafe(X_NONE, -1, mod);
+ LogMessageVerbSigSafe(X_NONE, -1, " (");
+ if (info.dli_saddr)
+ LogMessageVerbSigSafe(X_NONE, -1, info.dli_sname);
+ else {
+ LogMessageVerbSigSafe(X_NONE, -1, "0x");
+ FormatUInt64Hex((unsigned long)info.dli_fbase, string);
+ LogMessageVerbSigSafe(X_NONE, -1, string);
+ }
+ LogMessageVerbSigSafe(X_NONE, -1, "+0x");
+ FormatUInt64Hex(offset, string);
+ LogMessageVerbSigSafe(X_NONE, -1, string);
+ LogMessageVerbSigSafe(X_NONE, -1, ") [0x");
+ FormatUInt64Hex((unsigned long)array[i], string);
+ LogMessageVerbSigSafe(X_NONE, -1, string);
+ LogMessageVerbSigSafe(X_NONE, -1, "]\n");
}
- ErrorF("\n");
+ LogMessageVerbSigSafe(X_NONE, -1, "\n");
}
#else /* not glibc or glibc < 2.1 */
@@ -95,8 +118,8 @@ xorg_backtrace_frame(uintptr_t pc, int signo, void *arg)
{
Dl_info dlinfo;
ElfSym *dlsym;
- char header[32];
int depth = *((int *) arg);
+ char string[20];
if (signo) {
char signame[SIG2STR_MAX];
@@ -105,10 +128,20 @@ xorg_backtrace_frame(uintptr_t pc, int signo, void *arg)
strcpy(signame, "unknown");
}
- ErrorF("** Signal %d (%s)\n", signo, signame);
+ LogMessageVerbSigSafe(X_NONE, -1, "** Signal ");
+ FormatUInt64(signo, string);
+ LogMessageVerbSigSafe(X_NONE, -1, string);
+ LogMessageVerbSigSafe(X_NONE, -1, " (");
+ LogMessageVerbSigSafe(X_NONE, -1, signame);
+ LogMessageVerbSigSafe(X_NONE, -1, ")\n");
}
- snprintf(header, sizeof(header), "%d: 0x%lx", depth, pc);
+ FormatUInt64(depth, string);
+ LogMessageVerbSigSafe(X_NONE, -1, string);
+ LogMessageVerbSigSafe(X_NONE, -1, ": 0x");
+ FormatUInt64Hex((unsigned long)pc, string);
+ LogMessageVerbSigSafe(X_NONE, -1, string);
+
*((int *) arg) = depth + 1;
/* Ask system dynamic loader for info on the address */
@@ -123,15 +156,19 @@ xorg_backtrace_frame(uintptr_t pc, int signo, void *arg)
symname = "<section start>";
offset = pc - (uintptr_t) dlinfo.dli_fbase;
}
- ErrorF("%s: %s:%s+0x%lx\n", header, dlinfo.dli_fname, symname, offset);
-
+ LogMessageVerbSigSafe(X_NONE, -1, ": ");
+ LogMessageVerbSigSafe(X_NONE, -1, dlinfo.dli_fname);
+ LogMessageVerbSigSafe(X_NONE, -1, ":");
+ LogMessageVerbSigSafe(X_NONE, -1, symname);
+ FormatUInt64Hex(offset, string);
+ LogMessageVerbSigSafe(X_NONE, -1, string);
}
else {
/* Couldn't find symbol info from system dynamic loader, should
* probably poke elfloader here, but haven't written that code yet,
* so we just print the pc.
*/
- ErrorF("%s\n", header);
+ LogMessageVerbSigSafe(X_NONE, -1, "\n");
}
return 0;
@@ -183,7 +220,7 @@ xorg_backtrace_pstack(void)
if (bytesread > 0) {
btline[bytesread] = 0;
- ErrorF("%s", btline);
+ LogMessageVerbSigSafe(X_NONE, -1, btline);
}
else if ((bytesread < 0) || ((errno != EINTR) && (errno != EAGAIN)))
done = 1;
@@ -202,9 +239,8 @@ xorg_backtrace_pstack(void)
void
xorg_backtrace(void)
{
-
- ErrorF("\n");
- ErrorF("Backtrace:\n");
+ LogMessageVerbSigSafe(X_NONE, -1, "\n");
+ LogMessageVerbSigSafe(X_NONE, -1, "Backtrace:\n");
#ifdef HAVE_PSTACK
/* First try fork/exec of pstack - otherwise fall back to walkcontext
@@ -221,9 +257,13 @@ xorg_backtrace(void)
walkcontext(&u, xorg_backtrace_frame, &depth);
else
#endif
- ErrorF("Failed to get backtrace info: %s\n", strerror(errno));
+ {
+ LogMessageVerbSigSafe(X_NONE, -1, "Failed to get backtrace info: ");
+ LogMessageVerbSigSafe(X_NONE, -1, strerror(errno));
+ LogMessageVerbSigSafe(X_NONE, -1, "\n");
+ }
}
- ErrorF("\n");
+ LogMessageVerbSigSafe(X_NONE, -1, "\n");
}
#else
--
1.7.9.1
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