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libsysprof-capture: use signed int for backtrace return

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This allows us to more safely subtract 1 from the unw_backtrace() to get
the proper number of frames (and detect it in the collector).
This commit is contained in:
Christian Hergert
2020-02-18 14:03:19 -08:00
parent 9f43bf2813
commit 7490a774ab
3 changed files with 16 additions and 12 deletions
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6
src/libsysprof-capture/sysprof-capture-writer.h
View File

@ -72,9 +72,9 @@ typedef struct _SysprofCaptureWriter SysprofCaptureWriter;
*
* Returns: the number of addresses filled in @addrs
*/
typedef guint (*SysprofBacktraceFunc) (SysprofCaptureAddress *addrs,
guint n_addrs,
gpointer user_data);
typedef gint (*SysprofBacktraceFunc) (SysprofCaptureAddress *addrs,
guint n_addrs,
gpointer user_data);
SYSPROF_AVAILABLE_IN_ALL
SysprofCaptureWriter *sysprof_capture_writer_new_from_env (gsize buffer_size);

7
src/libsysprof-capture/sysprof-collector.c
View File

@ -383,6 +383,8 @@ sysprof_collector_allocate (SysprofCaptureAddress alloc_addr,
if ((ev = mapped_ring_buffer_allocate (collector->buffer, len)))
{
gint n_addrs;
/* First take a backtrace, so that backtrace_func() can overwrite
* a little bit of data *BEFORE* ev->addrs as stratch space. This
* is useful to allow using unw_backtrace() or backtrace() to skip
@ -392,9 +394,9 @@ sysprof_collector_allocate (SysprofCaptureAddress alloc_addr,
* scratch space anyway.
*/
if (backtrace_func)
ev->n_addrs = backtrace_func (ev->addrs, MAX_UNWIND_DEPTH, backtrace_data);
n_addrs = backtrace_func (ev->addrs, MAX_UNWIND_DEPTH, backtrace_data);
else
ev->n_addrs = 0;
n_addrs = 0;
ev->frame.len = sizeof *ev + sizeof (SysprofCaptureAddress) * ev->n_addrs;
ev->frame.type = SYSPROF_CAPTURE_FRAME_ALLOCATION;
@ -404,6 +406,7 @@ sysprof_collector_allocate (SysprofCaptureAddress alloc_addr,
ev->tid = collector->tid;
ev->alloc_addr = alloc_addr;
ev->alloc_size = alloc_size;
ev->n_addrs = CLAMP (n_addrs, 0, MAX_UNWIND_DEPTH);
mapped_ring_buffer_advance (collector->buffer, ev->frame.len);
}